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There are scores of saccharine quotes about friendship floating around — “Friends are the relatives we choose,” for example. (Really, the only one that resonates is “Friends help you move. Real friends help you move bodies.”)
A few weeks into the fall semester, new Sun Devils are joining clubs, forming study groups and, hopefully, becoming friends with their roommates, so we talked to two anthropologists in the School of Human Evolution and Social Change at Arizona State University about friendship.
Joan Silk studies how natural selection shapes the evolution of social behavior in primates, mainly baboons. Daniel Hruschka, a professor of anthropology and global health, has written a book on friendship: "Friendship: Development, Ecology, and Evolution of a Relationship."
“Friendships in humans fulfill a lot of our needs,” Hruschka said. “Friends bring your food when we can’t get it. They protect us in fights. A friend in a hostile village will protect you. In modern society, friends will give us advice.”
In Bangladesh, where Hruschka researches, friends help each other harvest and plant, prepare rice and help with child care and cooking. Friends back each other up in fights. They stay with each other.
“Those are some of the functions of friendship you see,” he said.
There is no phenomenon like friendship in baboons, but there are some similarities. Surprisingly, baboon relationships may be healthier for them than human friendship is for people. And while both baboons and humans help each other, it takes different forms.
Baboons are stressed pretty much most of the time. They’re about the size of an average dog, and everything around them wants to kill them. Males beat females, and females beat younger females.
“It’s not relaxing to be a baboon,” Silk said. “They’re constantly afraid of various things.”
Baboons live in large groups of adult females, a few young males and all the offspring. Males move out of the group so they don’t mate with relatives. Females stay. There are mothers, daughters, sisters, granddaughters, aunts, nieces. Within these groups, females form extremely close ties to certain other females. They sit together, groom each other and spend most of their time together.
“I wouldn’t claim that there is a phenomenon exactly like friendship in baboons,” Silk said. “But nonetheless I do think there’s a real connection here. It just works a little differently. I actually think the parallels are quite meaningful.”
Silk has worked on several different baboon populations.
“This happens routinely among baboons,” she said. “Females develop these very tight relationships. The partners are usually close relatives. It’s not exactly comparable to human friendship, because we make a big distinction in our culture between friends and family.”
Females who form the strongest ties to other females — the ones who have the most relationships — live longer than other females. Their kids are also more likely to survive than those of other females. In strong relationships, stress levels go down. When stress levels drop, immune systems work more effectively.
“That’s the parallel,” Silk said. “In both cases having a warm, supportive, close, predictable, stable relationship seems to have a whole bunch of effects on health and well-being.”
Stress relief isn’t necessarily a function of human friendship. In fact, the opposite is often true.
“It may be that (friends) also relieve stress because they are helping us deal with the risks of daily life, but I don’t know a lot of evidence that friends lower stress across the board,” Hruschka said. “In fact, friends can be quite stressful if they ask you to move over the weekend if you have other stuff going on. Friends can impose on you too. So I think friends can impose stress as well.”
Most primates only truly trust their relatives. People trust both relatives and friends.
“It’s the kind of relationship you have, not necessarily who you have it with, that really matters in terms of the positive consequences,” Silk said. “I think it’s ‘Can you rely on them? Do you feel comfortable with them? Is it a predictable, stable relationship?’ That’s what I think matters rather than who it is.”
Because of lions, leopards and myriad other threats, baboons are on high alert all the time. Female baboons have a dominance hierarchy. Some females can come along and beat you up, and there are females you can go and beat up.
“Things they can do to make themselves less afraid are really important,” Silk said.
When a female approaches another female, the female being approached doesn’t know what’s going to happen. A high-ranking female may attack. She might want to be groomed. She might want to look at your baby. In any case, the female being approached is afraid and may decide to just flee.
“What baboons do in that situation is they give these lovely little grunts,” Silk said. “They approach, and they grunt. It’s a quiet call; it’s not very spectacular. But to the baboons it means ‘I come in peace’ or ‘I’m not going to hurt you.’ It works, and it means they’re more relaxed. We’ve done a bunch of analyses of this and I call these grunts ‘signals of benign intent.’ It’s not that catchy, but they basically mean, ‘Relax; it’s going to be fine.’”
Related females, like mothers and daughters, don’t grunt at all to each other. It tells us something about how the relationship feels to the baboons. It feels safe and predictable, because mothers and daughters interact a lot, but they don’t feel the need to grunt very much.
Human friends help each other out with a lot, whether it’s unwanted advice at the grill on Saturday night, recommending a new app or moving a body.
“In some ways that’s unique to humans because there are so many different things we can help each other with, because culture creates so many different needs for us,” Hruschka said. “You might not see so many different needs among baboons.”
There is wide cultural variety in friendship. Human friendships can last for decades. In some societies, friendships are inherited over generations.
“Kids inherit friendships from their parents, almost formally, like it will be in a will,” Hruschka said. “You can see this happening over generations, so friendships might last for centuries ultimately. It’s not carried on by the same individuals, but by the same families.”
Above photos courtesy of Professor Joan Silk