PENN STATE (US)—Male physical competition, not attraction, was central in winning mates among human ancestors, according to a Penn State anthropologist.

“There is sexual competition in many species, including humans,” says David Puts, assistant professor of biological anthropology.

Humans are similar to many of the apes in using male competition to determine access to mates, where the winning male gets to choose the woman of his dreams, says David Puts, assistant professor biological anthropology at Penn State.

Details of the study appear in the current issue of Evolution and Human Behavior.

“On average men are not all that much bigger than women, only about 15 percent larger,” says Puts. “But, the average guy is stronger than 99.9 percent of women.”

The problem is that men and women do not appear sexually dimorphic—different sexes having radically different sizes and weights. But Puts notes that women tend to store more body fat, while men have 60 percent more muscle mass than women.

Other traits indicate physical prowess was the major force in human mate competition through history. Men are far more aggressive than women, and approximately 30 percent of men in small-scale foraging communities die violently.

Puts suggests that while a deep voice has been considered an appealing trait to women, it actually signals dominance.

“A deep voice makes men look dominant and older,” explains Puts. “A low voice’s effect on dominance is many times greater than its effect on sexual attraction.”

Other male traits also seem to imply competition. Males have thicker jawbones, which may have come from men hitting each other and the thickest-boned men surviving, explaining why males have more robust skulls and brow ridges than women.

Species that live in three-dimensional space—birds and insects in the air or swimming creatures in the sea—tend not to compete for mates using physical competition because it would be difficult for a male to defend females while fighting other males on all fronts.

Species that live on the ground, including humans, or the sea floor have it easier because there are only two dimensions to defend. Some insects that live in tunnels or burrows exhibit the most intense competition because it is impossible for the other male to get to the females except through the defender.

Humans and chimpanzees create male coalitions that are often strengthened by kinship. Coalitions can help males defend females from other males. However, when external forces are absent, these same males can compete with each other for mates.

These ideas may seem to paint a rather bleak picture of human nature with men duking it out among themselves for most of human evolution.

“Things are different for us now in many ways,” says Puts. “It’s heartening to think that human behavior is flexible enough that the right social institutions can increase equality and peace.”

More Penn State news: