M.A. Theses: Luseadra McKerracher, 2009

An Assessment of the Impact of Population History and Risk on Human Weaning Behaviour  

Among-population variation in human complementary feeding and weaning behaviour has rarely been studied in light of evolutionary theory.  To begin to rectify this, I tested the predictions of two evolutionarily-informed hypotheses proposed to explain among-population variation in the timing of events in the weaning process.  Specifically, I tested the null hypothesis that weaning variation reflects ancestor-descendent relationships among populations.  I also tested the alternative hypothesis that weaning variation is adapted to risk of resource failure.  Using cross-cultural data from contemporary or recent, natural fertility populations, I carried out regression, mantel, and partial mantel analyses to test or relationships between genetic distance (a measure of phylogenetic relatedness) or eco-geographic parameters (proxy measures of resource failure risk) and among-population variation in complementary feeding and weaning behaviour.  The evidence presented here does not support the phylogenetic hypothesis.  The evidence is consistent with the hypothesis that weaning variation is adapted to resource failure risk.  The results reported here suggest that among-population variation in the timing of weaning events is the product of adaptation.