‘Darling, you’re so average…’

The key to beauty? Symmetry and ‘averageness’

“Beauty is in the eye of the beholder,” as the saying goes. But not entirely. We mostly tend to agree who is attractive and who is not. So are there objective measures of human beauty? Or biological reasons why certain faces are seen as attractive?

For a long time, symmetry has been thought to be important to beauty. This was first noticed in scorpion flies: those with the most symmetrical wings were most successful in mating. In studies on people, those with the most symmetrical facial and bodily features were rated the most attractive.

Face of an average female Mancunian
An average female Mancunian from Nowgen’s Faces of Manchester project.


The reasoning has been that symmetry is an indicator of good genes and good health. All kinds of stresses will tend to break symmetry, so maintaining symmetry is evidence of high resilience – very attractive to a prospective mate. We do not consciously assess symmetry – it seems to be hard-wired into our brains.

There is also a theory that says the proportions of ‘beautiful’ faces conform to a similar ratio. This ratio, the so-called Golden Ratio, has been used throughout history in the design of temples and sculptures.

Another feature thought to correlate with beauty is averageness. When faces are blended to create an average, it is generally rated as more attractive than the individual faces from which it is composed.

However, if just attractive faces are morphed, and are then compared with an unselected average, features specific to facial attractiveness emerge. If these are exaggerated, the composite is considered to be even more attractive – ‘better than average’.

The fact that a computer can be taught to recognise attractiveness in human faces reasonably well indicates that beauty is, at least to some extent, an objective measure.

About this resource

This resource was first published in ‘How We Look’ in June 2008 and reviewed and updated in November 2014.

Statistics and maths, Physiology, Genetics and genomics, Health, infection and disease
How We Look
Education levels:
16–19, Continuing professional development