Wednesday, September 12, 2007

Popularity of pretty boys and frequency dependence   posted by agnostic @ 9/12/2007 10:10:00 AM

In the comments on a previous post about height of pretty boys, Jason suggested that they're so popular because they appeal to younger girls who value not-so-threatening guys more than do older women, and because their non-threateningness appeals to a given woman throughout the majority of her menstrual cycle, unlike the virile caveman-looking guys who only appeal to her during the narrow window of peak fertility. I think this view confuses pretty boys with safe, gentle father figures, and so do most studies that forces females to choose between safe, non-threatening guys and macho men. That's because there are not just two ideal types of guy -- the tough, polygynous alpha male vs. the supportive, monogamous dad -- but three, including the polygynous pretty boy / rockstar type.

This is a well established typology elsewhere in nature: the Common Side-blotched Lizard shows exactly these three types. The "sneaker" Yellow males, from afar, look just like females, allowing them to fly under the radar and copulate with numerous members of an Orange alpha-male's harem. The monogamous Blue mate-guarders have only one female to watch, and they cooperate with each other due to green beard effects (free text of the published article), so they can defend their female against sneakers. The three morphs play out a frequency-dependent game of rock-paper-scissors that cycles every six years.

Right away, we've discovered one reason why so much genetic variation is maintained in traits relevant to sexual selection in humans, from personality traits to dancing ability to height -- there is likely no Evolutionarily Stable Strategy, since alpha-males can invade a population of demure good dads, fly-by-night types (pretty boys, artists, musicians, etc.) can invade an alpha-male population -- the latter might not worry about a pretty boy being around his girl since he might assume the guy was gay or otherwise unattractive to women -- but monogamous good dads can then clamp down on the fly-by-night debauchery by cooperating to erect morally upright social practices.

There's probably some difference in the ecology of humans and the lizards that accounts for why the frequency of human morphs don't follow a clean, periodic pattern. We probably face greater temporal and spatial heterogeneity, so that there's rarely a winner-take-all moment when one morph displaces just about all members of the prevoius morph. So it's not like rock-paper-scissors where each strategy totally defeats exactly one other, and is totally defeated by exactly one other (separate from who it beats). Also, human females likely have much more choice than the lizard females, and could follow a mixed strategy (i.e., choose different types of males).

Getting back to the datum that women find different types of guys more attractive when they're at their peak fertility during a menstrual cycle, we now see why pretty boys cluster more with alpha-males than good dads. Well, just behaviorally, babyfaced rockstars and actors are more likely to be polygynous than drab but devoted dads -- that's true for the lizards too.

It's an error to suggest that pretty boys have a non-threatening appeal: if that were true, then they would appeal more to older females, who are more concerned about security than cutting loose and throwing caution to the winds. Also, which cohort of females is most likely to date drug dealers, gang members, or other dangerous males? Or to commit crimes and act dangerously and barbarically themselves? Not the older ones. And it's pretty clear that females who dig Johnny Depp or Jared Leto are not thinking what a great father he'd make. Rockstars and dreamy actors have legions of eager groupies throwing themselves at them -- hardly a long-term strategy. That's true even with non-famous rockstars, although the groupies number fewer: think of how many talentless bums with guitars you've seen get the girls.

What is the more abstract trait that pretty boys and rockstars share with macho men, then? They're exciting, risky, volatile, and take-charge. So, the proper dichotomy is not "virile vs. wimpy" as has been supposed, but "exciting vs. drab," with the former having the two distinct sub-groups "macho man vs. pretty boy." Another way to see that this is the right dichotomy is to look around the world: wherever girls really dig macho men, they also dig the peacocky musician type too, finding safe guys a bit boring. And conversely, where devoted dads do the best, it's more difficult for macho men or in-town-for-a-day rockstars to make out like bandits.

Bobbi Low has shown that pathogen stress is positively correlated with polygyny (free PDF). So whatever it is about high-pathogen-load areas that selects for greater polygynous behavior -- maximizing your offspring's genetic diversity to stay ahead of the pathogens? -- will result in an increase in both gorilla-like and peacock-like males, since they're two viable ways to pursue a polygynous mating strategy. In particular, this resolves the paradox of why men of West African descent tend to show higher levels of both the belligerent tough-guy, as well as the high-pitched singer who can dance better than most girls and has a penchant for dapper dress. Scandinavia and Northeast Asia, by contrast, show lower levels of badasses and show-offs but higher levels of good dads. That follows from the pathogen-load hypothesis, combined with the three-part, as opposed to two-part, typology of ideal male types.

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