KEY POINTS:
A man's aggressive tendencies are written in his facial features, according to a study that found a link between bad temper and the shape of a man's face.
The distance between a man's cheekbones compared to the height of his face is a good indicator of how likely he is to explode with rage when provoked and this may be an evolutionary feature going back thousands of years, scientists said.
Research on Canadian ice hockey stars has found a significant correlation between the ratio of width-to-height distances of faces and the time spent by the players in the "sin bin" of the dugout as a result of committing fouls.
The scientists failed to find a similar link between aggression and female facial characteristics, which led them to believe the findings could help to explain why there is such a difference between masculine and feminine faces.
"We chose ice hockey players because there is a lot of aggressive behaviour in the games and it's usually an acceptable way of performing successfully. We could also measure this aggression in terms of the number of penalty minutes," said Justin Carre of Brock University in Ontario.
The study looked at three groups of men taken from either the general population, from university hockey teams or from national hockey teams. In all three groups, the researchers found a statistically significant correlation between facial shapes and aggressive tendencies.
"Together, these findings suggest that the sexually dimorphic facial width-to-height ratio may be an 'honest signal' of propensity for aggressive behaviour," the scientists say.
Facial shape was determined by measuring the distance between the outer edges of a person's cheekbones and dividing this by the distance between the eyebrows and the top of the upper lip. Previous work had found differences between the sexes in terms of facial shape, with men generally having wider faces relative to facial height than women, irrespective of body size.
The sexual "dimorphism" in the face suggests a long evolutionary history based on mating preferences stemming back many generations. Some studies have also indicated a more masculine face is used by women to predict certain features about that man, such as whether he is likely to make a good father or whether he is sexually more attractive than other men.
"Together, these findings suggest that people can make accurate inferences about others' personality traits and behavioural dispositions based on certain signals conveyed by the face," the scientists said.
Carre said the differences in facial characteristics between the sexes came about at the onset of puberty as a result of the surge in sex hormones, particularly testosterone in boys. It is also possible that testosterone influences aggressive tendencies, he said.
The next stage is to see whether people can judge a person's facial shape with any accuracy and form a judgment about their personality.
- INDEPENDENT
