Archived Abstracts
Death of the alpha: within-community lethal violence among chimpanzees of the Mahale Mountains National Park
Authors: Stefano S. K. Kaburu, Sana Inoue, Nicholas E. Newton-Fisher
During conflicts between communities, male chimpanzees (Pan troglodytes) can show extreme forms of coalitional violence. Individuals isolated in the periphery of their territory risk becoming victims of violent, potentially lethal, assaults by groups of aggressors from neighboring communities. Conversely, levels of violence tend to be lower between males belonging to the same community, as they cooperate when hunting, or patrolling the territory boundaries. Despite this, occasion coalitional attacks that target adults of the same community do occur, although only four cases resulting in the death of the victim have been reported: in all of these, the victim was a low-ranking individual. Here we report a case of coalitional lethal violence among wild chimpanzees of Mahale Mountains National Park (Tanzania) in which four adult males attacked and killed the top-ranking male. The aggression lasted more than two hours, during which the victim was periodically struck and bitten to death. We did not find any reason to suspect that the killing was due to changes in victim’s social interactions with the other males in the period prior to the attack as the victim had not increased his aggression rates or decreased his affiliative behaviors with the other males. We suggest, therefore, that the attack was an attempt to seize the alpha status by the third-ranking male. Intriguingly, the two adult males who led the attack, and seemed most intent on killing the alpha male, were those with whom he had previously had the most affiliative relationships. This report offers further insight into chimpanzee violence, potentially contributing to a major understanding of the evolution of lethal aggression among humans.
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