This study tests the weaning food availability hypothesis, that both the introduction of foods other than breastmilk and the cessation of breastfeeding will vary by society's subsistence type. This hypothesis has implications for demography, as accelerated weaning can lead to increases in both mothers' fertility (due to decreased birth intervals) and infant mortality (due to the presence of pathogens in new foods).

This study tests for a relationship between subsistence type and fertility using phylogenetic and statistical analyses. The authors find a clear relationship between dependence on agriculture and fertility among non-permanently settled groups.

In this article, the authors seek to understand the connection between male resource-holding potential and male mating success. This connection has been suggested by behavioral ecologists as a way of explaining differing rates of polygyny across cultures. The authors investigate this relationship by testing the relationship between rates of polygyny and male control of local subsistence sites among North American societies during the period of contact. They find a positive relationship between these two variables for both terrestrial and aquatic game, but not for gathered plants. This suggests support for the theory.

The Trivers-Willard hypothesis posits that concentrations of human milk immune factors vary with maternal condition (maternal diet diversity and body mass index) and the sex of the infant. Using linear mixed-effects models to analyze 358 milk samples from 10 international sites, the authors find minimal support for the Trivers-Willard hypothesis; only one immune factor, IgG, exhibited a significant relationship.