The Golden Age

In two recent papers,  Gerald Crabtree says two correct things.  He says that the brain is complex, depends on the correct functioning of many genes, and is thus particularly vulnerable to genetic load.  Although he doesn’t use the phrase “genetic load”, probably because he’s never heard it.  He goes on to say that that this is not his area of expertise: truer words were never spoken!

His general argument is that selection for intelligence relaxed with the development of agriculture, and that brain function,  easier to mess up than anything else, has probably been deteriorating for thousands of years.  We are dumber than out ancestors, who were dumber than theirs, etc.

The first bit, about the relaxation of selection for intelligence in the Neolithic -.  Sure. As we all know, just as soon as people domesticated emmer wheat,  social workers fanned out, kept people from cheating or killing their neighbors, and made sure that fuckups wouldn’t starve to death.  Riiight  -it’s all in the Epic of Gilgamesh. In the online supplement.

Why do people project a caricature of modernity back thousands of years before it came into existence?    Man, he doesn’t know much about history.

Nor does he know much about biology. If he did, he’d understand that truncation selection is what makes such complex adaptations possible. If only the top 85% (in terms of genetic load) reproduce, the average loser has something like 1 std more load , so each one takes lots of deleterious mutations with him.  But then, he’s probably never heard of truncation selection.  I’m sure they never taught him that in school, but that’s no excuse – they never taught me, either.

If his thesis was correct, you’d expect hunter-gatherers to be smarter than people from more sophisticated civilizations, which is the crap that Jared Diamond peddles about PNG.  But Crabtree says that everyone’s the same – stepping on the dick of his own argument.  Of course, in reality, hunter-gatherers score low, often abysmally low, and have terrible trouble trying to fit in to more complex civilizations.  They do a perfect imitation of being not-smart, amply documented in the psychometric literature. Of course, he doesn’t know anything about those psychometric results.

Which reminds me of secret clearances: it used to be that having a clearance mean that you were entrusted with information that most people didn’t have.  Now, it means that you can’t read Wikileaks, even though everyone else does.  In much the same way, you may have the silly impression that having a Ph.D. means knowing more than regular people – but in the human sciences, the most important prerequisite is not knowing certain facts.  Some kind soul should post the Index,  so newbies won’t get themselves in trouble.

He doesn’t even know things that would almost support his case.  Average brain size has indeed decreased over the Neolithic- but in every population, not just in farmers.  He might talk about paternal age effects, and how average paternal age varies – but he doesn’t know anything about it. He ought to be thinking about the big population increase associated with agriculture, and the ensuing Fisherian acceleration – but he’s never heard of it.

He even gets the peripheral issues wrong. He talks about language as new, 50,000 years old or so – much more recent than the split between Bushmen/Pygmies and the rest of the human race. Yet they talk.  He says that the X chromosome isn’t enriched for cognition and behavioral genes – but it is (by at least a factor of two) , and the reference he quotes confirms it.

Selection pressures and mutation rates can vary in space and time.  Intelligence could decrease – it’s not impossible.  But we know that the pattern he suggests does not exist. Or, to be exact, in exists only in that neighboring world that’s full of Melanesian super-hackers, gay men whose main concern is avuncular investment, and butt-kicking pixies.




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76 Responses to The Golden Age

  1. Fisherian acceleration…? I can’t find anything about it online (my fail). I wonder if you could explain it? Would appreciate it.
    Oh, and your blog…? Thanks – it’s very informative and introduces me to a lot of knowledge.

  2. Puck Naeco says:

    “gay men whose main concern is avuncular investment”
    How about other scales of investment? Multilevel selection happens at… well… multiple levels. If your pathogen idea is right, perhaps some behavior-altering organisms are more symbiotes than parasites. If homosexuality isn’t a distinct, adaptive phenotype, how do you explain the collection of useful (albeit, possibly at scales you don’t care about) biological differences?

    * “The functioning of the inner ear and the central auditory system in lesbians and bisexual women are more like the functional properties found in men than in non-gay women”
    * “Gay and non-gay people’s brains respond differently to two putative sex pheromones (AND, found in male armpit secretions, and EST, found in female urine).”
    * “Gay men and lesbians are more verbally fluent than heterosexuals of the same sex.”
    * “Gay men may receive higher scores than non-gay men on tests of object location memory (no difference was found between lesbians and non-gay women).”

    TL;DR: If this is *just* a horrible awful no-good dick-butt parasite turning our perfect children into
    The Gay, then explain why homosexual phenotypes are so specific and in many cases are clearly adaptive.

    • rightsaidfred says:

      Puck: interesting that you highlight phenotype differences, when usually we are told that you can’t tell.

      I’m suspicious of the claims here. It sounds like they didn’t control for intelligence differences between subjects.

    • gcochran says:

      Selection at levels above the individual is usually weak. I was just looking at a survey of gay men associated with a GWAS study from 23andme. They found nothing significant, genetically, but there were associated phenotypic traits. Gay men (self-reported) were significantly more likely to have panic symptoms, anxiety, to be bipolar, have depression, obsessive-compulsive syndrome, panic disorder, and PTSD. The question was not asked on this survey, but they also have considerably higher-than-average levels of illegal drug use.

      Homosexual men tend to have different interests than straight men, and concentrate in different occupations.

      Do I see anything that looks like selection acting at a higher-than-individual level? No, of course not. I don’t see anything that looks adaptive at all. That said, even when some syndrome is maladaptive in an evolutionary sense, individuals find roles for themselves and/or societies create such roles. Dwarves, for example, are great for tossing.

      • erica says:

        “Dwarves, for example, are great for tossing.”

        It’s a hard choice, but I’d put this in your top ten. 🙂

      • erica says:

        Just saw the 23&me results to which you refer, that :
        • We did not find evidence of SNPs associated with sexual identity in
        men or women, nor did we replicate previous findings showing an
        association with regions on the X chromosome.
        • Interestingly, our top (non-significant) hit was in 8q12.3 for men,
        which was also identified as a top (non-significant) hit in a previous
        linkage study among a small sample of gay men using
        microsatellites (2) as well as a current ASHG abstract (9).

        Interestingly, the second bullet refers to the big sample, years-long Sanders/Bailey gay brothers linkage study (9), the results of which I guess they have begun to give out
        “Our findings, taken in context with previous work, suggest that genetic variation in each of these regions contributes to development of the important psychological trait of male sexual orientation.”

        Since I’ve no idea what the numbers mean, whether they found anything of import or not, anything that might give them clues, perhaps in the near future you can do a post on the study.

      • SFG says:

        What about the idea that the genes are beneficial in the opposite gender? If there are genes coding for masculine behavior that helps men get laid, and genes coding for feminine behavior that helps women get their offspring to maturity, once in a while someone is going to get the wrong set turned on.

  3. Flemur says:

    rightsaidfred: “It sounds like they didn’t control for intelligence differences between subjects.”

    Object location: “However, the difference between heterosexual and homosexual men disappeared after controlling for IQ.”

    Verbal: apparently no control for IQ, small sample:

  4. AG says:

    Intellectuals or upper class tend to have intense curiority about knowlage. Reading blogs like this is an addiction to learn (or even mutually learn).
    Obviously, Gerald Crabtree needs to read this kind of blog.
    paul fussell american class system: Proles only visit place they well knew, afraid of any thing new (similar to alzheimer’s), upper class always like to explore new things due to their curiorsity.

    Xenophobia is obviously common in certain class of people.

    • You Can Dance, You Can Jive says:

      I’ll have you know I’m excellently equipped with curiorsity; I like new places but don’t want my country invaded by the rest of the world; I’d rather it stay where it is. Admittedly I’m an anecdote. But you can be curiorse and still want a base of your own kind.

    • SFG says:

      Actually, Fussell says days can go by without hearing a novel word in an upper-class household. He localizes intellectual curiosity pretty much in ‘Category X’ (bohemians, essentially).

  5. ubuuntu says:

    It appears that your critique is focused on effects that are orders of magnitude below the level of that discussed by professor Crabtree. I am not supporting entirety of his argument, but flailing Truncation selection and Fisher’s runaway doesn’t make you an expert either.

    • gcochran says:

      You’re wrong. Crabtree doesn’t have the faintest idea what he’s talking about. His theory, whether he knows it or not, predicts that remnant hunter-gather groups should be smarter than agricutural peoples. On the whole they’re a lot dumber. So he’s wrong. And widely ignorant. He doesn’t know jack about the genetics of selection. He doesn’t know jack about history – the idea that life became easy in a way that greatly reduced selection for intelligence thousands of years ago is ridiculous. If people were always getting dumber, why on Earth would the scientific revolution be recent?
      Give me a break !

  6. Mike Johnson says:

    Someone posted Crabtree’s paper on Slashdot. I posted your critique (in full, with a link) in a comment. Hope you don’t mind.

  7. t3 says:

    Your Melanesian super-hacker, gay man whose main concern is avuncular investment, and butt-kicking pixies sound like the plucky heros of a new adventure movie. Or a new ABC sitcom.

  8. A Erickson Cornish says:

    Crabtree seems intent on transcending the standard molecular biologist’s ignorance of pop/evo genetics in order to enter the realm of the social scientist’s ignorance of everything. Also, Googling the paper he cites in support of the notion that the X chromosome is not enriched for MR or other cognition genes and reading the abstract is a hoot: “A novel test, in which we distributed unmapped MR disorders proportionately across the autosomes, failed to eliminate the well-known X-chromosome overrepresentation of MR genes and candidate genes. This evidence argues against ascertainment bias as the main cause of the skewed distribution.” So, kind of like what he claims, except the exact opposite.

  9. Mike Steinberg says:

    ***ensuing Fisherian acceleration – but he’s never heard of it.***

    You and Henry, could perhaps submit some comments to Trends in Genetics or some other journal, maybe the journal Intelligence? It seems criminal that someone like Crabtree can publish this nonsense.

    • gcochran says:

      Nonsense on this and related topics is published every day. It’s been known to win the Pulitzer. Why, sometimes it even seems that there is more than one person wrong on the Internet.

      Mostly I ignore it, but today I didn’t feel like ignoring it.

  10. Mike Steinberg says:

    Then again, I wonder if Crabtree is strategically packaging his concern about dysgenics and the need for genetic technology advances to avert that, in a politically correct way? Or he may genuinely just be clueless.

    ***Luckily, the loss of brain wattage is so slow that advances in technology should solve our problems before we all turn completely stupid.

    At that time, we may be able to magically correct any mutation that has occurred in all cells of any organism at any development stage,” he said. “Thus, the brutish process of natural selection will be unnecessary.”***

  11. I love this blog and I love your work.

    Regards from Sweden.

  12. dave chamberlin says:

    The greater subject here is stupid people don’t know their place. What can we do. Mock ’em. April 2nd should be You Are Probably Fucking Stupid Day So April Fools Day Never Ends For You. I’ll bet you didn’t know one kangaroo decided to quit hopping and start running, now they are all starting to do it. yea…really.

  13. reve_etrange says:

    Perhaps the strongest counter-argument comes from Crabtree himself: “Probably the most significant is that genes used for intellectual development could be needed for early development or even fertility.”

    From a biochemical perspective it seems highly unlikely that a sizable proportion of “ID” genes could sustain mutations which *only* slightly reduce intelligence. This (perhaps inappropriate) categorization of genes lumps together structural proteins, motor proteins, various receptors, anabolic enzymes, etc.

  14. Weltanschauung says:

    Citations concerning the relaxation of selection pressure following the development of agriculture:

    And the seven years of plenteousness, that was in the land of Egypt, were ended. And the seven years of dearth began to come, according as Joseph had said: and the dearth was in all lands; but in all the land of Egypt there was bread.
    And when all the land of Egypt was famished, the people cried to Pharaoh for bread: and Pharaoh said unto all the Egyptians, Go unto Joseph; what he saith to you, do. And the famine was over all the face of the earth: and Joseph opened all the storehouses, and sold unto the Egyptians.
    (Genesis 41:52-56)

    Now it came to pass in the days when the judges ruled, that there was a famine in the land.
    (Ruth 1:1)
    And Ruth the Moabitess said unto Naomi, Let me now go to the field, and glean ears of corn after him in whose sight I shall find grace. And she said unto her, Go, my daughter. And she went, and came, and gleaned in the field after the reapers.(Ruth 2:2-3)

    [Elijah] called to her, and said, Bring me, I pray thee, a morsel of bread in thine hand. And she said, As the Lord thy God liveth, I have not a cake, but a handful of meal in a barrel, and a little oil in a cruse: and, behold, I am gathering two sticks, that I may go in and dress it for me and my son, that we may eat it, and die.(1 Kings 17:11-12)

  15. Matt says:

    He doesn’t even know things that would almost support his case. Average brain size has indeed decreased over the Neolithic- but in every population, not just in farmers.

    This was something I’d hoped you’d talk about…

    So I assume (and assumptions are no doubt as bad and as brow furrowing and frown inducing as my guesses and bets) your model is

    – the hunter-gatherer ancestors of agriculturalists and modern hunter gatherer populations had larger brains because the fitness return of those brains per volume (and per level of activity and tissue density) was higher, despite the lower power of those brains (overall and for a given level of volume, density and activity) due to lower efficiency, as they did not reap the benefits of Acceleration (due to larger Holocene hunter gatherer and in particular agricultural populations).

    – cooler climate populations generally have lower mutational load than warmer climate population because of lower polygyny, which in turn lowers average paternal age. this makes larger (and denser and more active) brains more evolvable, as they deliver a greater fitness benefit relative to their cost.

    Apologies if I’m hopelessly misunderstanding things.

  16. dearieme says:

    “I love it when people call it like it is. All true. Crabtree really does know none of it. He is a cell biologist, not geneticist.” Well, a cell biologist; what do you expect? It’s physicists who truly know better than everyone else, not cell bloody biologists.

    • gcochran says:

      Only if they work hard at it. I could tell you some really funny stories about physicists who decided to jump into some topic without bothering to learn anything about it first.

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  18. Riordan says:

    Mr. Cochran,

    A related question. Would you say the average modern man these days would have an easier and quicker time fitting and surviving in an average hunter gatherer environment/society due to his ostensibly higher IQ than even the native hunter gatherers?

    • Seth D. Long says:

      Yes, because your typical 100 IQ modern man would have enough sense to bring a rifle, ammunition, iodine tablets, loads of matches, a hunting knife, fishing tackle, GoreTec boots, all sorts of pills and clotting aids, a good tent and sleeping bag, all put into a nice Lowe Alpine pack. This should do him pretty well until he can extricate himself from said environment and get back to a road.

      By contrast, what might the hunter gatherers bring to survive a few weeks in L.A.?

    • Logically, if modern hunter-gatherers score low on intelligence tests, it follows that they are not being actively selected for IQ. Therefore a high IQ does not confer a survival advantage to a hunter-gatherer. (Or, at least, it ranks low on the list of survival skills.)

  19. Nono says:

    “Average brain size has indeed decreased over the Neolithic- but in every population, not just in farmers.”
    Can you provide citation for that?

  20. Paul says:

    The first bit, about the relaxation of selection for intelligence in the Neolithic -. Sure. As we all know, just as soon as people domesticated emmer wheat, social workers fanned out, kept people from cheating or killing their neighbors, and made sure that fuckups wouldn’t starve to death. Riiight -it’s all in the Epic of Gilgamesh. In the online supplement.

    Why do people project a caricature of modernity back thousands of years before it came into existence? Man, he doesn’t know much about history.

    No social workers, but states go back thousands of years. States have controlled violence within their societies and have made sure that fuckups wouldn’t starve, if they were useful fuckups and could serve as cannon fodder, labor, slaves, etc.

    • gcochran9 says:

      You are mistaken. Effective government aid to the general population was very limited in the past, even when the ruling classes felt like giving any, which wasn’t all that often. For one thing, in most circumstances, it was logistically impossible.

      • Paul says:

        I didn’t mean government aid. I meant through certain niches such as mass labor, military, slavery, etc. The West Indies are black today and not Amerindian because blacks made better slaves, not because they were more intelligent.

      • MikeP says:

        The West Indies are black today because the natives died of smallpox.

      • Paul says:

        “The West Indies are black today because the natives died of smallpox.”

        Right. They made better slaves due to greater disease resistance. Less turnover. It wasn’t because they were smarter. Crabtree mentions civilization selecting for greater disease resistance.

      • James James says:


    • States did control violence. Your odds of being murdered in your lifetime in medieval Europe were somewhere on the order of 1 in 50, which is high by modern standards, but about an order of magnitude high, compared to hunter-gatherers.

      However, it is the question of survival & reproduction of fuckups that is important here. Gregory Clark has some data on that in his book and it’s quite clear that, for example, in medieval England, there was a strong differential in reproduction rates between the rich and the poor.

      More generally, as much as the state might want to prevent fuckups from starving, it can’t do that with 100% efficiency as long as the society is stuck in the Malthusian trap. Which was the case for the majority of societies throughout history. The first Western society to get out of the Malthusian trap permanently was probably North America in the 1700’s, followed by Europe towards the end of the 19th century.

  21. Paul says:

    If his thesis was correct, you’d expect hunter-gatherers to be smarter than people from more sophisticated civilizations, which is the crap that Jared Diamond peddles about PNG.

    Crabtree sort of addresses this where he states:

    “Certainly, Jared Diamond, who has spent his career of 50 years among one of the few remaining such societies feels that this is the case, but also acknowledges the difficulty with testing the idea. Because all remaining hunter gather societies are restricted geographically, they have higher frequencies of reduction of heterozygous mutations to homozygousity, which as mentioned above is a particular concern when large numbers of genes are at issue.”

    • gcochran9 says:

      Diamond is lying. As for Crabtree’s notion that hunter-gatherers are all super-inbred – not true. The Hadza are, and possible the Ache, but the Bushmen are as heterozygous as anyone on Earth. Nor do runs of homozygosity make up much of their genome.
      Since this is easily established from recent papers, why did Crabtree say what he said?

  22. Paul says:

    I don’t see why the remaining hunter-gatherers today should be representative of hunter-gatherers of all times and places, any more than that Bantu agriculturalists should be representative of agriculturalists of all times and places.

    • gcochran9 says:

      So since all of the existing evidence is against you, you must be right.

      • Paul says:

        So do you believe contemporary Bushmen, Papua New Guineans, etc. are representative of, say, paleolithic Europeans?

        • gcochran9 says:

          Eskimos could well be – their technology is at least as complex. And their brains are the largest of all existing populations. But their IQ, although higher than that of other hunter-gatherer, is still significantly lower than 100.

    • Amber says:

      Sounds plausible enough to me. Taking a living relative for an ancestor was a common cause of misunderstanding evolutionary biology, too. Today we don’t say humans descended from apes any more but rather both have a common ancestor. The same is true on social level. Sometimes in the past we probably not only shared a common ancestor with present day hunter-gatherers but also a common social structure. For some reasons, however, our ancestors developed into what we call modern societies today. Other remained at that level or even stepped back, as we have evidence of the Tasmanian indigenous population. Generally spoken, the qualities that once caused our social progress most likely are missing among present day hunter-gatherers.

      • gcochran9 says:

        I’m sure that the Eskimos could have developed grain farming if they’d just tried harder.

      • Paul says:

        The Bantu developed agriculture. Plenty of other agriculturalists are less intelligent than Eskimos – South Asians, Mideasterners, SE Asians.

        • gcochran9 says:

          And plenty are not. Europeans and East Asians are smarter than _any_ hunter-gatherers. What’s your point? Crabtree’s idea predicts decline of intelligence in non-hunter-gatherers: there is no evidence for this. Not one iota. He throws in a lot of other things as well, such as the idea that extant hunter-gatherers are highly inbred. But many of them are not. He states that today everybody’s pretty much the same, intelligence-wise – and that is false as well, although I suppose he had to say that. He says that there is no unusual concentration of cognitive genes on the X chromosome – but there is.

          It is much easier to come up with a broad theory when you don’t know any of the facts that disconfirm it. Ignorance may not be strength, but it certainly confers a kind of freedom.

      • Strictly speaking, Eskimos couldn’t have developed grain farming. But not because they aren’t smart enough. (They probably are.) Reason one: even now, with modern agriculture technologies, fertilizers and such, there’s no grain farming in any regions populated by Eskimos. It’s just too cold there. There’s some wheat farming in Canada, but it does not extend far enough north. Reason two: most domesticated grains are native to Eurasia. The only native North American domesticated grain of note is corn. Corn is even less cold-tolerant than wheat.
        They probably could have handled potatoes, if only there were potatoes in North America.

      • MikeP says:

        Since apes comprise a paraphyletic group with respect to humans, it is entirely correct to say that humans descended from apes. If, on the other hand, apes were to represent the sister group to humans, then it would be correct to assume only that the common human/ape ancestor would have been “ape-like” given the derived nature of humans.

      • Paul says:

        My point was just that it doesn’t seem clear that the remaining hunter-gatherers today should be representative of hunter-gatherers of all times and places, any more than that contemporary Bantu (or any other non E. Asian or Euro agriculturalists) should be representative of agriculturalists of all times and places. Most agriculturalists aren’t East Asian or European and are significantly less intelligent. If civilization accelerated evolution towards greater intelligence in East Asians and Europeans and they only started getting up to 100 IQ relatively recently, then presumably they were below that level for much of civilization, down closer to the Eskimo level. And all the other agriculturalists who are already less intelligent than Eskimos may have been even less intelligent than they are today.

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  24. Paul N. says:

    The fauceir stance on the subject is here (

    This may answer your questions, too, at least partially. Maybe someone can cite better references.

    “Gregory Clark has some data on that in his book and it’s quite clear that, for example, in medieval England, there was a strong differential in reproduction rates between the rich and the poor.”

    That is probably why the industrial revolution happened in England and not in Russia where progressive people were eliminated to Siberia ( 🙂

    Intelligence is a quite ideological issue, so research into it is under strong ideological pressure. I wouldn’t even say that it’s a problem of code words. There is a lot of subconscious, ideologically enforced cognitive inhibition.

    • Jokes aside, England was, for whatever reasons, far ahead of Russia in terms of urbanization, literacy, and probably in terms of population mixing (due to downward mobility).

      Russian Empire was highly stratified. There was a thin layer on top that probably experienced the same selective pressures. Most renowned Russian scientists, writers and composers were born in families of government officials, military officers, or, rarely, priests. (All officers and sufficiently high-ranking government officials were hereditary nobles.) Below that layer there was a sea of peasants and workers which, long after the Industrial Revolution was underway, had the literacy rate in single digit percentages.

      Part of that nobility layer emigrated from the country starting in 1890’s and particularly after 1917. Today, Americans of Russian ancestry, mostly descendants of those emigrants, still have the highest per capita income of all significant ancestries in the United States. (Two other large ancestries near the top are Scots and Austrians.)

  25. Riordan says:

    Mr. Cochran,

    Can you clarify just what exactly do you meant by this statement regarding modern hunter gatherers?

    “They do a perfect imitation of being not-smart, amply documented in the psychometric literature.”

    Perfect imitation? They pretend to be “dumb” by scoring low on modern Western IQ tests but are otherwise “smarter”/more cognitively sophisticated than they appear? Or they score low and the implication is their even “dumber”/cognitively challenged than they appear? Or is it that their cognition is simply not fit for the Western IQ tests i.e. square pegs in round holes, independent and more relevant than the “smart vs dumb” appellations.

    Something’s being muddled here.

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  27. Paul says:

    If people were always getting dumber, why on Earth would the scientific revolution be recent?

    Right, but things like the scientific revolution and industrial revolution are notable for being singular during the history of civilization, despite civilization being around for a while in several different independent parts of the world. People look for special reasons why it was singular. Like Gregory Clark. The phenomenon of middle classes out-reproducing others may be relatively rare. People being pauperized or replaced with slaves certainly isn’t unheard of in civilization.

  28. athEIst says:

    Clark stated that the Black Death reduced the population and kept it down(by returning every 10 to 15 years)below the Malthusian trap level, particularly in England.

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