Monday, February 26, 2007

The Adaptiveness of Beauty

The evolutionary psychologist (amongst other things) Nikolas Lloyd (NL) - who has an interesting site here - wrote to me (NS) in response to my posing the following question.

NS. Since beauty is so highly adaptive in girls, why is the range so wide?

NL. This reminds me of a similar thing someone once said to me: "I don't believe in all this evolution of beauty stuff. If we have all evolved to be beautiful, then why aren't we all beautiful?"

The answer is that we ARE all beautiful, and that the range of beauty is very narrow. How many people do you know with eyebrows below their eyes? How many bald women do you know? Women are in fact very, very similar to each other. Near enough all of them have two arms of the standard configuration. Even the tiny details like the exact placing of the eyes and the length, colour and location of hairs varies verylittle. This standardisation comes from millennia of evolution towards an ideal norm.

However, evolving at the same time in parallel was the instinct of the observers. They evolved an instinct to find the most beautiful women around attractive, and the least beautiful repellent, and this instinct meant that no matter how beautiful the ugliest women got, they always lost out to their more beautiful rivals.

Put a plain modern woman next to a Neanderthal, and the modern woman would look a stunner by comparison, but the same woman next to the current ideal (Angelina Jolie?) and all eyes would turn to her rival. Try to measure the difference in looks between a normal modern woman and a modern stunner, and you find yourself dealing with tiny fractions all the time, but anything that gives a woman the edge will do the trick.

NS. So what I take you to be saying here is that in reality, the morphological 'beauty' space which the majority of women occupy is relatively small, and we are probably hyper-attuned to small differences.

NL. I am certainly saying that we are very sensitive to the differences, yes.

NS. I think we don’t have to go back to the Neanderthals. As a personal anecdote, there are racial groupings such as Australian aboriginals or native South American Indians where, at least to my eyes, the women do not seem attractive at all. Perhaps they would think the same about Caucasian women, Ms Jolie or not.

NL. I don't like the use of the word "back" here, because it suggests that Aboriginals are less evolved/advanced. they are equally evolved, just with a smaller gene pool, and an isolated one.

Many tests on beauty have been done. Indeed, beauty is one of the more studied of human traits, and people of all races around the world rate the same faces of other races as the most attractive. There seem to be a universal human appreciation of beauty.

NS. There is a line of research which might be taken to imply that strong selection for female beauty should not exist on the grounds that almost all females get to mate anyway. I quote:

NL. Oh dear, this sounds shaky...

NS. “In polygynous species, where only a handful of males but the majority of females will reproduce, it is expected that females with higher resource predictability will bias their offspring towards males, because male fitness depends more on size and condition than does female fitness.” The Trivers-Willard effect states that for polygymous species in situations where resource predictability is high, mothers would produce more sons than they would daughters.

NL. And some species do, just a bit, but generally only the best specimens. So, if a peahen is not an above-average peahen, she should stick to daughters.

NS. However, although high-status males may get to monopolise access to females, they still tend to be rather choosy so there should be a fitness gradient in female attractiveness anyway.

NL. We seem to be confusing species like peacocks (zero paternal investment in offspring) and humans (high paternal investmant). Peacocks are not choosy, they'll screw as many peahens as they possibly can. Men, meanwhile are very choosy indeed about long-term mates.In humans, women who are attractive get the best men. They get the best sperm by sleeping with the best men, and they are also better at getting long-term paternal investment. This is a big edge over other women. Even if all women mate, evolution will still in the long term favour the genes of the women who mated with the best men.

NS. Perhaps, however, there is more than one way to be attractive?

NL. Of course, but I was writing specifically about beauty. You could say that some things are an extension of beauty in a way. Musical ability, or poetry, for example - not a survival asset at all, but a way of demonstrating quality.

NS. In species with simple mating arrangements, markers for raw fitness are represented phenotypically in a species-specific physical ideal we could call ‘beauty’ (peacocks, for example). However, humans participate in complex social relationships and there has been a great deal of psychological work on the basis for longevity in relationships - things like personality compatibility and assortative mating on IQ. It would not be surprising if different kinds of high-status men were looking for different properties in their optimal choice of mates (and conversely, as women get to finally choose).

NL. There is quite a bit of difference between choosing a one-night stand and choosing a wife. Men are every bit as choosy about wives as women are about husbands.Then again, I have read that the best single predictor of which man in a group has married which woman, is to show the faces of the group to people and get them to match them by looks.

NS. If this is true, then putting the actively ugly women to one side - where ugliness is a marker for some definite lack of fitness - there should be a number of distinguishable optima for women and perhaps there are physical correlates to these.

NL. Sure, we label stupid people by forcing them to wear baseball caps.

NS. A very specific example: there is a footballer’s wife ‘bimbo’ stereotype, which many evolutionary biologists might hold up as some kind of optimum, based on appearance.

NL. She is an optimum for a one-night stand.

NS. However, many of us frankly would not wish to choose such a person as a long-term mate no matter how high our status was.

NL. For an explanation of this, see my essay "Why we follow fashion".

NS. In the pre-harem environment of evolutionary adaptiveness, this was probably a real issue. As usual in evolutionary psychology, so many questions and so little research to date.

NL. I'd say that beauty has been pretty thoroughly investigated, partly because people are interested in it, and partly because, since on the surface, it is easy to measure.

NS. Thanks, Nikolas, for the comments.

I would be equally interested in your views as to why there is widespread male/religious prejudice against male homosexuality, as we see with recent Catholic and Anglican disputes. Also why there appears to be relative indifference to female homosexuality.