They live longer if they have good friends

The secret to long life? Perhaps it was discovered by a certain breed of female monkeys: their friends keep them healthy.

Anthropologists have studied the behavior of female white-headed capuchins, which live in the tropical forests of northwestern Costa Rica, and discovered how beneficial it is for the animals to have friends. “As humans, we assume that social interactions have some benefits, but it turns out that it is very difficult to objectively measure the success of these social behaviors,” said Susan Berry, a professor of anthropology and biologist at UCLA. “Why do we invest so much in our relationships with others? Does it lead to a longer life? Does it lead to better reproduction? It is very difficult to determine that in humans and other animals.”

take care of each other
Driving Perry since 1990 Project Lomas Barbudal Capuchin Monkey in Guanacaste, Costa Rica, where her research team is documenting the daily lives of hundreds of monkeys with relatively large brains. You might expect chimpanzees and orangutans, which are closely related to humans, to provide the most interesting information, but it is precisely the white-headed capuchin monkeys that have very complex social structures that influence their behavior and pass on to others.

Throughout the year, Perry’s team roams the woods for 13 hours of observation days to try to draw conclusions that can help us understand our relationships, our culture, and our behaviour. The researchers followed the interaction between female monkeys and also between males and females for eighteen years. Interactions accounted for in the study included giving and receiving grooming, foraging for food nearby, and engaging in conflict (intervening to help each other through fighting, chasing, or making aggressive sounds and facial expressions).

Big differences
Their main finding: Female capuchins who are better integrated into social networks with other adult females live longer. The principal investigator explains that the differences are significant Kotrina Kajokaite off Scientias. “Our models show that a female monkey who barely grooms the female of other monkeys (grooming) has a 0.24 chance of dying within a year, while the most voracious caregivers have a 0.01 chance of dying. A female that often feeds around other females has a 0.08 chance of dying within a year, and a female that feeds most often around other females has a zero chance of dying, 01″.

higher in the hierarchy
Kajokaite and her team have not yet investigated the mechanisms behind the higher survival rate through social interaction. “This is the next step in our investigation.” However, there are thoughts about possible explanations. “Social interaction can lead to many benefits, such as better access to resources, reduced chances of falling prey, reduced risk of infection, and higher ranking in the hierarchy,” she explains.

“There may be a direct link: for example, social interaction improves access to food resources, which affects survival rates. But the link may also be more indirect: for example, female monkeys may trade in grooming to obtain Alliance support, which can lead to fewer injuries and a higher social standing for women It is also possible (and very likely) that females pursue multiple strategies and that there are multiple ways in which social interaction leads to a greater chance of survival The strategy can also vary for each female Monkey “.

just monkeys
So female monkeys need each other for a longer life. What does that say about women? Cajukaite explains that her monkey study is actually a consequence of the behavior we see in humans. “The relationship between social behavior and life expectancy is well known in humans, but we have recently started to investigate it in animals. This is mainly because the research takes many years and requires a lot of patience from researchers, students and other enthusiasts.” However, she can draw one important conclusion: “Despite the many differences in the social environment of humans and animals, the relationship between social integration and normal life expectancy is largely the same in humans and non-human primates. Moreover, the difference The individual in the influence of social life on survival is not unique to humans.”

And what about men?
Strikingly, there is no evidence that heterosexual relationships increase survival rates for female monkeys, at least not when it comes to the type of behavior measured in this study. But this does not rule out that some adult monkeys may benefit from social interaction with one or a few male partners with whom they live for long periods of time. “It was surprising that female-male interaction had no beneficial effect on female survival. Capuchins are physically larger and stronger than females, have large canine teeth and outperform females in the dominant hierarchy. This is what makes them partners in alliance and exchange,” Cajukaite explains. For example, females can receive combative support from the males in exchange for assistance with feeding or caring. Such an exchange can improve female survival by reducing the risk of infection and improving access to resources.”

Why does this not happen? “Males migrate several times in their lives. The majority only stay in a group for a short time, while females stay in the group in which they were born,” explains the researcher. As a result, the chances of adult females to form long-term relationships with male monkeys are reduced. as well as closer relationships with other women.” But this does not mean that this is always the case. “We do not rule out the possibility that adult females would benefit from social interaction with one or a few male partners who stay with them for extended periods.”

But the most important and most fascinating conclusion is by far: apes live longer if they have good friends.