Armand Marie Leroi says on Edge.org:
What of human physical beauty? This is something that interests me greatly. I'm not interested in the general aesthetic question here, but ourselves. Some people say that beauty is uninteresting and that it's just a matter of taste. I don't think so. I would say, and there are others who would certainly agree with me, that we have a general psychological program from which stems a universal notion of beauty. Incidentally, this idea that we all perceive certain features to be beautiful is one that Darwin would have disagreed with. Darwin believed that the perception of beauty was particular to particular peoples in particular times and places. He was probably wrong, or at least he was only partly right. I won't attempt to justify that answer, but I think it to be true. These days, the general thinking tends to be that there's a universal notion of beauty which is true for people around the world. And the question is, what is that and what drives it?
Certainly, there are different fashions in different eras, but I suspect the same people would have often tended to wind up on top of the beauty pyramid. If, say, the Madonna of 1991 had been around back in Marilyn Monroe's 1955, Madonna would simply have had the more relaxed body shape fashionable in 1955. I don't know for sure that Marilyn could have achieved Madonna's taut 1991 look, but I suspect she would have come close.
Many people think that beauty is a certificate of health; this is an idea that comes out of sociobiology. But it is more obvious than than that. It's simply the idea that beautiful people are healthy people and we search for healthy mates. And that's probably true. Or at least it was. But is it still? In the past, health was primarily a matter of environmental conditions—your exposure to contagious diseases and the amount of food that you had when you were growing up. Rich people had better environments, hence the positive association between beauty and wealth. But what of modern economically egalitarian societies such as Holland? In such societies, does the ancient association still obtain? If the variance in beauty is due to the variance in the quality of the rearing environment then it must be the case that the Dutch — who all eat much the same good food, live in much the same well-designed houses, and have access to much the same excellent health-care — must all be equivalently beautiful. But is this so? The answer is, of course, no. Among the Dutch you can find good-looking and not so good-looking people. And the question is then, why?
I would argue that the reason for this is that there is and will always be variance in beauty is because there is variance in mutational load. What is beauty fundamentally about? I would argue — and this is really just a postulate at this time, but it is one that interests me a great deal — that the fundamental reason why some of us are more beautiful than others is because of those deleterious mutations that we all carry We may carry 300 deleterious mutations on average, but there is of course a variance associated with that. Not everybody has 300. Some people have more, some people have fewer. If this is true—and statistically it must be true — then someone in the world has the fewest mutations of all. Someone in the world is the least mutant human of all. Indeed, we can actually calculate, making some assumptions about the shape of the distribution, how many mutations that person has — and it turns out to be 191 versus the average of 300. This, to my mind, is surprisingly many. I would suggest that if we could find that person, he or she would be a good candidate for being the most beautiful person in the world. At least she would be, assuming she did not grow up in some impoverished underdeveloped nation. Which, statistically, she will have done since most people do.
If we could use genetic engineering to get rid of all those deleterious mutations -- what Greg Cochran calls "genetic proofreading" -- then we could make people healthier without the risks inherent in trying to change adequate genes to better ones.
Still, I'm not convinced that this all there is to beauty, or at least to feminine beauty which I pay more attention to than masculine beauty.
Exhibit A is a British actress named Tilda Swinton, who recently played the Archangel Gabriel in Keanu Reeves' "Constantine" and is best known as Orlando in the movie version of Virginia Woolf's fable about an immortal, sex-shifting nobleman/woman.
There's no question that Swinton, even in her mid-40s, is beautiful in the objective sense that Leroi is using, but the reason she's not a big star is because her beauty is more androgynous than feminine, which is why she gets roles as angels rather than as romantic leading ladies. She looks a lot like Cate Blanchett (who won the Oscar playing Kate Hepburn), but Swinton makes Blanchett look like Sophia Loren in the ripe womanhood department.
So, female beauty seems to be composed of two parts: A. As Leroi notes, lack of deleterious mutations, lack of infections, and lack of other bad things, and B. Femaleness, and the more the better.
But femaleness as part of beauty leads to questions like: If 36-24-36 is good, why wouldn't 40-20-40 be better? Judging from cartoon characters, the males of the world would be all for 40-20-40 women, in theory, but in practice, they would probably tend to fall over a lot, develop back problems, and have lots of other health and safety difficulties. In other words, while sexual selection pushes for 40-20-40, natural selection, such as getting eaten by sabre-tooth tigers because less voluptuous girls from your tribe can outrun you, pushes against it.
Similarly, in "Constantine," a semi-androgynous demon named Balthazar is played Gavin Rossdale, singer for the band Bush, who has the classic high-cheekbones of a rock star. Johnny Depp, who moved to Hollywood to become a singer, has a classic rock star's face with his high cheekbones and delicate jaw. (In the sequel to "Pirates of the Caribbean," his father will be played by Rolling Stone Keith Richards). Depp is beautiful in Leroi's sense, but when he's supposed to play a regular guy, like in "Donnie Brasco," he's kind of funny looking because he's not very masculine.