Kleiman responds

Posted by Chris

Update: Oh crap. I've completely misunderstood both Kleiman's remarks and the basic issue. If you want to untangle my confusions, you're welcome to peek below the fold. But I don't think it's worth the time, really.

[And if you came here from a search engine looking for discussion of evolutionary psychology, this is probably a better post to read.]

Mark Kleiman was kind enough to respond to this post in the comments section. He writes:

In the environment in which humans evolved, the variance among males in reproductive opportunities was much greater than the variance among females, with the leading males siring most of the children and the bottom half of the male status distribution getting largely shut out. In such circumstances, characteristics leading to high variance will be reproductively rewarded. (In measures of risk-taking, men score consistently higher than women.)

Whether that particular explicans is right or not, the explicandum is indisputable: measure whatever mental ability you like, and men have a higher variance than women. That, in turn, surves as an explicans for the observation that there are more men than women at the very top of the distribution, even though women score as high, or higher, on average.

Well, there are undeniable asymmetries in the evolutionary mating opportunities of males and females, on account of the rather obvious fact that a male can mate with a very large number of females (as I tried to do with an almost complete lack of success in high school) whereas for a female each offspring resulting from such a union represents a significant investment - 9 months of risky pregnancy for starters, and that's even before you decide whether or not to keep the damn thing. The idea here is that that asymmetry makes different mating strategies optimal for males and females in the EEA. Moreover, the different strategies and opportunities might lead to precisely the kind of sexual dimorphism Kleiman cites.

Sure, sure. But even with something this basic, there are oodles of complications and things to wonder about.

1. The level of male parental investment found in a given species may alter our calculations, since that will obviously influence the extent to which procreation requires an investment for males.

2. The degree of egalitarianism in a given human society is also an important factor - and remember that hunter-gatherer societies (which is presumably roughly what you had in the EEA) tend to be fairly egalitarian. In egalitarian societies we might well expect trade-offs in favour of arrangements that contribute to social harmony. (I do understand that there's significant variation in the social structures of hunter-gatherer societies. Still.)

3. Sure, the more inegalitarian the society, the more unequal we might expect high status male opportunities for mating. But we can also ask - I always do - whether high status actually corresponds to much in the way of exceptional traits, as Kleiman seems to suggest.

4. Indeed, egalitarianism aside, all kinds of social complications resulting from mating with lots of females may also gum up matters. Hearkening back to my high school experience again, I do recall that my Iraqi girlfriend and I might well have been killed (really) if it had been discovered by my girlfriend's parents that I was shagging their darling daughter. To put the point with a bit more seriousness: sex can lead to all kinds of social tensions and that also matters when we're thinking about the kinds of behaviours which would have been optimal in the environment of evolutionary adaptation. Never, ever try to assess the optimality of a trait or strategy in isolation.

And so on, and on. I'm just riffing off the top of my head, but you get the idea: human beings can be an awful lot more complicated than birds and bees, and even chimpanzees. But I concede that in the basic asymmetry of mating opportunities, I can recognize one possible evolutionary pressure tending to sexual dimorphism. And there is obvious sexual dimorphism among humans - just look at body size, for example. But since things get so very fuzzy, I'm not sure we can tell much a priori about how strong a pressure this would have been in the EEA on any particular trait or range of traits. And that means that I'm still not sure how comprehensive an explanation the evolutionary pressure Kleiman refers to here provides. But whatever. I could be wrong about that. I'm clearly out of my depth and would welcome assistance in the comments section.

(Since I just launched a bitter attack on armchair theorizing, you might wonder what I'm doing here. But there's a world of difference between claiming that human nature is such and such a way because it fits some ad hoc evolutionary explanation you've devised and brainstorming about possible alternative explanations to a particular evolutionary explanation. Armchairs are perfectly good for some things. And notice that I haven't claimed anything about how the world actually is. I've just raised worries about how strong the considerations are for thinking that the world is a particular way.)

So much for the explanans. What about the explananda? Again, I'm not entirely sure. I would like to know a lot more about the (possibly quite subtle) relationship between culture, self-conception and cognitive development before I jumped to any conclusions, though. Since the issue here is the degree of variance - Kleiman says that women may even score higher on average in some measures, even as they show less variance - things are tricky: some of the simpler stories about gender inequities depressing performance will need fine-tuning if they're going to be convincing. But I still think that I would want to know an awful lot more about the influence of culture and environment on the traits in question before I jumped to conclusions. And no, no, I'm not saying that we're a blank slate, that it's all nurture. I may have bits of straw caught here and there in my clothes and hair - I admit I'm dashing this off - but I don't think I'm such a straw man. I'm just saying: We begin to handle infants differently depending on their gender at a few weeks; we're finally emerging from the darkest of sexist dark ages; we still have an awfully long way to go; that cultural influences can be both subtle and pervasive; and so on. All of this ought to give us pause as to how much of what we're currently measuring when we measure differences in traits is a result of the evolutionary pressure that Kleiman adduces and how much is the result of environmental influences. It might turn out that, as a result of the way we raise and nurture children of different genders, less gifted women do better than less gifted men for one set of reasons, and highly gifted women do less well than highly gifted men for a different set of reasons. In other words, the variance might be partly (or wholly for many traits, for all I know) an artifact of the effect that a sexist culture has on both women and men, rather than something that we can easily predict from a particular evolutionary scenario. We'll have to see.

We should also note in connection with the Summers kerfuffle that intellectual success is itself a slippery subject. One thing that it clearly isn't is simply a matter of wattage upstairs - that's a necessary condition, but not even close to being a sufficient one. Intellectual achievement seems to depend very much on temperament, stamina, interest, receptivity to ideas, and so on - things that we don't think of as strictly cognitive, and which we don't measure when we're measuring the sorts of things that we take to be the main determinants of intellectual success. And that too is something to bear in mind when we assess purely intellectualist explanations for the underrepresentation of women in a discipline. I am most emphatically not saying that women have less intellectual stamina, interest, receptivity to ideas, etc. etc. etc. (Indeed, those are precisely the things that might be most influenced by very subtle environmental factors.) Just that there is yet another layer of complexity and possible alternative explanation as we move from claims about performance on tests of various "raw" intellectual abilities to claims about the causes of intellectual performance and success in the wild.

And speaking of intellectual achievement, I need to get back to work if I'm ever going to finish my dissertation. If you want more discussion, you'll have to supply it in the comments section yourself.

Posted by Chris at January 20, 2005 08:40 PM