Male Baboons Live Longer When They Have Female Friends

Romance isn’t everything. Platonic relationships with the opposite sex can have benefits not just for people, but for other members of the animal kingdom too. A 35-year study of more than 540 baboons in Kenya finds that males who have close female friends have higher rates of survival than those who don’t.

Researchers have often believed that when a male is friendly to a female it’s for reproductive reasons: He might want to mate with her or protect their offspring. But this study suggests that having female friends also may boost longevity.

“Our study was inspired by a long history of work in the social sciences showing that both men and women who have strong social bonds typically live longer than people who are socially isolated. More recently, similar patterns have been shown in a number of other mammals, including some primates, senior author Susan Alberts, chair of the evolutionary anthropology department at Duke University, tells Treehugger.

However, all the earlier work in primates on this subject has been on females rather than males.

“And so it remained unclear whether male nonhuman primates show the same pattern,” Alberts says. “There were reasons to expect that it might not be so for male baboons, since they move between social groups every few years, unlike females, and don’t usually live with close family members, who are the closest associates for females.”

As part of the Amboseli Baboon Research Project, researchers have been following baboons in Amboseli National Park in southern Kenya almost daily since the early 1970s. They tracked their overall lives, as well as who they socialize with, which typically includes grooming each other. 

When baboons groom, they sit close to each other, picking through each other's fur, looking for ticks and other parasites. It's a bonding, reciprocal behavior that relieves stress, is soothing, and also helps with hygiene.

The Benefit of Strong Bonds

For the study, researchers analyzed data for 277 males and 265 females, estimating the strength of the bonds in their relationships by measuring how much time they spent grooming their closest friends. They discovered that baboons of both sexes benefited by having strong social ties.

Males who were the most socially connected to females had a 28% higher mortality rate than those who were more socially isolated. This difference translates into several years of life.

For females, the effect of having close bonds was even stronger. There was a 31% decrease in mortality for having strong ties with females and a 37% decrease for having close relationships with males.

The findings were published in the journal Philosophical Transactions of the Royal Society B.

“More and more evidence from social species — not just humans, but also nonhuman animals, from hyrax to orcas to bighorn sheep — shows that that close social bonds are strongly linked to health and life span,” Alberts says, which is why researchers weren’t completed surprised by their findings.

“On the one hand, the classic view of male baboons (and some other primates) is that their social behaviors and strategies are pretty much entirely driven by reproductive interests. On the other hand, we’ve seen plenty of evidence over the years that males seek social relationships with females for other reasons, including care of young and sometimes, it seems, just companionship.”

Alberts says more research needs to be done to confirm the link and figure out how friendship affects baboon life spans.

“We’d love to be able to do this!” she says. “Understanding how social relationships translate into a longer life span is a big question, for both humans and nonhuman animals.”