PULLMAN, Wash. - The idea that human beings, and especially those in hunter-gather societies, have an intrinsic tendency toward equal sharing persists in science and popular culture.
However, a new study by a Washington State University researcher and others used an experimental game to demonstrate that members of the Hadza tribe in Tanzania, a modern hunter-gatherer culture, rarely shared equally with others when given the chance to keep more - and in many cases took everything for themselves.
The study, published in the journal PNAS Nexus, was based on a game researchers used in which participants were given different amounts of tokens representing food - sometimes more and sometimes less than another member of the community. Then they were given the chance to anonymously share tokens or take more for themselves.
Researchers conducted the game with 117 Hadza adults at 11 camps across the East African country in 2019.
"This work's really examining this idea that we have these innate preferences to share with others and have these equal exchanges with one another," said Kristopher M. Smith, an assistant professor of anthropology at WSU and lead author of the paper.
While the Hadza were not entirely self-interested, they tended to keep or take more for themselves, and were more tolerant of inequality when it benefited them than when it didn't. More than 21% of the time, participants took all of the tokens.
"The fact that the most common response, whether they had more or less than the other person, was to take everything the other person had was quite surprising, given the emphasis on how cooperative they can be," Smith said.
Smith's co-authors included anthropologists from Baylor University, Durham University and the University of Pennsylvania.
To conduct their experiment, the researchers used a variant of what is known as the "dictator game," in which one person is given all the resources and asked to choose how to share with others. In Smith's experiment, each participant was given a scenario in which they had more or fewer tokens than another person from the camp, and allowed to either give the other person more tokens or take theirs away. Participants would be given a banana chip for each token at the end of the game.
When Hadza participants were given more than their campmate, just 41% of them chose to give some away, while 30% took even more. When given fewer tokens than their campmate, 59% of participants took from the other player-and often took more than needed to achieve equality.
Relatively equal sharing resulted only when participants were taking resources from others.
The authors also found that men and younger people were more willing to give away tokens when they had more, and that participants who had greater familiarity with market-based societies outside the Hadza were less likely to take from others when they had more, but more accepting of the idea of inequality generally.
The findings suggest that Hadza sharing is not maintained primarily by intrinsic preferences for equality, but by demands from those who have less and extrinsic norms of fairness.
