How Did Sexual Selection Shape Man's Face?

What makes a typically 'macho' face? Large jaws, well-defined cheeks and large eyebrows are hot or at least were in the eyes of some naughty women ancestors, as a team at the Natural History Museum has found.

It is well known that facial attractiveness played a crucial role in the sexual selection during human evolution, and researches showed that our extinct ancestors' sexual selection shaped the face of modern humans.

The face traits are the main clues for determining the sex of our ancestors and what turns us attractive to the opposite sex as a possible mating partner.

The team at the Natural History Museum said that men have got through selection short faces between the brow and upper lip, fact that makes the size of their jaw, the flare of their cheeks and their eyebrows look bigger.

The shorter and broader masculine face has been also connected to a shrinkage in the canine teeth's size, so than human males look less threatening to competitors (but attractive to mates) as in our species, the males have to cooperate when hunting. But shorter canines made the jaws look smaller, so that an artifice was necessary to improve this.

These selected proportions in men are reached at puberty, the time of sexual maturation, when the area between the mouth and eyebrows, called upper facial height, presents a different development in men and women. Opposite to other facial traits, this man-woman difference is not linked to differences in size between men and women. Even if men are generally bigger than women are, their upper face has the same height like in women, but it is much broader.

The same face differences can be encountered throughout human history in all races. This sexual selection led to fixed parameters, and a simple ratio of measures could establish a man's level of facial attractiveness in a biological and mathematical approach.

"The evolution of facial appearance is central to understanding what makes men and women attractive to each other. We have found the distance between the lip and brow was probably immensely important to what made us attractive in the past, as it does now," explained Dr Eleanor Weston, paleontologist at the Natural History Museum.