The Mother’s Dilemma: Ancient maternal trade-offs explain egalitarian moral cooperation.

Ben Thomas Gleeson 

The emergence of egalitarian moral norms is widely regarded as a crucial transition in human social evolution, yet it remains a puzzle. Existing explanatory models leave several issues unresolved and share a common reliance on male social agency and alliance-making, which predisposes them towards mechanisms based in social competition. By contrast, drawing on comparative panin socioecology, this article describes specifically female fitness incentives for collaborative counterdominance against ancestral male alpha-dominance strategies, which likely included opportunistic infanticide. In chimpanzees and bonobos, females use contingent maternal tactics to avoid male aggression, but collaborative defence is strongly moderated by habitat abundance due to effects from female feeding competition. Using game theory payoff matrices, I formalise this maternal trade-off as ‘The Mother’s Dilemma’—an ecologically contingent coordination game where individually fitness-enhancing female cooperation becomes viable only when habitat abundance eliminates costs from feeding competition. This model predicts that variable ecological conditions mediated ancient in-group social cooperation across distributed sub-populations of early hominins. I develop the implications of this female-centred ecological model for hominin social evolution and argue that collaborative female counterdominance offers a more compelling explanation of egalitarian human moralities, allomaternal provisioning, and prestige-based male social competition, than existing male-centric or sexually undifferentiated alternatives.