Lethal warfare drove the evolution of selfless behaviour among ancient humans

June 5th, 2009 - 2:10 pm ICT by ANI  

London, June 5 (ANI): A new study, based on archaeological records and mathematical simulations, has claimed that lethal warfare drove the evolution of selfless behaviour among ancient humans.

If correct, the new model solves a long-standing puzzle in human evolution: how did our species transition from creatures interested in little more than passing down their own genes to societies of law-abiding monogamists?

No one knows for sure when these changes happened, but climactic swings that occurred between approximately 10,000 to 150,000 years ago in the late Pleistocene period may have pushed once-isolated bands of hunter-gatherers into more frequent contact with one another, Samuel Bowles, an evolutionary biologist at the Santa Fe Institute in New Mexico and the University of Siena, Italy, who led the study, told New Scientist.

“I think that’s just a recipe for high-level conflict,” he said.

“We’re talking about groups of men who got out in twos or threes or fives. They didn’t have a chain of command and it’s hard to see how they could force people to fight,” he added.

For this reason, altruistic intent on the part of each warrior is key.

“Each person would do better to stay home than to put their life on the line for their neighbours - yet they still went out and risked their lives,” Bowles said.

To assess whether or not people with a random genetic predisposition to altruism could flourish via armed conflicts, Bowles culled archaeological and ethnographic data on the lethality of ancient warfare and plugged them into an evolutionary model of population change.

In ancient graves excavated previously, Bowles found that up to 46 per cent of the skeletons from 15 different locations around the world showed signs of a violent death.

On average, warfare caused 14 per cent of the total deaths in ancient and more recent hunter-gatherers populations.

The cost of losing an armed conflict as a group is high enough to balance out the individual risks of warfare, especially if a population is relatively inbred, Bowles’ model concludes.

Since evolution acts on genes, it makes more sense to make more sacrifices for a related neighbour than an unrelated one.

Since Bowles had no way of knowing how inbred Pleistocene populations were, he compared contemporary hunter-gatherers such as African pygmies and native Siberians.

He found that individuals in these populations were closely related enough to justify going to war. (ANI)

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