The relationship between facial shape asymmetry and attractiveness in Mexican students

It has been postulated that symmetric faces are considered more attractive than asymmetric ones because symmetry may signal high quality due to developmental stability. However, other studies showed that both symmetric and slightly asymmetric faces are considered attractive. Here we aim to explore this discrepancy, beginning with the analysis of the normal prevalence of facial symmetry in a population as a necessary first step prior to any attractiveness assessment.

We collected facial landmarks from two-dimensional digital images of a sample of Mexican individuals (280 females and 285 males aged 18-68 years) that were analyzed using geometric morphometric methods. Then, we chose a subsample of 100 photographs (50 females and 50 males aged 18-27 years) selected to represent a broad range of asymmetrical variation, in order to evaluate attractiveness using a sex-opposite test. Finally, we analyzed the linear correlation between attractiveness and asymmetry.

We found that every evaluated subject presents some degree of facial asymmetry, and that both fluctuating asymmetry and directional asymmetry were significant (P < 0.0001) components of total facial asymmetry. Fluctuating asymmetry was slightly associated with age (r = 0.0858, P = 0.0414) and there were no differences between geographical regions (P = 0.413). Attractiveness was not correlated to levels of asymmetry in either sex (males: P = 0.0973; females P = 0.7415).

Asymmetry was a prevalent feature in the present sample, and preferences for symmetric faces were not operating in the studied population.