for National Geographic News
Bees do it. Monkeys do it. We do it. Cooperate, that is.
Why humans cooperate and why we select particular collaborators are questions scientists have puzzled over for years.
Now research into the behavior of chimpanzees—our closest confirmed genetic relations—is providing new insights into the ways kinship affects cooperation.
The work also offers some of the first evidence that humans are not the only species to develop complex cooperation with both relatives and nonrelatives.
Kevin Langergraber, a biological anthropologist at the University of Michigan, led the six-year study of chimps in Kibale National Park, Uganda.
By combining field observations with DNA analysis of fecal samples, his team found that male chimps prefer to work with their brothers by the same mother.
The chimps often teamed up with these siblings to perform one of six observed behaviors, such as grooming fur or forming a two-chimp alliance to beat up a third individual.
But the scientists also discovered that male chimps frequently cooperate with unrelated or distantly related males in their community to perform tasks such as group hunts for red colobus monkeys or patrolling territory boundaries for intruders.
Langergraber team's results appear today in the early online edition of the Proceedings of the National Academy of Sciences.
Why humans, chimps, or any other animal evolved cooperative behavior gets at the age-old question, What's in it for me?
(Related news: "Monkeys Show Sense of Fairness, Study Says" [September 17, 2003].)
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