In the 26th June 2010 issue of New Scientist magazine (Vol 206 No 2766), p14, there is an interesting article entitled "Chimpanzees kill to win new territory" by Ewen Callaway. The primatologist John Mitani and his team observed many lethal attacks in a Ugandan national park by the males of one group of chimpanzees on another, smaller group of chimpanzees. After some ten years, the larger group completely seized the territory of the smaller, and the males moved in with females and youngsters. At least part of the reason for the aggression seems to have been an abundance of fruit trees in the smaller group's territory.
It seems that John Mitani does not want to link this to human aggression, and has pointed out that human warfare may involve reasons other than access to resources, such as religious differences, and disputes may be settled eventually by negotiation rather than fighting. But it is hard to imagine that there is no link at all between male chimpanzee willingness to kill others of their own kind, and the male human propensity to do the same. It is hardly surprising that purely human factors like religion become involved as well, or that human intelligence and language may be used to help to end a fight.
Even more curiously, such aggressive chimp and human behaviour has been linked, but in studies of cooperation and even altruism! The chimp warriors do better if they cooperate closely like humans do, and it has been suggested by Samuel Bowles that human altruism emerged in warring groups who were willing to die for each other.
An editorial in the same issue of New Scientist supports these views, suggesting even "war between democratic nations is relatively rare" (p3)!
In the case of the chimpanzees, it is certainly only the males who take part in this aggression. The human situation is more complicated, not surprisingly, but aggression certainly involves males far more than females. Thinking about this vaguely reminded me of something that Ted Turner said a few years ago. I soon found it again in his Wikipedia biography. In 2006 he said, "Men should be barred from public office for 100 years in every part of the world... The men have had millions of years where we've been running things. We've screwed it up hopelessly. Let's give it to the women."
I must say I rather agree. Even if the chimpanzee data does not apply to the human situation, such an experiment could certainly do no harm, and would very likely do good. I don't know why Turner suggested that "men have had millions of years" - the human species is almost certainly not much more than 100,000 years old. Maybe he was already including chimps - our last common ancestor with them probably lived around 5 to 7 million years ago!