Men with round faces tend to be more aggressive, a study of sportsmen has shown

The male sex hormone testosterone makes faces more circular and now scientists have studied whether this characteristic is also linked to behavior. A Canadian team studied 90 ice hockey players and found the rounder the face, the more aggressive the players. For male varsity and professional hockey players, the facial ratio was linked in a statistically significant way with the number of penalty minutes per game, report Justin Carre and Prof Cheryl McCormick of Brock University, Ontario. The penalties were incurred by players for violent acts including slashing, elbowing, checking from behind, fighting and so on. However, there was not a link between facial shape and aggression in women. "The facial structure of a man provides an indication of how aggressive he will be in a competitive situation," says Prof McCormick. "Therefore, we are able to predict, with some accuracy, the behavior of men on the basis of their facial features. If men's faces are providing cues as to their potential for aggression, then likely people are probably picking up on this cue, although likely on a subconscious level." The findings, published in the Proceedings of the Royal Society: Biological Sciences suggest that the shape of the face may have been honed by evolution as a marker of the propensity for aggressive behavior: ancestors who did not pick up this warning sign could have found out to their cost that they were dealing with a more volatile and violent person. By one theory, testosterone is responsible for the development of rugged looks, a jutting jaw and brow, a deep voice and other trappings of masculinity but it also damps down the body's protective immune system, so only high-quality (that is those with healthy, good 'genes') men can afford to display these macho characteristics. But the hormone affects more than appearance and a range of earlier work has shown that testosterone levels affect behavior, other than aggression. For example, women's judgements of the extent to which a man was interested in infants based on his face predicted his actual interest in infants: more feminized faces were seen as more trustworthy. People also show some accuracy at identifying 'cheaters' from their looks in an idealised game of cooperation. "Together, these findings suggest that people can make accurate inferences about others' personality traits and behavioral dispositions based on certain signals conveyed by the face," say the researchers.