Oops! Evolutionary psychology bedrock turns out to be made of manure

Much of evolutionary psychology’s work on gender has rested on a simple paradigm: females are choosy in mate selection, while males will just promiscuously stick it anywhere. I’ve written before on how evolutionary psychology has a tendency towards producing retroactive explanations for modern gender roles and saying we somehow evolved that way.

The mate selection paradigm in particular holds a singular intuitive appeal–if you happen to be a sexist. This is why vast swathes of pseudoscientific theory rest upon it, which trickles down into sexists arguing that they’re not being sexist, this is just how things are and it’s a scientific fact.

But what if that paradigm turned out to be wrong? It rests, largely, on a single iconic study of fruit fly mating behaviour. Now, if we pretend that human and fly mating behaviour is in any way comparable in the first place, it turns out that the study was fatally flawed and impossible to replicate.

The original study was carried out in 1948. Geneticist Angus Bateman put some mixed fruit fly populations in jars, let them mate, and then had a look at whose offspring survived into adulthood. Being 1948, he couldn’t do this by analysing the offspring’s DNA, so he went for the next best thing: he used fruit flies with really distinctive mutations and only bothered examining the offspring who had freakish hideousness identifiable from both parents.

These mutant fruit flies, as it happened, had a nasty habit of dropping dead before adulthood if they ended up with a mutation from both parents: having curly wings and thick bristles has a fairly poor effect on aerodynamics. This effect completely skewed the sample and fucked everything up statistically. While Bateman concluded that males have more offspring when they’re promiscuous and this doesn’t work for females, the findings of the replication were incredibly conclusive.

Also, applying the mating habits of ugly fruit flies with human mating behaviour is probably a little bit silly, evolutionary psychology.

The lead author of the replication study, Patricia Gowarty interprets the results positively: it’s time to build some new paradigms. I wholeheartedly agree with this, but the cynical part of me wonders if this will happen. There are many vested interests tied up in the mate selection paradigm: vast areas of theory are built upon this one study, which will require revision and–shock, horror–examination of the social implications of this.

I would welcome this. I am not sure if the institutions are ready.

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10 responses to “Oops! Evolutionary psychology bedrock turns out to be made of manure

  • spudman101

    OK, for our next ludicrous study that we try to and shoehorn human behaviour into, may I suggest mantises? Thereby proving that human women will often devour a man after/during sex.

    That’s how evolutionary psychology works, right?

  • Derek Walsh

    Fortunately for evolutionary psychologists – and perhaps for sexists – the entire field of evolutionary psychology does not depend on a single fruit fly study from 60 years ago. Studies on humans and other primates as well as a wide range of other animals, along with comprehensive mathematical models lend credence to the belief that male humans are more promiscuous and less selective than female humans.
    The basic reason is very straightforward. In the absence of reliable – and available – contraception a man who will “stick it anywhere” will impregnate more females with little or no cost to his own fitness, thereby tending to pass on genes that tend to result in such behaviour. A woman who puts it about in the same way is liable to end up pregnant which results in a huge cost in time and resources.
    I’d like to begin this paragraph with the phrase “Needless to say” but I can’t because I know it’s absolutely necessary for me to say this. That I believe there are genuine biological differences between men and women which have real evolutionary consequences does not mean that I base my morality on those consequences. I can choose to be monogamous (and indeed to use contraception) despite knowing that this is detrimental to the long-term propagation of my genes. I believe it is easier to do this when I understand why I have a desire to behave otherwise.

  • jemima101

    I had the great good fortune to study undeDr Helena Cronin, her stance as a feminist and a Darwinist is well worth reading if you haven’t already.

    • Cadno

      I looked her up on t’internet, this quote is from her wiki page. She puts it very well – the differences in the shape of that biological standard – the bell curve.

      “I used to think that these patterns of sex differences resulted mainly from average differences between men and women in innate talents, tastes and temperaments. After all, in talents men are on average more mathematical, more technically minded, women more verbal; in tastes, men are more interested in things, women in people; in temperaments, men are more competitive, risk-taking, single-minded, status-conscious, women far less so. But I have now changed my mind. It is not a matter of averages, but of extremes. Females are much of a muchness, clustering round the mean. But, among males, the variance—the difference between the most and the least, the best and the worst—can be vast. So males are almost bound to be over-represented both at the bottom and at the top. I think of this as ‘more dumbbells but more Nobels’.”

  • Dorian

    Have you read ‘Sex At Dawn’ yet? ‘Tis fun (though not perfect). I’ll lend it you :)

  • davidpschmitt

    Odd that Gowaty et al. don’t provide the actual data on sex differences in number of mates or variance in RS (see the “What We Did Not Do” section). They note it’s not reliable, as are Bateman’s old methods, assuming the new data are accurate. It would be more convincing if they found that literally there were no sex differences in variability of RS. Maybe they did.
    In any event, there’s decades more data since Bateman in most species (especially mammals; 97% or so) to support sex differences in RS variances (including quite a bit in humans; see Brown et al., 2009) in ways that would likely affect sexual selection processes in most species (as predicted by Trivers’s PIT). This also includes supportive findings of sex-role reversals of Bateman among pipefish, etc.
    And decades of work that has in many ways questioned a simplistic interpretation of Bateman as applied to humans, such as work by Kenrick, Buss, Gangestad, Haselton, and others that emphasizes the adaptive benefits of short-term mating in women (see Thornhill, R. & Gangestad, S.W. (2008). The evolutionary biology of human female sexuality. Oxford University Press: New York, NY.).
    So, in some ways evolutionary psychologists who study humans already live in a post-Bateman world.
    I sure hope more of the blogosphere doesn’t go on spree of “debunking” the erroneous view that all males are promiscuous and all females are monogamous. That simplistic characterization of evolutionary psychology is wrong in so many ways, it’s hardly worth being called a straw man (see http://www.psychologytoday.com/blog/sexual-personalities/201202/men-women-and-interplanetary-promiscuity). More like a spectre man (no offense to the actual spectreman; http://www.superheroeslives.com/internationals/spectreman_(1971).htm).

  • Randy

    Why do people want evolutionary psychology to be wrong so badly? People would rather throw it all out the window than admit some of it may be true.

    • stavvers

      You do realise the bulk of it has absolutely no empirical basis, right?

      • Derek Walsh

        That’s not remotely true. It’s abundantly clear that our psychological mechanisms – like everything else about us – have evolved and been shaped by selection pressure. I suspect that you’re morally opposed to this being true because you think some of the findings in the field can be misused by sexists to justify their behaviour. Nonetheless, that’s not a good reason to dismiss one of the most important and fruitful branches of science.

        • somebody

          The fact that men could opress women because of their physical power and because of the fact that they don’t bear children(saying that human reproduction is some kind of a curse for women is really “smart”), doesn’t mean that we evolved that way because of reproduction. Were are your evidence? This is why evo psyche is not science.
          I will give a simple example. Chimpanzees, as far as I know, have a violent sex life and use sex(or sex motions) for punishment, we people, do the same. We believe that the passive is degraded, this is why men accept lesbos. So people compare them with us and say that this kind of behaviour is natural. In the same time female chimpanzees are promiscuous, but this fact is ignored.The truth is that the more promiscuous people are, the more offspring they will have, the problem is if this offspring will survive. So if men wanted to spread their genes so much, wouldn’t they care about their offsping a little bit more. Also nature doesn’t care whose the babies are, as long as they are babies, so actually abandoning a woman isn’t the best idea. However, the same people, who argue about this, say that men sacrifice their lives for women, (even though it actually happened a few times and generally isn’t true), because women are more valuable in terms of reproduction, because pregnancy rate depends on women. So, some men decide that they will sacrifice for humanity, because other men can impregnate their women and in the same time, they wouldn’t take care of their wife’s child if they are not sure that they are the father, even though men have never been sure till now.
          Also I have doubts about the whole story of the pregnant woman, who is left to die, because she had sex with another man. Women evolved to have so difficult prеgnancy, because they could afford to be taken care of, also, as far as I know, we lived in groups and women have always cheated. Also I really wоnder why we needed orgasm, if our instincts were so strong, why women can get pleasure from being with another man and why it happens that being with a single man too much time may bore us, and a single caress of another man can do much more to excite a woman, just because he is new, nothing more. I have heard so many times that women are frigid ot have hormonal problems, but you men, never think about that you could be judged only based on how much you sexually attract a woman, because that scares you a lot.
          Before talking about evo psyche again you should try to find a woman, who isn’t bored by her man. Some people remain as attracted as they were in the begining, but this is rare.

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