There is a qualitative difference between being XY and X0 (Turner’s syndrome). Being XY, a guy, is the physical embodiment of an evolutionary strategy: a certain genetic pattern that has a way of making more copies of itself. It’s a complex strategy, but that’s what it is. X0 people are sterile: they don’t generate more X0 individuals. Not every XY individual succeeds in reproducing, any more than every maple seed starts a new maple tree – but on average, it works. An X0 individual is the result of noise, errors in meiosis: Turner’s syndrome isn’t a strategy. In the same way, someone with Down’s syndrome isn’t Nature’s way of producing more people with Down’s syndrome.

Parenthetically, being a guy that tries to reproduce is a strategy. Actually reproducing is a successful outcome of that strategy. Similarly, being an alpha dude in a polygynous species like elephant seals is not a strategy: trying to be an alpha dude is the strategy. I see people confuse those two things all the time.

In eusocial species, like ants and bees and naked mole-rats, evolutionary strategies include individuals that seldom or never reproduce – worker and soldier castes. They still contribute to the reproduction of close relatives. Are humans eusocial? Obviously not.

A leper is an example of someone that’s been heavily influenced by the reproductive strategy of some other species.

Natural selection tends to make physical embodiments of a successful reproductive strategy common. So stuff like Down’s syndrome, Turner’s syndrome, androgen insensitivity, etc, are all rare. Successful evolutionary strategies usually involve actually getting things done: so there is a tendency for natural selection to develop and optimize various useful abilities, like walking and talking and thinking. All part of the strategy. Many non-strategies [like Downs or Fragile X] mess up those abilities

How many such strategies are there in humans? At least two, XX and XY. Guys and dolls. Are there are any others? Logically, there could be. For example, some species have two or more male morphs, embodying different strategies. Most male salmon go to sea, try to survive and get big, eventually coming back to freshwater to spawn. But some [jack salmon] become sexually mature when younger, after a shorter time at sea. They’re smaller, but less likely to get eaten by sharks.

Is there any evidence for alternate evolutionary strategies in humans, other than just male and female? Not really, so far. For example, schizophrenia looks more like noise, sand in the gears. Not much of the schiz genetic variance shows up in GWAS samples: it looks like it’s mostly driven by rare variants – genetic load. There may actually be some truth to the notion that happy families are all alike.

So, is sex a spectrum in humans? No: obviously not. Two basic strategies, plus errors.

Why would a geneticist be unable to make the distinction between an evolutionary strategy and an error of development (i.e. caused by replication errors or pathogens)? Well, the average geneticist doesn’t know much evolutionary biology. And being embedded in a university, the current replacement for old-fashioned booby hatches, he’s subject to pressures that reward him for saying stupid things. and of course some people are pre-adapted to saying stupid things.

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67 Responses to Strategies

  1. dlr says:

    “How many such strategies are there in humans? At least two, XX and XY. Guys and dolls. Are there are any others? ”

    You bet, there are at least two strategies for men, so well known they’ve got their own catchy names: cads and dads. Cads bring, presumably, better than average genes, at least better than average genes for talking girls into having sex with you; dads bring poorer genes for that skill, but also provisioning for offspring.

    Probably there is a third as well, that no doubt worked great in historic times: join the army, or a raiding party against the next village over, and rape all the girls you can find/capture. No doubt worked great for everyone from Mongols to Vikings.

    In polygynous societies, and societies with brideprices, making money means you can afford to marry, or marry a second or third time, making ‘work hard/get rich’ another sexual strategy for men.

  2. reinertor says:

    A Hungarian lawyer recently lectured me on Facebook about how gender was non-binary, and that I must be “afraid of my own sexuality” or somesuch bullshit. Why can’t I live in an age when people believed in rational things, like vampires, werewolves, and witches?

  3. Anuseed says:

    And if my grandma had wheels she’d be a bike LOL.

  4. Wilbur Hassenfus says:

    I’m thinking about writing a progressive feminist SF story where sterility is an adaptive trait. Generations of sterile young people inherit sterility from their parents. It’s More Evolved, you see.

    It might take a little fancy footwork to keep the doublethink from colliding, but I’ve seen worse handwaves in SF.

    Kin selection might be so obvious that even a correct thinker would figure it out. But then maybe not: Once you start being deliberately retarded, it’s hard to know where to stop.

  5. Gord Marsden says:

    Gender and generate or regenerate have the same root word . The lastest politically correct cornucopia of genders is nothing more than newspeak.

  6. Kornfacy says:

    This may be a dumb question, but what about frequency dependent selection and e.g. psychopathy? I remember Pinker citing Linda Mealey’s theories speculating that it is sort of adaptive.

    • gcochran9 says:

      The idea that psychopathy is a strategy with a frequency-dependent payoff is not crazy. But I don’t know that it’s correct, either. It should be fairly easily to tell in the near future: if it’s driven by rare alleles, it’s not a strategy. Although one should also consider the possibility that it might become a strategy.

    • JayMan says:

      Well, the same idea would seem to apply to any personality trait. We don’t really know why variation in personality exists.

      • Yeyo says:

        I’d say it is to be expected since complex human societies tend to open up a lot of different niches with different selection pressures, you have farmers, traders, priests, military etc. Some level of assortative mating should create some stratification of personality traits

  7. manwhoisthursday says:

    You have to know what the end or purpose something has to know if it is functioning correctly. Things like Turner’s Syndrome or being intersex interfere with the goal of reproduction. So, in terms of Aristotle, Turner’s Syndrome or being intersex have no final cause, no purpose that they serve.

  8. Linda Seebach says:

    Apparently the percentage of trans people among autistics is much higher than in the general population – I’ve seen estimates of 7 to 8 percent (e.g. – and if autism is an effect of either brain chemistry or brain wiring, which is plausible, then it is also plausible that whatever is nonstandard in their development has multiple effects, and one of them could be what sex their brain thinks they are.

    My son is autistic and married to an autistic gay guy – the way they use “spectrum” with regard to gender is like the way they use it for autism, not a smooth gradation like the rainbow, but more like varying patterns of spectral lines.

    • Eugine Nier says:

      My theory about that is that autistics are more likely to take whatever they’re taught literally and act on it. Thus if what they’re taught in school is that masculinity is toxic and that being gay and/or trans is good, then well they may very well act on that in the obvious way.

    • Anonymous says:

      Makes sense. If you have something in your brain making you think you should be the opposite sex, but others are treating you like the sex you were born as, I think a non-autistic would be more likely to naturally grow into the gender role others expect them to have until there’s no longer any internal conflict.

        • Anonymous says:

          Let me be clear: I’m not saying you could raise a girl as a guy or vice versa solely through the power of social expectation (that experiment has been tried). But I think it wields real leverage nonetheless, unnoticeable in most cases because it tends to push in the direction of confirming your biological gender rather than opposing it. If your brain has some abnormal features that throw a wrench into your internal gender representation, making it ambiguous or heterogenous in some way, social conditioning might just be the crucial input preventing that seed from growing into something.

    • gcochran9 says:

      If there’s not any reproduction & never was, not a strategy. Just a syndrome.

  9. brokenyogi says:

    So many examples of genetic variants that can have both high and low survival benefits. Tay Sachs and Sickle cell anemia being two of the best known. One copy confers benefits, two copies severely punishes. Same may be true for homosexuality. Studies seem to indicate that families in which gays appear have higher reproductive results than those in which gays are absent. Could be some genetic factor that in women produces higher fertility, while in men produces lower fertility. If the advantage to women is greater than the disadvantage to men, it’s a net positive for the species.

  10. gyddyn says:

    Sorry, but “Are humans eusocial? Obviously not.” line needs support.

    It looks like “Yes, humans are not completely eusocial, but…”. Constant existense of non-reproducing groups (from monks to more recent phenomena) looks like we do have something like “non-reproducing working bees”. Or not?

  11. crew says:

    Isn’t it all just a matter of survivorship bias?

  12. georgioxblog says:

    Gcochran9. Do you think Crispr could help to cure psychiatric diseases?

  13. kirkmike157 says:

    I wrote a blog post awhile back on two reasonable hypothetical human reproductive strategies that transcend gender. See

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  15. Not much of the schiz genetic variance shows up in GWAS samples: it looks like it’s mostly driven by rare variants – genetic load.

    This is overstated, if not outright false. You have made similar claims about intelligence, contrary to the recent evidence. Why?

  16. Erik Sieven says:

    but aren´t there different strategies successful among human males, a bit like with the salmon? My impression is that e.g. for male lions there is just one strategy. That is being big, strong and having a mane as dark as possible. For human males there is this differences being physically attractive in the “Adonis” or the “Hercules” way. Or some attract women by being loud at party, others by being very diligent workers, others by being very good at Sports or being very intelligent.

    • Ursiform says:

      Varying ways of demonstrating fitness.

    • Greying Wanderer says:

      I was thinking that but I guess it’s like the difference between strategy and tactics. You could see what you’re describing as different strategies or different versions of the same strategy for different environments i.e.

      in an environment where the women can feed the kids on their own then “cad” (r-type ish) behavior would lead to more reproductive success
      in an environment where the kids died without male provisioning then “dad” (K-type ish) behavior would be selected for instead

      but the overall strategy would be the same – reproduction. So is cad vs dad a distinction in strategy or a distinction in grand tactics?

      • Erik Sieven says:

        But also within “cad” vs “dad” cultures there have been these differences – also before widespread contact between Europeans, Subsaharan Africans and East Asians. I also wonder whether the differences are big enough to be called different strategies. There is also this difference between endomorph and mesomorph body types. Again, for a lion being fit means simply being big (and healthy), there is only one type of successful lion. Yet for humans the world champion in weight lifting, in (amateur) wrestling, triathlon, in climbing or in decathlon could each be called the fittest man on earth, but each in his own way. Those champions each are the optimum of different kind of bodies, and the same is true of masters of different professions. A world star conductor, scientist, carpenter or physician each have different mental traits.

        • Ursiform says:

          People aren’t lions, and vice versa. The lion that wins the fight gets the pride. (Although if the loser is sufficiently fit he might find another pride where he can oust the male.) With people most highly-fit males can find a decent mate.

        • Greying Wanderer says:

          Cad vs dad exists in all cultures it’s just the proportions that differ imo – like an 80:20 thing and in reality those proportions vary within individuals as well so individuals are generally not 100% cad or dad but maybe 80:20 one or the other and the dadness or cadness of a society is the sum of the individual scores.

          Among the old industrial working class before offshoring cads existed but either pushed on the margins or stealthed in some way (e.g. dad with women from their in-group and cad with women from an out-group) so it was like 80:20 dad/cad and it’s been gradually switching over to 20:80 dad/cad since full employment stopped being a policy aim and. even in the most cad dominated cultures there’s still a percentage of dad type men as it still confers some advantage just not as much i.e. women in the welfare underclass may not need a man to stick around to help with feeding the kids but they still want it (hence why a lot of “alpha” behavior is just lying to girls when they’re young and trusting).

  17. marshall lentini says:

    More interesting, but not very rewarding, is the question of exactly why white people are so eager to “transcend gender” and other pretend activities.

    • j says:

      It is not a specifically white thing, third world peoples are no less eagerly interested in gender issues. Whites you call them twogs but the others also have a word for the same thing in reverse. Travel should broaden your mindset.

  18. Greying Wanderer says:

    my understanding is some of the differences between males and females are caused by certain genes being switched on or off by hormone levels – hence children being sterilized by injecting them with the hormones of the opposite sex.

    if that is the case then couldn’t some level of transgenderism be being induced by something in the environment, like the food, causing hormone imbalances and if on balance it was all one way e.g. excess estrogen, you might start getting more effeminate men.

  19. thomas hahn says:

    OK, just a syndrome, good arguments indeed. But then why does transgenderism – or related irritations – seem to be not rare? Sampling bias? Cultural bias? Just the ususal nonsense/gullibility? If my memory does not mistake me, Dr. Cochran himself once posited that male homosexuality was unheard of in hunter-gatherer societies. Infectious? Memes (outchtch)?

    • Greying Wanderer says:


      “It has been hypothesized that plants use phytoestrogens as part of their natural defence against the overpopulation of herbivore animals by controlling female fertility.”

      “In the 1940s and early 1950s, it was noticed that some pastures of subterranean clover and red clover (phytoestrogen-rich plants) had adverse effects on the fecundity of grazing sheep.”

      gay rams?

      “…in a Western diet, foods with the highest relative phytoestrogen content were nuts and oilseeds, followed by soy products… ”

      soy, not even once


      early puberty in girls = what in boys? reduced sperm count? switching on the female expression version of certain genes?

      • Greying Wanderer says:


        since the anti-fat diet fad kicked in in the 1970s the total consumption of trad fats (butter, cream, olive oil etc) has gone down dramatically and largely replaced with seed oils.

        i think we may have been poisoning our kids by accident.

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  21. Re Down Syndrome. It may be slightly more complicated than that. Yes, its tough to see it as an adaptive response (and I’m not arguing that it is). It is generally assumed that Down syndrome males are sterile but Sheridan did report on a case of a male with trisomy having a non Down child. Its rare. Women with Down syndrome do reproduce (Bovicelli found that about 1/3 of the kids also had Down)
    What about Down people reproducing together? (this really tests folks liberal sensibilities and egalitarian pretentions to breaking points in my experience). Studying this is complicated by the fact that the ” right to develop and express sexuality in an emotionally satisfying and socially appropriate manner” is simulataneously enshrined in the human rights act, while being technically statutary rape when folk with intellectual impairment are involved. There is no satisfactory resolution of this paradox that I am aware of to date.
    That aside. People with Down syndrome do have kids and about 50% of those kids also have Down syndrome. So…its not unimaginable that at some point in the future, trisomy could provide a protection against some hideous bi-weapon (say) and, despite its obvious drawbacks be selected for. Kind of like sickle-cell anemia (sort of). And if that happened then humanity would end up going down a different path. Maybe…this path….

    (Hey Greg, you are the sci fi fan after all)

    Bovicelli, L., Orsini, L.F., Rizzo, N., Montacuti, V. & Bocchetta, M. (1982). Reproduction in Down syndrome.Obstetrics and Gynecology, 59,13S-17S.
    Sheridan, R., Lierena, J., Natkins,S. & Debenham, P. (1989). Fertility in a male with trisomy 21.Journal of Medical Genetics, 26, 294-298.

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