Science News - April 7, 2012

“These animals know so much about each other’s relationships, and it’s conceivable that this type of social cognition is very important in being able to establish and maintain bonds,” Cheney says. “Which would suggest that there is real evolutionary advantage to, in a sense, being a social wire and being highly motivated to know about each other.”

Got your back

Scientists have long known that animals form bonds. Primates and horses that spend more time in close proximity will generally be friendlier and less aggressive with each other. Chimps and elephants share food, comfort the injured and appear to grieve at the deaths of peers.

Still, for decades the prevailing view was that most interactions occur between closely related individuals. Bonds formed between unrelated animals were supposedly only transient, designed to gain some immediate benefit. Scientists now know that isn’t true. Studies of dolphins, horses, lions and chimpanzees show that even unrelated animals often form stable bonds lasting for years. And evidence indicates that one animal may do something costly to help a nonrelative, while receiving a benefit later.

Such exchanges, known as contingent cooperation, operate daily in human relationships, says biologist Liza Moscovice of Binghamton University in New York. “You might buy coffee for your coworkers, but you expect that at some point they’re going to buy coffee for you too,” she says.

Though it remains unclear whether nonhuman animals keep track of all the favors they give and receive, experiments suggest that contingent cooperation plays a big role in their relationships. In 2010, Moscovice and Cheney, along with others, showed that a shared positive experience can increase the odds that one individual will help the other at another time.

Among the female baboons studied,
the primary way of bonding is through
grooming. Grooming entails sitting with
another and methodically cleaning her
fur, a task that provides an immediate
benefit to the animal being groomed.
“It’s like getting a hug,” Moscovice says.

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Hobnobbing chimps Male chimpanzee pairs that engaged in friendly behavior more often than expected by chance were more likely to be distantly related (blue) than closely related (tan). the findings suggest chimps are motivated to cooperate with nonrelatives, not just close kin.