Male baboons with close but not necessarily sexual bonds with females of similar age live longer, a new study has found. Female baboons benefit from friends of either sex.
The debate as to whether men and women can be friends without sex getting in the way has inspired some of the most successful romantic comedies of all time. Despite the heterosexual assumptions underlying the question, primatologists have asked the same thing when observing close bonds between male and female baboons.
Surely, some have thought, the only reason a male would devote so much time to grooming females is the hope that he’ll be first in the queue when she comes into heat or possibly to protect any offspring that are theirs. However, 35 years of observations in Amboseli National Park, Kenya, call this into question.
Like many other primates, baboons spend a lot of time grooming each other. It not only helps remove parasites but helps keep a troop together. "It's a baboon's way of bonding and relieving stress, as well as providing some help with hygiene," said Professor Susan Alberts of Duke University in a statement. Female-female grooming is common, but males seldom groom other males.
That means males that don’t do a lot of grooming with females are socially isolated, and Alberts found they pay a high price. Males that have at least one strong bond (measured by grooming frequency) are 28 percent more likely to survive until their next birthday than those that don’t, she reports in Philosophical Transactions of the Royal Society B.
Unexpectedly, males with greater dominance within the baboon hierarchy actually had shorter lives, although the effect was on the border of statistical significance. So far, Alberts has only established a correlation between grooming bonds and survival, not causation. “Healthier individuals, in better condition, may be more likely to live long lives, more likely to maintain strong social bonds, and more likely to achieve high social status,” the paper notes
However, we know that friendships can extend life for humans – indeed they matter as much for one’s chances of growing old as a good exercise regime. Female dolphins, monkeys, and horses have been found to gain similar benefits from their friendship networks. Male friendship in animals has been much less studied, in part because in many species males move between groups and are harder to track. However, we do know male orcas live longer when they have strong social networks.
In this context, it seems likely forming grooming bonds with females really does extend males’ lives, although whether this is because of all the parasites removed, better predator warning, or more subtle benefits is harder to say.
Either way, the finding discredits the idea that male baboons only groom females in the hope of getting sex down the track. Hopefully, it will do the same for the equivalent assumptions that any human man being friends with a woman is doing it too for sex.