There's an interesting discussion of height and selection at Razib's blog Gene Expression. I can think of lots of plausible tradeoffs related to greater height -- increased calorie requirements, perhaps not so adaptive for females, effects on metabolism or other body systems, etc. But what about facial attractiveness or symmetry? Every so often I see a really good looking face and the effect is very striking. Surely there are lots of benefits from this, but are there any plausible genetic costs? I would guess that evolution can tweak facial bone structure without affecting the brain or other bodily systems... If so, why aren't we all much better looking? :-)
See earlier post female faces.
[Posted from CDG in Paris; see you in Genova soon!]
In the paper, Mueller & Mazure “Evidence of Unconstrained Directional Selection for Male Tallness”, they claim that tall men have more children because they are more likely to have second families. Oddly, they found no link between height and socioeconomic success in this study, which should raise eyebrows. However, it is a military sample and therefore not typical.
ReplyDeleteKeep in mind, however... the only measure of evolutionary success is reproduction, not "success". I've not been able to find any studies correlating attractiveness with number of children, but I'd not be surprised at all to find that the correlation is _negative_ in many modern and near-modern environments. Similarly to how high IQ leads to low fertility in modern and near-modern environments (this one is very well established).
http://en.wikipedia.org/wiki/Fertility_and_intelligence
Ironic.
Probably for the same reason such a large percentage of the population has poor eyesight. Presumably it isn't difficult to find the right genes to have good eyesight (the vast majority of animals do), but having poor eyesight doesn't exert a strong negative selection pressure among humans. Likewise, the vast majority of humans can reproduce regardless of whether they have perfectly symmetric features. Your chances of getting an attractive mate may decrease, but I don't believe your chances of getting a mate in general decreases. Our tribe is so big that there's almost always /someone/ you can mate with.
ReplyDeleteThrow in genetic drift (the 2nd Law of Thermodynamics, essentially) and what you would expect to see in the long run is a spectrum of humans such that the low end is right about at the level where /no one/ would be willing to mate with them. And, looking around, that is exactly what we see.
Yes, that's one of the stranger aspects of modernity.
ReplyDeleteConsider someone who works extremely hard, achieves considerable professional success at some personal cost and with little leisure, and has the standard upper-middle-class 1.7 children or whatever.
Constrast with someone who drops out of high school, goofs around but has lots of fun times, works at a dead-end job and marries someone similar, lives a life without any social prestige or refined luxuries, but endlessly enjoys himself watching lots of TV and drinking lots of beer, while having the 2.6 children pretty typical for such lower-class lifestyles.
Even if we exclude the more extreme cases, Darwin still seems to smile these days on the lazy, the indolent, and the unambitious...
Supermodels are not physically well suited to extensive childbearing. The link between upward social mobility and increased biological fitness is very tenuous.
ReplyDeleteWe have huge parts of our brain devoted to face recognition. We are just extremely good at discriminating between faces. There could have been an arms race between beauty selection and beauty discrimination. I'm sure we all look identical to a bonobo.
ReplyDeletePerhaps we are better looking. If you go to an art museum in Genoa, look skeptically at the faces in the Old Masters. How would they do if they entered modeling today?
ReplyDelete"If so, why aren't we all much better looking?"
ReplyDeleteSpeak for yourself (just kidding). People have gotten a lot better looking over the years, I'm sure. If you compare you average caveman to today's man, I would bet the cave man would have more ugly face genes.
Supermodels are picked out by gay men who think that their clothes will look good on a human coat hanger with a pretty face. If you want to get an idea of the types of bodies and faces men find attractive, you have to look at pornography.
ReplyDeleteThis is also one area where it's important to keep in mind how evolution works. It's not just females selecting male beauty, males have a strong influence.
ReplyDeleteOne thing that can be deduced from the fossil record is that we've had a sharp downturn in "hyper-masculine" facial characteristics. This isn't due to apparent female preference, the best theories are that this is because human males tend to gang up on and kill sociopaths with ranged weapons - where sociopathy / low team-spirit tends to correlate with what you call "caveman face".
"The Evolution of the Human Capacity for Killing at a Distance" 12/2/09 Duke University anthropologist Steven Churchill presents his research on the evolutionary origins of projectile weaponry<
http://feeds.feedburner.com/~r/AmSciPizzaLunch/~4/qU2zA9Q1lm4
http://feeds.feedburner.com/AmSciPizzaLunch
You really think only gay men prefer real breasts to fake?
ReplyDeleteGenoa produced less great art than any Italian city half its size, as Ezra Pound liked to point out.
ReplyDeleteIf the caveman was doing the comparison, he might come to a different conclusion.
ReplyDeletehttp://en.wikipedia.org/wiki/Koinophilia
ReplyDeleteQuestion could be better posed. Why isn't the standard deviation tighter? Mean = most attractive
Must have todo with benefits of competiton, no?
Spot on. That has to be the most common misinterpretation of natural selection; it's one of the things that bothered me about that Paleo-MMA video Prof. Hsu posted a little while back. People project their own idealized view of humanity and nature onto Darwin and take survival of the fittest to mean survival of the strongest, most aesthetically pleasing, highest IQ etc. But there's a reason why Megalodons and the other awesome animals of the past are now extinct...and why bacteria easily outlive the last human.
ReplyDeleteCause ugly people are still hooking up. Barf.
ReplyDeletePretty people don't have more kids in part because women are distracted by status. If Brad Pitt or Ralph Fiennes
or whatever you favorite flavor is was a garbage man he'd get nothing but a fat chick.
Well said. This is more or less what I came here to post. The selection pressure for beauty simply isn't that strong. Especially in modern monogamous patriarchal western societies. Also there's a sex selection bit here as well: do women care as much about male beauty as men do about female beauty? I would argue that they do not. Or have not, traditionally.
ReplyDeleteI think that beauty at least for females was at one point connected to fitness and more offsprings. However, like IQ, it is no longer so in modern societies. I think being a beautiful woman still gives you better options of marrying a better mate, which includes status and money, things that help you procreate if you decided to do so. Since most people are more self centered these days, beautiful women tends to be more self centered than average since they can get away with it more. Self centered people are just worried about how to live this life more comfortably, not having more kids. This may have stop the eugenic impact on facial beauty similar to the dysgenic impact on IQ that is going on now. We can ask a similar question on IQ, since there is a signifcantly higher need for high IQ in terms of employment, why is there still a dysgenic trend which has been ongoing for many decades.
ReplyDelete