Behavioral Ecology Blog

There has been a fair about of “buzz” as a result of a news piece published yesterday in Reuters “Women drawn to men with muscles“. Most of it however, has been of the elementary variety- you know, i.e. Oddly Enough, Women Attracted to Attractive Men. Others have`produced a little more thoughtful response (surprisingly at GAWKER) Do Muscly Dudes Get More Play, Less Stay?

Here is the punchline from Reuters:

“Women are predisposed to prefer muscularity in men,” said study author David Frederick of UCLA.

“Most research is focused on what men find physically attractive in women and the career traits women find attractive in men,” Frederick said by telephone. “Much less research is devoted to what women find attractive.”

He said prior studies concluded a man’s desirability was influenced more by his earning potential and commitment. His study found physical characteristics mattered more.

Women were more physically attracted to brawny men, especially for a fling. But when it comes to finding a long-term partner, they tend to pick a regular man over a mate with huge biceps.

“On the one hand, it makes them more sexy to women. On the other hand, it makes women more suspicious about their romantic intentions,” Frederick said.

There is a subtle point regarding sexual selection theory that is nicely illustrated… We usually think about female choice being all (mostly) about resources (direct benefits). In non-human animals, we’re taking about nest sites, feeding grounds, paternal care (in those species where paternal care is relevant), etc. Now on to modern humans- resources primarily take the form of $$$. This is why you are more likely to see men in fancy cars than women… The paper in question here is looking at paternal care as the relevant resource.

Now what the authors propose is that there is a continuum that runs from “Muscular low investment males” to “puny high investment males”. I’m not sure about the strength of the correlation between muscularity and likelihood of paternal investment- but I’ll concede that point for now… Their main conclusion is that females prefer a male in the middle.. not too flabby, not too muscular. This represents a trade-off between reliability of paternal investment and “good genes” effects- including sexy sons type stuff. (assuming that muscularity is an honest signal of some heritable component that conveys offspring fitness- itself a BIG assumption).

The secondary conclusion was that women consistently choose the “muscle bound males” for one-night stands.. Now, I’ll admit that I don’t know a whole lot about the evolution of non-procreative sex, but thats OK, because I don’t think thats what’s going on here….

I suspect that mate choice as it relates to “flings” is more related to extra-pair copulations than it does to non-procreative sex, although I admit that there could be a fair amount of overlap between the 2. One of the most successful hypotheses in explaining female EPC’s has to do with indirect benefits- i.e. good genes.

Turns out, females are more likely to solicit extra pair copulations from a high fitness male- (You’ve got to have your eye on something pretty sweet to risk losing your mate). But the real idea here is that in the contest of EPC’s, the sweetness of the deal depends ONLY on the indirect benefits *thinking sexy sons hypothesis especially* (presumably the cuckolded mate provides food, nest site, parental care, etc…) For females, it seems likely that in a given pool of males, the most muscular one is likely the best choice. Maybe they are not going to be good fathers- but quite likely they’ll provide you with amazing…, um… genes.

Interesting- what do you think?