Last weekend there was an NYT opinion piece titled, “Darwin Was Wrong About Dating” which got linked a bunch of places including by Libby Anne and at LessWrong. I finally got around to reading it, and it was definitely… disappointing (see here for my previous comments on the subject).
The article starts off talking about the book Sex at Dawn, a book which I read when it first came out a couple years. I don’t remember all of it, but I do remember finding the claim that there is no innate human impulse towards jealousy pretty implausible–even in the polyamory community today, it’s widely recognized that jealousy is normal and something you have to learn to deal with if you want to be poly.
Which isn’t to say there isn’t also a natural human impulse to want to screw around a bit. Hence why illicit affairs are considered illicit but people keep having them anyway. This shouldn’t be surprising: it’s just another example of how, given the way humans are, not everyone can get everything they want all the time.
Robin Hanson has a post where he says he was persuaded, “at least on its ‘key claim, that forager females were sexually promiscuous,'” but also details a number of things the authors apparently got wrong. The one thing I’d add is that the claim “forager females were sexually promiscuous” is vague. How promiscuous is promiscuous?
The evo psych line I’ve always heard is that in other animals, promiscuity and male testicle size are correlated, because more promiscuity means sperm competition is more important. Human testicles are larger than gorilla testicles, but smaller than chip testicles, so the inference is that prehistoric humans were moderately promiscuous.
But where the article gets really bad is when it talks about the studies supposedly showing sex differences in behavior aren’t real. Here’s the first one:
Take the question of promiscuity. Everyone has always assumed — and early research had shown — that women desired fewer sexual partners over a lifetime than men. But in 2003, two behavioral psychologists, Michele G. Alexander and Terri D. Fisher, published the results of a study that used a “bogus pipeline” — a fake lie detector. When asked about actual sexual partners, rather than just theoretical desires, the participants who were not attached to the fake lie detector displayed typical gender differences. Men reported having had more sexual partners than women. But when participants believed that lies about their sexual history would be revealed by the fake lie detector, gender differences in reported sexual partners vanished. In fact, women reported slightly more sexual partners (a mean of 4.4) than did men (a mean of 4.0).
Now here’s why it’s silly to see this as contradicting evolutionary hypotheses about difference in sexual behavior: in a population with equal numbers of men and women, it’s mathematically impossible for the two groups to have a different average number of heterosexual sex partners.
So when the first studies showing a difference came out, everyone who was thinking it through knew something was fishy: either people weren’t self-reporting accurately, or the sample somehow wasn’t telling the full story. One example of the latter type of hypothesis I’ve heard floated (though it always struck me as implausible) is that the studies were failing to sample a small number of women with an unusually high number of sexual partners (say, prostitutes).
But now we know the “people weren’t self reporting accurately” hypothesis is right. This doesn’t necessarily mean people were lying–it could be an issue of one group counting more accurately, or women being less likely to count blowjobs, or something. In any case, confirming a mathematical certainty about actual average numbers of partners doesn’t tell us what people would prefer to have.
Here’s the description of the second study the article cites:
In 2009, another long-assumed gender difference in mating — that women are choosier than men — also came under siege. In speed dating, as in life, the social norm instructs women to sit in one place, waiting to be approached, while the men rotate tables. But in one study of speed-dating behavior, the evolutionary psychologists Eli J. Finkel and Paul W. Eastwick switched the “rotator” role. The men remained seated and the women rotated. By manipulating this component of the gender script, the researchers discovered that women became less selective — they behaved more like stereotypical men — while men were more selective and behaved more like stereotypical women. The mere act of physically approaching a potential romantic partner, they argued, engendered more favorable assessments of that person.
And the third study discussed by the article:
Those results seemed definitive — until a few years ago, when Terri D. Conley, a psychologist at the University of Michigan, set out to re-examine what she calls “one of the largest documented sexuality gender differences,” that men have a greater interest in casual sex than women.
Ms. Conley found the methodology of the 1989 paper to be less than ideal. “No one really comes up to you in the middle of the quad and asks, ‘Will you have sex with me?’ ” she told me recently. “So there needs to be a context for it. If you ask people what they would do in a specific situation, that’s a far more accurate way of getting responses.” In her study, when men and women considered offers of casual sex from famous people, or offers from close friends whom they were told were good in bed, the gender differences in acceptance of casual-sex proposals evaporated nearly to zero.
This, again, is not terribly surprising. Biologists have realized since the time of R. A. Fisher that the reasons females (of most species) have for being selective about mates aren’t just about finding a mate who is able and willing to help raise the offspring, it’s also about finding a mate with good genes.
This shows up even in supposedly “monogamous” species where recently there’s been genetic studies showing a substantial portion of the offspring in these species are fathered by a male other than the mother’s pair-bonded mate. The likely explanation is that the females are cheating in order to have offspring fathered by a male with better genes.
The classic examples, though, are in species where the males don’t invest in raising offspring at all like peafowl. There, you’ll see a situation where all the peahens mate with the few peacocks that have the most impressive plumage. There have been a few different explanations of why example “impressive plumage” would correlate with “good genes,” and I recommend you read The Selfish Gene to get the full story on those, but “impressive plumage signals good genes” seems to be the basic story about what’s going on.
Of course, peahens don’t know anything about genetics. As with most evolutionary hypotheses about behavior, statements like “peahens mate with the peacocks that have the most impressive plumage in order to get better genes for their offspring” are meant in different sense than every-day talk about the reasons for behavior. What it means is that in the past, a tendency to mate with the peacocks with the most impressive plumage led to fitter offspring which led to more grandoffspring which led to the tendency becoming widespread. A similar point applies to evolutionary hypotheses about human behavior.
Now even without knowing about Conley’s study, rock groupies are a thing and to an evolutionary psychologist, the obvious thought about that whole phenomenon is that maybe in humans, fame plays a role similar to the peacock’s tail. Except that of course in prehistoric humans, we’re not talking about “national-level celebrity,” just “reputation for being the best musician in the village.” And hey, maybe a reputation for being good in bed does the same thing.
A general comment to make about the first and third studies is that in our society, there are clear differences between how men and women typically behave. There are ways you could argue these differences are cultural, such as by showing a cultural hypothesis explains the evidence better or by presenting evidence that past cross-cultural studies were flawed. But looking at studies documenting sex differences in some areas, and trying to argue against them by documenting a lack of sex differences in other areas, is completely nonsensical.