Nick Wade has a good piece in today's New York Times about John Mitani's chronicling of warfare between troops of Chimpanzees in Uganda.
Dr. Mitani's team has now put a full picture together by following chimps on their patrols, witnessing 18 fatal attacks over 10 years and establishing that the warfare led to annexation of a neighbor's territory.
The fact that male chimpanzees systematically and stealthily patrol their boundaries in groups to kill neighbouring males has been known for a long time in Gombe in Tanzania, but critics have charged that it was unnaturally caused by human feeding of the chimps. That now seems unlikely.
This catches my attention because it explains how hard it must have been to invent trade between groups. If your only contact with other groups was homicidal how do you ever suggest swapping food or tools instead? I am often asked why, if trade is so valuable, did other species not adopt it, Neanderthals especially.
My answer is that getting past this warfare habit was a big hurdle.
Neanderthals did not manage it, as witnessed by their reliance on local rather than imported stone for their tools.
`We Africans' did get over this hurdle. How? I don't know. It might have been serendipity, or it might have been because we pre-conditioned ourselves to working for each other through the invention of the sexual division of labour.
Why did not females, who don't take part in warfare, invent trade behind males' backs?
