Ilaria Pretelli , Monique Borgerhoff Mulder, Bakar Makame Khamis, Richard McElreath

Childhood is a period of life unique to humans. Childhood may have evolved through the need to acquire knowledge and subsistence skills. In an attempt to evaluate the importance of learning for the evolution of childhood, previous research examined the increase with age of returns to foraging across various resources. Any increase could be due to increases in knowledge or other factors such as body size and strength. Here, we first estimate age-specific foraging returns for two different resources. We then model the relative importance for foraging of ecological knowledge, grip strength and height in a population of part-time children foragers on the island of Pemba, Tanzania. We use anthropometric measures, such as height and strength, and estimates of ecological knowledge for more than 250 and 90 individuals respectively, in association to behavioral observations for 63 individuals across 372 foraging trips. We find slower increases in foraging returns with age for trap hunting than for shellfish collection. We do not detect any effect of individual knowledge on foraging returns, potentially because relevant information can be shared within foraging parties. We also find positive effect of individuals height on shellfish collection.
This is the first study providing accurate estimates of individual traits contribution to foraging performance, which is important to evaluate evolutionary hypotheses for the emergence of childhood.