Then die Pimu (Image: Jennifer Scott)

ET TU, chimp? The leader of a wild chimpanzee troupe was recently attacked by four of his underlings, who banded together to beat him to death. It’s unusual for chimps to kill their alpha male – and this event gives rare insight into group structure in our closest relatives.

From 2007, Pimu was the alpha male of a chimp group living near Lake Tanganyika in Tanzania. His rule came to a violent end in October 2011 – and the moment was captured on video. Stefano Kaburu of the University of Kent in Canterbury, UK, and colleagues investigated the incident and conducted an autopsy on Pimu’s body (American Journal of Primatology, doi.org/kn4).

The attack happened one morning after Pimu had started a fight with the second-ranking male. This male fled, while four others charged and beat Pimu, biting his hands and feet.


It’s rare for chimps to kill their alpha but it happens, says Michael Wilson of the University of Minnesota in Minneapolis. “There was an earlier case in Gombe.”

Wilson says male chimps compete for access to small numbers of females, so they have an incentive to kill each other. But rival groups sometimes attack them, so they also have a reason to keep their fellow males around for support. It is a trade-off. Kaburu says Pimu’s group did not have close neighbours, so the other males may have been less worried about outside threats.

This article appeared in print under the headline “Chimp leader assassinated by gang of underlings”