Childhood evolution and foraging skills / Ilaria Pretelli / IAST

Our species’ long childhood is hypothesized to have evolved as a period for learning complex foraging skills. Researchers have focused on assessing this hypothesis, yet studies present inconsistent conclusions regarding the connection between niche complexity, the development of foraging skill development, and ecological knowledge . I will present three studies addressing this hypothesis using both cross cultural and detailed individual level data from the Island of Pemba, Zanzibar. 

We first look at published records of child and adolescent foragers from 28 societies to assess whether children’s foraging proficiency increases more slowly for more skill-intensive resources, such as game and tubers, than for easier-to-extract resources, i.e. fruit and fish/shellfish, a prediction we find confirmed. We then move to individual level measures from Pemba, Zanzibar (TZ). There we measured ecological knowledge of 93 children and teenagers between 4 and 26 years to find that, while children learn during the whole pre-reproductive period, this happens at varying rates, with fastest increases in young children. Sex differences also appear during middle childhood and are mediated by participation in different activities. Both these results are consistent with the idea that childhood is necessary to learn how to forage. But does ecological knowledge actually help with foraging? To answer this question, we model the relative importance for foraging of ecological knowledge, grip strength and height in our population of part-time children foragers. To our surprise, we do not detect any effect of individual knowledge on foraging returns, potentially because relevant information can be shared within foraging parties. I will also provide some details concerning causal inference and statistical methods, before providing some final considerations on the future direction of my research and of our understanding for the evolution of childhood more in general.