January 30, 2010

The evolution of better looks as societies grow richer

Although better nutrition undoubtedly makes people more attractive -- for example by giving them enough vitamin A and the proteins and fatty acids needed to maintain healthy skin and hair -- this is only a minor improvement on the pre-existing genetic endowment. And better medicine certainly plays little or no role at all in enhancing people's looks simply because most medicine was harmful until the 20th C.

What could have so altered the genetic blueprint for outward appearance that a population looks a lot better as it grows richer? Note that I'm not comparing richer vs. poorer societies at a moment in time -- those differences could reflect all sorts of other differences -- but how a given group like the Scottish become more attractive over time as their material welfare rises.

There could be many reasons for greater selection for beauty in more prosperous environments, but a very simple one is the disappearance of the looks-vs-money trade-off that men used to face when choosing a wife. Dowries -- material stuff given to husbands by brides -- were routine until fairly recently, surviving into the 19th C. In the poor, Malthusian world that humans lived in before capitalism lifted all boats to comfortable levels, a key factor in a husband's genetic success was having sufficient material wealth to make sure his kids could survive and thrive. So how much dough the wife would bring to the household was a big deal in his choice of mate.

However, once the average man becomes incredibly wealthier and everyone better fed, the dowry that the wife would bring would not contribute that much more to taking care of their kids' necessities during childhood. Therefore he will choose less on the dimension of the woman's wealth and more based on other still important factors such as her looks (a signal of good genes). The magnitude of this selection pressure is going to be pretty big because it's the one that men naturally obsess over the most, and only something like a compelling looks-vs-money trade-off will dam it up. That means that even over 5 to 10 generations, people will become noticeably better looking as cuter women are chosen as wives / mothers.

Overly romantic social scientists often characterize this transition as one that finally frees up the human heart to choose based on true love rather than mere material wealth. It may do that -- but more importantly, it makes it possible for guys to almost entirely vote with their cock. This unbridled lust has done more to make the average person more attractive than have all the feeble endeavors of do-gooders to secure a toothbrush and balanced diet for every child.

By preferring the support of a comely to that of a wealthy wife, he intends only his own Darwinian fitness; and by directing that marriage in such a manner as its produce may be of the greatest pulchritude, he intends only his own gain, and he is in this, as in many other cases, led by an invisible hand to promote an end which was no part of his intention. Nor is it always the worse for the society that it was not part of it. By pursuing the good looks of his own children he frequently promotes those of the society more effectually than when he really intends to promote them.


  1. So now that women are more free to choose good-looking guys, without having to take the guy's financial status into much consideration, humans should become exponentially even more good loooking.

  2. Regarding...
    "That means that even over 5 to 10 generations, people will become noticeably better looking as cuter women are chosen as wives / mothers."

    How does this play out with populations (in a more prosperous environments) where monogamy isn't common?

    If a population has it so nearly all females reproduce (which I assume would be the case where monogamy isn't common), then you wouldn't have this selective pressure on (all or most) women (for better looks) despite a more prosperous environment, would you?

  3. Pure speculation. I'll speculate the opposite. Attractive women are more successful in the meat market. This causes them to play the field for too long, until they are unattractive, cantankerous, infertile, and no longer desirable as mates.

    Attractive women also have more options in the work force, not only in positions that obviously require beauty such as model, actress, news anchor, prostitute but in any profession that involves contact with the public - waitress, concierge, flight attendant. With their self sufficiency, they are less inclined to marry early. They waste their most fertile years "pursuing their career", until it's too late, same as above.

    Uglies latch on to the first prospect that shows interest. They are faithful because they have no temptations. No prospects in the meat market, fewer (than attractives) in other positions so they (happily or otherwise) pump out offspring during their most fertile years.

    My experience: I see no correlation between attractiveness and number of offspring. The desired data would be X vs. Y scatterplots of all permutations of X and Y where X is:

    Physical attractiveness
    Personality type (e.g. Myers-Briggs)

    and Y:

    number of offspring
    number of marriages
    lifetime earnings

  4. Girls aren't so obsessed with male looks, unless they're under 25 or so, and those females aren't having many kids in richer societies. So the direction of the female-choice effect is also in the "better-looking" direction, but the magnitude is going to be small.

    If every woman reproduces, then it just turns into a question of whose children get more investment than the others. Wives aren't equally taken care of by their common husband.

    Attractive women playing the meat market too long and having good careers hasn't been going on for even 2 generations. Again, you shouldn't look at a slice in time but over time. Look at all Swedish women from 500 years ago up through today: are the better-looking ones having more kids then or more recently? And the wealthier ones?

  5. Agnostic, the post reminds a bit of the hypothesis that smart and pretty correlate because smart men earn more money, so they marry prettier women. Their daughters are on average smarter and prettier.

    If couples like that also enjoyed greater reproductive success, the population would get hotter and smarter. And any alleles that contributed to both would have an even larger selective advantage, causing IQ and intelligence to be connected genetically.

    First anon, maybe. It depends on the extent to which alleles that increase attractive in one sex affect the other negatively.

    Selection either sex for symmetry probably increases attractiveness by purging genetic load. Fluctuating assymetry is partially a result of genetic load and vulnerability to environmental insults, so it must be reasonably heritable. Low FAS makes both sexes more attractive.

    When women are selected for curviness, thin jaws, and light skin, hair and eyes, the next generation of women are prettier. Will the next generation of men have wasp-waists, less pigmentation, and thinner jaws, too? Selecting for femininity in women may inadvertently make men more effeminate.

    Likewise, if women choose men for masculine features, the effect may up masculinity in women too. This is somewhat analogous to African-Americans. Many people find blacks more masculinized. Black do reasonably well in interracial dating, and their handicaps are not a matter of physical appearance. Most whites and Asians do not find black women attractive.

    Second anon, Agnostic is talking about what selective pressures operated in the past, not ones that are new. In the recent study of female reproductive success in Framingham(?) is generally accurate, women in are under selection for shortness and higher BMI.

    However, I'm not sure that secular attractiveness change within-population necessarily points to huge genetic effects. People with fetal alcohol syndrome are not pretty. The blogger at cold equations speculated that the old Irish look was FAS, and the Irish got more attractive as they drank less. OTOH, selecting for pretty would select against vulnerability to alcohol addiction, which would be a genetic effect.

  6. I said, "Black do reasonably well in interracial dating..."

    Meant Black men do reasonably well...

    I should point out that, if Greg Clark ("A Farewell to Alms") is mostly right, that the Brittish were selected for lower time preference(itself strongly correlated with IQ) because dudes with middle-class temperaments had higher incomes, and therefore more children, and the high-income-pretty wife correlation was true, it causes a feedback loop. Selection for personalities and intelligence that cause wealth makes society wealthier overall.

    As society gets wealthier, more people are free to act on their preference for beauty. Most likely, some of the variation of both attractiveness (through symmetry) and IQ within a population is caused by genetic load, come to think of it, genetic load probably makes people shorter too. So even poor men are selecting for (relative) attractiveness instead of, say a strong back for doing the wash. The selection for attractiveness purges genetic load, leading to higher intelligence and attractiveness. The next generation is even better at creating wealth, so the effect goes down the class ladder further...

    Some effect like this might explain why people have gotten smarter and better looking despite the negative relationship between SES and reproductive success in modern societies.


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