The effects of resources and population expansion on female–male protein consumption among hunter-gatherers

This paper investigates the effects of terrestrial vs. marine resources and population expansion on sex differences in the consumption of protein among hunter-gatherers. We propose that differences in protein consumption emerge under conditions of greater specialization on terrestrial resources and population expansion. Consistent with this hypothesis, hunter-gatherers in pre-contact Texas display more pronounced sex differences in ${\delta }^{15}$N isotope values when they exploit terrestrial and riverine resources rather than coastal and estuary resources. Further, where foragers harvest terrestrial and riverine resources, sex differences in ${\delta }^{15}$N isotope values first decline and then increase coincident with population expansion on the Texas Coastal Plain. In coastal ecosystems, sex differences in ${\delta }^{15}$N isotope values remain minimal as population expands. These patterns support the hypothesis that population expansion and associated changes in the production of resources may create incentives for more or less overlap in the dietary niches of males and females. The direction of change depends on the resource options that foragers select to scale-up their production of food.