Epistemic Spot Check: Sapiens (Yuval Noah Harari)

Usually I try to write full reviews and only on things I recommend, because take downs are easy and there’s enough negativity in the world.  But a few people on facebook expressed interest in having me factcheck early chapters in books, so they could know what was worth trying.  This is my test of that.  Please let me know what you find useful and not useful about the formatting or information here.

How this worked:  I listened to Sapiens.  When he said something interesting, counterintuitive, or that conflicted with other information I had, I looked it up.  In this post I’ve detailed the claims he made and what my investigation revealed, regardless of who was right.  I’ve also included some correct claims I didn’t need to look up because it’s important to talk about what people get right, and because it changes the way I read the book for the better.

I realize page numbers would be very helpful here, but I’m listening to this on tape so no dice.

False Claims

Claim: humanity’s big break was using tools to access bone marrow from carcasses left behind by lions and hyenas (in that order).  

Marrow is a fantastic source of calories and micronutrients, so this would certainly be a good way for an expensive brain to pay rent.  But I have two problems with this explanation.  One is that we’ve known for decades that lions steal from hyenas much more than the reverse.  Repeating the trope that lions are majestic predators and hyenas dirty scavengers is just lazy.  My second problem is that hyenas can eat bones.  And none of this pansy using a tool to extract the fat nonsense.  They put a bone in their mouth and chew.  Eating marrow after hyenas pick over the carcass is not a viable plan.  There are lots of other ways sapiens could still have made bone scavenging work for them, like working between the lions and the hyenas.  But this is starting to sound much more like a nature show fairy tale than science.

There is a strong school of thought that humans did in fact start as scavengers, although no one can decide if they were the scavengers of last resort, or if social coordination let them push lions off their own kills (PDF).  Personally I’m partial to the endurance hunter hypothesis, but they’re not mutually exclusive and interestingness is not a good predictor of truth.

Claim: Dunbar’s Number, both the value and what happens when you exceed it, is settled science.

I didn’t actually research this one, but nothing in sociology is as settled as he presents this to be.

Claim: Humans are the only animals that have cultural evolution independent of genetic evolution.

This is not true.  There are many documented reports of social transmission of new tool use and behavior  within monkey troops.  Not to mention persistent communication and behavioral differences between primate and cetacean social groups.

I will freely admit that humans are in a league of their own when it comes to cooperative tool design and use, but that’s not what Harari said.  He denied all cultural transmission of ideas among all other animals.

Tenuous Claims

Claim: something overly poetic about the ascendency of man 

“the world had time to adjust to lions becoming awesome.  Humanity became an apex predator so quickly the world didn’t have time to adjust.  Humans themselves didn’t have time to adjust.  “…Sapiens, by contrast, is more like a banana republic dictator.  Having so recently been the underdog of the Savannah, we are full of fears and anxieties over our position, which makes us doubly cruel and dangerous.  Many historical calamities, from deadly wars to ecological catastrophes, have resulted from this overhasty jump.”

My first instinct was that this is not even wrong enough to investigate.  On the other hand, approximately 104% of my friends have anxiety disorders- could that be because we didn’t have time to evolve out of our fear of predation?  A fairly well accepted but hard to test hypothesis is that a lot of modern human problems come from a mismatch between a stress system meant to handle predation and the problems we’re exposed to now.  Cortisol, the longer lasting of the stress hormones, increases heart and breathing rate, and inflammation, and decreases energy sent to digestion and the long term immune system.  This is a great trade if you are running from a tiger; the increased blood flow and heavy breathing send more oxygen to your muscles, which facilitates running the fuck away.  The inflammation increases the rate at which wounds close.  Your sleep will be lighter so you’ll hear the tiger coming.  Difficulty digesting and fighting parasites is irrelevant if you’re dead, so who cares?  But if the problem is, say, you work in an unstable industry and are constantly afraid of being fired, cortisol is not very helpful.  Sleep deprivation will muddle your thinking.  You’ll get sick more and get fewer nutrients.  And inflammation is responsible for approximately everything bad, so good luck with that.

So there is a sense in which the original statement is close enough for poetry’s sake.   And in one sense it’s tautologically true that if the world had time to adjust to our evolution we wouldn’t cause quite so many ecological dumpster fires.  But framing this as some sort of Napolean syndrome seems suspect to me.  We are so secure in our superiority over lions we get sad when you kill our favorites.  We have a whole week dedicated to celebrating 400 million year old killing machines in the one niche we don’t dominate.

So this claim is a little too gaia-worship to me, but not actually wrong.

True Claims

Claim: Humans are the only animal that barter.  

I thought this was wrong, but it turns out to be correct.  The closest thing to an exception is chimpanzees, who will trade food for sex, but it seems more like a gift economy.   They can be trained to trade food products in a lab, but even with extensive training will do so only reluctantly.  Neither of these impugn the point.

Claim: The development of cooking opened up early humans’ options.

It rendered undigestible foods digestible, made all foods take less energy to digest, and killed pathogens, letting us invest less in our immune system (especially important if any of the scavenger hypotheses are true).

Claim: intelligence and walking upright combine poorly.

A combination of larger heads and the pelvic changes required to walk upright were hell on women, leading to human babies being born underdeveloped and a higher maternal death rate in childbirth.

Slightly suspect: comparisons of the abilities of human neonates to gazelle neonates.  Prey animals are always born more developed than predator animals because your parents can hunt for you in a way they can’t run from predators for you.  Harari also makes the much more valid comparison to tiger kittens, and the point isn’t wrong; human infants are shockingly undeveloped for placental mammals.  But including the gazelles is pointlessly misleading.

Claim: Homo sapien mostly killed other homo species but did interbreed with them a little

DNA analysis shows that Europeans have small amounts of neathanderthal DNA and east asians have small amounts of denisovan DNA.

Claim: The word Homo in Homo sapien means “man” or “human” in Latin.

I was going to get really snotty about this, because everyone knows homo means same.  Turns out that’s what it means in Greek.   In Latin Homo does in fact mean “human.”  Touche, book.

You Lost Me At…

Timestamp 1:18 (out of 14:04)

This is where Harari lays out his thesis: humans ability to create universally agreed upon abstractions like gods, laws, and corporations is the thing that led us to create civilization.

This sounds plausible and I would like to hear more.  However I get the distinct impression he thinks cultural evolution is opposite or at least orthogonal to biological evolution, as opposed to a tool of it.  He uses Catholic priests and Buddhist monks as examples of people driven by cultural forces to take paths that are obviously evolutionary dead ends.  I know more about the Catholic Church than I do about Buddhist monks so that’s talk about that .

The most obvious flaw: taking a vow of celibacy is not the same as being celibate.    Hard number for low ranking priests are hard to find, but please enjoy this list of sexually active popes.  Additionally, the reason I struggled to find accurate numbers on medieval priests is that the google results were dominated by the modern Church’s sexual abuse scandals.

Next, not having children is not the same as being an evolutionary dead end.   Naive group selection is not a thing, but kin selection totally is.  Being a local priest and putting your thumb on the scale in favor of your nephews is a perfectly viable evolutionary strategy.

Third, he asserts that myths such as Catholicism drive people to actions independent of environmental conditions.  This is not true.  As societal wealth rises (and nobles no longer need someone safe to stash third sons) the Catholic Church has had a harder and harder time finding people willing to take vows.  They increasingly rely on unordained deacons and priests from third world countries.

Culture can definitely induce changes that are counter to one’s genetic interests.  But that’s an accident, the same way that cancer is an accident.  The interesting thing is how biological evolution created a platform through which cultural evolution could serve our biological interests (on average).

For a while I worried I was being uncharitable because he wasn’t paying sufficient respect to my pet subject.  This doubt went away at 1:18, when he said “The cognitive revolution is accordingly the point when history declared its independence from biology.”  He does walk this back a little, but some things can’t be unsaid.


A couple of sloppy simplifications that aren’t deal breakers but do lower the value of the author’s word.

Author’s understanding of evolution too weak for me to want to hear more.  Sometimes I like seeing other people’s models of the world even if they’re not literally true, but explaining culture without genetics feels completely unmoored to me.

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