Epistemic Spot Check: The Alchemy of Air (Thomas Hager)

[content warning: war, the Holocaust]


Fixed nitrogen is a startlingly important molecule, essential in both explosives and farming. Until the 1900s, turning atmospheric nitrogen (which is abundant) into fixed nitrogen was the purview of a handful of bacteria, and countries went to great length to get more.  Several wars were fought and decided over/by who had better access to nitrogen stores.

In the early 1900s, German scientist Fritz Haber invented (and engineer Carl Bosch industrialized) a process for producing fixed nitrogen.  This changed the world on a number of levels:

  • Removed the nitrogen-induced cap on the human population, which was ~4 billion people.  You know how people say it’s impossible for everyone to eat organic?  This is why.  There is not nearly enough natural fixed nitrogen to feed everyone.
  • Prolonged Germany’s involvement in World War 1 by one to two years, by both increasing the volume of explosives they had access to and by making it possible to feed people from relatively poor farmland.
  • Was part of a larger shift in Germany becoming an economic and scientific power.

The Alchemy of Air starts with a longer description of why fixed nitrogen is so important.  The meat of the book  is the invention of the Haber-Bosch process and the life stories of the two men responsible for it.  It touches on the chemistry of nitrogen, how a proof of concept becomes and industrial process at the age when those were beginning to separate.  At the end, it offers a glimpse into the rise of Hitler and the Nazi party as viewed by the scientific community.

Fact Checking

Claims: “Nitrogen is the most important element… for humans”, “more interesting than other elements.”  “Nitrogen is a/the rate limiting factor in life on Earth.  If you put more fixed nitrogen in a field, you can grow more.” (Prologue).

True-ish. I don’t know how to fact check which element is more interesting.  I went through 7 semesters of college chemistry without picking a favorite element.  But the more factual claim that nitrogen is a major limitation of growth on life on Earth checks out.  The other major elements we need- carbon, oxygen, and hydrogen- are relatively cheap to create from molecules found in the air (although oxygen is the limiting factor in certain aquatic ecosystems- and as you learn at the end of the book, fixed nitrogen abundance makes this worse).    Atmospheric nitrogen makes up 80% of the air, but it is incredibly energetically expensive to convert that into nitrogen useful to plants and animals (known as fixed nitrogen)

Claim: “N2 is [harder to break down because it is] held together with a triple bond, the strongest bond in nature.” (prologue)

True but incomplete. Nitrogen does use a triple bond.  On average, triple bonds will be more expensive to break or form than double or single bonds.  But carbon can form four bonds.  You can’t actually have a stable quadruple bonds because of complicated shape things, but they can triple bond with each other and each have a side chain.  It’s possible HCCH is just as expensive to break apart, but there’s enough carbon in easily accessible forms that it doesn’t matter.

Also, the fact that N2 (the kind of nitrogen found in the atmosphere) is expensive to break doesn’t explain why fixed nitrogen makes such an excellent explosive.  The fact that it is implies that fixed nitrogen is also energetically expensive to make.  The internet is rather lacking on this topic, but the fact that fixation is net negative on ATP (the energy currency of living things) suggests that I’m right.  “This bond stores a lot of energy” is not actually a good argument for why no one breaks it.

Claim: “Using [their complicated farming system involving three different animals and five different types of plants], the Chinese could feed as many as ten people per acre of farmland, a yield of food five to ten times greater than the European average of the 1800s” (p5)

True but misleading. Verifying this is surprisingly hard, but I do know that Chinese agriculture was incredibly labor intensive, much more so than European farming.  That’s why 1800s China has a bunch of proverbs about working hard and Europe had a bunch of proverbs about hoping it rained (source, although I’d like to do a fact check on this one).

Claim: Haber-Bosch uses 1% of the Earth’s energy (p271)

True, although this refers only to generated energy and not natural sources like the sun or underwater vents.

Claim: “Half the nitrogen in your blood, your skin and hair, your proteins and DNA, is synthetic” (p272)

False.  The atom was nitrogen when you found it and it’s nitrogen now.  The molecule that delivered it to the plant was synthetically produced, but the nitrogen has always been itself.  At a minimum, synthetic should mean you found different atoms and combined them into something new, but chemistry has an even stricter definition: elements that do not exist naturally and must be created in a lab.

Claim: “Nitrogen pollution in the water has been to linked to health problems like methemoglobinemia, or “blue baby syndrome”” (p274)

True.  The EPA supports this, although it appears there’s still some scientific controversy over exactly how large a role nitrogen plays.

Claim: Nitrogen run off causes algal blooms that devastate aquatic ecosystems (p274)


Claim: A long history of saltpeter I’m not going to transcribe fact-by-fact (chapter 1)

True.  I didn’t run down every fact but everything I could find checked out, and his conclusions (saltpeter was incredibly valuable) are supported by other information he didn’t mention.

Claim: Darwin was hired onto the Beagle as someone of suitable social stature for the captain to talk to so he didn’t go mad.


Claim: After saltpeter, bird shit became the coveted resource (chapter 3)

True. Again, I didn’t run down every single thing, but guano was the immediate catalyst for the South American colonies to revolt against the Spanish, the USA still has a law on the books allowing any citizen to claim guano rich islands for the country.

Other thoughts

Alchemy of Air is a weirdly uneven book.  I don’t think this is writing style, I think it’s just covering a lot of different material and what people find interesting varies a lot.  For example, I loved the sections on the history and economics of nitrogen, and how the Haber-Bosch industrial process for producing fixed nitrogen from the air affected World War 1.  The fourty three chapters on Bosch taking Haber’s proof of concept to a scalable industrial process?  Do not care.  Almost quit book until I remembered I could just skip them.

The parts on the personal lives of Bosch and Haber were very mixed bag.  Mostly boring, but intricately involved with the extremely interesting things that were happening at the time (~1900 to the rise of the Nazis).  Fritz Haber was a German Jew who merged love of science with love of country in his mind, and converted to Christianity in part so he could be viewed as more fully German.  The Haber-Bosch process probably bought Germany another year in World War 1, probably two.  He played a major role in inventing chemical warfare (Alchemy would have you believe he invented it, but is prone to exaggeration).  You can guess how this ends.  In 1934 he flees the country, made more difficult by the fact that the rest of the world still considers him a German war criminal.  The chemical he invented for use on Allied soldiers in WW1 is adapted for use in the concentration gas chambers in WW2.

Bosch’s life is also complicated.  Between the wars he dedicated everything he had and then some to inventing a way to synthesize gasoline.  This included collaborating with the early Nazi party for funding.  They were happy to do so because they, correctly, anticipated that an internal source of gas would be necessary in the upcoming war.  At some point Bosch realized what he’d done, made a bunch of symbolic gestures against the Nazis, and died in disgrace.  It’s weird because those symbolic gestures probably cost him a lot and accomplished nothing, whereas there’s some chance he could have prevented WW2 and the entire Holocaust by not working quite so hard to create synthetic gasoline.  By the time the Nazis were in power it might have bankrupted his company to stop, but it was still doable.  Maybe someone else would have invented synthetic gas… but Bosch’s company was uniquely well positioned to do so, and he basically willed it into existence by convincing an increasingly large collection of people to toss money at the process.  He didn’t even have to give up, he just had to try less hard on fundraising.

And of course both men have saved/enabled billions of lives by creating the process that feeds them.

I don’t know what to do with this information.  The world is complicated and I want the right thing to be obvious.


Generally reliable, moderately stylized.  I trust the author for broad strokes but not to give me non-nitrogen related nuance.

This post supported by Patreon.

If you like my epistemic fact check posts you’ll probably enjoy Scott’s extremely thorough review of The Hungry Brain.

One claim is that hyperpalatable foods (through a long scientific process) lead to weight gain, and bland foods lead to weight loss or maintenance.  I think we should not assume bland is the opposite of hyperpalatable.  Hyperpalable refers to food with a very high ratio of [calories/sugar/fat/unami] to [fiber/anything else that makes us feel full].  There are foods that have a reasonable ratio of those things and yet are not bland, because they have so many spices.

Conventional wisdom is that variety spurs us to eat more, but my personal experience is that I will feel full faster with a novel food, or even a familiar food with a novel twist.  I will go through a bunch of staples never feeling full, then eat three cashews with weird spices on them and be totally fine.

Meanwhile soylent, which is the blandest thing in existence, only registers as food on a certain level.  This is good when I really don’t feel like eating but need nutrients, but bad when I’m traveling and would really like to feel full and the other option is pretzel bits.

World War Technology

[Content Warning: both World Wars, the Holocaust]

I have a very vivid memory of reading Cryptonomicon, where a character explains that the Allies won World War 2 because they worshiped Athena (technology, strategy), and the Germans worshipped Ares (Brute Strength, physical and moral).

[Some of you may be thinking “But German craftsmanship was better, right?  It took 5/10 American tanks to take down 1 German Tank?”  I thought so too, but apparently no.  To the extent it was true, it was craftsmanship, not technology.]

The Axis did do better in encryption originally, but by the end we were reading much more of their mail than they were reading of ours.  Although it’s important to give credit to this to Polish Intelligence, who broke the Enigma code early on, enabling them to keep up as Germany increased its complexity.  If they hadn’t sent their results to Britain just as Germany invaded, Alan Turing et al. may never have been able to crack it.  That was some high leverage work there.

Anyways, I’m reading The Alchemy of Air (Thomas Hager) now, which is about the history of nitrogen chemistry, which played a much larger role in World War 1 than I would have guessed.  Fritz Haber’s invention of a way to transform atmospheric nitrogen into a usable form, something previously only accomplished by lightning and a handful of bacteria, is estimated to have prolonged the war by at least one year, possibly two. We’ll get into why in a later post.  That’s Athena.  According to the book, a lot of what the Allies wanted in reparations was not actually money, but German technology, especially chemistry.

[I do not entirely trust Hager on the relative important of chemistry and money here.  He’s spent the entire book waxing lyrical about the importance and beauty of nitrogen.  The internet was not terrible helpful; I’ve confirmed that dyes and pharmaceuticals were among goods taken as reparations, but not the amounts.  Some guy on Quora says the US, Britain, and Germany were equally competitive in technology in 1914.]

Even if Alchemy is overestimating German dominance in chemistry, I think it’s safe to say that technology was a major force behind German military power in World War 1.  And by World War 2, it wasn’t.  They made some advances and would have done worse without them, but no one ended the war thinking “man, getting access to this German technology will save us 20 years in research”.  But 60 years later, Germany is again a leader in technology, and has one of the more functional economies in the world.

This was going to be a “me wondering about a mystery” post, but once I thought about it the answer to “what changed?” is obvious.  Germany exiled or killed 25% of their scientists.  Fritz Haber, the guy who added years to the war with one invention and went on to pioneer chemical warfare?  Jewish  “Germany hurt itself while killing several million people” is not exactly news, but I think it’s important to note individual stories of how.

Although this puts me in the weird position of honoring the guy who more-or-less created chemical warfare.  But that’s maybe okay, because the same process that made Germany gun powder is also feeding half the world right now.  Utilitarian morality is complicated.



Other Ways to Learn About Homonid Diversity

Reading about homonid evolution has me thinking about  Kage Baker’s The Company novels.   This is not exactly a recommendation.   Like many things, The Company series was a dumb story in an interesting setting.  8 years later I’ve completely forgotten the story but the world is still pretty cool.

It’s the year 2300.  Your company has invented immortality… but it has to be done before age 6, and only works on a small percentage of the population, and you’re only kind of human afterwords.  Your company also invents time travel… but you can only go back and you can’t change recorded history.  Neither of these are monetizable on their own, but together The Company R+D department manages to pull itself out of the fire.  It sends a few people back in time to create immortal ~humans, who steal famous art pieces and such right before they were due to go missing any way, and preserve them until you can sell them in the present.  It isn’t exactly creating value, but you’re making money off of it.

That idea was fine, although it’s impossible to do 10 time travel books without paradoxes or an idiot ball.  But every once in a while there’d be a mention of another homonid species that survived without humanity’s awareness.  There were a bunch of immortal semi-robotic neanderthal-and-older knights the Company couldn’t get rid of because immortality is forever.  There’s also a population of eusocial, potion making dwarves that continued to hide from humanity right through 2400 that occasionally pop up.

Again, not recommending, but if you need light reading and really like homonids evolution you could do worse.

Support Aceso Under Glass

TL;DR: you can give me money here, but only if you want to.

Have you ever thought a book sounded interesting if true, but were unsure if you could trust it, or if it was even worth the time to find out?  Wouldn’t it be great if someone marginally qualified investigated the first few chapters and wrote up the results, so you could make an informed judgement without spending much time on it?  I am that marginally qualified person.  I have a BA in biology and computer science, but mostly my qualification is “reading a lot”.  For a demonstration, see my finished list on goodreads.  My other qualification is that, according to witnesses, it is quite fun to watch me yell at things.  I am only going to pick books I think will be valuable, this isn’t going to be a rant-fest, but if I happen to pick a dud you will at least get some entertainment value out of it.

Because this is a little less intrinsically fun than other posts I write, and several people said they would value this kind of thing enough to pay for it, I’ve started a Patreon specifically for book related posts, including the epistemic spot checking described above, summaries of the books that pass, and occasionally summaries of books that didn’t need exhaustive fact checking but I think are important.  If this is a thing you’d like to see more of, please consider contributing.

Why is the Patreon only for book-related blog posts?

The expense and value of my posts vary so widely there was really no one price that was fair for all of them.  The three early-human-history-book fact checks took a couple of hours each, and produced one recommendation for an interesting thing to read.  My post on Tostan took months to write and raised at least $60,000, with good reason to believe that’s a severe underestimate.  You would think getting some money for these posts would be better than getting no money, even if it wasn’t a lot, but no.  I’m trying to work out an explanation for why as part of a longer post on what money means, but it’s not done yet.

On a practical level, epistemic spot checks are the most price sensitive of the posts I do.  In particular, I have a family resistance to buying books when the library is full of free books.  It’s not rational, but having the books provided for me or paid for will make it easier to buy them, which will save me a bunch of timing hassles.  No more feast and famine reading, and I’ll be able to group books by topic.  I also notice I discard books faster if I can buy replacements, which is on the margins good for me.  Once books are paid for, money will go towards buying me time.

What if I want to support something besides the book related posts?

If you would like to commission something specific or purchase a portion of the funders’ credit for an existing post, please contact me at elizabeth-at-this-domain-name.

If you would like to give me an unrestricted grant, you can paypal or send amazon gift cards to this-domain-name-at-gmail-dot-com or buy a book off my amazon wish list (kindle format please).

What if I don’t want to give you any money?

You will lose your chance to read my notes as I work, and if I ever hit it big, the chance to brag that you supported me before it was cool.  You’ll probably cope.


Epistemic Spot Check: A Brief History of the Human Race (Michael Cook)

I was worried my epistemic spot checking project was doomed before it began.  The well regarded Sapiens dismissed a link between cultural and genetic evolution, and Last Ape Standing made two explosively wrong errors in the first chapter.  Neither related to human evolution (one was about modern extreme poverty and the other about cetacean evolution), but I just couldn’t let them go.  I worried that every book was terrible if you actually fact checked it, or maybe just every book on the emergence of homonids?

And then I started A Brief History of the Human Race.  Two chapters in, I cannot find a flaw in it.  There are a few simplifications, and some broad statements he later walks back, but nothing I can point to and say “that is miseducating people.”  Meanwhile there are a lot of things I can point to and say “that is right”, even things I initially thought were wrong.  So I think A Brief History… might be the one.

Here’s a list of statements I checked and their results.  Normally I sort claims into true and untrue sections, but that proved unnecessary in this case because it is a beautiful rigorous snowflake of a book.

Claim: The holocene era has had unusual climactic stability, and is warmer than typical for the planet (page 6).
This checks out, but it’s a little weird that his graph doesn’t label the temperature axes, and it’s a graph of oxygen ratios from a single glacier rather than the wider variety of evidence available.
Cook further claims that this warmth and stability is what let farming, and thus history, start.   There’s some counter evidence to the claim of the holocene as the absolute start of agriculture. but it certainly seems legitimate to say that’s when it really took off.
Claim: there exists art “well over 20,000 years old” (page 9)
I was very surprised by this but if anything he’s underselling it; there’s claims of 50,000 year old art 
Claim: most human DNA is junk DNA that serves no purpose, and mutations have no effect (page 11):
He’s a little behind the times on junk DNA. Even when A Brief History… was published (2003) we knew it that while lots of DNA didn’t encode any proteins, much of it does seem to serve some purpose and mutations in it are significant.  At a minimum noncoding DNA definitely plays a role in the regulation of DNA transcription, the structural cohesion of the chromosome, and protecting coding DNA from degradation.  This is the closest thing to a falsehood I found in the first two chapters.  At the level of genetics this book is discussing I think it’s a forgivable simplification, although an addendum noting the real world was more complicated would have been appreciated.
Claim: humans are inbred (page 12)
Very true.
Page 13: AFAIK this explanation of multiorigin vs out of Africa human evolution hypotheses is correct, and he’s picked the correct winner.
Claim: evidence of human tool use half a million years ago (page 16)
me: there is no way there were tools that long ago.
internet: yes there is.
Claim: early hominid and chimp tool use are both culturally transmitted (page 17)
I’m pretty sure this is correct, and I appreciate the distinction he is making
Claim: it was hard for nomadic hominids to combine their tools in novel ways, because they had so little room. There are exceptions, but they might have been better off sticking with lower technology (page 20).
I am extremely happy to see this guy acknowledge that hunter gatherers had a pretty kick ass life and farming sucked.
Claim: iron is more abundant than copper because of something about supernovas (page 29).
Claim: cattle domesticated multiple times (page 30).
Claim: humans adapt to domesticated animals culturally but not genetically (page 32).
This ignores the co-domestication of humans and wolves but is basically true for everything else.
Claim: humans did not genetically adapt to farming (page 33).
me: ehhhhh….lactose tolerance was a pretty big deal.
p34: exceptions: lactose tolerance and disease resistance.
me: I accept your apology.
Claim: Maori had and then lost the technique for pottery (p36).
Not only is A Brief History… not saying wrong things, it is throwing out tangential facts at about the right rate.  I was never going to look up which molecules supernovas produced.  But now I have a general idea of the concept of “primary elements” and how this affected human history, which makes me happy.
Verdict: A Brief History of the Human Race has passed the epistemic spot check with flying colors, and is enjoyable to read.
This post supported by Patreon.

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.