People all over the world and through history have tended to judge someone’s personality and trustworthiness just from looking at their face. For example a study of undergraduates found that 75% believed they could judge a person’s character from their face.
Given that facial (and body) symmetry are indicators of general physical fitness and condition, this makes them popular with evolutionary psychologists, who reason that it would be very useful to be able to instinctively judge symmetry in others (especially when choosing a mate). Stretching this further, it might make sense for other traits, such as personality traits, to correlate with facial symmetry, making the face a quick one-stop checklist for physical and psychological fitness. Basically—if you choose a mate with good symmetry, you are likely to have fitter children. If it’s heritable, you may pass on your preference and so on through your descendants.
In a recent test of this theory, Nicholas Holtzman, Adam Augustine and Angela Senne investigated the relationship between physical symmetry and personality. Although their sample size was modest (175 undergrads) they assessed an unusually large range of 203 personality variables from eight well-documented tests. They were hoping to settle the dispute over which personality traits—if any—are linked to evolutionary fitness
What they found was that higher symmetry scores also had higher anti-social trait scores, such as aggression and hostility, and lower pro-social trait scores, such as empathy and socialization. The temptation at this point is to equate facial symmetry with attractiveness (an association with some basis in research) and conclude that beautiful people are less kind. This has a satisfying fairness to it—a kind of consolation prize for us less beautiful people. And it’s easy to speculate how this could come about: maybe beautiful people just don’t need to be nice—they learn early on that they have a power over others without trying. In support of this idea, there is evidence that the reverse is true: apparently, men with less symmetrical faces co-operate more.
Or maybe, traits like aggression and anger come as a genetic package with physical symmetry because they have (or have had) advantages. For example, choosing short-term partners has been linked to a preference for symmetry—and people with socially aversive personalities tend to prefer short-term ‘relationships’. In this case, as long as there are enough children born from these encounters, symmetry and aggression would continue to be selected for together.
But does facial symmetry itself make a face attractive? Studies disagree on this one—and, for me, the most curious result is that symmetry predicts attractiveness even when you can only see one half of the face! So, it can’t be the symmetry itself which is signalling attractiveness—there must be another factor linking the two.
If symmetry signals physical and genetic fitness, you might expect that humans have got more symmetrical, stronger and fitter over their evolutionary history. But the fossil record tells a different story. Although symmetry is hard to judge in ancient fossils, it is clear that humans have become less physically robust over the millennia as the use of our brain and hands to make tools and weapons has overtaken brawn. Perhaps a link between symmetry and socially aversive traits is a fading echo from our species’ history, when our lives were relatively ‘nasty, brutish and short’.
This study is far from the last word in the discordant proliferation of research on facial symmetry, attractiveness and personality. But it is certainly a thought-provoking addition.