Mon, 29 Aug 1994

Male chimpanzees help their brothers

By Lisa Seachrist

WASHINGTON (UPI): Cooperation is in the genes. At least who chimpanzees are likely to cooperate with is determined by how closely related the individuals are, biologists have said.

By comparing the DNA in the animals' hair, a team of researchers has determined that male chimpanzees who were most likely to cooperate were cousins and half brothers rather than unrelated animals, researchers said in the journal Science.

"In the chimpanzees we studied, genetic relatedness has evolved into cooperation," said David S. Woodruff, a University of California San Diego evolutionary biologist. "In humans that would translate to nepotism and looking after your own."

Studying the chimpanzees made famous by co-author Jane Goodall at the Gombe Stream Research Center in Tanzania, the team found that the male animals in a group were more closely related genetically and would cooperate with each other.

The females, though, were less closely genetically related than the males and less likely to cooperate with other members of the group.

"This genetic information allowed us to confirm a hypothesis arising from behavioral information," said Woodruff. "In most social animal groups, the males leave the group to establish territories. With these animals, it is the females who leave."

Because the females leave their childhood group, they are less genetically related to their adulthood group and not related to the females in that group. The females neither help nor hinder each other.

Behavioral studies suggested a link between genetic relatedness and cooperation. The genetic study proved that link by showing that male half-siblings and cousins cooperated more fully than less closely related animals.

"This study would have been impossible without 30 years of observational work by Jane Goodall," said Woodruff.

In order to perform the study without disturbing the animals, the researchers climbed to the chimpanzees vacated nests and gathered samples of hair that had shed overnight. The team genetically identified the individual animals without taking blood sample or even touching them.

"This is great stuff," said William McGrew, a primatologist at Miami University in Ohio. "It is likely to impact anyone who works with primates."

The method may also be important in conservation. Woodruff says that the genetic information may be used to help scientists manage endangered wildlife populations by helping them prevent inbred genetic diseases.

"This method can be used on elephants, tigers and panda bears," said Woodruff. "Anything that has hair or feathers."