PICTURE the scene: a weak leader is struggling to hold onto power as ambitious upstarts plot to take over. As tensions rise, the community splits and the killing begins. The war will last for years.
No, this isn’t the storyline of
, but real events involving chimps in Tanzania’s
. A look at the social fragmentation that led to a four-year war in the 1970s now reveals similarities between the ways chimpanzee and human societies break down.
has been studying the chimpanzees of Gombe for over 50 years. During the early 1970s the group appeared to split in two, and friendliness was replaced by fighting. So extreme and sustained was the aggression that Goodall dubbed it a war.
at Duke University in Durham, North Carolina, and colleagues have re-examined Goodall’s field notes from the chimp feeding station she established at Gombe to work out what led to the conflict.
In the past, researchers have estimated the strength of social ties based on the amount of time two chimps spent together at the station. But the notes are so detailed that Feldblum could get a better idea of each chimp’s social ties, for instance, by considering if the chimps arrived at the same time and from the same direction.
His team then plugged this data into software that can describe the chimps’ social network. They did this for several periods between 1968 and 1972, revealing when the nature of the network changed.
The results suggest that the Gombe community was united until 1971. Then the chimps suddenly split into two groups – one based in the north, one in the south – that spent less time socialising with each other. Feldblum presented the work at the
in Calgary, Canada, last month.
It’s hard to say what caused the split, but a senior male called Leakey died at the end of 1970. “As soon as Leakey died they started splitting,” says Feldblum. “He seems to have been a bridge between the northern and southern chimps.”
After Leakey’s death a chimp called Humphrey became alpha male, but he was weak and faced pressure from two brothers from the south, Hugh and Charlie. The other chimps began to follow either Humphrey or the brothers. The battle began.
Over four years Humphrey’s group destroyed the brothers’ group, and the seven rebel males died or vanished. Groups of males would slip into rebel territory and savagely beat a single chimp.
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