Men developed thicker foreheads and jaws due to fighting over women in the past, according to anthropologists.
A new study has claimed that winning a mate used to depend only on physical prowess and men with the strongest jawlines and thickest skulls were better able to survive onslaughts from love rivals.
And, that meant that over time all men developed thicker bones in the jaws, around the eyes and on the forehead than women, the study says.
The also developed a greater proportion of muscle to fat than women and became taller than women, it claims.
David Puts, whose findings are published in the Evolution and Human Behaviour journal, said unlike many animal species men and women are similarly sized although men develop more muscle and women more fat.
“On average men are not all that much bigger than women, only about 15 per cent larger. But the average guy is stronger than 99.9 per cent of women,” the Daily Telegraph quoted Puts of Pennsylvania State University as saying.
Men are also far more aggressive than women, with about 30 per cent in small scale foraging communities dying violently. While a deep voice has been considered an appealing trait to women, it actually signals dominance, he says.
“A deep voice makes men look dominant and older. A low voice’s effect on dominance is many times greater than its effect on sexual attraction,” he said.
The main sticking point with human male competition compared to other species is men do not possess inherent weapons like antlers and claws.
But they have always manufactured them instead including bows and arrows, spears and knives.
And, according to Puts, 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 as it would be very difficult for a male to defend females while fighting other males on all fronts.
Puts said that humans and chimpanzees create male coalitions that are often strengthened by kinship. Coalitions can help males defend females from other males.
But when external forces are absent, these same males can compete with each other for mates. “Things are different for us now in many ways. It is heartening to think human behaviour is flexible enough that the right social institutions can increase equality and peace,” he said. —PTI