By Kristopher Smith
What kind of people do you like to surround yourself with? If you’re like the participants in most psychology studies, you probably prefer to be friends with people who are trustworthy and generous. This makes sense; when the going gets tough, you want friends you can rely on to be there for you. It’s not difficult to imagine our hunter-gatherer ancestors, living in dangerous environments with scarce resources where help would often be needed, having similar preferences.
But the people who participate in psychology studies are not like most people, and on a number of psychological traits, are outliers from the rest of the world. In fact, most participants in the behavioral sciences are WEIRD: Western, Educated, Industrialized, Rich, and Democratic. For example, compared to populations from East Asia, WEIRD people have a more independent concept of self and value self-consistency more, and compared to subsistence populations, WEIRD people are more likely to offer fair offers and reject unfair offers in the ultimatum game.
And there’s reason to think WEIRD people differ on their preferences for generous friends, especially compared to hunter-gatherers. For example, hunter-gatherers have strong norms of food sharing, and these norms are often more important for determining whether a person is generous than their disposition to share. In such a situation, it may be more important to prefer a friend who brings back food in the first place, regardless of their willingness to share it.
While we cannot go back in time to see who ancestral hunter-gatherers preferred as friends, contemporary hunter-gatherers may provide some insight into how these conditions can shape social preferences. Of course, present-day hunter-gatherers are different from ancient hunter-gatherers in many ways, and depictions of them as the “natural state” of humans are problematic, ethically and scientifically. However, studies with hunter-gathers provide an opportunity to examine psychological variation in an environment without agriculture or its associated institutions.
In 2016 and 2019, I visited the Hadza, a group of hunter-gatherers living in northwestern Tanzania around Lake Eyasi. The Hadza live in small camps of about 20 to 30 adults and children, usually consisting of multiple unrelated nuclear families. These camps are highly interdependent, and members of a camp are expected to share food, childcare duties, and protection with everyone else. Camps move locations every six to eight weeks as local resources are used, and people within a camp can move to a new camp as they wish. That is, if a member of a camp is frustrated with her neighbors, she could walk to a new camp with more desirable campmates.
Along with a team of research assistants, I visited about a dozen camps in both years and took photos of all the adults. We used these photos to ask participants to rank their campmates on a number of traits, including who was the most generous, hard-working, and honest, who was the best hunter or gatherer, and who they would like to live with the most in a new camp. We used these rankings to examine whether who Hadza wanted to live with was better predicted by character traits, like generosity, effort, and honesty, or by their ability to produce food.
Research assistant Victoria Maghali interviews a participant about her campmates.
Coren Apicella and I found that, in 2016, it was the campmates who were perceived as the best hunters who were most desired as campmates, and those perceived as high on character traits were only weakly preferred. While this contrasts to the preferences observed in WEIRD people, it supports previous results with the Hadza. In a study mapping their social network in 2010, it was people who were more physically fit, which is related to hunting ability, that had the most social ties in their network, not people who gave more in economic games.
In 2019, however, the pattern reversed; Hadza participants had stronger preferences to live with campmates they perceived as being more generous, honest, and hardworking compared to campmates perceived to be the most productive. So, over a ten-year span, the Hadza increasingly preferred to live with more generous Hadza. Why the change over time? One possibility is that the Hadza are becoming increasingly exposed to the surrounding cultures, with more Hadza attending school, working jobs in local villages, and traveling further to larg towns in the past decade. In 2019, I had surveyed participants about their exposure and knowledge to non-Hadza culture. And, in fact, participants who had greater exposure had the strongest preference for campmates high on character traits.
“Hadza participants had stronger preferences to live with campmates they perceived as being more generous, honest, and hardworking compared to campmates perceived to be the most productive.”
Exactly why exposure to other cultures is changing who Hadza prefer as campmates is unclear. We hypothesize that as Hadza have more experience in situations without strong norms of helping and sharing, where how generous a person is less determined by norms and more by their disposition to help, Hadza learn to discern how generous a person is and prefer to interact with people they perceive as helpful. We hope to test this hypothesis and better determine how exposure is changing their social preferences in future research.
Our research reveals both similarities and differences between WEIRD people and hunter-gatherers in social preferences. Like WEIRD people, Hadza are choosy about who they would prefer to be around and such choosiness may have deep evolutionary roots, as chimpanzees and even cleaner fish have strong preferences of who they want to cooperate with. What traits Hadza choose their friends on though has historically differed. Hadza had preferred people who were more productive rather than more generous; however, their preferences seem to be changing over time, and quite quickly. The findings highlight how ecological and cultural conditions can shape human psychology and the importance of mapping the full extent of human psychological variation.