The myth of facial symmetry

If you ask people what makes a face attractive, many will say it's symmetry, because apparently that shows whether the person is healthy, i.e. free of parasites and genetic defects. But it turns out the common wisdom is wrong.

Sure, gross asymmetry — what we'd consider a deformity — is unattractive. But in wealthy countries that level of asymmetry is extremely rare, since most cases are corrected with cosmetic surgery at a young age.

So, what makes people think that symmetry is attractive? Well, decades ago, some researchers took pictures of female faces, cut them down the middle, and mirrored both the left and right sides. This produced two perfectly symmetrical versions of each face.

What they found was that for most of the faces, a symmetric version was a bit more attractive than the original. Not always, but more often that you'd expect by chance. So, on average, the symmetric faces were a bit more attractive. And this study got a lot of publicity.

But the effect was weak. If you imagine a graph of facial symmetry versus attractiveness, it isn't a clear line trending upwards. It's a random-looking scatter-plot, with a line-of-best-fit that trends slightly upwards.

In other words, taking an ugly face and making it perfectly symmetrical doesn't suddenly make it beautiful. It only makes it a bit more attractive — the photo equivalent of "putting lipstick on a pig".

Beauty without symmetry

There's also the fact that we can only see symmetry when we view a face front-on. Yet we have no trouble identifying attractive faces from the side, as with the picture on the right. Is her face symmetrical? Who knows. Is it attractive? Absolutely.

In other words, we can tell how attractive a face is without knowing its symmetry. Which means symmetry can't be what determines beauty.