Evolutionary Psychologist Shares How Women Select Men

Maybe we could start our discussion of sexual differences in mating strategy with that. So first of all, what's the evidence that suggests that women are, in fact, choosier when it comes to sexual partners than men, and how much choosier are they?

Okay, okay, great question. Well, maybe first we could just define for listeners what sexual selection theory is, because most people, when they think about evolution, they think of survival of the fittest and that sort of nature red in tooth and claw and kind of randomness too, which, you know, that's kind of implicit in the natural selection theory. Whereas sexual selection is anything but random.

Yeah, absolutely. So sexual selection, if natural selection—this is oversimplified but—is the evolution of adaptations due to their survival advantage or the survival advantage that accrues to the possessors. So things like fear of snakes, fear of heights, spiders, darkness, strangers, and so forth—food preferences, things that led to better survival.

Sexual selection deals with the evolution of qualities that lead to mating success. Darwin identified two causal processes by which mating success could occur. One is same-sex competition or intrasexual competition. The logic there is that whatever—he thought about it in terms of contest competition, where there was a physical battle like two stags locking horns in combat—with the victor gaining sexual access to the female, loser ambling off with a broken antler, dejected with low self-esteem and probably needing some psychotherapy.

But the logic was that whatever qualities led to success in these same-sex battles, whether it be athleticism, strength, agility, cunning, or whatever, those qualities got passed on in greater numbers due to the sexual access that the victors accrued. Qualities associated with losing basically bit the evolutionary dust.

The second component is intersexual competition, which actually the logic is more general than Darwin envisioned. In our species, as we were alluding to, we often compete for position and status hierarchies. We can engage in sexual competition without engaging in this physical battle or contest competition. Although I think that the contest competition was also part of human evolutionary history with males.

The other component process is basically what Darwin called female choice. The logic there is that whatever qualities—if there's some consensus about the qualities that are desired—that men possessing the desired qualities have a mating advantage. They get preferentially chosen. Those lacking the desired qualities basically become incels or involuntarily celibate; they get shunned, banished, or ignored.

Now, the twist on that is that I think sexual selection is by far a more interesting process and definitely has occurred with respect to humans. The twist there is that we have mutual mate choice, at least when it comes to long-term mating. Especially when it comes to long-term mating.

That gets to the issue of Trivers' theory of parental investment, where he asked the question: well, which sex does the choosing? Which sex does the competing? His answer was the sex that invests more in offspring tends to be choosier; the sex that invests less tends to be more competitive for access to those desirable members of the opposite sex.

But in long-term mating—now we know from our reproductive biology that women have that nine-month pregnancy which is obligatory. So women can't say, "Look, I'm really busy with my career; I really only want to put in three months." It's just part of our reproductive biology.

To produce one child, men can conceive that same child through one act of sex. So women are, at least in terms of sex, the choosier sex, the higher investing sex. In part, because the costs of making a bad mating decision are much more severe for women than for men.

If a man and a woman hook up, have sex for one night, and in the morning they both realize, "Oh, this is a mistake; I shouldn't have done that." If the woman gets pregnant, she might be pregnant with a guy who is not going to invest in her offspring; a guy, perhaps, is someone that has poor genetic material, does not have a robust immune system, etc.

So anyway, that's a long-winded answer to your question about sexual selection. Go ahead, please.

Oh, I was just going to say that you asked about the evidence for females being choosier, and they are choosier primarily in the context of casual sex or short-term sex. That's where you find the big sex differences.

One of the classic studies—there's a ton of evidence for this. This is a sex difference that I capture in the book under the category of desire for sexual variety. Men have a much greater desire for a variety of sex partners than women do. The choosing comes in on... I'll just give you one experiment.

This is a classic study done by Elaine Hatfield and Russell Clark, where they had male and female Confederates—members of the experimental team; it doesn't mean people from the South United States—simply walk up to members of the opposite sex on a college campus and say, "Hi, I've been noticing you around campus lately. I find you very attractive. Would you..." They asked them one of three questions: "Would you go on a date with me tonight?" "Would you come back to my apartment with me?" "Would you have sex with me?"

It was a between-groups design, so they simply recorded the percentage of individuals who agreed to these three different requests. Of the women, about half—about a little over 50%—agreed to go out on a date with the guy.

6% agreed to go back to his apartment. 0% agreed to have sex with him. Most women need a little more information about the guy before they're willing to have sex. Of the men approached—also about 50%—by the female Confederate, about 50% agreed to go out on the date.

69% agreed to go back to her apartment, and 75% agreed to have sex with her. So if you talk about choosiness, are you willing to have sex with a total stranger who you've met for 30 seconds? Women are unwilling to, and in general, men are very willing to.

This is a study that's been replicated now in several European studies. Very difficult to do this, as you might imagine, to get this by the IRBs or ethics committees in the United States, anyway. I assume it's similar in Canada or worse.

But yeah, the kinds of studies we really want to do are more difficult nowadays. It's been replicated in several Western European countries, and you can get women off of the 0%. You can get a few percent of women saying yes if the guys are really, really charming; you know if he's a Brad Pitt or, I don't know, what the modern equivalent is—Ryan Gosling or one of the, you know, perhaps a famous rock star.

That's one illustration of the answer to your question about what is the evidence for female choosiness. Now the interesting thing—here's I'll give you one more—there are studies that ask what is the minimum percentile of intelligence that you would accept in a potential partner?

You know we explain percentiles to people so they understand: 99th percentile, 1st percentile, 50th, and so forth. Basically, for things like a marriage partner, men and women are roughly equal. They both are very exact. They say what they want—let's say 65th, 70th percentile intelligence.

Where the sex difference comes up is just as a sex partner, a pure sex partner with no investment. Women still maintain—they still want, let's say, 60th or 60+ percentile in intelligence, whereas men drop to embarrassing levels. It becomes irrelevant if 30th, 40th percentile men go, "You know, if she can mumble a little bit, that's fine," or even not.

That's another indication of female choosiness. They maintain greater choosiness when it comes to short-term sex and are simply less comfortable with having sex with total strangers or casual sex.

Here's I'll give you one more—now that I'm rambling on—and then I'll get to some other interesting issues. This is an item on the sociosexuality inventory that colleagues Steve Gangestad and Jeff Simpson developed a long time ago. One of the items is an attitude item, and it says, "Sex without love is okay. Do you agree with that or disagree with that?"

There you get a large sex difference. On the seven-point scale, where four is the midpoint, men average about 5.5. So they say, "Yeah, sex without love, yeah, that's okay." Women are about 3.5; they're below that midpoint. It's another indication of this sex difference in choosing.

Do you know if that's modulated by Big Five trait agreeableness?

Oh, that's a great question. I haven't seen any studies that link that, okay, Big Five, to that item or the sociosexuality inventory in general.

Well, you'd wonder why if compassion and empathy might be one of the things driving that, and the value that's placed on that as a consequence of being higher or lower in agreeableness. That would fit in to some degree with the dark triad work because the primary difference there is— we'll talk about the dark triad in a minute—is that the dark triad types are low in agreeableness. Essentially, it's not the only thing, but that's central.

Yes, and that's where there's a big sex difference.