it's nooootttt evvoluuuuuuttionn

WNYC’s Relatioshow tackles the question “Can men and women just be friends?” Men say no, women say yes.


Because men say they are sexually attracted to their friends, and women say they are NOT sexually attracted to their friends. Quoth the researcher:

Men who are involved or single don’t differ in how how attracted they are to their female friends, whereas women do, so if women are involved or their friend is involved, they’re off limits, and men don’t seem to experinece that.

Which sounds fine as far as it goes – but then we get to:

WHY do men report being sexually attracted to their friends, and why do women report NOT being attracted to their friends?

Evolution, of course.


I think that men have a more strongly evolved sexual strategy for engaging in sexual opportunities. … Men who received subtle signals or ambiguous signals of sexual interest needed to act on them? Because if they didn’t they would have been out-reproduced by men who did.

This is so many kinds of ugh that I hardly know where to start.

But let’s start first with some methodological issues.

(1) You can’t tell an evolutionary story on the basis of a study with a WEIRD (Western, Educated, Industrialized, Rich, Democratic) population. We’re not living in anything that could be argued to resemble the environment of evolutionary adaptedness, and human behavior is nothing if not context-dependent, so it’s just silly to say that anything we alone do or say is “evolutionarily adaptive.” It’s ENVIRONMENTALLY adaptive, sure, I can see a case for that, but not evolutionarily.

(2) This study asked for attitudes, opinions, it didn’t ask for behavior; attitudes and opinions don’t tell us about what people actually DO. Thus it did not assess the behavior that is being proposed as related to evolution.

Are the men who report being more sexually attracted to their friends (and perceiving their friends as more sexually attracted than the friend herself reports she is) actually HAVING more sex? The question remains unanswered here, but let’s go to the errors in reasoning to see why, in fact, it doesn’t matter what the answer is.

Giant Reasoning Error:

There’s no relationship between greater FREQUENCY of intercourse and greater reproductive success. Men who have more intercourse do not, as a rule, reproduce more. So it truly does not matter whether or not guys actually HAVE more sex with more women; it doesn’t cause them to reproduce more.

How you ACTUALLY test an evolutionary hypothesis is by assessing four things (following Nikolaas Tinbergen):

What’s the proximate causal mechanism here?

How does this develop over an organism’s lifespan?

How does it compare to other related species?

And how does it influence reproductive success? (In humans, reproductive success is PRODUCING offspring who SURVIVE TO REPRODUCTIVE AGE – in other words, you can think of yourself as reproductively successful when you become a grandparent.)

So I’ve already said that frequency of sex is not related to reproductive success except in the loosest sense that you must have SOME sex in order to reproduce. So boom, we’re done with question 4.

I’m pretty sure we can get all the information we need from question 1: what’s the proximate causal mechanism?

Why do people report feeling sexually attracted (or not) to their friends? And why does this behavior seem to split along gender lines?

Because there are different cultural rules about men and women being allowed to experience or acknowledge sexual attraction, and because sexual attraction is context dependent, especially for women. (Why are there different cultural rules? That’s a different and very, very interesting question, but this post is already too long.)

Now there MAY be some ultimate (rather than proximate) explanation for why women’s sexual motivation is more context dependent than men’s – that’s possible. But that’s a very indirect route to travel just to explain why women say they’re not attracted to their men friends.

The direct route is simply to say that women have learned to keep the brakes on their sexual interest, when the circumstances aren’t right. There don’t need to be REPRODUCTIVE costs because the CULTURAL and SOCIAL costs are high enough to account for the difference.

It’s a complex and interesting question, this question of whether and when men and women experience and/or report sexual attraction. It just doesn’t happen to be one that requires any kind of evolutionary explanation.

And this from me, who LOVES evolutionary explanations.