Work in Children’s Lives

Herbal medicine is the first response to illness in rural Dominica. Every adult knows several "bush" medicines, and knowledge varies from person to person. Anthropological convention suggests that modernization generally weakens traditional knowledge. We examine the effects of commercial occupation, consumerism, education, parenthood, age, and gender on the number of medicinal plants freelisted by individuals. All six predictors are associated with bush medical knowledge in bivariate analyses. Contrary to predictions, commercial occupation and consumerism are positively associated with herbal knowledge. Gender, age, occupation, and education are significant predictors in multivariate analysis. Women tend to recall more plants than do men. Education is negatively associated with plants listed; age positively associates with number of species listed. There are significant interactions among commercial occupation, education, age, and parenthood, suggesting that modernization has complex effects on knowledge of traditional medicine in Dominica.

Humans have a much longer juvenile period (weaning to first reproduction, 14 or more years) than their closest relatives (chimpanzees, 8 years). Three explanations are prominent in the literature. (a) Humans need the extra time to learn their complex subsistence techniques. (b) Among mammals, since length of the juvenile period bears a constant relationship to adult lifespan, the human juvenile period is just as expected. We therefore only need to explain the elongated adult lifespan, which can be explained by the opportunity for older individuals to increase their fitness by providing for grandchildren. (c) The recent model by Kaplan and colleagues suggests that longevity and investment in "embodied capital" will coevolve, and that the need to learn subsistence technology contributed to selection for our extended lifespan.We report experiments designed to test the first explanation: human subsistence technology takes many years to learn, and spending more time learning it gives reproductive benefits that outweight lost time. Taking away some of this time should lead to deficits in efficiency. We paid Hadza foragers to participate in tests of important subsistence skills. We compared efficiency of males and females at digging tubers. They differ greatly in time spent practicing digging but show no difference in efficiency. Children who lost "bush experience" by spending years in boarding school performed no worse at digging tubers or target archery than those who had spent their entire lives in the bush. Climbing baobab trees, an important and dangerous skill, showed no change with age among those who attempted it. We could show no effects of practice time.These findings do not support what we label "the practice theory," but we discuss ways in which the theory could be defended; for example, some as-yet-untested skill may be greatly impaired by loss of a few years of the juvenile period. Our data also show that it is not safe to assume that increases in skill with age are entirely due to learning or practice; they may instead be due to increases in size and strength.