Obscure Dinosaur Facts

When Earth Was Middle Earth: Speculations on the Hominins of the Middle Stone Age (Part 2)

Mon, 23 Feb 2026 07:01:11 +0000

Last post, I ran out of steam after describing only two of the five species in my book: Homo naledi, or “treefolk” and Homo erectus, or “firstfolk”. This post, I’ll finish the series off with Homo longi or “dragonfolk”, more commonly known as Denisovans, Homo neanderthalensis or “tidefolk”, commonly known as Neanderthals, and Homo sapiens, or “kinfolk”.

Homo longi: “dragonfolk”

Other than H. sapiens, the dragonfolk play the largest role in my book. They’re also known from very little fossil material - just a handful of fragmentary bones, two half-mandibles, and two skulls, though more already-discovered material is being referred to the species all the time these days. It’s like finding jigsaw puzzle pieces: if all you have is middle pieces, you can’t place them anywhere relative to each other. But someone digs up some edge pieces, and bam, many previously-unidentifiable fragments fall into place. My dragonfolk are called that because the skull that was recently reidentified as Denisovan was known for a long time as “Dragon Man”, and the species epithet longi means “dragon”. In-universe, it’s not explained where the name comes from (but it likely comes from their close association with nonhuman animals, which is purely speculative).

Denisovans (named after the cave in which their remains were first definitively identified, which in turn is named after some guy called Denis) were large and robust people. The largest fossil woman known, the Jinniushan woman, stood five foot six and was likely a Denisovan or close relative. That may not seem giant, but back then H. sapiens women likely averaged under five feet due to malnutrition. Just imagine how tall Denisovans might’ve been if they had access to modern abundance!

The earliest high-altitude fossil known, the Xiahe mandible, is Denisovan, from 160 ka on the Tibetan plateau, over a hundred thousand years before H. sapiens made it to those heights. Modern Tibetans have a high-altitude-adapted gene that actually entered the gene pool through interbreeding with Denisovans, and multiple studies have found that around 5% of the genomes of modern Oceanians consist of Denosivan DNA. That’s a lot - essentially the equivalent of having a Denisovan great-great-great-grandparent. Other Asians and indigenous North and South Americans have only a little Denisovan DNA, around 0.1%, and Europeans and Africans have virtually none.

Since Denisovans were an Asian species, I depicted mine as looking vaguely Asian. Maybe something about that area of the world selects for eyes that tilt up at the corners and straight hair - who knows? But beyond the face, my Denisovans are quite different: they’re tall, dark-skinned, and have a lot of body hair. We know from DNA evidence that they were likely dark-skinned, but it also makes sense as an adaptation for UV resistance, important when you’re living at high altitudes. We don’t know whether or not they were woolly, but that also makes sense as a cold-weather adaptation and gives them yeti vibes, which is fun to imagine. In the past, there may actually have been elusive furry humanoids living in the Himalayas! They weren’t primitive ape-men, though, but rather were human enough that our ancestors interbred with them, and the subsequent hybrids were able to successfully find mates as well.

Denisovan braincases were long in the back rather than tall, so from the front they would’ve had small, sloping foreheads. The page image is a Denisovan man atop a Palaeoloxodon recki elephant, showing the unusual skull shape. Their brains were slightly larger than modern humans; due to that and their larger body size, my dragonfolk grow up slower and are longer-lived than H. sapiens. Denisovans had large brow bones in the shape of an “m” rather than H. erectus’s straight brow, but flat faces, similar to H. sapiens and distinct from the more prognathic Neanderthals and H. erectus. They had strong jaws but weak chins, though being woolly (in my head-canon at least) their chins would’ve been obscured by facial hair. All this together - the height, the body hair, the jawline, and the large brow - would’ve made dragonfolk quite manly and intimidating, and this affects how my hybrid kinfolk/dragonfolk protagonist is perceived. Among kinfolk (H. sapiens) she’s a masculine-looking girl and is therefore considered ugly, but among dragonfolk she’s hyper-feminine, and therefore beautiful.

I have a hypothesis about why Denisovan fossil material is so hard to find relative to that of H. sapiens and Neanderthals that also ties into where they’re from: maybe Denisovans practiced “sky burials”, or offering their dead to the vultures, the way Tibetans traditionally did. This type of funeral rite is practical in places with super-rocky or frozen soils, which would’ve described a lot of the places Denisovans lived: the Himalayas and the mammoth steppe. This cultural aspect doesn’t appear in the book, though. Maybe a sequel!

Other than a handful of wood, stone, and antler tools, that basically sums up everything we know about Denisovans as of right now. Since we know basically nothing about their culture, I did a lot of extrapolating. My dragonfolk are polygamous and live in smallish clans of five to eight breeding males, their harems, and their children, as well as a few yet-unpaired teenagers who transferred from other clans (to prevent inbreeding). This represents a larger group than Neanderthals are thought to have lived in, but smaller than H. sapiens: since group size is thought to inversely correlate with body size, as larger individuals require a larger territory to get enough calories to feed themselves, I thought it made sense for the stocky, muscular, cold-adapted Neanderthals to have the smallest groups and the taller, slenderer Denisovans to require maybe not quite as many calories. They are polygamous mostly just to contrast with H. sapiens’ monogamy and to give the plot’s love triangle an interesting twist.

A couple of purely speculative elements I gave my dragonfolk are being more commonly left-handed and always giving birth to twins. Given their football-shaped heads and larger bodies, I wonder if birth would’ve been somewhat less dangerous for them, and if they grew up slowly and possibly gestated for longer, squeezing more babies into one pregnancy might have made evolutionary sense. After all, we have two breasts! The left-handed thing was just for variety.

Finally, I gave my dragonfolk a close relationship with elephants, since, with bigger ears and skulls, they may have been able to hear the infrasonic rumbles elephants use to communicate, and with larger throats they may have been able to attempt to talk back. If you could hear elephant infrasound, I’m sure it would be extremely attention-grabbing, since it’s incredibly loud!

Homo neanderthalensis: “tidefolk”

The final extinct species that makes an appearance in my book are the Neanderthals, which I call “tidefolk” because their homeland is mostly around the Mediterranean. Actually, since the novel takes place in Ethiopia, only a single tidefolk appears, a wanderer who’s lived with a bunch of different species and speaks a bunch of languages. He has light-colored hair, skin, and eyes, which the other characters have never seen before, and which causes him chronic sunburn in the ruthless African heat, leaving him prematurely wrinkly; this is an adaptation to the cloudy, low-UV areas Neanderthals natively hail from. When hunting, he favors a large, heavy spear, which is something we have direct evidence for. Neanderthals likely hunted by bracing spears like this against the ground while their compatriots drove a large prey animal to impale itself on them. This hunting style is effective at killing the extremely large Ice Age megafauna, but it requires a huge amount of strength and is very dangerous. As a nod to that, my one tidefolk lost his family in a hunting accident years before the story begins. It’s estimated from the relative abundance of differently-aged fossils that 80% of Neanderthals who reached adulthood died before the age of forty.

Neanderthals had the biggest brains of any known hominin, significantly bigger than even modern H. sapiens and likely way bigger than the tiny, malnourished H. sapiens who lived back then. People vaguely blame “inferior brain organization” for the technological stagnation seen in the archaeological record of Neanderthal tools - in the Middle Palaeolithic, Neanderthals made long stone blades and hafted (wooden-handled) weapons that were far more advanced than anything H. sapiens could make at the time, but Neanderthals never advanced beyond this, while H. sapiens famously went on to invent the longbow and then the microchip. However, I (and Rebecca Wragg Sykes in her book Kindred: Neanderthal Life, Death, Love, and Art) think a much simpler factor is the real culprit: body size. An adult Neanderthal man in a cold climate required around 7500 calories per day, and therefore required a much larger territory to hunt in. If Neanderthals lived only with their immediate family and only came together in large groups once every few months, it would’ve been much harder to share ideas and make technological improvements at all, and whatever technological advances did happen would been more likely to have been lost to time. I think that given in the rest of the animal kingdom, a bigger brain within the same clade almost always results in a smarter animal regardless of body size (eg, a raven is smarter than a chickadee and an African grey parrot is smarter than a budgie), Neanderthal individuals would’ve been pretty bright. They just didn’t have a social structure that enabled the “technological ratchet”. Accordingly, my one tidefolk representative is a polyglot and a mentor-figure for the protagonist. Furthermore, my tidefolk are the only species to build musical instruments (the others have music but it’s just singing and clapping) and to make art (in charming dirty-old-man fashion, my tidefolk character sculpts busty figurines out of stone a la the Venus of Tan-Tan). Later Neanderthals made all kinds of art and self-decoration out of bird feathers, stones, bones, and pigments, but at the time my story is set, 240 ka, these art forms hadn’t been invented yet, by Neanderthals or H. sapiens or anyone else.

From fossilized Neanderthal ear bones, we can tell that their hearing range was optimized for picking out high-frequency consonants the same way ours is, and from their hyoid (throat) bones and rib cages, we think their voices may have been somewhat higher (due to a shorter vocal tract and flatter skull base) but possibly louder (due to a larger chest cavity) and more nasally (due to cavernous nasal passages that were likely an adaptation for humidifying freezing, dry air). In my novel, this is one reason the tidefolk are good instrumentalists: their singing voices aren’t very nice.

Unlike Denisovans, from whom we have very few tools and remains, we have direct evidence that Neanderthals were mostly right-handed: their right arm bones were routinely thicker than their left, and their teeth show wear characteristic of working hides with a scraper in the right hand (teeth were used as a third hand to pull the hide taut). This also doesn’t figure into the story, I just thought it was cool that we know that.

Homo sapiens: “kinfolk”

Just a couple very brief notes on the modern humans that appear in my book, since you likely know them intimately. My kinfolk live in large groups of sixty to eighty individuals who are monogamous and all sleep together in one giant tent. Being slenderer than tidefolk, they favor non-hafted wooden javelins that they throw at prey, since back then no one knew how to make stone tips that were delicate enough not to throw a projectile’s flight out of whack. This strategy doesn’t let these archaic kinfolk bring down as large of prey as tidefolk can, but it allows them to stay further away and is therefore much less dangerous. They also have a system of “transfers”, requiring boys to join a different tribe upon reaching adulthood in order to prevent inbreeding. This is common practice among other social mammals from deer to baboons, but sometimes, as in the matriarchal bonobos, it’s the girls that are forced to leave. Most ancient human cultures are thought to have been patrilocal (wives left their families and joined their husbands’) but there were also many that were matrilocal (boys kicked out, as in my book). In my personal experience (which is probably not at all representative of humanity as a whole, given I live in Silicon Valley), it seems like young men are much more likely to move across the country in search of a better life than young women are, an observation shared by Ravenstein in his “Laws of Migration” and primatologist Robert Sapolsky in his essay “The Young and the Reckless”. Thus, my kinfolk are matrilocal. Also, it makes a better call to adventure when the protagonist has to defy social norms to choose to go on a quest rather than just being forced.

Conclusion

Hope you enjoyed these speculations! Again, if you’d be interested in reading something like this (and especially if you know any agents or editors who might), I’d love for you to reach out!

When Earth Was Middle Earth: Speculations on the Hominins of the Middle Stone Age

Tue, 13 Jan 2026 07:01:11 +0000

I recently wrote another novel (again, not yet published - I’m working on that) that takes place in the Middle Stone Age of Ethiopia, 240,000 years ago (coincident with the Middle Paleolithic in Europe). I chose that setting because it offered a high density of different human species in the same time and place, but also offered a technology level high enough not to encumber the story. There are five different species of humans the protagonist encounters on her journey: Homo neanderthalensis, the strong and stocky Neanderthals; Homo naledi, a small hominin adapted for life in the trees; Homo longi, the high-altitude adapted, mysterious and elusive Denisovans; Homo erectus, the most successful and widespread human prior to Homo sapiens and the progenitor of the other species; and of course, Homo sapiens themselves. In real life, it was unlikely a single individual would meet members of all of these species, but it was theoretically possible; the world would’ve felt a bit like Middle Earth, with multiple intelligent species that could freely interbreed. Each of these human species would have led different lifestyles and practiced different cultures, none of which we can reconstruct with certainty. But given the little evidence we have from their artifacts and what we can extrapolate from their bones and fragmentary DNA, it’s a fun exercise to speculate on what they might have been like in life. In this post, I’ll describe my depictions of each of these five species, what is speculative and what is fact, and why I made some of the decisions I did.

One of the main reasons I wanted to write this book is because in most media about cavemen, they are ugly, stupid, and often only communicate only in grunts.

There’s also a glut of paleoart depicting them as horrifyingly ugly. But there’s really no reason to think they would have been ugly or unsophisticated. H. sapiens 300,000 years ago were nearly physiologically identical to humans today. With the same brains, the same hands, the same wants and needs, I think they’d have been much more similar to us than that. In my book, I may go too far to the other extreme, giving my cavemen modern morality and peaceful dispositions, but I think this is both not out of the realm of possibility and makes the story much easier to digest. If there was a bunch of rape and mutilation, no one would want to read it. The characters’ extensive vocabularies and modern slang like “cool” I’m going to hand-wave as translation convention.

Similarly to how paleoartists bridge the gap between the very dry descriptions of autapomorphies in scientific papers and the T. rex the public knows and loves, I think there’s a place for paleo-writing to educate non-experts about our ancient ancestral cousins and to get people to imagine the ways they might have lived.

Homo naledi: “treefolk”

H. naledi is an interesting little hominin, standing between four and five feet tall and possessing a mosaic of basal and derived features, making it difficult to confidently place on the human family tree. There’s a cave in South Africa called Rising Star Cave that preserves the bones of dozens of individuals, only fifteen of which have so far been excavated and identified. The bones belong to hominins of both genders and all ages, from infant to elderly, and show no signs of predation, indicating they were placed there intentionally by other members of the same species. There is also evidence of fire in the cave, probably for light.

Prior to this discovery in 2015, it was generally held to be true that big brains were always better, and anytime a new, bigger-brained human species came on the scene, the older, small-brained ones went extinct. However, H. naledi’s brain size is close to that of the very earliest australopithecines, and yet it lived way more recently, surviving for hundreds of millennia alongside H. sapiens. It was therefore probably not doing the same things as our ancestors were, using different resources to avoid competition. And whatever it was doing, it was good at it.

From the numerous bones, we can reconstruct their anatomy quite well. They had narrow chests and wide abdomens, with shoulder blades situated higher on the back and further from the center than other humans, features more similar to apes. Their legs and feet were suited for walking, but not distance running the way most other hominins were. Their fingers were long and curved, which together with the wide-set arms indicate that they were good at swinging and suspending their weight from their arms, critical for life in the trees. In my book, the treefolk are graceful acrobats in the trees, but have a bit of a waddle when on the ground. They stay concealed from H. sapiens when they can, smearing themselves with mud and leaves and staying in the trees as much as possible, even living in nests of dried foliage up in the trees like birds. In my book, the treefolk live only a day’s walk from the protagonist’s kinfolk (H. sapiens) tribe, but due to their secretive practices most kinfolk have never seen one. I chose to have them be elusive for two reasons: because that’s how they survive alongside H. sapiens, and because it makes them sort of like “fair folk”, curious and mysterious and diminutive forest creatures.

H. naledi teeth are also more similar to those of apes, with big molars and dental wear indicating a diet of tough plant material. The wide abdomen may have housed a long digestive tract to break down the raw plants they consumed. In my book, they are strict vegetarians, and may even be crudivores (not cooking their food) - you don’t see them cook on the page, but since they do have command of fire, they might just do it elsewhere. Since they don’t need to eat animals, they consider killing animals to be immoral, and wear only grass skirts, while all other human species in the book wear animal skins.

Their ear bones were more similar to those of non-human apes, giving them less acute hearing at high frequencies. This is important because consonants, which are produced by pushing air through constricted lips, tongue, and throat, and are used in every H. sapiens language, fall in these frequencies. Like chimps, H. naledi would’ve been able to hear them, but not with much clarity, making verbal communication more difficult. In my book, they get around this limitation by using sign language, which is hypothesized to be the progenitor of verbal language anyway.

Their brains were smaller than expected for a Homo of their size, with an encephalization quotient more similar to the more primitive Australopithecus. However, their brain structure was definitely Homo, with a humanlike frontal lobe, so it’s not clear how intelligent they would have been. There are stone tools in the style of the Early and Middle Stone Age known from this time and place, and no other hominin remains in the area, so it’s likely that they belong to H. naledi.

The chamber where the bones are found is quite hard to access, requiring people to belly-crawl through a tight section and climb up a fifty-foot sharp rock formation. To the tiny and climbing-adapted H. naledi, this was probably a feature: it kept those pesky, oversized H. sapiens out! The fact that they laid their dead to rest here intentionally and brought light to work and navigate by means that they were likely capable of complex, symbolic thought and coordinated, ritualistic behaviors. In my book, they are sophisticated enough to know how to treat a broken leg, and are very curious, but they have a short attention span, sort of like a very gifted eight-year-old. They use fire but don’t have the ability to create it; they took some out of a wildfire once, and now they keep a fire burning in a cave continuously, or else they’d lose it completely. This is not based in fact, but is inspired by a population of H. sapiens native to Papua New Guinea who lost the ability to make fire and never rediscovered it. Friction bows and flint and pyrite are not intuitive!

Fun fact about the excavation of this cave: since the “Superman Crawl” section is only ten inches in diameter, the discoverer put out a want ad on social media looking for small women scientists to perform the excavation, since only they could get in and out while loaded down with tools and specimens. He got sixty applicants and assembled a team of six, who became known as the “Underground Astronauts”.

Homo erectus: “firstfolk”

H. erectus was the first species of human to go intercontinental, expanding from where they originated Africa to colonize much of the Old World and evolving into various daughter species while still living alongside them. They made stone tools and used fire, though it’s unknown to what extent and whether they could create it. Since they were such a long-lasting and widespread species, there was a lot of variation in their physiology, with some populations having very small brains and others having brains nearly as large as modern humans, some having huge, gorilla-like molars and prognathic (protruding) jaws while others had more delicate teeth, and likely some having lighter skin and some darker. This leaves a lot of room for artistic interpretation; whatever my firstfolk are doing, it’s likely some population of H. erectus did it at some point.

Their growth and development was intermediate between chimps and later humans, with babies being born less helpless and growing up faster, precluding as complex of language and culture as slower-growing human species. Similar to chimps, they would probably not have lived as long as us. Their bones were unusually thick - so thick that sometimes their braincases are confused with fossil turtle shells. We don’t really understand why, but it probably would’ve made them quite strong and sturdy; in my book, they are able to lift heavy things, run for hours, and dig away hillsides with ease.

H. erectus remains are associated with butchered remains of all kinds of large herbivores, and they’re the likely culprit in many megafaunal extinctions due to overhunting. However, there isn’t consistent evidence of fire usage at H. erectus sites, indicating that they ate this meat raw. This is further supported by genetic evidence from tapeworms, which are transmitted through raw meat and speciated into human-specific forms at the same time and place H. erectus first originated. In my book, the firstfolk just bite into their raw meat and have the dental equipment to successfully chew it, while the kinfolk (H. sapiens) protagonist does not. But it’s likely that some populations of H. erectus did cook their food, some pounded or cut it with hand axes before eating it, and some just ate it the way my firstfolk do. My hypothesis is that the inability of most H. erectus populations to smoke meat may have been what caused the overhunting: animal protein comes in large packets but goes bad quickly, so whatever the tribe couldn’t eat within a couple days would be left to the hyenas, and then they’d have to go kill a fresh gigantic animal.

In my book, the firstfolk don’t have tents, but instead sleep behind a dug windbreak. This is based on an archaeological site where a ring of piled stones was found associated with H. erectus remains, and one interpretation of this was that it was a low wall intended to break the wind. But other interpretations include that it was a foundation of a larger structure that didn’t preserve, and that it was formed naturally by tree roots or something. I ran with the windbreak idea and had my firstfolk dig one out of a hillside instead of piling stones, since they live on the savanna where stones would not have been easy to find.

We don’t have direct evidence of whether H. erectus had fur or not, but it’s likely they did not because the gene for dark skin, only necessary as protection against the sun if you don’t otherwise have your skin covered, arose long before other hominins had evolved. This also makes sense as an adaptation for persistence hunting in grasslands, which H. erectus is almost always associated with, as it would have allowed them to sweat to keep cool while their prey would eventually fall to heat exhaustion. The tropical populations of H. erectus would therefore likely have been quite dark-skinned.

Because they’re strong, smooth-skinned, and very fit from running miles and miles every day, the other characters in my book think the firstfolk are very beautiful. In some ways, my firstfolk are Proud Warrior Race Guys - they’re impressive physical specimens and they’re very set in their traditional ways of doing things, refusing to adopt new technology like fire and hafted spears even when other hominins evolve and offer it to them. But at the same time, they’re very goofy. I had fun naming my firstfolk very stereotypical “caveman” names, like Hoona, Drig, Onga, Gog, and literally Thag. They also speak like cavemen, talking in the third person and omitting most articles.

One completely speculative element I gave to the firstfolk is colorblindness. The code for the three cones in your eyes that allow you to see color, red, blue, and green, is located on the X chromosome, and some people have faulty code for either the red or the green cone, making red and green appear the same to them. However, colorblindness is much more common in men than women, because they don’t have a backup copy of the X chromosome. For a woman to be colorblind, she has to have two faulty copies that are faulty in the same way, which is quite unlikely. In my book, the firstfolk have two different types of X chromosomes, both of which are faulty in different ways: one type codes for red and blue cones, while the other type codes for green and blue. This way, all men and half of women will end up with only two cones and be colorblind, while the other half of the women have all three cones and be able to distinguish red and green, since they have two different varieties of X chromosome.

The probable reason colorblindness is not weeded out by natural selection is that it can be adaptive when you’re trying to spot camouflaged prey, since most camo assumes color vision. During WWII, the American and British armies employed colorblind people to spot enemy hides from the air. So it’s not crazy to imagine a population that intentionally has both color-seers and camo-spotters. The reason I gave them this trait is because I wanted one of my fantasy races to be matriarchal, rather than just egalitarian. Matriarchy has never occurred in humans because there are some types of foraging men are better at (like big game hunting) and there are some types that men and women are equally good at (like gathering plants), but there aren’t any that women are strictly better at. If all the men are colorblind, the non-colorblind women would be better at tracking, would bring in more calories, and would control access to food.

One ape species that is actually matriarchal is bonobos, in which the troop is run by a matriarch who gains power through consensus among other females. They speciated from their common ancestor with chimps due to geographic isolation, where bonobos ended up on the side of the river with more resources and less competition, making them peaceful and cooperative, while chimps ended up on the wrong side of the tracks, with few resources and competition from gorillas. (Minute Earth has a good video explaining this.) The reason this made bonobos matriarchal isn’t exactly clear, and it’s different from my firstfolk, but I think the matriarchal society that results would’ve had some similarities, even though the origin is different. Like bonobos, my firstfolk are promiscuous, having casual sex with anyone else in the tribe and using sex as a tool of social communication, especially as a way to make up after disagreements. However, since this is a young adult novel, that element of firstfolk culture is not very thoroughly explored.

Conclusion

Well, I ended up writing a whole lot about only two of the five species that appear in my book, and I think I’m going to stop there for now. The page image is a treefolk character in the book; you can see her small, sloping forehead and weak jaw, but beyond that I wanted her to be pretty. At some point soon I’ll write a follow-up post about the other three hominin species; the Denisovans, which I call “dragonfolk”, have a culture that’s particularly fleshed out in my book. If you want to read this book and know any authors, agents, or editors, I would appreciate a connection :)

Breastfeeding: An Evolutionary History

Mon, 29 Dec 2025 07:01:11 +0000

It’s been awhile since my last post - a lot of life has happened in the interim, namely having a baby. Now that baby is three months old, I’ve spent a cumulative ~180 hours breastfeeding and another 139 hours pumping milk, which has given me a lot of time to wonder about… breastfeeding. Why do I have to pump every three hours while a cow only has to be milked twice a day? How long do other apes breastfeed their young for? Why do other apes not have visible breasts unless they’re breastfeeding? This post will answer those questions and more.

How did milk evolve?

You may have heard (or not) that milk derives from sweat - that sweat glands came first, and as newborn mammals licked their parents’ skin for bonding and hydration, the young of those with more nutrients in their sweat did better. After that, localizing this nutritious sweat into smaller areas that are easier for babies to feed from was advantageous, leading to teats. This is supported by the fact that monotremes (platypuses and echidnas) don’t have nipples, instead “sweating” milk diffusely out of their bellies, which the babies lap up. Makes sense. Except when you realize that a vast majority of mammals don’t actually sweat.

Sweating to cool down is a rare trait, exhibited only by humans, horses, and camels, who all developed the ability independently. Other animals have to pant, wallow, or find shade. This includes pigs; the phrase “sweating like a pig” apparently derives from pig iron, which would gather condensation on it as it cooled, rather than actual pigs. So if sweating is a recent development, how did milk arise?

It turns out that sweating to cool down is a recent development, but sweating to be smelly is older than mammals. Humans have two different types of sweat glands: eccrine glands all over the body, which excrete salt water, and apocrine glands in the armpits and groin, which excrete thicker, oily, smelly sweat. Eccrine glands derive from the older apocrine glands, and many mammals have this type of gland, which they use for scent signalling. A dog’s anal glands, which put informative pheromones onto their poo, are derived partly from apocrine glands and partly from sebaceous (skin oil) glands. Those glands, by the way, are why dogs are instantly terrified when walking into the vet: since vets routinely do stool samples, an unpleasant experience, the place reeks of dog pain and fear. These glands are also usually why dogs scoot on the carpet. Rather than trying to loosen bits of poo, which are uncommonly present because dogs’ anuses can turn inside out a little ways, keeping things contained, they’re trying to unclog their gland ducts.

Anyway, the earliest mammals back in the Triassic Period (252-201 million years ago) would have had apocrine glands, but laid eggs, like modern monotremes. Over time, as they invested more energy into caring for their young in their burrows, the young would have had the chance to lick their parents’ skin, selecting for more nutritious proto-milk, and the rest is history.

Why don’t female apes have visible breasts?

If you’ve ever been to a zoo that has primates, you’ve probably seen female chimps, gorillas, and orangutans, who appear to have flat, masculine chests. How do they breastfeed, and why do humans have breasts?

Apes grow breasts during pregnancy, the way a pregnant cat gets distended, low-hanging teats on her belly. Milk glands form under the skin, which go away when the animal is no longer lactating. Convenient.

Human women, on the other hand, have nonfunctional fatty tissue in the breast area at all times. During pregnancy, we also grow glandular tissue, making the breasts much larger during pregnancy and lactation than at other times. But in humans, breast size doesn’t correlate with milk production. You can have lots of fatty tissue making your breasts large, but not grow that much glandular tissue and therefore have low milk production, and vice versa, lots of glandular tissue and not much fatty tissue. So what’s the evolutionary purpose of the fatty tissue?

Well, for apes, the butt is a very important female secondary sexual characteristic. Since they’re quadrupedal most of the time, they often find themselves face-to-butt with the ape walking in front of them, and in tests, chimps have been able to identify which butt belongs to which face with great accuracy. When humans started walking upright, we stopped being able to easily see the butt in the course of normal social interaction. So the permanently engorged breasts took the keister’s place as the most important female secondary sexual characteristic. Some people hypothesize that the bosom is supposed to look like a false butt, but I think it’s more likely that large breasts simply signal reproductive fitness in a similar way as a round bottom does: if you have enough spare fat to have nice round squishy features, you’re more likely to be able to support the demanding caloric needs of pregnancy and nursing.

This also means that the “free the nipple” people are wrong, from an evolutionary standpoint. They argue that breasts are simply a tool for feeding infants, and should not be sexualized. But the fact that they persist outside of pregnancy and lactation means that evolutionarily, they must be objectively sexy.

Why two breasts? Most animals have them in rows.

This is likely due to great apes’ dextrous arms and small litter size. Other animals have to be able to nurse lots of young at the same time, and can’t move while nursing. Laying on the ground is a pretty vulnerable and inconvenient position to be in for hours every day, so when apes became able to carry their young around and hold them to the breast, that was an evolutionary advantage. We only have two arms, so two breasts makes sense; additional breasts would just waste calories and potentially get in the way. And we have only one or two babies at a time, so two breasts is enough to meet demand. Lemurs, which are more basal on the primate family tree, still have multiple rows of nipples and nurse their numerous young while laying on their side, which likely represents the ancestral primate condition.

Before birth control, that is, for a vast, vast majority of human history, it was common to be either pregnant or lactating all the time. This was necessary to keep up the population due to the high rate of infant mortality. If you could expect half of your children to die before sexual maturity, and maybe another one to simply fail to reproduce for whatever reason, you had to have six children just to achieve the replacement rate of two! Aren’t you glad you’re not a caveman?

Anyway, in modern hunter-gatherer societies like the San, this is still the case. Yet, they only have children once every three to four years. This is because their lifestyle requires them to walk something like 1500 miles per year, and children younger than that can’t keep up on their own and must be carried. Carrying two closely-spaced children at the same time is prohibitive, so it’s unlikely both would survive, selecting for more distantly spaced children. The way they keep from having children more often is through constant breastfeeding, as the babies are strapped to the mother throughout the day as she forages, and through food availability. The hormone prolactin suppresses ovulation, making it more difficult to conceive while lactating. And being too thin also lowers the chance of conception, so the caloric demands of nursing an infant while living in an environment with seasonal food availability also suppress fertility.

All this to say, it’s likely that hunter-gatherers breastfed their babies, supplementing with solid food, for two to three years. This feels like a long time until you consider the fact that orangutans breastfeed for three to six years, only having another infant every four to seven years. They represent the most extreme case, but chimps and gorillas also have longer periods of breastfeeding than humans do. Usually, whatever apes do, humans do but more so. But in this case, humans are less ape-like than the other great apes. What gives?

Well, evolutionarily, it’s best to have children as frequently as you can. Orangutans only have them so infrequently because having them more frequently would decrease the infants’ chance of survival, likely for similar reasons that hunter-gatherer humans wait four years between children: because it takes that long for the child to be independent enough to keep up. Orangutans and other apes live in complex societies (while orangs are solitary these days due to low population, it’s thought that their typical condition is to be social) and forage in complex ways that require a long time to master. Humans are the same way, but we’ve developed technological and social tricks to enable us to overcome some of these limitations and have children more frequently than would be expected for our developmental schedule. First, baby food: cooking and tools allow us to produce higher-quality, easier-to-digest soft mush than simply by pre-chewing it. This is a double benefit, since it both allows babies to wean earlier, letting the mother get pregnant again sooner, but also takes some of the caloric load off of the mother. In other great apes, the mother provides 100% of the calories the infant needs for years on end; in humans, she’s only on the hook for a few months until the baby can start to supplement with prepared baby foods, spreading the cost of raising the child over more individuals and reducing risk. This is also why it’s hypothesized that humans undergo menopause, yet live decades longer, something no other ape does. Some studies have found that in premodern societies, for every decade a maternal grandmother lives past fifty, two additional grandchildren survive.

Premodern agricultural humans, who show some physiological adaptations to this new lifestyle compared to the hunter-gatherers that came before, such as shorter jaws with crowded teeth and smaller brains that allowed them to live shoulder to shoulder and work nine to five, would also have been able to wean babies earlier, having children approximately every two to three years. The reason for this is twofold: first, agriculture doesn’t require everyone in the tribe to walk great distances; there are tasks nursing mothers can do that are sedentary, allowing them to watch an infant in a playpen or similar rather than physically carrying them at all times. And second, when child labor isn’t illegal, children are a net economic benefit to the family. They can output more useful work than they consume in calories, incentivizing farmers to have as many children as possible.

For industrialized humans, the situation has changed yet again: babies are a net economic drain, since childcare is expensive and child labor is frowned upon, so people are incentivized not to have children. Furthermore, technology has improved to the point where infant mortality is mostly not a concern, so the replacement rate doesn’t require as many pregnancies to achieve. So modern humans tend to have only a couple children, closely spaced in order to reap the benefits of economies of scale (daycare for two often costs less than double daycare for one, baby clothes can be reused, and so on). And to have babies closely spaced, you have to stop breastfeeding early. But breastfeeding has significant health benefits for the child, in terms of setting up their immune and digestive systems for success. So a year is a good balance between physical health of the child and economic health of the family.

All this to say, the “natural” length of breastfeeding varies depending on the situation we find ourselves in and has generally decreased over time as technology has improved our ability to care for young babies and control reproduction in other ways.

Why do cows only have to be milked twice a day?

Cows are the result of around eight millennia of artificial selection centering around their udders. (They were first domesticated for meat and leather around ten millennia ago, but eight thousand years ago is when we find the first evidence of cheese making, a necessary step to digest milk products for the then-lactose-intolerant humans. Lactose tolerance only became widespread around three thousand years ago, after a long history of eating cheese and yogurt.) The wild ancestor of cows, known as aurochs, would’ve had the regular two rows of nipples along the underside, rather than a large udder. However, they did have a rudimentary milk storage system, called “cisterns”, or expanded portions of the ducts, that allowed some of the stored milk to come out much more quickly than the milk kept inside the alveoli where it’s produced, increasing the efficiency of the first few gulps during a feeding. Humans selected for animals that could produce more milk and store more of it for longer periods. In all lactating animals, milk production level is governed by demand: the more milk is removed, the more the body will produce. Cows are the same way. If you milk a cow more often than twice a day, the animal will produce more milk in total than it would otherwise, and indeed factory farms have cows hooked up to milking machines near-constantly, in order to maximize output. But in pre-industrial dairy farming, since milking every cow in a herd takes quite a long time, it’s prohibitive to milk more often than twice a day.

Conclusion

I hope this post has answered some of the questions you were wondering about and some that you weren’t when it comes to milk and breastfeeding. It’s one of the core things that define Mammalia, so it seems worthwhile to know about!

Rate My Dino 6: Dino Days at the Cal Academy of Sciences

Sat, 30 Aug 2025 07:01:11 +0000

“Dino Days” is a temporary exhibit of mechatronic dinosaurs in the courtyards of the Cal Academy of Sciences that I’d been putting off going to for quite awhile, even though it’s right in my backyard in SF. It’s clearly for kids, and isn’t super extensive, with just two areas with a handful of models in each place. It closes September 7, so this review isn’t all that useful I suppose, but I wonder where the statues go after they remove them. If the exhibit moves somewhere else, maybe this will still apply. Let’s jump right in!

The first statue in the first courtyard is the spinosaurid Suchomimus, carrying a fish in its mouth and also…spitting…at passersby? The statue would turn its head a little, groan, and spray water out of its mouth. It seems like the artist was trying to show how this dinosaur was related to water, but instead of putting it in a watery environment just included the water in the statue itself.

All the signs in the exhibit feature paleoart by Fred Wierum, a renowned paleoartist, so kudos to them for using that. For some reason, all the art is very blue - I’m not sure if it started out that way or got really quickly sun-bleached.

While the statue gets the very basics right - horizontal posture, non-pronated hands, croc-like head, overall proportions - there are numerous issues.

It’s way too small. The sign states correctly that Suchomimus was around 36 feet long, but the statue is only around fifteen feet.
It’s shrink-wrapped. You can see its hipbones sticking out of its belly, as well as the outlines of the holes in its skull and its ribs.
It shouldn’t have a sail on its back. While Suchomimus did have taller than average neural spines, they weren’t the super-elongated ones Spinosaurus had that would have been visible outside the body outline, but would have looked more like a bison-like hump.
What’s with the comment about the thumbs? Literally all dinosaurs had thumbs. Do they mean opposable thumbs? Even if that’s the case, Suchomimus did not have opposable thumbs. I have no idea what they were trying to get across here or how they came to this conclusion.

I do like how they gave the statue slits for pupils and osteoderms, making it even more reminiscent of a crocodile. Overall, 3/10.

Here are a bunch of baby Parasaurolophus along with their mother. Again, the scale is way off - the sign again says 36 feet, and the statue is maybe fifteen at the most. I think it would be good to note “not to scale” somewhere. This statue moved its arms, mouth, and head, the babies moved their heads, and one of the eggs moved as if it was in the process of hatching. This one has some good aspects and some bad.

Good: Parental care was a thing in hadrosaurs, so the scene is reasonable. Also good: The hatchlings aren’t just miniaturized copies of the parent, but have shorter crests and plumper bodies. Bad: The hatchlings have crests at all, and have the same coloration as the parent. Since the crest was almost certainly a display feature, any bright colors would have developed during puberty. Good: The other sign (not pictured) mentions Parasaurolophus using its crest as a musical instrument, and that scientists were able to force air through its head pipes and get a trombone-like sound out. Bad: The sounds that the model is making are totally not that sound, they’re way higher pitched and shorter. Also bad: The adult’s legs are hyperextended and super chonky, though maybe this is just a practical consideration for the statue to be able to hold up its own weight. Overall 5/10.

This one I actually have few complaints about. I think the sign specifies “juvenile” because this is clearly not a full-sized Brachiosaurus. It has the correct number of toes and toenails on each foot, and its body is fairly believably bulky. The only issues I could spot are that its teeth are sticking out of its mouth and that the top of its head/snout is very concave; there was likely soft tissue there in life for large, air-conditioning nasal passages. The top of the statue’s head was clearly a favorite perching spot for pigeons. Rip. 8/10.

Unfortunately, not all dinosaurs are as straightforward as sauropods. This freak of nature is supposed to be Deinonychus. Just look at the difference between the picture on the sign, which looks like a big ground-hawk, and the Halloween monster model behind it. Could the artist not tell the difference? There’s almost nothing redeeming about this statue.

Its teeth stick out of its mouth
It has no feathers on its face
Its feathers look unnatural and glued-on
It has no feathers on its hands
It’s shrink-wrapped and its pubic bone is sticking out
Its legs are columnar and extremely chonky

Basically, this statue follows all the tropes of “how not to draw feathered dinosaurs”. The only thing it didn’t do wrong is give it pronated hands. 1/10 for that.

Nowhere to go from there but up. Here’s Styracosaurus. The sign isn’t wrong per se, but ceratopsians were likely quite fast, since they were built like rhinos, with thick, strong arm bones with large muscle attachment points, and their frills were pretty lightweight and would only have been used as a weapon when desperate. The statue is still a bit undersized but overall closer to accurate, but for some reason the head is enormous relative to the body. Compare the art on the sign to the statue - the proportions are totally different. Other than that, though, the depiction is fine… he just looks kind of dopey. 7/10.

Here’s the piece de resistance - Tyrannosaurus. This is the biggest sculpture in the garden, and one of the few that seem to be actually to scale. It’s also pretty decent in gross proportions: very chunky around the middle and with powerful but not overly elephantine hind legs. The coloration is okay, though not very creative. And I wouldn’t have made the scales on the face so large, especially on the lips, but at least it has lips.

There are only a few minor issues with this one:

The arms are much too long and skinny, detach from the body too high, and are held weirdly forward.
You can see the skull holes through the skin of the face.
While it does have a bit of a keratinous brow ridge, it’s missing any horn bumps on top of the snout.

Overall, though, not too bad. 8/10.

Here’s Euoplocephalus, an ankylosaur. Now this animal would likely have had to defend itself against predators rather than running away. The turtle-like carapace isn’t right. While some ankylosaurs did have large plate-like osteoderms over the hips like Polacanthus, Euoplocephalus was not one of them; its spikes would have just been buried in the skin. The shell edge that this artist has given the animal is likewise completely imaginary.

Beyond that, we have the sign, which states that recent research finds that ankylosaurs may have partially buried themselves to protect their soft undersides from predators. That’s not a hypothesis I’d heard of before, but after Googling I found this open-access paper by Phil Currie et al that does a little bit of speculation on the topic, but for some reason triggered a lot of news articles at the time (2021) reporting this specific theory. What the paper actually says is that ankylosaurs probably could dig to some extent, and that this behavior might have been useful for digging up tubers, finding water, finding minerals, or creating shallow depressions to lie in so they were less visible to predators when sleeping. The osteoderms around their edges would have helped to break up their silhouette, similar to horned lizards, which do this. However, “partially buried” to “protect their soft underbellies” is a bit of an overstatement. I’ll give them credit for trying to include a tidbit from recent research, but clearly they didn’t look beyond the headline. 4/10.

Oh god. What do we have here?

This is supposed to be Troodon, a tooth-only genus of birdlike dinosaur that’s only famous because it was discovered so long ago. Why troodontids, which are the sister group to dromaeosaurids or “raptor” dinosaurs, often don’t get the same feathering treatment as true raptors is beyond me (although we’ve seen what this artist’s feathering looks like and should maybe be grateful we were spared another Deinonychus). Both of these groups were highly birdlike, very closely related to birds and to each other, and would have probably been nearly indistinguishable from each other if you were being chased by one. Troodontids even have the sickle claw on the foot! Why does that not scream “raptor”?

Beyond just the obvious lack of feathers, these statues are so shrink-wrapped they’re basically mummified, their hands are pronated and their thumbs are weirdly sticking out, their legs are hyperextended and detach from the body waaay too far up, and their feet are… actually I’m not even sure what’s specifically wrong with the feet, they’re just weird, the toes appear fused and seem to be too short.

For context, here’s what these animals should look like, drawn by paleoartist Emily Willoughby:

It’s night and day! 0/10.

Moving on from that crime against reptilia, here’s a Pachyrhinosaurus that doesn’t move, so that you can play on/around it. That’s a fun touch! And I like the pose. He looks like a friendly dragon chameleon! The enormous scales are likely fanciful, as well as the dragon-like ridge of spines down the back, but it’s technically not ruled out. This one is also fairly close to actual size. I’ll give this one a 9/10. Mostly because it’s always fun to climb on things.

Lastly, here’s the enigmatic sail-backed sauropod Amargasaurus, the inspiration for the Pokemon Aurorus. First of all, the irony on the sign is pretty hilarious. It simultaneously claims that the sail prevented the animal from raising its neck and contains a picture of Amargasaurus with its neck erect…

Here are all the things wrong with this statue.

Teeth sticking out of mouth (should have lips)
Nostrils on top of head (should be on the end of the snout like, you know, all real life terrestrial animals)
Front feet have visible nails (should only have a thumb claw)
Baby has full sails (they would likely have developed during puberty)
Baby has very chunky legs (would not need thick legs as a smaller animal)
Baby is around at all (sauropods likely did not practice parental care)
Not to scale (is less than half the appropriate size)

Overall, 3/10, mostly because Amargasaurus is a fun genus to include at all. As an aside, I Googled “did baby sauropods have proportionally short necks” (they did) and Gemini offered me this gem:

Yeeeeah. Nursing reptiles. Be careful using AI, folks…

That’s all! I hope these statues find a good home after they leave the Cal Academy. Even though they have many inaccuracies, they are certainly fun. Just an update of some of the signage and maybe giving Deinonychus a new coat would go a long way.

Book Review: Dinosaurus

Sun, 10 Aug 2025 07:01:11 +0000

I was recently contacted by someone from Smithsonian Books to see if I’d be interested in doing a review of a book that’s coming out soon, Dinosaurus by Rhys Charles. I responded that I was happy to, but my review would be completely honest. From the blurb, I was not optimistic.

“The Therizinosaurus”? And why use this generic theropod skeletal, which is missing its fibula, its pubis, and its temporal and antorbital fenestrae, has pronated hands, appears to only have one coracoid, and has a shoulder girdle that is connected entirely wrongly, as the cover image? (Is it supposed to be Tyrannosaurus?)

However, turning the (digital) page, I was pleasantly surprised: the rest of the skeletals are a lot more accurate. And the animals shown are quite varied, with previews of Hesperornis the penguin-like Cretaceous toothed bird with toothpick arms, what’s probably supposed to be Morganucodon, a Mesozoic mammaliform, and on the next page, a rauisuchian and a rhynchosaur. We’ll find out if I was right later in the dictionary!

I’ll probably stop posting screenshots at this point, though, since the book isn’t out yet. You’ll have to just trust my descriptions of things.

Bottom line up front: This book is a confusing mix of up-to-the-minute research and elementary errors. I learned quite a few new things while reading it, which is what I look for in a book (if I didn’t, that means it doesn’t fill any new purpose in the market beyond things I’ve already read). But it’s also riddled with grammatical, spelling, and a few taxonomy mistakes. Maybe the author is dyslexic and the proofreader isn’t a paleontologist and therefore didn’t catch the taxonomy stuff? But it seems like the spelling/grammar stuff should’ve been flagged at some point…

It’s also unclear who the audience is supposed to be. It doesn’t seem to be for children - it’s pretty dense and there are no life depictions, just skeletals. I guess that means the book will likely age better. But it also makes it more difficult to visualize the dinosaurs in life. I think if a small kid were reading it, they would probably think dinosaurs were just walking skeletons! But the book is also not super in-depth, nor does it have a pop science-like narrative structure. So… who’s expected to read this? The book is fairly pretty, though, with attractive skeletals and nice pastel colors. Maybe people will buy it just based on that. Maybe it’s intended for precocious children?

In the rest of this post, I’ll go through each section and give an opinion on each, with more attention paid to the dinosaur section than the others.

Dinosaurs: nit by nit

The first entry in the dictionary is Aerosteon, a Cretaceous megaraptorid famous for having preserved pockets in some of its bones that air sacs, part of a birdlike respiratory system, would have filled in life. This is a fun genus to highlight, and a good one to start with, since dinosaurs’ relationship with birds is important and not every reader would know it. The skeletal is also much more accurate than the cover image, thankfully. However, I have a couple nits to pick. The text refers to dinosaurs and birds each as “species” rather than groups, clades, or families. And the text doesn’t tell us when this dinosaur is from and who it’s related to. Its relations are maybe less important in this case, as megaraptorids have been very difficult to place among theropods. But I think having a sense for when each genus lived is useful for understanding the overall arc of dinosaur evolution, especially since the immediately preceding page had a geologic time scale on it. Also, a super minor nit - each entry has a “pronunciation guide”, and in this case it’s “AIR-OS-TEE-ON”. To me, this isn’t very helpful, as I can’t tell if “os” is supposed to be pronounced like the British “arse” or the Japanese “osu”, and I also can’t tell where the emphasis is supposed to lie. But…eh, whatever.

The next genus is Albertosaurus, which the text says is “lighter and leaner” than its southern cousin T. rex and thrived across a wide swath of North America. All good. But this entry has some spelling and grammar issues. It says it’s part of the “Tyrannosauroidae” family (should be Tyrannosauridae), switches from “it” to “they” halfway through a sentence, and calls intraspecific combat “dinosaur-on-dinosaur hunting”.

After Allosaurus comes Anchiornis, which is a neat one to include because of the fossilized pigment. The silhouette around the skeletal shows shaggy feathers, which is accurate. There are a few more grammatical / writing style issues here, though. “Anchiornis, or Anchiornis huxleyi to give the species its full name [cringe], was denominated [cringe] in honor of Thomas Henry Huxley, a nineteenth-century biologist who was one of the first champions of Darwin’s theory of natural selection. It was also Huxley who, in 1868, became the first to suggest that birds were in fact types [sic] of dinosaur”.

Ankylosaurus gets a whole page to itself (previous entries were each half a page). This entry mentions Victoria Arbour’s work on trying to determine whether the clubs were more often used in intraspecific combat or against other species, which is a neat bit of very recent research to include. It also mentions the time period, life habits, and contemporary dinosaurs of Ankylosaurus, which is nice to include and lacking in some of the other entries. One nit: there’s a sidebar that has a detail iso view of the tail club, but provides no new information about the club (and even reuses the same skeletal on the same page, just reflected left/right).

Argentinosaurus’s entry is pretty good, mentioning how it’s one of the largest to ever live but how determining that accurately is a difficult process due to the fragmentary nature of the remains. And then it goes and says that Argentinosaurus was “around…94,492 kg”. Um. What. This is because they just directly converted 93 imperial tons to kilograms and then didn’t round. *cries in significant digits*

In Deinonychus’s entry, Dromaeosauridae is misspelled as “Dromeosauridae”, there’s a typo (“North of America” instead of “of North America”), and the dinosaur is reported to have been six feet tall (it was closer to three).

I like Dilophosaurus’s entry. It’s basically what I wrote for my pocket alphabestiary.

In Diplodocus’s entry, which is another full-pager, there’s kind of a massive malapropism: “niche portioning” instead of niche partitioning. It’s neat that they included the bit about skin impressions further along in the entry, but amateurish to call them “diplodocuses”.

Edmontosaurus’s entry is generally a good one. This guy is up to date on the latest research, as he mentions a particular fossil with soft tissue that’s still being worked on today. But again, calling them “Edmontosaurs” shows ignorance…

Another wrong word used: calling Guanlong’s later tyrannosaurid relatives “ancestors”. Pretty sure the author meant “descendants”.

I’m learning interesting things about Herrerasaurus and Giganotosaurus I didn’t know, like there are some isolated lower jaws of the former that are twice as long as the best-known skull, indicating maybe they could get a lot larger, and that the latter had a notable chin that might have helped distribute bite force. Jobaria’s entry is also interesting, explaining the special adaptations sauropods needed to move around their enormous necks: cervical ribs!

The text claims Lambeosaurus was one of the largest non-sauropod dinosaurs. This is not true at all. Lambeosaurus was around three tons; the contemporary Parasaurolophus was bigger at five tons, and the truly biggest non-sauropods like Shantungosaurus and Ledumahadi would have reached ten to twelve tons. I have a whole blog post about it!

Back to the weird pronunciations… I’m pretty sure Masiakasaurus is supposed to be pronounced “ma-SHEE-ka-so-rus”, not what the book proposes, “MAS-EE-A-KA-SAW-RUS”. And Megalosaurus’s pronunciation has a typo and is rendered as “MH-GA-LOW-SAW-RUS”.

I’m glad Oryctodromeus got an entry. Also, Ouranosaurus and Neovenator being used to highlight different paleobiomes is cool. Calling multiple pachycephalosaurs “Pachycephalosaurs” and missing the italics on “protoceratops” (group names should not be italicized, genus and species names should be) is less cool.

Okay, here’s one more illicit screenshot:

I was really confused by what those paddle-shaped things coming off the ribs are, since I haven’t noticed this in any skeletals I’ve seen before, and they’re not mentioned in the text. Qantassaurus is known from very limited material, not including ribs, so most skeletal reconstructions of it do not include these features. However, other bipedal ornithopods like Hypsilophodon and Talenkauen are known to have had them, so it’s definitely possible Qantassaurus did too. They’re called intercostal plates, and likely served a similar purpose to a feature known from many modern birds called uncinate processes, which are spiky bits coming off the ribs that allow for increased muscle attachment to facilitate efficient breathing. However, it seems like ornithopod dinosaurs evolved these plates independently from birds. The more you know…! The entry doesn’t tell you what those plates are, though.

Shunosaurus’s entry unsurprisingly discusses its distinctive tail club. But I didn’t really think about the fact that it lacks the “handle” reinforcement that ankylosaurs developed, and therefore would have been much less effective as a weapon - flinging it around would have dislocated the animal’s vertebrae! Therefore, maybe it wasn’t a weapon at all, but some kind of sensory organ or display structure. If you’re not familiar with what Shunosaurus looks like, here’s a weird cartoon I did of Shunosaurus back in 2019.

Unfortunately, we whiplash from those two thought-provoking entries back into questionable territory with the next entry, Sinosauropteryx. The text claims that it “was the first feathered dinosaur ever found” and that it at last “confirmed” that birds were dinosaurs. This is very untrue. Archaeopteryx was the first feathered dinosaur ever found, way back in 1861, over a century before Sinosauropteryx, and scientific consensus held that birds were dinosaurs since at least the Dinosaur Renaissance and the discovery of Deinonychus, though the idea was floated as far back as the mid-1800s. In fact, Sinosauropteryx was the first non-maniraptoran dinosaur - that is, one not in the direct lineage leading to birds - found with preserved feathers, and it was important in showing that feathers were not strictly a bird-line trait, but a broader dinosaur thing.

The Tyrannosaurus entry is…meh. A bite force of 40,000N? What does that even mean? No one is familiar with Newtons. It also states, “In order to balance out its heavy skull, the arms of T. rex were much smaller relative to its body size.” This is kind of a weird thing to say, implying that either big arms would’ve put its center of mass too far forward, or that it spent too many evolution points beefing up its head and had none left for the arms. Either way, it doesn’t really follow. Spinosaurus, for example, was much more unbalanced-looking and seems to have been able to walk just fine. And there’s nothing stopping an animal from having multiple weapons or multiple limbs that do approximately the same thing, as in the four-winged Microraptor or the shoulder-spiked and tail-spiked Gigantspinosaurus. Rather, Tyrannosaurus had short arms because short arms were better for whatever it was doing. Also, while most of the time it’s referred to correctly as T. rex, there is one instance of “T-rex”.

The Velociraptor full-page entry is also meh. While it gets the basics right (small, feathered, with mention of the “Fighting Dinosaurs” fossil), it doesn’t say why Jurassic Park depicted them as much larger and as pack hunters. Maybe the author didn’t know why. But there is a good reason: the much larger Deinonychus used to be considered by some to be a junior synonym of Velociraptor, so the animals in the book and film were based on Deinonychus. And many Deinonychus specimens were found in one place alongside the ornithopod Tenontosaurus, inspiring the pack-hunting theory. It’s very likely that some raptors were social and some antisocial, like how lions and tigers have opposite habits even though they’re in the same genus.

I’d never heard of Xuanhanosaurus before reading this, and it has quite the interesting scientific story. Apparently someone suggested that this very normal theropod-shaped theropod was quadrupedal back in the ’70s (it wasn’t). I wonder why? A fun tidbit.

Prehistoric Beasts

This section includes not just individual genera, but entries for whole groups, including birds. I personally would’ve put the birds in the dinosaur section, but the author explains why they made that decision in the intro to this section, so I guess it’s okay. This section is a lot shorter than the Dinosaurs section and hits a lot of the highlights, but there are some animals whose skeletals were teased in the beginning of the book that are notably missing, like rauisuchians, rhynchosaurs, and mammoths. Overall, this section gives a decent look at Mesozoic non-dinosaur animals and I have fewer complaints about the information presented. But it’s still not exactly a page-turner.

Nits:

Archaeopteryx’s silhouetted flight feathers are way too short. Perhaps this is just because longer ones wouldn’t have fit on the page? But it gives an inaccurate idea of how wings work…
Hesperornithes did not diverge from non-avian dinosaurs later than birds did; that would imply that they are not within Avialae, which they are. They were certainly an early bird branch, but they were birds. Also, the demonym for a member of Hesperornithes is hesperornithean, not “Hesperornithe”.
Grammatical and spelling errors: in Morganucodon’s entry, “analysis have [sic] shown”; in the Pliosaurs entry, “did not fair [sic] so well”; in Xiphactinus’s, teeth are called “nashers [sic]”.
Quetzalcoatlus is missing one of its phalanges.
There’s some confusion over different Repenomamus specimens. The text says “a specimen was found that appeared to have been attacking a juvenile dinosaur (a Psittacosaurus).” But there are actually two specimens of Repenomamus found in association with Psittacosaurus remains: one with a juvenile in its stomach, and one attacking an adult.
For some reason the Sarcosuchus skeletal is missing all its ribs?
Inconsistency in singulars, plurals, and group names. If Hesperornithes is an entry, then the entry for marine crocs should be called Thalattosuchia, not Thalattosuchians. Also in the Thalattosuchian entry: the text states that live birth “is a rare trait among reptiles”, which is not true; squamates have evolved ovovivipary dozens of times. It is a rare trait among archosaurs, which is probably what the author meant to say…

Events And Time

The geologic time scale is done well and covers not just an overview of each period but is also punctuated by important events, like extinctions and radiations. My only major complaint here is that the skeletals at the top of each section are not described within the section. Here’s where they’re using the rauisuchian and rhynchosaur skeletals, but the reader would not know what they were supposed to represent. A couple nits: the Mesozoic Marine Revolution is incorrectly called the “Marine Mesozoic Revolution”, and the Paleogene is incorrectly called an epoch (it’s a period).

Prehistoric Planet

In addition to the definitions of important landmasses and oceans throughout time, this section goes over many important fossil localities. I personally think that’s cool, but would a typical reader? Maybe this book is for adults after all. Nits: Edmontonia in the Dinosaur Provincial Park entry is misspelled as “Edmontia” and Phoenix (a tectonic plate) is misspelled as “Pheonix” in the Panthalassa entry.

Scientific Terms

This section is a nice thing to include, as it goes into more detail than just a glossary would. The paleontology concepts it includes are important ones, well-chosen in my opinion. And it ends with a “further reading” section that cites the work of a lot of the best leading modern paleontologists, like Steve Brusatte, Darren Naish, and Mark Witton. Nits: “Scarring” is misspelled as “scaring” in the Pathology entry, Megalosaurus is not italicized in the Wastebasket Taxa entry, and the picture of a phylogenetic tree in the Phylogeny entry is a bit confused, where the artist thought that the last branches needed to be connected into boxes for some reason.

Conclusion

Overall, I was pleasantly surprised by the quality and recency of the information presented in this book, but was unpleasantly surprised at the shoddy editing. I suppose the author is a scientist and dinosaur enthusiast first and a writer second. I guess if you’re looking for more dinosaur books to buy, this isn’t a bad option, depending on how much nits like the ones listed above bother you. Maybe if the book isn’t in print yet, my complaints will get fixed before it does! I’d give this three and a half stars. Solid effort, mediocre execution.

Rate My Dino 5: Paris Galerie de Paléontologie et d’Anatomie Comparée

Sun, 20 Jul 2025 07:01:11 +0000

The other thing besides birding that I always make sure to do when I travel is to hit up the local natural history museum. In Paris, that’s the Galerie de Paléontologie et d’Anatomie Comparée located on the eastern end of the botanical garden, NOT the Muséum National d’Histoire Naturelle, which is on the other end of the gardens and contains taxidermied animals. The paleontology gallery is quite a small building, but is packed absolutely to the gills with fossils as well as the skeletons of modern animals.

This is a very Gilded Age way to display fossils, with lots of mounted skeletons facing the same direction and no prescribed path for visitors to walk. Cool to see a museum that’s not only a tribute to the deep past, but also to the more recent past!

The main downside to this museum was that there were no English translations anywhere. I took photos of as many signs as I could and translated them later, but there are definitely a lot of things I missed due to not knowing French.

The first thing you see when you enter the museum is a really strange statue of an orangutan choking out a human:

(I couldn’t get a clear photo of it because it was behind the line of people waiting to get in.)

Apparently this orangutan is called Maurice (which is maybe why the orangutan character in Rise of the Planet of the Apes was named that?), and was said to have killed one of his Southeast Asian handlers. However, from Googling around, it seems that this story may be apocryphal. The sculptor is Emmanuel Fremiet, who is known for his sculptures incorporating animals, including one of a gorilla kidnapping a woman and one of a man fighting a bear. I’m not sure why the museum has this; maybe just because the sculptor was famous and French?

Entering the ground floor hall, there is an overwhelming number of mounted skeletons of modern animals.

But let’s get on upstairs before the field trip kids realize there are no dinosaurs in here, shall we?

As in most museums, the large mounted fossils are a combination of original, composite (fossil plus fabricated parts to fill in the blanks), and cast material (copies of real fossils). A lot of the biggest dinosaur skeletons in here, like Carnotaurus and their mounted sauropod, are full casts, which I didn’t take pictures of. But they did still have plenty of interesting original fossils. I’m not going to go age by age because (a) I only translated a sporadic selection of things, and (b) there was no clear walking path to go in a particular direction in time. I’m just going to do a highlight reel.

Let’s start with some of the oldest fossils. They have an original Metaspriggina here, which is a really, really ancient (pre-Cambrian) early chordate, or ancestor of animals with backbones. Unfortunately, it’s not really clear what we’re looking at in this fossil.

The info in this display was new to me - it explains how pterapsidomorphs, or an early type of jawless fish from the Ordovician, employed a primitive type of bone called aspidine, which was different in structure from modern bone. At the bottom, there is a transverse cross-section of a cave bear’s leg bone (left), showing the thick walls and hollow center, and a longitudinal cross-section of a moa (giant bird) foot bone, showing the thin walls and numerous trabeculae (struts), as well as the way that the bone ends differ from the center.

Jumping ahead to the Devonian, here are some neat jawless fishes. The caption on the rear left one says that the gray lines aren’t part of the fossil but are chisel marks, which is a good thing to call out, because they look a lot like how sting rays’ fins get fossilized. I wonder why this fossil was prepared this way? I’ve never seen this kind of thing before.

Moving ahead to the end of the Devonian, here are some small placoderms (the family of fish with bony armor that includes the famous Dunkleosteus) and some info on them. Their drawing of Ctenurella is pretty decent: its bony head plates are not visible on the outside of its body, a common error. I’m not sure why the artist decided to put a fin halfway along its tail, but I’m pretty sure we don’t know enough about this genus to know for sure whether that’s wrong.

The sign states that placoderms were ovoviviparous, or giving live birth by holding the eggs inside the female’s body, and that the males had claspers they used for internal fertilization, similar to sharks. This is accurate to the extent that we know - there have been pregnant placoderm fossils found with young preserved inside, as well as a specimen named Materpiscis (“mother fish”) that died in the process of giving birth, with even the umbilical cord intact. This sign also says that the young would have been basically mini adults and self-sufficient right away. As far as I could find, we don’t know whether placoderms practiced parental care, but we do have some juvenile Bothriolepis specimens that do look like mini adults, so this is plausible.

Here’s one of the three Dunkleosteus the museum had on display. The sign behind it says that even though placoderms didn’t have teeth, you can tell by the shape of the jaw what they were feeding on, and gives examples of a predator’s jaw plates, a filter feeder’s, and a durophage’s. I think this is a cool detail, and it’s not something I’ve seen before! I knew placoderms filled all kinds of niches, but seeing the different jaw types involved was new to me.

The sign directly under the Dunk fossil explains that the hole in the top of the head is not part of the fossil but was caused by some aspect of its preservation. I appreciate them pointing this out.

Here’s Dunk Number 2, the biggest of the three. Alongside it is an outdated life reconstruction, with the old-fashioned eel-like fin and long body.

And here’s the final Dunkleosteus, the smallest of the three, and embedded in a rock. I’ve never seen one preserved this way. It looks a lot more similar to other slabbed placoderms I’ve seen in museums. Seems like only the big ones merit taking out piece by piece and mounting!

Contemporary to the placoderms are the early cartilaginous fish, including modern sharks and rays. I like how they highlight the many crazy experimental anatomies early sharks exhibited in their art. I’d never heard of Iniopera before, but it’s so funny-looking! I also just like the word “incroyable”.

This was an interesting one: the black blob on the left is a nodule containing the head of Iniopera, which they scanned and resized to construct the cast, second from left, at 5x scale. The preservation actually included both the skull bones and the actual brain, so they also made casts of these: the endocast of the skull cavity is the shape in the middle with the two “handles” at 50x scale, and then the brain is shown at both 5x (matching the skull) and 50x scale on the right side. This highlights the limitations of drawing conclusions about an animal’s brain based on the size and shape of its braincase, and/or the effects of taphonomy (the fossilization/preservation process) on brain tissue. (This last is the reason behind the persistent myth that koala brains only take up 60% of their braincase. The specimens they were studying had been pickled in a way that made them shrink. In fact, koalas have completely normal-sized brains for their head size.)

This is a cool mini-slab! The largest fish there is the one on the sign, Scyliorhinus, which is a genus of catsharks that’s still around today. The sign says “here we can also see 3 smaller actinopterygians” - two that are obvious plus one in the mouth of the shark.

And here’s the final important fish group, the bony fish. I like how they show the homologous structures between the different lineages.

Here are a bunch of temnospondyls, a type of early amphibian, that died together when their swamp dried up. This happens often in places that get sporadic rain or flash floods, but in the past it would’ve been a lot more dramatic, since these animals are each the size of a small gator!

Here are some fragments of other temnospondyl skulls that show different patterns in the rugosity of the bone. Like crocs, temnospondyl skin was stuck directly to the bone with minimal flesh in between, so you can tell a lot about the outer appearance of the animal from the patterns in the bone surface, called osteological correlates. However, this sign doesn’t tell you what each means. What do they mean?

Here is a little guy I am particularly fond of, Lystrosaurus! I’ve written about him twice before on the blog, once in a profile of his own and once in the context of other Permian synapsids. But I think this actually might be my first time seeing a mounted skeleton of one! Everyone always calls them “bulldog-sized”, but this was definitely more like sheep-sized. But apparently there were four species of Lystrosaurus, and three of them were truly knee-high, but murrayi was quite a bit larger. TIL! The one weird thing about this display is it suggests that Lystrosaurus was semi-aquatic. This is a bit of a fringe theory; there’s no direct evidence for it, but it has been proposed by some researchers as being a potential reason this animal was such a good survivor. But the French sign also says it was adapted for digging, which seems to conflict with also being semi-aquatic? Confusing.

Onward to the Mesozoic! Here is a case shared by the plesiosaur Cryptoclidus and the “Monte Bolca Triptych”, which is a totally unrelated thing from the Eocene, millions of years later. Not sure why they displayed these two fossils together? Apparently the Count of Monte Bolca gave this fossil in person to Napoleon. Imagine him receiving it… “Uh… thanks? Put in in the wagon, I guess”

This thalattosuchian (marine croc), Pelagosaurus, is mounted with its osteoderms separated from its body, enabling viewers to see the body more clearly. According to the sign, the quarry this came from was destroyed by bombs during World War 2. But the sign doesn’t say anything about how this animal lived, in particular.

On the topic of crocs, here’s a big ol’ Sarcosuchus, one of the biggest crocs to ever live. This is the fossil I based my page image on, and it’s also the type specimen and even the page image for the Wikipedia entry for this genus! This is a famous fossil. Like many of the big mounted fossils, it has both a drawing and a little clay model presented with it. A cute, low-budget touch.

Here are a few other impressive marine reptiles, including a tiny ichthyosaur and a giant plesiosaur head. But the coolest one is the skeleton at the top, which belongs to the marine croc Metriorhynchus, the most marine that archosaurs (the bird/croc/dino lineage) have ever become. As far as we know, no archosaur has ever evolved to give live birth - except maybe this guy. It was so adapted for aquatic life, with a long fluked tail and paddles for limbs, it’s hard to imagine it coming up onto land to lay eggs… but maybe it still did, just very awkwardly. Need more fossils!

Did you know that there was once an aquatic tuatara? I didn’t, but that’s what Pleurosaurus is. It’s soooo long! And it lived in the Late Jurassic, a time of great marine reptile diversity, when it would’ve faced competition from plesiosaurs, ichthyosaurs, and metriorhynchids, rather than during the wacky, anything-goes Triassic, which is when I would’ve bet something like this would come from.

Finally, some dinosaurs! This is one of the big mounted dino skeletons that’s actually an original, an Allosaurus. Its coracoid (chest) bones are not touching and its legs are too close together, but overall not a terrible pose.

This is one of the two specimens known of Compsognathus, a famous small theropod dinosaur that was discovered back in 1859. For many years it was the only small dinosaur known, and it was notable for being obviously reminiscent of birds, especially Archaeopteryx when that was discovered.

This tail segment belongs to a dubious sauropod genus called Bothriospondylus. As the sign here explains, a dubious genus is one whose validity is doubted, but the name is still in use because no one has yet done the work to figure out how this fossil should actually be classified. A neat tidbit.

Here’s a cool pterosaur specimen, Cycnorhamphus, a bird-sized species that might have fed like an openbill stork, but might have been doing something more mysterious (the exact anatomy of the end of its bill is debated). Strangely, this sign says that the number of pterosaur species declined in the Triassic due to competition with the ancestors of birds. This is not true, nor has it ever been proposed seriously, as far as I know. Pterosaurs were doing quite well for themselves throughout the Jurassic and Cretaceous, and birds only achieved flight in the Late Jurassic. Why would early flightless bird-relatives compete with fully flighted early pterosaurs at all?

Here’s another pterosaur, Aurorazhdarcho, an early, very small azhdarchid (the group that includes the later plane-sized pterosaurs such as Quetzalcoatlus). However, this specimen was originally identified as a species of Pterodactylus, which is why the sign still claims that its name means “wing finger”. “Aurorazhdarcho” means “dawn dragon”. Confusing…

For our last stop in the Mesozoic, here are some intimidating mosasaur jaws. Isn’t it crazy that mosasaurs lived and died within the Late Cretaceous? Such a short time on this Earth for such cool creatures.

There were more dinosaur and other Mesozoic specimens, but they were either casts, or I didn’t think they were interesting enough to mention, or I didn’t get a clear enough picture of the sign to know what the museum was saying about it.

The museum focused a lot on Paleocene mammals, which I expected due to the famous father of paleontology Georges Cuvier (1769-1832), who hailed from France and discovered a lot of them. He basically invented the concepts of extinction and biostratigraphy, and did a lot of work on taxonomy as well, building on Linneus’s foundation. However, it was a weird time to be a paleontologist, because he died decades before Darwin’s work was published. So Cuvier’s working theory was that there were Biblical floods every few million years that wiped out everything, and then God created everything anew each time.

All the posters on this side of the hall were much older and more technical than the ones on the Paleozoic/Mesozoic side. This one talks about the weirdness of the post-apocalyptic Paleocene fauna, how there were a bunch of mammals that very quickly adapted from small burrowers to filling all the large animal niches, but were soon displaced in the Eocene by other mammals that were more specialized and more representative of what we have today.

Underneath that poster is this skeleton of Arctocyon, a Paleocene mammal of uncertain affinity. The sign claims it’s related to artiodactyls, which is a valid hypothesis but far from the only phylogenetic placement possible. This specimen is the page image of Arctocyon’s Wikipedia page.

Here are some more Paleocene mammal skulls, as well as an art piece depicting Arctocyon facing off against a mother Gastornis and her chick. The black and white makes it a bit hard to interpret what’s going on. And hasn’t this museum ever heard of museum-grade anti-glare glass?

This enormous Palaeotherium specimen was placed not in the fossil hall, but in the stairwell! This genus was one of the ones named by Cuvier, back in 1804. The two little drawings there were done by Cuvier. The sign describes that the fossil was found as part of the roof of a cave. It also calls Palaeotherium a “pachyderm”, an outdated term that meant “large gray-skinned mammal” but was not a meaningful phylogenetic group and has thus fallen out of use.

This skeleton, also in the stairwell, is labeled “Macrotherium”, a synonym of Chalicotherium. The sign says something to this effect, except in a really confusing way. It says that the head of “Macrotherium” was attributed to Chalicotherium, but this skeleton shows that the head of Chalicotherium belongs to the body of “Macrotherium”? What?? Anyway, they both refer to the same animal, a horse relative that walked on its knuckles like a gorilla, from the Miocene.

Here’s a neat mounted skeleton of Thalassocnus, the aquatic giant sloth from the Miocene. You can really see its heavy, heavy bones, especially the ribs! Those would have weighed it down in the water, enabling it to dive.

This terrifying skull belongs to Acrophyseter, a Miocene sperm whale. Sperm whales eat soft squid; why do they need such crazy teeth? Maybe because killing the squid is the hard part, not eating them?

This skull of Diceratherium, an Oligocene rhino, has some really interesting stone patterning inside. I’m pretty sure this doesn’t have to do with the way the animal was in life, but is just a characteristic of the way it was fossilized. It’s weird to think that fossils are actually made of stone, not bone.

This is a cave bear, Ursus spelaeus, a relative of today’s grizzly bears that was more herbivorous. There was certainly an impressive amount of mounted Pleistocene megafauna in the back of the hall. Apparently in French, DNA is ADN.

This skeleton might not look like much, but this genus represents the oldest known ape, Proconsul, which lived 28 million years ago.

These…suspicious-looking objects are segments of the tails of glyptodonts, which were giant Pleistocene armadillos. This museum also had a big mounted glyptodont skeleton, but I thought these pieces were interesting detail views.

Heading upstairs to the third floor, we find the invertebrates. This section of the museum was the most technical of all, with diagrams like this all over the walls explaining the phylogeny and anatomy of things like sea urchins (“oursins”) and brachiopods.

Here are some impressively large ammonites, including the weirdly uncoiled Acrioceras. I really don’t understand how such un-hydrodynamic creatures could have been selected for. But they were! And even weirder shell shapes existed, like the tangled Nipponites, the helical Didymoceras, and the paperclip-shaped Polyptychoceras.

I won’t go into much further detail on the inverts because I don’t have that much background in them and I was running out of time in this museum by this point. But I wanted to discuss rudists, just a little. These were bivalves like clams, except each side of their shell was huge and horn-shaped. How did they live?? It seems like they would not have been able to easily open and close the valves, and the space in between would’ve been so tiny that there would have been very little interaction with the environment relative to their total internal volume.

Here’s an artist’s interpretation of a living rudist. In the Mesozoic, these gigantic mollusks (up to 2 meters across) were important components of reefs. But…how??? What was all that internal volume for?

There was a lot more than this on display in this museum - it would take a long time to get through everything despite the deceptively small size of the building! But overall I thought this was a really interesting experience, especially because the museum is a combination of new and old science communication techniques.

Dinosaur Photography #14: Birds of France

Sat, 24 May 2025 07:01:11 +0000

I recently went to France for the first time. You know the drill–here are the birds!

Paris Birds

In most places, the Rock Dove is by far the most numerous pigeon. But in France, these gigantic Common Wood-Pigeons were everywhere. About twice as big as a regular pigeon and with neat white collar markings, they made very loud cooing sounds from the bushes in all the parks we visited.

They also liked to perch on top of statues. There were lots of opportunities to do so!

They did have Rock Doves too, though. This one was doing an even fancier version of the standard pigeon mating dance, adding a move where it would slap the ground with its tail. As usual, it was unsuccessful.

This European Starling was actually where it was supposed to be! They’re invasive in the United States, introduced intentionally by some Shakespeare fanatic in the 1800s. There’s something wrong with one wing on this one.

Starlings exhibit a lot of sexual dimorphism, with the males having galaxy patterning and the females just being brown.

This Short-toed Treecreeper had a very loud, distinctive call. I identified it by sound using the Merlin app, which allowed me to know what I was looking for and where to look to get this photo.

Another bird with a distinctive song was the Eurasian Blackbird. You might have heard its song on the Beatles track “Blackbird”. It’s very melodic.

Like starlings, blackbirds exhibit significant sexual dimorphism. But to me, the females are sometimes prettier! They’re just not black.

In America, we have American Crows, but in Europe, they have Carrion Crows. They look almost the same though.

This one is actually eating carrion!

Like in Hawaii, there is a feral population of Rose-ringed Parakeets (Indian Ringnecks, or IRNs) in Paris.

They’re much smaller than the ubiquitous Common Wood-Pigeon, but much more aggressive. This one was scaring off the pigeons to get access to grain a human was distributing.

Parrots are so much louder than temperate birds. They evolved to be heard through the cacophony of a jungle, so in a Parisian park they’re just unnecessarily strident.

Annecy Birds

For the second half of our trip, we took the train to Annecy, a town in the Alps bordering Switzerland. There was a mountain lake that was impressively scenic and hosted some different birds than we saw in Paris.

These Eurasian Coots were very similar to American Coots, which I’ve seen before. But given the crystal-clear lake waters, we could see them diving to the bottom to grab food!

This is a male and female Common Merganser on a surfboard. The males have shiny black heads while the females have shaggy red heads. Another case where I think the female looks cooler.

This is a Black Redstart. Seems like an oxymoron, but it did have a little red on the tail.

This is a Great Tit. Their calls and behavior were quite similar to those of the American Bushtit, but the Great Tit is much bigger, hence the name. These are the birds that famously learned memetically how to open the foil tops of milk bottles, back when milk delivery was a thing, and skim off the layer of fat on the top.

This Common Chaffinch was singing its heart out. That was the only way I could tell what it was, since it wouldn’t come out of these bushes!

This Yellow-legged Gull was carrying off…something. I later saw one nab an abandoned duckling! Brutal!

This is a White Wagtail, a bird that doesn’t look water-worthy but nevertheless was often flying very close to the surface of the water. It did wag its tail a lot.

Like everywhere in the world, there were plenty of House Sparrows in France. This female posed very nicely for me.

This is just a male Mallard, but his bluish head and wind-ruffled feathers looked cool enough to merit a picture.

Canada Birds

I also went to Canada twice last year and never made a post for the birds I saw there! Canada is kind of French…right?

Mountain Birds

These were ones I saw on a trip to Banff. Most of them were spotted on the hike up to the Lake Agnes Teahouse from Lake Louise.

This is a Clark’s Nutcracker, a relative of crows with a long beak for picking seeds out of pine cones. I’m not sure if this one has something wrong with his beak, since the lower mandible is longer than the upper. Maybe the tip of the upper broke off?

Another crow relative, this is the Canada Jay, also known as camp robber or whisky jack. Its overall patterning and size are similar to Clark’s Nutcracker but the beak is much smaller and the head patterning is mottled.

This one found a cheese puff!

Like in Denver, there are Black-billed Magpies in Canada. This one had some molting going on on its neck.

And this one found another cheese puff!

We have Steller’s Jays in California too, but I haven’t seen any with this distinct a white eyebrow before.

I also don’t think I’ve gotten pictures this decent of them before!

A Common Raven.

According to the bird people on Reddit, this is a Golden-crowned Kinglet? I only saw one and only from far away and backlit!

Vancouver Birds

There was a small falconry demo at the Capilano Suspension Bridge. This is a Harris’s Hawk with its neck fully retracted. Cozy!

The other bird they had was a Gyrfalcon. Falcons and hawks are in totally different bird families, with falcons more closely related to songbirds than to hawks. The power of convergent evolution!

In California, we only have Double-crested Cormorants, but in Canada they have both those and Pelagic Cormorants, which lack the orange throat patch. Otherwise, they’re very similar.

This is a Double-crested Cormorant drying its wings in a horaltic pose.

This is a flock of Black Oystercatchers, a type of shorebird that digs up large invertebrates from the mud using its powerful beak. Unfortunately, my camera was confused what to focus on…

We have Great Blue Herons in California too, but I don’t think I’ve captured quite as good an action sequence before.

This one was sitting on a seaplane in the harbor.

This American Crow was eating a dead pigeon when this juvenile Glaucous-winged Gull showed up and took over.

Here are a couple adult Glaucous-winged Gulls. Everywhere in the world you go, the gulls look almost the same, but they’re usually different local species.

These funny ducks are male and female Buffleheads. The males are the ones with the…buffle.

A Song Sparrow. Not a House Sparrow for a change!

Okay, here’s the obligatory photogenic House Sparrow. They have those too.

This Dark-eyed Junco (also known as Snow Sparrow) was singing its heart out. Too bad its song is just like a car alarm.

Some Red-winged Blackbirds among reeds.

Non-birds

This tiny creature was hanging out on the side of a hiking trail. I think it’s a vole?

A chipmunk?

Some honeybees going about their business.

Others

Here are some other photos that weren’t part of a set large enough to make a blog post, but I thought were cool anyway.

A Prairie Warbler seen in Florida in December. Warblers are so hard to take photos of and to identify! Why are they always yellow?

I’ve gotten pictures of Tree Swallows in flight before, but never seen one at rest. This one was in California.

Similarly, here’s a Barn Swallow spotted in Washington, DC. These are usually either in flight or inside their mud nests.

Swallows and swifts are very boat-shaped for optimal aerodynamics!

A Loggerhead Shrike, a small crow relative, seen in Florida. I’ve gotten photos of them before, but this is the closest I’ve been to one.

A Red-bellied Woodpecker seen in Florida. What red belly, you ask? Good question. But Red-headed Woodpecker was already taken.

This Osprey has caught another bird! So much for being a fish specialist!

A very photogenic cat, seen in Florida.

A rare daytime sighting of a raccoon, also in Florida.

Prehistoric Beast Profile #6: All the Permian Synapsids

Mon, 21 Apr 2025 07:11:11 +0000

As a final installment in my comprehensive prehistoric world maps, I present the world of the end-Permian, right before the most terrible extinction the world has ever seen. The configuration of continents during the Permian period was much the same as in the Triassic, except that since the climate was a bit cooler and drier, more land area was exposed, and the big uncrossable desert in the middle of the C-shaped continent wasn’t quite as intense or uncrossable. This means that the faunal assemblages of the north and south were more similar than during the Triassic, with representatives from all major groups present in both places.

The further back in time we go, the less fossil material exists that’s survived that long. As such, my Triassic map had fewer animals on it than my Cretaceous one, and my Permian map has even fewer, with huge blank expanses from where no fossils are known. That doesn’t mean that animals didn’t live there at the time–it’s overwhelmingly likely that a similar fauna as was found in Siberia populated North America, and perhaps some strange isolated, monsoon-adapted extremophile animals lived in the Cimmerian archipelago.

As with my previous two maps, I only drew the most diverse and abundant group on Earth at that time–in this case, the mammal precursors known as synapsids. While it’s unfortunate that many weird and wonderful synapsids like the fin-backed pelycosaurs, long-necked dinocephalians, and tiny-headed caseasaurs had already gone extinct by the end of the Permian, there were many charismatic taxa still thriving right up until the apocalypse began.

Since tetrachromatic vision is the ancestral condition and mammal ancestors hadn’t undergone two hundred million years of subjugation by the dinosaurs yet, it’s likely that these animals were very colorful! Unlike certain dinosaurs, there isn’t any preserved evidence of color known from Permian synapsids, so I took liberties to color them however I wanted, taking inspiration from modern mammals, reptiles, and birds (which, though not related to synapsids, are probably representative of the level of colorfulness our Paleozoic ancestors might have been).

Also, none of these guys have external ears. It’s not known exactly when external ears arose, but it’s probably sometime during the Jurassic. Some of the more advanced end-Permian critters like the cynodonts may have been able to hear some airborne sounds, but with much less acuity than modern mammals, since their ear bones were still part of the jaw. This would have made them less able to freely vibrate, both because they were bulky and because they were attached to other skull components, and it would have made it so that breathing and chewing noises would significantly interfere with hearing. Cynodonts and more basal synapsids would have been able to hear sounds conducted through the ground, though, like the vibrations of each other’s footsteps or low rumbles they may have used to communicate, like elephants.

Let’s go through each major group, from least closely related to modern mammals to most mammaly.

Biarmosuchians

Burnetia, Paraburnetia, Lycaenodon, and Ictidorhinus

These guys are the most basal of the groups still alive at the end of the Permian. These mostly medium-sized carnivores were almost certainly fully cold-blooded, and therefore weren’t furry, though I have given some of them whiskers that would have been useful for sensing. It’s likely that hair first evolved for sensory purposes and later was repurposed for thermoregulation and display.

Three of these biarmosuchians were in or very closely related to a more derived subgroup called burnetiids, which had all kinds of weird bumps on their skulls. In Paraburnetia and Burnetia, those things on the sides of the head aren’t earflaps, but are bony protrusions that may have supported keratinous horns. Given the extreme showiness of their skulls, the bumps had to have been important display features, and burnetiids were therefore probably particularly showy, colorful animals.

Most biarmosuchians are monotypic, or known from a single fossil specimen, so not a lot is known about these flamboyant creatures. Did only the males have those bumpy protrusions? Were they covered by skin, horn, nothing, or something else? The bone shows signs of being very fast-growing, indicating that it probably was a sexual characteristic that developed during puberty, but the preservation is too poor on the specimens we have to allow scientists to guess what it might have looked like in life [1].

Ictidorhinus was not a burnetiid or close to one, so I didn’t give it head bumps. But since biarmosuchians are so basal, it’s the most reptilian of all the animals on the map.

Gorgonopsians

Leontosaurus, Cyonosaurus, Aelurosaurus, Arctops, Arctognathus, Sycosaurus, Inostrancevia, and Smilesaurus

Perhaps the most charismatic of all Permian fauna are the gorgonopsians, with their lion heads and saber teeth. While still basal and cold-blooded, they were the top predators of the Late Permian, the largest of which, Inostrancevia, may have weighed half a tonne, or the size of a very large tiger.

While it’s unknown whether their saber teeth would have been visible outside the mouth in life, it’s not impossible that they would have been, especially because ancestral amniotes didn’t have the flexible, loose facial skin that allow modern mammals to chew with their mouths closed and make complex facial expressions. Certain modern animals with large, non-tusk canines, like muntjac deer, red foxes, and Tasmanian devils, have their teeth protruding from their mouths most or all of the time, without ill effects on the enamel. So I chose to depict my gorgonopsians that way, mostly because it’s more fun.

While Inostrancevia might have been the biggest, the wolf-sized Smilesaurus had perhaps the proportionally largest canines, along with a chin flange to protect them from sideways knocks. Unlike later mammals, gorgonopsians constantly replaced their teeth throughout their lifetimes, more like modern reptiles, and would have been able to regrow their sabers if they were broken or lost. It’s likely that new sabers would’ve started growing in on the inside of the old ones, resulting in periods of double saber teeth, rather than periods of missing teeth, which would have made it difficult to hunt. This is also how later saber-toothed cats and cat relatives handled it, though they only replaced their teeth once in their lives. It takes a long time to grow a saber–possibly as long as 30 months in Smilodon fatalis [2]!

A funny note–Cyonosaurus means “dog reptile” while Aelurosaurus means “cat reptile”. I tried to color them accordingly.

Dicynodonts

Lystrosaurus, Compsodon, Dicynodon, Odontocyclops, Dinanomodon, Kwazulusaurus, Rhachiocephalus, Vivaxosaurus, Gordonia, Daqingshanodon, Jimusaria, Turfanodon, Diictodon, Myosaurus, Katumbia, Kombuisia, Pristerodon, Oudenodon, Dicynodontoides, Daptocephalus, and Aulacephalodon

Another famous group of early synapsids was the rolypoly dicynodonts, a group of beaked, tusked herbivores that ranged from guinea pig-sized to hippo-sized. There’s evidence in the form of bone histology and preserved fur in gorgonopsian poos that point to dicynodonts as having been warm-blooded, so I drew all mine as being fuzzy. But since other synapsids more closely related to modern mammals are thought to have still been cold-blooded, it seems that dicynodonts evolved endothermy independently.

Some of the smaller dicynodonts like Diictodon and Lystrosaurus are known to have been social burrowers, as entire families have been found entombed in their burrows.

Small dicynodonts like the Antarctic Myosaurus and Kombuisia, as well as the prolific Lystrosaurus, are known to have survived the Great Dying at the end of the Permian and later radiated back into even bigger forms like the seven-tonne (elephant-sized) Lisowicia. Here’s what the world looked like a mere 100,000 years after the snapshot at the top of this post:

When Siberia explodes, everyone is Lystrosaurus.

Therocephalians

Muchia, Karenites, Scaloposaurus, Scalopognathus, Scalopodontes, Scaloporhinus, Annatherapsidus, Malasaurus, Chlynovia, Perplexisaurus, Ictidosuchus, Ictidosuchops, Ictidosuchoides, Homodontosaurus, Lycideops, Choerosaurus, Promoschorhynchus, Tetracynodon, and Moschorhinus

The largest, catch-all grouping on this map, this is likely a wastebasket taxon that needs some sorting out. Sometimes Therocephalia is recovered as the sister group to Cynodontia (which includes modern mammals), but sometimes Cynodontia is nested inside Therocephalia, making it a paraphyletic clade, or an evolutionary “grade” on the road to true mammals. Either way, I’m running with the hypothesis that only dicynodonts and true cynodonts developed endothermy, so my therocephalians are not furry. There’s some evidence in the form of bone histology (growth patterns in thin slices of bone) that suggest therocephalians like Moschorhinus were able to grow faster or slower depending on resource availability, which is a characteristic of ectotherms [3].

These Late Permian therocephalians were quite diverse in size and shape. The possibly semiaquatic Perplexisaurus was only about a foot long (30cm), as was the mole-like Homodontosaurus with its upturned snout, while the super-elongated Ictidosuchoides and the chunky, gorgonopsian-like Moschorhinus were closer to 5 feet long (1.5m) and may have weighed close to 100kg, or the size of a jaguar.

Interestingly, it’s the larger therocephalians that seemed to survive the end-Permian extinction better, though the sample size is very small, so it could just be chance. Usually, the smaller, more generalist members of a lineage are the most likely to survive, but maybe in the case of therocephalians it was the larger members that were the generalists.

Cynodonts

Galesaurus, Progalesaurus, Platycraniellus, Thrinaxodon, Dvinia, and Procynosuchus

Last but certainly not least, we have the cynodonts, the group that includes true mammals. I am a cynodont!

In the Permian, cynodonts were certainly not the most important movers and shakers in their environments. They were mostly small, weasel to dog-sized carnivores and insectivores living in the shadows of the much larger gorgonopsians and dicynodonts. Who could have predicted that this group of underdogs would go on to inherit the planet, some 200 million years later?

Cynodonts and dicynodonts seem to have been particularly good at weathering the Great Dying, perhaps due to their fossorial habits, their warm blood granting them the ability to move around actively to forage even during a nuclear winter, and their ability to save energy in a state of torpor when food was particularly scarce. Or it could’ve been pure luck, or all of the above.

Many of the survivors of the Great Dying seem to have migrated to Antarctica as a way to escape the heat: after all, Siberia was exploding, and Antarctica was the furthest possible land area from there. After things quieted down a little and the lava began to cool, they radiated back across the still-walkable continents. Thank goodness it was Siberia that was on fire, rather than, say, Africa, which was much more central. The Great Dying was the closest that life has come to being reduced to only invertebrate, or even only microbial survivors. Since large-bodied tetrapods could only survive on the very furthest point from where the lava was flowing, if Pangea had been just a little smaller or the eruptions just a little less northerly, we probably wouldn’t be here today!

References

[1] Kulik, Z. T., & Sidor, C. A. (2019). The original boneheads: histologic analysis of the pachyostotic skull roof in Permian burnetiamorphs (Therapsida: Biarmosuchia). Journal of Anatomy, 235(1), 151–166. https://doi.org/10.1111/joa.12987

[2] Tseng, Z. J. (2024). Bending performance changes during prolonged canine eruption in saber‐toothed carnivores: A case study of Smilodon fatalis. The Anatomical Record. https://doi.org/10.1002/ar.25447

[3] Huttenlocker, A. K., & Botha-Brink, J. (2013). Body size and growth patterns in the therocephalian Moschorhinus kitchingi (Therapsida: Eutheriodontia) before and after the end-Permian extinction in South Africa. Paleobiology, 39(2), 253–277. https://doi.org/10.1666/12020

Pregnancy Brain: What You Should Know Before You Sign Up

Sun, 30 Mar 2025 07:11:11 +0000

The last time I discussed pregnancy on the blog, I focused almost entirely on various strange phenomena that occur in non-human animals who give live birth. This time, I’m focusing on the way one phenomenon occurs in humans: “pregnancy brain”.

Many women in their second and third trimesters report feeling foggy, absent-minded, forgetful, and inarticulate. These are symptoms of a very real, very dramatic brain reorganization triggered by those raging pregnancy hormones. It should really be called second puberty, not just because of the suite of extreme and systematic physiological changes, but also because the brain development shares some striking parallels to what goes on in both male and female brains during adolescence. The main obvious observation is a large reduction in gray matter, or the wrinkly outside part of the brain. In this post, I’ll give you an overview of what the latest science has to say about this, and answer as many questions I had about it as I can. Does it result in cognitive impairment? Does it recover after pregnancy is over? Is it cumulative across multiple pregnancies? What’s the evolutionary purpose–something must be gained, right?

What’s happening, physically?

In adolescence, people lose around 17% of their gray matter over a period of about 15 years [1]. And though “losing 17% of your brain” sounds bad, this time period, from age 11 to 26, is associated with large increases in executive function (self-control), temporal discounting (ability to refuse a small, immediate reward in order to hold out for a larger, later one), and general computational skills (could you do the math you can now when you were 11?). The way the brain grows seems to be by overproducing neurons and synapses, and then pruning excess or redundant ones to improve speed and prioritize relevant connections.

During puberty, though, the decrease in gray matter is offset by a corresponding gain in white matter in the same structure or network [2]. Gray matter is composed of neuronal cell bodies, while white matter, the layer located just below the gray matter in the brain, is made up of the long tails that stick off each neuron and connect to others. Myelin sheaths, or the fatty rings that wrap around the long portion of a neuron, which you may have heard of and which famously increase signal speed, are a component of white matter. In light of that, the increased cognitive capabilities associated with puberty make sense: the brain is getting faster and more streamlined.

In contrast, women lose around 5% of their total gray matter from 80% of brain structures during pregnancy - sweeping changes, for sure, but around three times less in magnitude than what happens during normal maturation. But there’s no accompanying white matter increase. During pregnancy white matter does increase, peaking in the second trimester, but by the time birth rolls around, the white matter is back to pre-pregnancy baseline [3]. The reason for this transient change isn’t known, but it seems like it’s likely related to the way the brain goes about performing this pruning, since the mechanisms driving brain changes during adolescence and pregnancy are much the same [4]. But the upshot is, at the end of pregnancy women have less brain than before, while at the end of puberty adults have a different but comparably-sized brain.

Physically, during both pregnancy and adolescence, the brain is flattening: the wrinkles get shallower, resulting in less gray matter without changing the overall space the brain takes up [4]. This makes sense–it’s not like your brain rattles around inside your skull more as you go through puberty.

It’s important to note that “changes in [gray matter] signal extracted from MRI images can reflect various processes, such as changes in the number of synapses, the number of glial cells, the number of neurons, dendritic structure, vasculature, blood volume and circulation, and myelination” [7]. Other factors can also include average cell body size and volume and pressure of cerebrospinal fluid [8]. That is, MRI is a pretty crude tool for measuring what’s actually going on inside a brain, because it can’t distinguish between any of these cases that all can lead to brain volume changes. As I’ve often said, medicine is in the Bronze Age compared to most sciences, and neuroscience is in the Stone Age. There is a lot that is not well understood.

Is this reduction associated with cognitive impairment?

Short answer: Yes. Pregnancy brain is real.

Long answer: Some cognitive functions are impaired, some are unaffected, and a few are enhanced. Verbal recall, or finding the word you’re looking for in real time, takes the biggest hit, with a p<0.001 confidence level difference between non-pregnant women and pregnant women [5]. The test that the researchers employed in that study to test verbal recall is pretty hilariously basic. “Naming objects and fingers: Participants were asked to name twelve real objects that were shown to them and state the name of each of the fingers of the dominant hand. Scoring: each object or finger correctly named was graded one point, to a maximum total of 17 points.” The median score in both groups was 17/17, but only pregnant women couldn’t name some of the objects or fingers and lost points. Other studies have backed up these results, such as when a “trend was observed for a reduction in the number of correct responses on the verbal word list learning task” [7].

Other areas of decreased ability include working memory, free recall, subjective memory, and processing speed. However, that doesn’t include reaction time, as there was “no difference in reaction time between pregnant and non-pregnant women in a snakes in the grass pop-out task, and further found that pregnant women were more accurate than non-pregnant women at detecting threatening stimuli (spiders) amongst nonthreatening stimuli (flowers and butterflies)” [6].

Areas of increased ability during pregnancy include recognition, especially of faces, especially same-race male faces (the most likely to attack you in the environment of evolutionary adaptiveness?) [10]; “encoding of emotions denoting threat (anger, fear, disgust) and sadness, [which] suggest that there may be a cognitive bias towards threatening stimuli in late pregnancy” [11], and “increased vigilance, which serves a protective function. Approximately 20% of the pregnant women in the study reported driving more carefully since becoming pregnant…Eight of 17 non-pregnant women were involved in a virtual collision on at least one trial, but only 1 of 13 pregnant women was involved in a virtual collision” [6]. All of these changes make sense from an evolutionary standpoint. Pregnancy is a huge investment of resources, and it’s best to avoid things (strange men, disease, dangerous situations) that could cause a miscarriage and waste all your effort so far.

Furthermore, “stress response is dampened in pregnancy; blood pressure, heart rate, and cortisol reactivity to a variety of stressors are mitigated during pregnancy…women in later pregnancy perceived major life events as less stressful than women in earlier pregnancy. For example, women who experienced a major earthquake in late pregnancy reported the event as less stressful than women who experienced the earthquake in early pregnancy” [6]. This also makes perfect sense: stress is generally bad for you. Being less stressed puts less…stress…on the baby’s fragile systems. Stress dampening is especially interesting when connected to the aforementioned increased ability to detect threatening emotions in others, because in non-pregnant people, higher sensitivity to others’ emotions is correlated with higher anxiety [6]. Pregnant women get the increased empathy without the downside.

One thing that irked me about this study, which was a review of other studies on the topic (which is why I’m citing it so much), was how they criticized how the literature tended to focus on the decline in memory performance associated with pregnancy, while not investigating potential other areas that may not be affected or even show improvements if anyone thought to ask those questions. “We suggest that the narrow focus on memory decline may be eclipsing potential advantages shared by women…A criticism that may be directed at much of the current research investigating cognition in pregnancy and the postpartum period is that the tasks employed are often abstracted verbal tasks that are devoid of ecological validity and relevance to everyday life” [6]. This is a valid point–you can only learn about the things you think of to test, and there are almost certainly tasks whose performance is affected by pregnancy that scientists just haven’t thought to test. However, the reason for the focus on memory lapses is because this is the most commonly reported symptom that pregnant women notice about themselves. Furthermore, calling the memory tests “devoid of…relevance to everyday life” is pretty dismissive. Sure, these tasks aren’t things you’d do as a cavewoman in the environment of evolutionary adaptiveness. But we don’t live that way anymore. Many women go to work, where they’re engaged in cognitively demanding tasks every day, the outcomes of which are important to their livelihoods. Dismissing these cognitive impairments as not representative of daily life is just that: dismissive.

There are also myths that mothers are better at picking out their own infants’ cries from others’, and that mothers are more accurate at decoding what the baby is crying about than fathers. But this has been found not to be true. The only variable that matters in the ability of the parent to recognize and understand their baby is how much time they’ve spent with the baby. In most households, the mom spends more time with the baby, hence the perceived gender difference. But after correcting for that, men and women perform about the same [13].

This is all during pregnancy. What about after?

The good news is, there’s a large rebound in gray matter volume immediately after pregnancy–within the first 4-10 weeks. That’s a lot of brain growth in a short time! However, it doesn’t all come back, leaving the mother with an average of 2.5% less gray matter than pre-pregnancy. And doesn’t come back the same way [8].

“We hypothesize that since the brain lies in a limited space and closed box, this prior shrinkage is required in order to prepare it for further development after parturition. The mother-baby bonding requires lots of adaptive changes in the postpartum mother’s brain, which are linked to areas concerned with social cognition, primarily in networks involved in motivation, somatosensory information and executive functions. These may be then mediated by experience-dependent plasticity during the postpartum period” [5]. In other words, there are a bunch of motherly instincts you need to download in order to succeed in child-rearing, but your existing brain doesn’t have the storage space. So you first have to delete some stuff in order to get the update.

As with adolescence, pregnancy and the immediate postpartum period are the times in a person’s life in which they’re at the highest risk of developing a psychological abnormality, like schizophrenia, bipolar disorder, or depression [4]. Large-scale brain reconfigurations are risky, as you’re destabilizing a very important and complicated system. This is what’s behind postpartum depression, anxiety, and psychosis (yes, that’s a thing): the growing pains of reinventing your brain. Or, in some rare cases, a software update that corrupts the system.

Some interesting predictive trends can be observed once the baby is out, since you can now show the woman pictures of her baby (and other babies, and other stuff) while she’s in the MRI scanner. “Several of the regions that showed the strongest neural activity in response to the women’s babies corresponded to regions that lost [gray matter] volume across pregnancy” [7]. And “increased gray matter volume in the midbrain including the hypothalamus, substantia nigra, and amygdala was associated with maternal positive perception of her baby” [9]. While at first it may seem counterintuitive that lost gray matter is associated with those brain structures that are needed to interact with your baby, it makes sense when coupled with the regrowth of gray matter after birth. Those were the areas in need of an update. And if the update doesn’t take so well–if you get the gray matter reduction but not as much recovery–it’s associated with more reported hostility toward the infant.

What causes the update not to take? While it would be interesting to know exactly what childrearing activities encourage brain growth, there are so many confounding variables across households that this is really hard to study. It would also be useful to know how the effects stack up across multiple pregnancies. I looked really hard for studies focusing on these questions, but didn’t find any. Future work!

Does it ever recover back to baseline?

No.

Even “at six years after parturition, it is still possible to accurately discriminate between mothers and nulliparous women” [12]. The transformation into a mother is a one-way trip. The structural changes to the brain that occur during a single pregnancy last a lifetime.

However…

There are silver linings. People who have kids are more resistant to the gray matter loss associated with natural aging than those who don’t. “Parity was associated with larger total gray matter volume later in life, a finding that persisted following adjustment for sociodemographic factors. The larger gray matter volume associated with parity appeared not to be driven by specific lobar brain regions, but rather was globally proportional across lobes” [14]. This applies to both men and women [15]! Not fair! Men don’t have to undergo a big brain shuffle, but still get the benefits of their wives shouldering that burden for them. In the six-year study, you can see how the controls (gray line) are also undergoing gray matter loss, just offset by the massive drop during pregnancy.

The fact that this affects both men and women indicates that the mechanism is completely unrelated to everything that happens in pregnancy, but rather is related to childrearing. We’d therefore predict that adoptive parents would enjoy the same benefits. There have been a few studies on the brain chemistry of adoptive parents and how it does become similar to that of birth parents given long enough exposure to the adopted child, but I don’t know of any studies on whether adoptive mothers’ brains undergo the same structural changes, nor of any examining adoptive parents’ brains later in life.

In addition to the benefit of hanging onto more of your brain for longer, parents always report more satisfaction with life and hopefulness about the future than non-parents [17]. This result is repeated again and again in polls–kids are good for your mental health.

Another weird note is that someone trained a machine learning model to assign an age to an MRI brain scan. It got quite good at accurately predicting people’s ages from snapshots of their brains. When applied to pregnant women, it was also accurate; but at 4-6 weeks after birth, it predicted that the mothers were on average five years younger than it thought they were before they gave birth [16]. Given AI models are black boxes, we don’t know what characteristics it’s picking up on. There’s definitely been some recent growth and reshuffling in those brains–is that what it’s seeing? Or is there some other property of young brains that postpartum women share?

Conclusion

In preparing for my own pregnancy, I read a lot of long-form books and scientific papers, trying to learn what I was in for. I think a short-form blog post would’ve been helpful to me, so I thought I’d write one to fill the gap. The pattern of brain loss and regrowth is easily observable, but still not well-understood. Most of the papers on this are quite recent, with the most recent published just this past January, so it appears that the scientific community is finally taking an interest in this phenomenon that impacts 85% of women at some point in their lives. Hopefully there will be more research soon addressing my out-standing questions… and more education generally about both “pregnancy brain” (gray matter loss) and “mommy brain” (brain rebuilding). I think it’s unacceptable that a vast majority of women go into pregnancy without understanding that they’re signing up for a complete identity overhaul. If one person reads this before pregnancy, I’ll have helped.

References

[1] Mills, K. L., & Anandakumar, J. (2020). The adolescent brain is literally awesome. Frontiers for Young Minds, 8. https://doi.org/10.3389/frym.2020.00075

[2] Bray, S., Krongold, M., Cooper, C., & Lebel, C. (2015). Synergistic Effects of Age on Patterns of White and Gray Matter Volume across Childhood and Adolescence. eNeuro, 2(4), ENEURO.0003-15.2015. https://doi.org/10.1523/eneuro.0003-15.2015

[3] Pritschet, L., Taylor, C.M., Cossio, D. et al. Neuroanatomical changes observed over the course of a human pregnancy. Nat Neurosci 27, 2253–2260 (2024). https://doi.org/10.1038/s41593-024-01741-0

[4] Carmona, S., Martínez‐García, M., Paternina‐Die, M., Barba‐Müller, E., Wierenga, L. M., Alemán‐Gómez, Y., Pretus, C., Marcos‐Vidal, L., Beumala, L., Cortizo, R., Pozzobon, C., Picado, M., Lucco, F., García‐García, D., Soliva, J. C., Tobeña, A., Peper, J. S., Crone, E. A., Ballesteros, A., . . . Hoekzema, E. (2019). Pregnancy and adolescence entail similar neuroanatomical adaptations: A comparative analysis of cerebral morphometric changes. Human Brain Mapping, 40(7), 2143–2152. https://doi.org/10.1002/hbm.24513

[5] Barda, G., Mizrachi, Y., Borokchovich, I., Yair, L., Kertesz, D. P., & Dabby, R. (2021). The effect of pregnancy on maternal cognition. Scientific Reports, 11(1). https://doi.org/10.1038/s41598-021-91504-9

[6] Anderson, M. V., & Rutherford, M. D. (2012). Cognitive Reorganization during Pregnancy and the Postpartum Period: An Evolutionary Perspective. Evolutionary Psychology, 10(4), 659–687. https://doi.org/10.1177/147470491201000402

[7] Hoekzema, E., Barba-Müller, E., Pozzobon, C., Picado, M., Lucco, F., García-García, D., … Vilarroya, O. (2016). Pregnancy leads to long-lasting changes in human brain structure. Nature Neuroscience, 20(2), 287–296. doi:10.1038/nn.4458

[8] Servin-Barthet, C., Martínez-García, M., Paternina-Die, M. et al. Pregnancy entails a U-shaped trajectory in human brain structure linked to hormones and maternal attachment. Nat Commun 16, 730 (2025). https://doi.org/10.1038/s41467-025-55830-0

[9] Kim, P., Leckman, J. F., Mayes, L. C., Feldman, R., Wang, X., & Swain, J. E. (2010). The plasticity of human maternal brain: Longitudinal changes in brain anatomy during the early postpartum period. Behavioral Neuroscience, 124(5), 695–700. https://doi.org/10.1037/a0020884

[10] Anderson, M. V., & Rutherford, M. (2011). Recognition of Novel Faces after Single Exposure is Enhanced during Pregnancy. Evolutionary Psychology, 9(1), 47–60. https://doi.org/10.1177/147470491100900107

[11] Pearson, R., Lightman, S., & Evans, J. (2009). Emotional sensitivity for motherhood: Late pregnancy is associated with enhanced accuracy to encode emotional faces. Hormones and Behavior, 56(5), 557–563. https://doi.org/10.1016/j.yhbeh.2009.09.013

[12] Martínez-García, M., Paternina-Die, M., Barba-Müller, E., De Blas, D. M., Beumala, L., Cortizo, R., Pozzobon, C., Marcos-Vidal, L., Fernández-Pena, A., Picado, M., Belmonte-Padilla, E., Massó-Rodriguez, A., Ballesteros, A., Desco, M., Vilarroya, Ó., Hoekzema, E., & Carmona, S. (2021). Do Pregnancy-Induced Brain Changes Reverse? The Brain of a Mother Six Years after Parturition. Brain Sciences, 11(2), 168. https://doi.org/10.3390/brainsci11020168

[13] Gustafsson, E., Levréro, F., Reby, D. et al. Fathers are just as good as mothers at recognizing the cries of their baby. Nat Commun 4, 1698 (2013). https://doi.org/10.1038/ncomms2713

[14] Aleknaviciute, J., Evans, T. E., Aribas, E., De Vries, M. W., Steegers, E. a. P., Ikram, M. A., Tiemeier, H., Kavousi, M., Vernooij, M. W., & Kushner, S. A. (2022). Long-term association of pregnancy and maternal brain structure: the Rotterdam Study. European Journal of Epidemiology, 37(3), 271–281. https://doi.org/10.1007/s10654-021-00818-5

[15] Orchard, E. R., Ward, P. G. D., Sforazzini, F., Storey, E., Egan, G. F., & Jamadar, S. D. (2020). Relationship between parenthood and cortical thickness in late adulthood. PLoS ONE, 15(7), e0236031. https://doi.org/10.1371/journal.pone.0236031

[16] Luders, E., Gingnell, M., Poromaa, I. S., Engman, J., Kurth, F., & Gaser, C. (2018). Potential Brain Age Reversal after Pregnancy: Younger Brains at 4–6 Weeks Postpartum. Neuroscience, 386, 309–314. doi:10.1016/j.neuroscience.2018.07.006

[17] Morning Consult. (2023). THE PUBLIC, PARENTS, AND K–12 EDUCATION. https://edchoice.morningconsultintelligence.com/assets/226853.pdf

[18] Luders, E., Kurth, F., Gingnell, M., Engman, J., Yong, E.-L., Poromaa, I. S., & Gaser, C. (2020). From Baby Brain to Mommy Brain: Widespread Gray Matter Gain After Giving Birth. Cortex. doi:10.1016/j.cortex.2019.12.029

Book Review: Sapiens

Sun, 26 Jan 2025 07:11:11 +0000

I’d been avoiding reading Yuval Noah Harari’s Sapiens for many years, ever since it appeared on the shelves of every bookstore. I’d read on the internet that it had an agenda, that it romanticized the hunter-gatherer lifestyle and was full of bad science and unsubstantiated claims. My friend started reading it a couple years ago and independently agreed with this assessment, abandoning it after a few chapters.

But more recently, it came up again in conversation, and I decided I should finally see for myself what it was like. Since my friend owned the book, I went and got it from her, so I didn’t have to monetarily support Harari. Since it was her copy, it was also full of angry post-its, which were fun to find in the course of reading.

Bottom line up front, what was the verdict? I think the world is on net better for this book existing. It definitely has some issues, overstating the effects of certain things and downplaying others to fit the author’s narrative, but it does a lot of things well and provokes readers to think about alien philosophies, which real people who were just as rational as modern people truly believed, in ways they wouldn’t normally. And this book enjoys a wide audience, bringing archaeology and philosophy and evolutionary psychology to the masses, which encourages people to find other sources and dig in deeper if it piqued their curiosity.

The main thing to know about this book is that it’s a long-form blog post, not popular science. There are some citations, but they’re fairly sparse, and the main points of the book are extrapolated from observations following a chain of verbal reasoning rather than robustly supported by evidence and statistics. That doesn’t make them necessarily wrong, and many of the conclusions he makes are interesting and persuasive, but I’m not sure if readers–including myself–are really capable of drawing this distinction long-term, when they recall topics discussed in the book. When you read something, it just goes on top of the big pile of stuff-you-know, and you don’t tend to store where you read that information and how trustworthy the source was. It’s very difficult to actually take things with a grain of salt–if you thought they were convincing at the time, they become beliefs, even if they really should only be held with like sixty percent confidence.

This is why I think the world is on net better for this book existing. There are definitely bad effects this book may cause, by presenting tenuous conclusions with high confidence. But I think the positives slightly outweigh the negatives in this case.

The takeaway

The book’s core abstract is basically, humans have been able to cooperate in large numbers and change the world because we’re capable of believing common myths. You can’t pack a thousand chimps into Trafalgar Square and expect them to behave with civility because there’s no social taboo or repercussions against flinging poo, running around, and screaming. Humans share beliefs on what is acceptable social behavior, such as wearing clothes, walking upright, not being too loud, and not making prolonged eye contact with strangers, and, more importantly, everyone else knows that everyone knows it. This common knowledge leads to the expectation that if one person violated these norms, he would be ostracized by all others, and therefore the common myth enforces specific, useful behaviors even when no one in Trafalgar Square personally knows each other. No other animals are able to do this, and therefore can only cooperate among individuals they know personally, limiting cooperation to a couple hundred individuals at most, or among individuals they are closely related to, as in a beehive, which limits optionality among individuals (you can’t decide to change careers and be a soldier if you’re a worker) and cooperation at a higher level, like between hives.

I think some people are confused or offended at Harari’s claiming stuff like “human rights” and “capitalism” are myths. But this is just disputing definitions. He defines “myth” not as something that’s inherently false, but as something that doesn’t have physical roots outside of human imagination. If humans collectively decided that humans don’t have rights, or that paper money was not legal tender, it would be so. I’ve read enough other books on evolutionary cognition to have the context to make that connection, but I could see how many readers would not. Harari does spend quite a bit of time explaining these definitions, though.

Culture tends to argue that it forbids only that which is unnatural. But from a biological perspective, nothing is unnatural. Whatever is possible is by definition also natural. A truly unnatural behavior, one that goes against the laws of nature, simply cannot exist, so it would need no prohibition. No culture has ever bothered to forbid men to photosynthesise [or] women to run faster than the speed of light (147).

Culture is a myth, in that it doesn’t have any true basis in the laws of nature. But since cultures are always incentivized to claim that they’re immutable and inevitable, most readers will probably have internalized those claims to some degree.

Things it got wrong

This is what you’re here for, right? Let’s get right into it.

Romanticizing hunter-gatherers.

The main complaint that I’d heard and read before reading the actual book was that it presented the hunter-gatherer lifestyle as healthier than the modern lifestyle, and twisted evidence to show it. This was something it did do, but it only lasted for the first hundred pages or so, and then the book moved on. It wasn’t Harari’s main point, and indeed the end of the book takes on a rather trans-humanist bent. He was mainly stressing the fact that the agricultural revolution that took place between twelve and ten thousand years ago resulted in a short-term worsening of quality of life, yet for evolutionary and game-theoretic reasons, once one group started agriculture everyone else had to follow or else lose the arms race. However, he says this in very sensational language–“The Agricultural Revolution: History’s Biggest Scam!”–and does not clearly distinguish that later, higher-tech peoples eventually surpassed the forager quality of life bar.

I think the sensational language, which is employed throughout the book, is probably one of the reasons this book sold so well. I’m not sure what to think of that. On the one hand, a paleontology book selling well is probably good for paleontology and science communication generally. But if the clickbaity word choice muddles the message, is it worth it?

The “Tree of Knowledge” mutation.

This is kind of skimmed over, perhaps because Harari was aware it wasn’t a very strong argument. He states,

Although Sapiens had already populated East Africa 150,000 years ago, they began to overrun the rest of planet Earth and drive the other human species to extinction only about 70,000 years ago. In the intervening millennia, even though these archaic Sapiens looked just like us and their brains were as big as ours, they did not enjoy any marked advantage over other human species, did not produce particularly sophisticated tools, and did not accomplish any other special feats....Teaching such an ancient Sapiens English, persuading him the truth of Christian dogma, or getting him to understand the theory of evolution would probably have been hopeless undertakings....

The appearance of new ways of thinking and communicating, between 70,000 and 30,000 years ago, constitutes the Cognitive Revolution. What caused it? We're not sure. The most commonly believed theory argues that accidental genetic mutations changed the inner wiring of the brains of Sapiens, enabling them to think in unprecedented ways and to communicate using an altogether new type of language. We might call it the Tree of Knowledge mutation (21).

This is probably the worst section in the entire book. Let’s dissect it a bit at a time.

First, he states that there was no technological progress between 150,000 and 70,000 years ago. This is simply false. This time period roughly spans the Middle Paleolithic, during which both Homo sapiens and Neanderthals were inventing different lithic cultures–that is, ways of working stones to make tools with sharp edges–that slowly progressed and evolved over that period [2]. The first burials that contain decorative or ritual grave goods such as seashells and particular animal bones are known from 130 kA and 100 kA, indicating a shift in how people viewed and treated their dead, implying some level of culture, communication, and potential spirituality. By 77-75 kA, Homo sapiens is known to have produced beaded bracelets, pigments, and carved statues [3].

Next, he claims that Middle Paleolithic Homo sapiens would not have been able to learn the way a modern human can. There is no evidence for this. While there are error bars on the emergence of anatomically modern humans, they definitely existed by 150 kA, and since they were by definition anatomically modern, that means we don’t believe there was some magical brain switch that hadn’t been flipped yet that would enable them to think the way we do. There were small further anatomical changes that came with the advent of agriculture between 12 and 10 kA, such as 3-4% smaller brains and smaller jaws more susceptible to impacted wisdom teeth, but that’s not what Harari is talking about here. He suggests that the “Tree of Knowledge mutation” occurred around 70 kA and revolutionized the way humanity operated. He also says that this is “the most commonly believed theory”, which is also totally off-base. I don’t know of any serious paleontologists who believe this. There are examples in the fossil record of rapid leaps forward, such as the emergence of neotenic chordates during the Cambrian explosion (larval sea squirts that refused to grow up, giving rise to the first fish), but the evidence simply doesn’t support the theory in this case.

The way humans are raised obviously plays a big part in what they are capable of later in life, so it’s likely you wouldn’t have been able to teach a caveman the theory of evolution because there are so many intermediate steps he would need to understand first. But if you took a Homo sapiens infant from 150,000 years ago and raised it in the modern world, it would almost certainly grow up indistinguishable from its peers. It might have a better chance of not having to have its wisdom teeth out, and it might be more vigilant and jumpy and less able to focus for long periods on delicate tasks or feel comfortable in crowds, but those differences would be minor compared to the things that it would have in common with everyone else.

He’s super down on Neanderthals.

Throughout the book, Harari makes claims that Neanderthals were incapable of certain complex behaviors, and that was what gave Homo sapiens an edge, leading to the former’s extinction. For example, he states,

Neanderthals usually hunted alone or in small groups. Sapiens, on the other hand, developed techniques that relied on cooperation between many dozens of individuals....One particularly effective method was to surround an entire herd of animals, such as wild horses, then chase them into a narrow gorge, where it was easy to slaughter them en masse....If violence broke out between the two species, Neanderthals were not much better off than wild horses. Fifty Neanderthals cooperating in traditional and static patterns were no match for 500 versatile and innovative Sapiens. And even if the Sapiens lost the first round, they could quickly invent new strategems that would enable them to win the next time (36).

This is again not true at all. Neanderthals are also known to have employed the tactic of driving herds into terrain where the hominids would have an advantage–and in fact, they routinely did this, while Homo sapiens more often simply out-marathoned their prey, chasing it until it could no longer move [4]. The claim that Neanderthals could only behave in “static patterns” is not based on anything; Neanderthals existed in Eurasia over a wide range of time and space, covering conditions from the tropical rainforests of Eemian Spain to the icy tundras of Ice Age Russia. Neanderthals who lived in different conditions had to be adaptable in order to persist there, and there’s ample evidence that groups in different places gathered different plants and hunted different prey, depending on what was available.

The more likely reasons that Homo sapiens ended up outcompeting the Neanderthals is not due to inherent superiority of one over the other, but rather due to the way their slight differences in biology influenced the way they lived. Neanderthals required many more calories to survive, potentially as many as 7000 per day for an adult male living in a cold climate [2]. This meant that they required a larger range to support a smaller number of individuals. Since individuals were more sparsely distributed, this limited their ability to trade, communicate, and cooperate between family groups, slowing technological progress. This progress was further hindered by the fact that Neanderthals didn’t benefit as much as Homo sapiens from projectile technology or things like needle and thread. Neanderthals delivered the killing blow to their prey by bracing a heavy spear against the ground and having other party members drive a large animal to impale itself on it. They were strong enough to take down mammoths and other giant animals in this way, while Homo sapiens would have been crushed if they’d tried the same. And since Neanderthals were larger and stockier, they ran hotter, and wouldn’t have needed clothing to fit as snugly or layer as easily as Homo sapiens. Since they didn’t need the tech, they didn’t develop it. But while projectiles were superfluous for hunting mammoths, they would have been perfect for Homo sapiens to repurpose for slaughtering Neanderthals.

In addition, due to Neanderthals’ higher caloric requirements, they were simply never as numerous as Homo sapiens. That meant that even if Homo sapiens never killed Neanderthals and only interbred with them, the resulting hybrid species would be expected to come out looking mostly like Homo sapiens. The reality is that we did both kill them and interbreed with them, and now most people are somewhere in the range of 1-5% Neanderthal. But that’s still a fairly large and detectable amount–you share only 3.1% of your genes with your great-great-great-grandparents–indicating that interbreeding was happening on the regular. If Neanderthals were considered human enough that first-generation hybrid children were allowed to go on and reproduce, they couldn’t have seemed that alien to our long-ago ancestors.

Neanderthals continue to crop up throughout the rest of the book, always used as an example of a brutish, stereotypical caveman. On the second-to-last page, when discussing potential transhuman creations, the author says, “We would have a hard time swallowing the fact that scientists could…create something truly superior to us, something that will look at us as condescendingly as we look at the Neanderthals (412).” I crossed out “we” and wrote “I, Yuval Harari”.

Claims that modern humans are no happier than the ancients.

In one of the last chapters of the book, Harari asks the question whether we can determine how happy people were in the past (do we even know the right questions to ask, given their expectations around what constitutes a good life would have been quite different?), and if we can, whether humans are happier now or back then. He argues,

Compare a medieval French peasant to a modern Parisian banker. The peasant lived in an unheated mud hut overlooking the local pigsty, while the banker goes home to a splendid penthouse with...a view to the Champs-Elysées....When the medieval peasant completed the construction of his mud hut, his brain neurons secreted serotonin, bringing it up to level X. When in 2014 the banker made the last payment on his wonderful penthouse, brain neurons secreted a similar amount of serotonin, bringing it up to a similar level X....Consequently the banker would not be one iota happier than his great-great-great-grandfather (389).

This is true–happiness levels are largely inborn and quite resilient to external conditions, recovering back to baseline even after winning the lottery or sustaining a life-changing disfigurement. However, it does not take into account the fact that the medieval peasant had much higher chances of something tragic happening to him: barbarians could burn down his village, rape his wife, and tie his intestines to a tree; he could easily contract cholera, smallpox, TB, plague, etc; he could scratch his arm on a berry bush and have the cut become infected, resulting in death; he could expect to lose fifty percent of his children before age fifteen, and his wife to childbirth at some point. All of those things have a measurable effect on happiness levels, and it’s absurd not to include these risk factors when determining if people in the past were happier.

Reducing things to dichotomies and being generally overconfident.

The book often reduces complex hypotheses to simple “some scientists believe extreme A, while others believe extreme B” dichotomies, as a sort of rhetorical method of introducing ideas. It then goes on to describe how reality is probably somewhere in the middle, which is true. One memorable example is regarding the above-discussed reason for Neanderthal extinction at the hands of Homo sapiens: Harari states that some believe Homo sapiens went on a genocidal rampage, while others believe we absorbed them through interbreeding. In reality, no one believes either extreme, so the framing of the explanation is misleading. Another example is on the topic of the family structure of ancient foragers. According to Harari, some believe that they lived in communes and had free sex with everyone, while others believe they were strict monogamists. In all likelihood, the full range of human behavior was represented at some particular time and place. No one really believes that ancient human social customs were uniform and rigid.

He also states things that are pet theories in tones that make it seem like they are fact. Many of Harari’s pet theories are pretty good, but they’re a long way from scientific consensus. For example, he says, in the chapter on capitalism,

The problem in previous eras was not that no one had the idea [of credit] or knew how to use it. It was that people seldom wanted to extend much credit because they didn't trust that the future would be better than the present. They generally believed that times past had been better than their own times and that the future would be worse, or at best much the same....As Jesus said, 'It is easier for a camel to pass through the eye of a needle than for a rich man to enter into the kingdom of God'. If the pie is static, and I have a big part of it, then I must have taken somebody else's slice (308).

This is an interesting argument that probably has some basis in fact. Basic financial instruments like loans with interest have existed for nearly as long as coinage has existed, and certainly existed in Jesus’s day. But the machinery of capitalism didn’t really take off until the era of colonialism and exploration, in the 15th century. This worldview is one way to explain that gap. However, I think it’s unlikely that Jesus had that in mind when saying the line about the rich. It probably had more to do with the fact that rich people could easily become distracted by the accumulation of more wealth and the pleasures of living in luxury instead of spending time thinking about God and praying. If you have everything you need, what do you need to pray for? It’s a bit of a stretch to include this famous Bible verse as an argument in favor of this economic theory.

Things it got right

The two things that stand out to me that Harari does well are (1) favoring mechanistic explanations of phenomena–how a property of one strategy or belief results in it outcompeting others–and (2) assuming that ancient humans were rational, thinking beings like ourselves, and trying to get into their mindset to see how they could’ve believed crazy things like Zeus literally hurling thunderbolts. Both of these rhetorical strategies come through in his writing throughout the book, and I think they’re both pretty rare in other writing–Paul Graham comes to mind as another writer with this level of empathy and mechanistic understanding, but it’s definitely not the norm. This alone I think makes up for Sapiens’s shortcomings.

The gradual takeover of agriculture (and monotheism and imperialism)

If you believe Harari’s claim that agriculture was history’s biggest scam, why did we fall for it?

Whenever they decided to do a bit of extra work--say, to hoe the fields instead of scattering seeds on the surface--people thought, 'Yes, we will have to work harder. But the harvest will be so bountiful! We won't have to worry any more about lean years. Our children will never go to sleep hungry.'...But people did not foresee that the number of children would increase, meaning that the extra wheat would have to be shared between more children....If the adoption of ploughing increased a village's population from a hundred to 110, which ten people would have volunteered to starve so that the others could go back to the good old times? (87)

The key insight is that often, incentives result in outcomes nobody wants [5]. Since agriculture is more efficient, allowing the same land to feed more people, once you’ve made that transition you can’t go back to foraging, because there are too many people for that inefficient way of life to support.

Harari provides similarly mechanistic, gradual explanations of how monotheism became the dominant religious mode over polytheism, animism, and what he calls “dualism” (belief in a good and evil god, not to be confused with Cartesian dualism, which is the belief in separation of body and soul).

Since monotheists have usually believed that they are in possession of the entire message of the one and only God, they have been compelled to discredit all other religions. Over the last two millennia, monotheists repeatedly tried to strengthen their hand by violently exterminating all competition (218).

In all worlds, you would therefore expect monotheism to outcompete all other faiths, due to the inherent incentives of monotheism.

Similarly, imperialism is by nature a dominant philosophy. Empires made all kinds of other excuses to themselves about why they were doing what they were doing, such as spreading the good word of Christ or democracy or technology to peoples who lacked it. But conquering and exploiting foreign lands was very profitable at the time (it’s no longer that profitable because the biggest wealth-generators are educated humans), and profit could be reinvested in more expeditions to make more profit. Regardless of the secondary reasons, it was a self-perpetuating system.

Explaining how smart people could believe unintuitive philosophies (and deconstructing familiar ones)

There’s a long chapter on religion, why and how different families of religion sprung up throughout history to suit the needs of that particular time and place. In particular, his descriptions of polytheism and of Nazism (which he calls a type of “evolutionary humanism”) are notable, since I’ve never really heard a compelling explanation of why those belief systems would have captured rational people before.

Polytheism does not necessarily dispute the existence of a single power or law governing the entire universe. In fact, most polytheist and even animist religions recognized such a supreme power that stands behind all the different gods....[but] the supreme power governing the world is devoid of interests and biases, and therefore it is unconcerned with the mundane desires, cares and worries of humans. It's pointless to ask this power for victory in war, for health or for rain, because from its all-encompassing vantage point, it makes no difference whether a particular kingdom wins or loses (214).

Furthermore, polytheism does a better job of explaining both the question “if God is omniscient, omnipotent, and omnibenevolent, why do bad things happen to good people?” and “if God and the Devil are fighting, what rules must they both obey, and who made those rules?” than monotheistic or dualistic religions. The gods are not all-powerful, and they’re often at odds with each other’s goals, but they’re all beholden to the impersonal power that’s above them all. As a sort of funny aside, Harari suggests a method for monotheism to explain the question of evil:

Monotheism explains order, but is mystified by evil. Dualism explains evil, but is puzzled by order. There is one logical way of solving the riddle: to argue that there is a single omnipotent God who created the entire universe--and He's evil. But nobody in history has had the stomach for such a belief (221).

After monotheism, Harari claims that what he terms “humanist” religions have dominated the last couple centuries. Among these are “liberal humanism” (belief in human rights), “socialist humanism” (Communism, the belief in the greater good), and “evolutionary humanism” (Nazism, the belief that humans might evolve into superhumans or devolve into subhumans, and believers must encourage the former and discourage the latter). Linking these three belief systems because they all worship humanity as the source of morality (and terming them “religions”) is an interesting strategy that I think a lot of readers would disagree with, at least at first. But I think the detailed explanation of how a reasonable person might believe these things is useful for understanding people who are often portrayed as historical villains.

“Evolutionary humanists” were right about the capacity of humans to evolve, and it makes sense that given that premise you would want to encourage “advanced” people to breed and “primitive” ones not to. They were wrong about most of the practicalities of distinguishing between groups of people, though, and in the brutal methods of enforcement. Harari notes that ironically, the Nazis’ extreme policies doomed more than just themselves, but racism as an acceptable philosophy across the world. Prior to World War 2, many respected scientists and politicians believed in evolutionary humanism to some degree. Afterward, no one would touch anything that sounded remotely similar to eugenics with a ten-foot pole.

Interesting conjectures

In addition to the confident-sounding explanations he gives for most historical happenings covered in the book, there are a few places where Harari makes conjectures with a little less force. These hypotheses are interesting, but either unsupported or too fresh to know the long-term outcome yet.

Decline of extended families and rise of the individual

A small section in the last few pages is dedicated to explaining how we got from medieval noble boys living together in a hall of the castle, their behavior on display at all times and the most important property of each boy being what the other boys thought of him, to children expecting to have individual bedrooms with closable doors that parents must knock on to ask permission to enter, and being told that they can do anything that they set their mind to, screw the haters. In other words, how the extended family and neighborhood community became much less important, and the sense of individualism much more important in the last century or so.

Even in large empires such as China or Rome, people in the past used to be organized into family-based community groups, who were responsible for working out all internal affairs among themselves and collecting their own taxes to then relay on to the kingdom. They provided their own education, healthcare, police, and legal services, and if they didn’t meet the kingdom’s standards, were punished collectively. This was for simple logistical reasons: the empire couldn’t feasibly go out to every peasant and understand his income and production well enough to collect appropriate taxes, and similarly couldn’t enforce consistent laws or educational standards across its entire domain. But as transportation and communication technology improved, it became possible for the government to have more insight into what individuals were up to. Now, if parents abused their children, the government could know and take the children away. If children weren’t being educated, the government provided schools. If people were dying of disease, the government built hospitals. And if you committed a crime, your cousin wouldn’t be punished for it alongside you. With the advent of lots of state-sponsored services, people were no longer dependent on the services their extended families once provided, and with the simultaneous consolidation of people into cities with corresponding job opportunities there, people started moving away from their hometowns at much higher rates than before.

All this makes sense, and the haphazard nature of the transition explains why we don’t really have good substitutes for the sense of community that the extended family used to provide. No one was consciously trying to create individuals and expiate the extended family; technology simply allowed people to drift away. However, Harari doesn’t put forth a theory to explain how the culture shifted so radically and so quickly, from your sense of self-worth coming from being respected by your peers to coming from your own individual accomplishments. The transition happened quite rapidly and mirrored the actual changing conditions, but it didn’t logically have to be that way. People could in theory still tell their children that the most important thing was to bring honor to the family, but we don’t.

The flip in consumerist messaging

Given capitalism is a very successful, self-perpetuating system, and it requires people to buy things to fuel continued economic growth, it makes sense that consumerism rose up alongside it. Capitalists are incentivized to try to incentivize consumption. But in the past, conspicuous consumption was seen as morally wrong, while today, basically any chocolate bar you pick up has the words “decadent” and “indulgent” printed on it. Snack foods claim “you deserve it”, spas tell you to “treat yourself”, and fancy cars advertise themselves as being the height of luxury.

Throughout history, people were likely to have been repelled rather than attracted by such a text. They would have branded it as selfish, decadent, and morally corrupt. Consumerism has worked very hard, with the help of popular psychology...to convince people that indulgence is good for you, whereas frugality is self-oppression (348).

But he doesn’t explain how consumerism managed this remarkable reversal.

Against the plow hypothesis

Going back a ways, Harari asks the question why patriarchal societies are so much more common than matriarchal ones (though the latter does exist). I’ve written about this before, particularly the “plough hypothesis”, which finds a strong correlation between geographical areas where plowed cultivation was practiced and modern-day markers of misogyny. However, Harari isn’t a fan of this hypothesis, attempting to debunk it along with two other hypotheses to explain the prevalence of patriarchy.

First, regarding the plough hypothesis, he says, if strength is key to men’s dominance, why are the people in charge usually coalition-building strategists rather than strong individuals? Who your allies are is much more important in human, chimp, and bonobo society (chimps are patriarchal while bonobos are matriarchal) than your physical strength. There’s nothing he can think of stopping women from banding together to fragment and overpower men. This doesn’t address the actual numeric findings of the plough hypothesis, but asks it to hypothesize a mechanism for the correlation, because the obvious one doesn’t seem to fit.

Next, the aggression hypothesis: since men are more aggressive due to higher levels of testosterone, they’re more motivated to take risks and seek power. But while true that men make better foot soldiers (in an era of simply charging at the enemy and overwhelming through brute force), it doesn’t follow that generals should also be hyper-aggressive. To win wars, generals have to be more strategic than blindly rushing in, and per this hypothesis, women might make better generals.

Finally, there’s the demands of biology. Giving birth to and caring for children is very physically and calorically demanding, and women with support from others have much better outcomes than hermits. It indeed takes a village. But this doesn’t necesarily imply they need a man; why can’t they get help from other women–grandmas, sisters, adolescent babysitters, and the like?

After dismissing all these hypotheses, though, Harari doesn’t present an alternative.

Conclusion

There’s definitely a lot about this book that I’d consider problematic, in that either opinions are presented as fact or some conclusions are simply wrong. But the early history stuff is not a large part of the book, and even then, it’s still thought-provoking, and it’s rare that a paleontology book gets this wide of distribution. So if you think you’re capable of reading with a grain of salt (or at least, rereading this post afterward to remind yourself of what it got wrong), I do think reading this book will spark some interesting conversations, make you consider points of view you hadn’t before, and potentially lead you to look more into topics you didn’t know you were interested in.

References

[1] Harari, Y. N. (2014). Sapiens: A Brief History of Humankind: The multi-million copy bestseller. Random House.

[2] Sykes, R. W. (2020). Kindred: Neanderthal Life, Love, Death and Art. Bloomsbury Publishing.

[3] BBC NEWS / Science/Nature / Cave yields “earliest jewellery.” (15 April 2004). http://news.bbc.co.uk/2/hi/science/nature/3629559.stm

[4] White, M., Pettitt, P., & Schreve, D. (2016). Shoot first, ask questions later: Interpretative narratives of Neanderthal hunting. Quaternary Science Reviews, 140, 1–20. https://doi.org/10.1016/j.quascirev.2016.03.004

[5] Alexander, S. (2023, November 19). Meditations on Moloch. Slate Star Codex. https://slatestarcodex.com/2014/07/30/meditations-on-moloch/

Obscure Dinosaur Facts

When Earth Was Middle Earth: Speculations on the Hominins of the Middle Stone Age (Part 2)

Homo longi: “dragonfolk”

Homo neanderthalensis: “tidefolk”

Homo sapiens: “kinfolk”

Conclusion

When Earth Was Middle Earth: Speculations on the Hominins of the Middle Stone Age

Homo naledi: “treefolk”

Homo erectus: “firstfolk”

Conclusion

Breastfeeding: An Evolutionary History

How did milk evolve?

Why don’t female apes have visible breasts?

Why two breasts? Most animals have them in rows.

Pediatricians recommend breastfeeding for a year. How long is “natural”?

Why do cows only have to be milked twice a day?

Conclusion

Rate My Dino 6: Dino Days at the Cal Academy of Sciences

Book Review: Dinosaurus

Dinosaurs: nit by nit

Prehistoric Beasts

Events And Time

Prehistoric Planet

Scientific Terms

Conclusion

Rate My Dino 5: Paris Galerie de Paléontologie et d’Anatomie Comparée

Dinosaur Photography #14: Birds of France

Paris Birds

Annecy Birds

Canada Birds

Mountain Birds

Vancouver Birds

Non-birds

Others

Prehistoric Beast Profile #6: All the Permian Synapsids

Biarmosuchians

Gorgonopsians

Dicynodonts

Therocephalians

Cynodonts

References

Pregnancy Brain: What You Should Know Before You Sign Up

What’s happening, physically?

Is this reduction associated with cognitive impairment?

This is all during pregnancy. What about after?

Does it ever recover back to baseline?

However…

Conclusion

References

Book Review: Sapiens

The takeaway

Things it got wrong

Romanticizing hunter-gatherers.

The “Tree of Knowledge” mutation.

He’s super down on Neanderthals.

Claims that modern humans are no happier than the ancients.

Reducing things to dichotomies and being generally overconfident.

Things it got right

The gradual takeover of agriculture (and monotheism and imperialism)

Explaining how smart people could believe unintuitive philosophies (and deconstructing familiar ones)

Interesting conjectures

Decline of extended families and rise of the individual

The flip in consumerist messaging

Against the plow hypothesis

Conclusion

References