The Scientific Fundamentalist

A look at the hard truths about human nature.

Beautiful people are more intelligent II

Maybe beauty isn't just skin-deep.

In my previous post, I explain that the reason people have the perception that beautiful people are more intelligent is that they indeed are.  Just like virtually all “stereotypes,” this “stereotype” has an empirical basis; beautiful people in fact are more intelligent.  But now the important question is why.  Why are beautiful people more intelligent?

There are two possible explanations for the observed positive association between intelligence and physical attractiveness.  First, the evolutionary psychologist Geoffrey F. Miller suggests that there is a common source of variation between intelligence and physical attractiveness:  the genetic quality of the individual which he calls the general fitness factor (the f factor).  According to Miller’s theory, those who have better-quality genes are simultaneously physically more attractive (because beauty is an indicator of health and genetic quality, as I explain in an earlier post) and more intelligent, hence the positive association between the two traits.

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This is a very plausible theory, but I have doubts that it explains the association between intelligence and physical attractiveness.  If Miller is correct, then the association between intelligence and physical attractiveness should disappear once genetic quality is controlled.  At least in the Add Health sample, however, this does not appear to be the case.  The positive association between intelligence and physical attractiveness is not at all attenuated when measures of genetic quality are controlled.

Alternatively, the association between intelligence and physical attractiveness may emerge from the process of assortative mating.  If more intelligent men are more desirable to women than less intelligent men, because they achieve higher status, at least in the modern environment, and if physically more attractive women are more desirable to men than physically less attractive women, then there should be assortative mating of intelligent men and beautiful women, and of less intelligent men and less beautiful women.  Because both intelligence and physical attractiveness are heritable, such assortative mating should create an extrinsic (non-causal) correlation between intelligence and physical attractiveness in the next generation.  Children of intelligent men and attractive women should simultaneously be intelligent and beautiful, and children of less intelligent men and less attractive women should simultaneously be less intelligent and less attractive.

So which theory is correct?  We don’t know yet for sure.  Available empirical evidence does support all crucial causal links in the second theory:  More intelligent men do attain higher status than less intelligent men; higher-status men do marry more beautiful women than lower-status men; intelligence is heritable; and physical attractiveness is heritable.  So there is some empirical evidence to support the second theory, but more research is necessary to adjudicate between the two theories.  Or perhaps both theories are wrong and there is a third explanation for the association between intelligence and physical attractiveness.  There is very little doubt that more beautiful people are indeed more intelligent, as the “stereotype” holds, but the proverbial jury is still out as to why this is so.

Satoshi Kanazawa is an evolutionary psychologist at LSE and the coauthor (with the late Alan S. Miller) of Why Beautiful People Have More Daughters.

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