Men in conflicts have more wives, children

Under certain conditions, violent conflict may offer a biological benefit to those who take part in it, a Harvard study has found.

In the study over members of an East African herding tribe, the team noticed that those who engaged in conflict - in the form of violent raids carried out on neighbouring groups - had more wives and children.

"The currency of evolution is reproductive success. By having more wives, you can have more children. What we found was that, over the course of their lives, those who took part in more raids had more children," said Luke Glowacki, a doctoral student working with Richard Wrangham, Ruth Moore Professor of biological anthropology at Harvard University.

For Glowacki, the project involved living with the Nyangatom, a group of nomadic herders living in a region of southwest Ethiopia and South Sudan, for more than a year.

The team observed virtually every part of day-to-day village life - from digging water holes to migrations.

Typically carried out by Nyangatom men between 20 and 40 years old armed with weapons like AK-47 rifles, the raids sometimes result in serious injuries and deaths.

Those who take part in the raids, however, must turn over any livestock they obtain to village elders, who use them to obtain wives for themselves.

It may not be until years later that elders agree to provide a raider with the cows necessary to obtain their first wife, or subsequent wives.

"In many cultures, particularly in east Africa, in order to get married you have to give livestock to the bride's family - we refer to it as bridewealth," Glowacki said.

If you do not have cows, you simply cannot get married.

Glowacki was able to build conflict histories for the young men that took part in raids and village elders detailing who participated in raids, how often they participated, whether they were married and the number of wives and children they had.

In an analysis of 120 men, Glowacki said, the data was clear - those who participate in more raids had more wives and more children over the course of their lives.

The study appeared in the journal Proceedings of the National Academy of Sciences.