Their new evidence shows that the Hadza are generally willing to share. But, that doesn’t mean that they always do. In fact, whether a particular individual will share generously depends less on the individual and more on the group they happened to live with at the time.
“We found that year after year, willingness to share with others clustered within residence groups or what we call ‘camps,'” says lead author Coren Apicella of the University of Pennsylvania. “People were living with other people who were similar to them in levels of generosity.”
“We also found individual willingness to share changed from year to year to match their current campmates and found no evidence that people preferred living with more cooperative people,” adds Kristopher Smith, the study’s first author. Importantly, those trends persisted even as the Hadza people changed campmates about every couple of months.