Two Tsimane men returning from a hunt. Credit: Chris von Rueden

Seeking social status is a central human motivation. Whether it's buying designer clothing, working the way up the job ladder, or making a conspicuous donation to charity, humans often seek and signal social status. Human cooperation and competition aren't mutually exclusive, they are two sides of the same coin. Christopher von Rueden from the University of Richmond and Daniel Redhead from the Max Planck Institute for Evolutionary Anthropology led a study to assess the relationship between men's cooperation and status hierarchy over a period of eight years in a community of Tsimane Amerindians in Amazonian Bolivia.

Among the Tsimane, status is informal and evident in who has more verbal influence during community meetings. Influential men in this community also enjoy greater health and have more surviving children. At three points over the eight-year period, the researchers asked men to rank other men within their community on their status and to report other men with whom they regularly cooperate, in terms of food-sharing or joint hunting, fishing, or horticultural labor. The researchers show that high status men gain more cooperation partners over time, and that men gain status over time by cooperating with men of higher status than themselves. By cooperating with high-status individuals, one may gain valuable information, resources or coalitional support that increases one's own status. Alternatively, cooperation with high-status individuals may increase one's status by more effectively broadcasting generosity or other desirable attributes to other community members.

"The finding that status depends on cooperation provides insight into why human societies, particularly small-scale societies like the Tsimane, are relatively egalitarian compared to other primates," says von Rueden, joint lead author of the study. "Humans allocate status based on the benefits we can provide to others, often more than on the costs we can inflict. This is in part because humans evolved greater interdependence, relying on each other for learning skills, producing food, engaging in mutual defense and raising offspring. Individuals who can offer unique services in these contexts gain status. However, the transfer of information and resources from higher- to lower-status individuals, as well as the potential reputational benefits to cooperating with higher-status individuals, may constrain or even erode status differentials. Status inequality is constrained when, by cooperating, status-dissimilar individuals influence each other's statuses. This likely changed with the spread of agriculture 10,000 years ago, as human communities grew in size and began producing more private wealth. Widespread cooperation among community members becomes difficult as community size increases, and individuals with more wealth can lose incentive to cooperate with the non-wealthy outside of more market-based or coercive transactions. These processes limit upward mobility and fuel stratification by wealth class."

A Tsimane man helping resolve a dispute over land, which is illustrative of the largely informal way in which political influence operates in this society. Credit: Chris von Rueden

Daniel Redhead, joint lead author of the study, adds, "This is one of the first longitudinal studies of social status. Our findings provide some of the first evidence that the relationship between cooperation and social status among humans is bidirectional. That is, humans, compared to other animals, give status to those who provide benefits to groups, and are thus more attracted to these individuals as cooperative partners. At the same time, individuals increase their own status by cooperating with such high status. These findings provide empirical evidence that stresses the broader importance of social interdependence—be it food sharing, food production, friendship or advice—in shaping human behavior, and that this interdependence makes the ways that we obtain social status quite distinct from other animals."

More information: The dynamics of men's cooperation and social status in a small-scale society, Proceedings of the Royal Society B, rspb.royalsocietypublishing.or … .1098/rspb.2019.1367 Journal information: Proceedings of the Royal Society B The dynamics of men's cooperation and social status in a small-scale society,