Sex differences in altruism and the demography of human warfare

Alberto Micheletti

May 7, 2019, 12:45–13:45


Room MS 001


Recent years have seen an increasing interest in understanding possible links between warfare and the high levels of within-group altruism observed in human societies. At the same time, sex has been shown to modulate incentives to express social behaviours in populations characterised by warfare demographies. However, the potential for sex differences in altruism in the context of warfare has been relatively neglected and the possibility that such differences might be driven by sex biases in demography has not been explored formally. Here, we develop a kin selection model to investigate how the sex of the altruist and that of the beneficiary influences patterns of such behaviours in populations that experience between-group conflict. We find that sex is a fundamental modulator of altruism in the context of the demography of warfare: members of the sex that competes more globally and/or is more philopatric are favoured to behave more altruistically towards same-sex groupmates than opposite-sex ones. The effects of these two factors may reinforce each other, potentially explaining recently-observed patterns of sex-specific altruism in populations with different post-marital dispersal norms.


Alberto Micheletti, Sex differences in altruism and the demography of human warfare, IAST Lunch Seminar, Toulouse: IAST, May 7, 2019, 12:45–13:45, room MS 001.