(Medical Xpress)—Men find women with whom they share certain facial features more attractive. This is the conclusion of a study carried out by a French team from the Institut des Sciences de l'Evolution de Montpellier (Isem, CNRS) . The scientists focused on certain facial characteristics such as eye and hair color, lip and eyebrow thickness and the presence or absence of a chin dimple. However, unlike most previous studies, they compared the features of the men surveyed with those of the women that they considered attractive. This work, published on 21 November in the journal PLoS One, reinforces the theory of homogamy, whereby individuals seek a sexual partner that looks like them - extending it here to genetic traits.
Numerous studies have been carried out on the characteristics that make a woman physically attractive. Most of these studies have focused on traits linked to hormonal levels and fertility. The work reported by the Isem researchers is, on the contrary, based on characteristics that offer no particular selective advantage, such as eye color and lip thickness.
The aim of the experiments was to test two separate but non-mutually exclusive evolutional hypotheses. The first is that of homogamy. It has been observed in numerous animal species that individuals sometimes have a tendency to opt for potential partners that resemble them, in other words individuals that are genetically similar to them. The second hypothesis is that of the uncertainty of paternity, which is specific to species that provide parental care to their offspring. In order to avoid investing energy in a child that is not their own, men tend to prefer recessive features in women. For example, a man will prefer blue eyes or thin lips, which are recessive characteristics, to brown eyes or thick lips in order to be able to recognize his own characteristics in the child.
To test these hypotheses, the researchers first asked about a hundred men to choose, from photos of feminine faces, those that they found attractive. They then repeated the experiment on another group of men, but this time with computer-generated faces. The results showed that the men preferably selected faces whose features were similar to their own. For instance, when presented with four different faces in the second experiment, 37% chose the face with which they shared the most features. On the other hand, there was no evidence to back up the paternity uncertainty hypothesis.
The researchers then analyzed photos of real-life couples with at least one child in order to determine whether these preferences have an actual influence on partner choice. The results showed that, once again, spouses share more facial traits than two randomly selected individuals. The importance of homogamy in the choice of a partner has been the object of very few studies and still raises many questions. For example, does descent from a couple that are relatively similar genetically offer an advantage? The researchers now intend to determine whether this phenomenon is local, and specific to the Western World, or if it occurs within other cultures.
Bovet, J. et al., Men's preference for women's facial features: testing homogamy and the paternity uncertainty hypothesis, PLoS One, 21 November 2012.