Your face is not only an important source of social information, but its attractiveness is one property that is quickly noticed. Now, in a new research, scientists have highlighted why symmetry and sexual dimorphism - how masculine or feminine a face is - are key variables that determine how attractive a face is.
In the study - published in the May 7 issue of the journal PLoS ONE - Anthony Little of the University of Stirling and colleagues show that measurements of symmetry and sexual dimorphism from faces are related in humans, both in Europeans and African hunter-gatherers, and in a non-human primate.
In all samples, symmetric males had more masculine facial proportions and symmetric females had more feminine facial proportions.
No one disputes that symmetrical faces, such as that of Kate Moss, are more attractive.
But why? One idea is that the trait is an advert of genetic quality or fertility.
An alternative view is that preferences for a symmetrical face arose from cultural factors and say nothing about health, fecundity and other biological factors.
Faces certainly have the potential to be advertisements of mate 'quality' and one way to examine this idea is to look at interrelationships between proposed adverts of quality.
The findings therefore support the claim that sexual dimorphism and symmetry in faces are signals advertising quality by providing evidence that there must be a biological mechanism linking the two traits during development.
For example, individuals resistant to disease may be able to grow both symmetric and sexually dimorphic. Such work also suggests that faces may advertise quality across different human populations and even across different primate species.