The research team used statistical techniques to calculate mortality risk – the likelihood of dying – for each baboon age, using scarce data, and then examined whether the relationship between survival and friendships was the same for male and female baboons.
Since 1971, researchers have identified individual baboons (Papio cynocephalus, yellow baboons) are monitored almost daily in southern Kenya as part of the Amboseli Baboon Research Project. They noted who the baboons interacted with socially and how they fared over the course of their lives.
Baboon best friends don’t go out for a drink together, of course, but they spend time together fleas – a give and take where they sit close together, stroking and examining each other’s fur, looking for ticks and other parasites. “It’s how baboons bond and reduce their stress, and it helps them somewhat with their body hygiene, too,” Alberts said.
Males spend very little time fleas from each other, but they do so with females, and not just when the females are fertile.
The team analyzed data from 277 males and 265 females and estimated the strength of the bonds in each baboon’s circle of friends by measuring how much time he or she spent fleaging his or her closest friends.
The team showed for the first time in wild monkeys that, unsurprisingly, both sexes benefit from strong social ties. Like humans, “male baboons live longer when they are socially connected,” Alberts said.
Males who had strong friendships with females were 28 percent more likely to make it to their next birthday than their socially isolated counterparts.
The team found that the flip side of the friendship medal, social isolation, may pose a greater threat to the males’ survival than the stress and dangers they face as they fight their way up the social rank of the group. . On the other hand, males who occupy a high position in that social order for their age appear to have a shorter life expectancy.
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