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Alex Kraft<\/p>\n
By Stephen Beech<\/p>\n
Chimps in the wild<\/a> engage in deadly battles with rival troops to increase their reproductive success, suggests new research.<\/p>\n The Ngogo chimps of Uganda\u2019s Kibale National Park<\/a> have long been known for violent clashes with their primate neighbors, often leading to fatalities – a phenomenon described as \u201cchimpanzee warfare.\u201d<\/p>\n Now, a team of anthropologists has discovered “clear links” between lethal aggression, territorial expansion, and increased reproductive success among wild chimps<\/a>.<\/p>\n Their study, published in the journal Proceedings of the National Academy of Sciences<\/a> (PNAS), offers rare evidence linking lethal conflict to reproductive benefits, providing insight into the evolution of violence.<\/p>\n They say their findings provide the clearest evidence yet that territorial expansion after lethal conflict can directly boost reproductive success.<\/p>\n Following a series of coordinated attacks that claimed the lives of at least 21 chimps<\/a>, the Ngogo group\u2019s territory grew by 22%.<\/p>\n New research led by UCLA and the University of Michigan has shown that chimp communities that kill their neighbors to gain territory also gain reproductive advantages. (Kevin Langergraber via SWNS)<\/p>\n By Talker<\/p>\n In the years that followed, females gave birth more often, and their infants were far more likely to survive.<\/p>\n Professor Brian Wood, who led the study in collaboration with University of Michigan<\/a> Professor John Mitani, says it provides valuable evidence about the evolutionary roots of intergroup aggression and its fitness consequences for chimpanzees<\/a>.<\/p>\n Anthropologist Wood, from the University of California, Los Angeles<\/a> (UCLA), said: \u201cOur findings provide the first direct evidence linking coalitionary killing between groups to territorial gain and enhanced reproductive success in chimpanzees.\u201d<\/p>\n In the three years preceding the territorial expansion, Ngogo females gave birth to 15 offspring.<\/p>\n In the three years after, they gave birth to 37, more than doubling their fertility rate.<\/p>\n Infant survival also improved “dramatically” – from a 41% chance of death before age three to just 8% afterward.<\/p>\n Mitani said, “In retrospect, we knew what happened.<\/p>\n “We were observing all these births, and there are good theoretical and empirical reasons for thinking something like this might happen.”<\/p>\n Andrea Qoqonga<\/p>\n By Talker<\/p>\n But he says the extent to which births and survival rates ballooned was a surprise, adding: \u201cWhat we saw were very high numbers.”<\/p>\n Mitani has been part of a research team that’s observed this group of chimps<\/a> for more than three decades.<\/p>\n<\/p>\n
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