Abstract
Background: A fundamental characteristic of human nature is our ability to coordinate with one another in order to achieve common goals and protect shared interests, engaging what evolutionary scholars call coalitions when interests conflict. Evolutionary theory posits that human males have had the largest reproductive gains by succeeding in coalitional conflict and competition and predicts that their psychology will therefore be more attuned to achieving coalitional dominance than will the psychology of women, a proposal which empirical psychological research among adults supports. Here, I investigate whether preschoolers and preverbal infants, too, have social preferences that align with the ancestral demands of coalitional conflict, and whether adult gender differences in such coalitional motives have antecedents in early ontogeny. Previous research indicates that young children and infants are in fact sensitive to coalitional formidability in that they expect members of larger groups to prevail over members of smaller ones in conflicts of interests. However, it remains unknown whether infants and young children themselves prefer being part of a larger, more formidable, coalition, and if any such coalitional motives are greater among male children. Methods: We showed a total of 153 3–6-year-old preschoolers and 180 6–13-month-old infants animated videos of two social groups, one large and one small, which moved in two different synchronous patterns, and asked participants to choose between a member of the larger and smaller group. Preschoolers indicated their preference on a touch screen computer, and infants reached for one of the two agents. A control study (N = 164) instead asked preschoolers to choose between two members of a large or small set of objects which moved randomly. Findings: Results showed that male preschoolers prefer a member of a larger, rather than smaller, group more often than do girls, and that boys tend to choose a member of a larger group more often than chance. This preference did not extend to sets of objects which move randomly. In contrast, we found positive Bayesian evidence for the null-hypothesis that preschool girls, as well as preverbal infants, do not prefer members of larger or smaller groups. This suggests that precursors of adult gender differences in coalitional motives emerge in early ontogeny among preschoolers, but not among preverbal infants.