For most folks, macho-looking men (broad-faced, square-jawed) are usually perceived as being uncooperative, cold and even dishonest. But these latest findings might just prove that such assumptions aren't entirely accurate.

These "masculine faces" are usually cause by exposure to high testosterone levels in the womb. Such differences become clearer at puberty, when testosterone levels rise in boys and their faces mature. And since testosterone is associated with aggression, research has linked wide faces with aggressive behaviour.

But the latest research published in the journal Psychological Science found that these men are also more likely to sacrifice for their team. More via Huffington Post:
They gave University of St. Andrews students money to play a group game in which they could either freeload off other players or risk their money to benefit the group as a whole. Half of the students were told that their winnings would be compared with the winnings of other St. Andrews groups. The others were told that their winnings would be compared with the winnings of groups from Edinburgh University, a rival school.

The wider a man's face, the less likely he was to cooperate with his group when told that he'd be compared with other men from his school. But when given an outside rival, these broad-faced macho guys got competitive. Suddenly, they became more likely than average to gamble their own money for the good of their group.

The findings reveal that masculine traits can come out in both pro-social and anti-social ways. In other words, masculine guys may be more aggressive in general, but their manly characteristics are downright warm-and-fuzzy in some circumstances, such as when they need to support the home team.
The researchers believe that this might explain a previous study which showed that wide-faced CEOs tend to lead better-performing companies than their narrow-faced counterparts, since they are more willing to sacrifice for their team.