Sex-related structural differences in language areas of the human brain and their implications for intergroup relations in ancestral groups

•Sex-related structural differences in the language areas of the brain.•Reproductive women were most likely taken as war spoils.•Sex differences in the environment likely have major effects on brain biology.•Males and females were exposed to different environmental pressure in human history. In his research on the bilingual brain, Hagen (2008) shows adult learners’ foreign language achievement variability and universal success of language acquisition by children as the reflections of minimal intergroup and maximum intragroup contact in our ancestral societies. However, his arguments are criticized by Hirschfeld (2008) who states that the capacity of children to acquire multiple languages before the critical period, without a negative effect on first language acquisition, signals the availability of intergroup contact in prehistoric hunter–gatherer societies. He argues that groups achieved peaceful intergroup contact through marriage or sustained long distance trade. In this study, I consider the argument between Hagen (2008) and Hirschfeld (2008) with an emphasis on sex-related structural differences in the language areas of the brain and their implications for the dynamics of ancestral inter-group interaction. Within the context of the male warrior hypothesis, the current study hypothesizes that these differences could be because of minimum intergroup interaction (minimum second or foreign language exposure) that males in our ancestral societies had and relatively more inter-group interaction that females were exposed to than males.