Economic preferences may be shaped by exposure to sex hormones around birth. Prior studies of economic preferences and numerous other phenotypic characteristics use digit ratios (2D:4D), a purported proxy for prenatal testosterone exposure, whose validity has recently been questioned. We use...

Leadership studies concentrate on large-scale societies and organizations with formal hierarchies, large power differences, and diverse membership. Much less is known about leadership in small-scale, homogeneous, and relatively egalitarian societies in which humans have spent most of their...

Observation of leadership in small-scale societies offers unique insights into the evolution of human collective action and the origins of sociopolitical complexity. Using behavioural data from the Tsimane forager-horticulturalists of Bolivia and Nyangatom nomadic pastoralists of Ethiopia, we...