Childhood and the evolution of the human life course

Childhood has been the focus of research and debate among anthropologists, developmental psychologists, demographers, economists, and other social scientists for fifty years (Konner 1991; Panter-Brick 1998). As a result, there are diverse research traditions and trajectories that have arisen with varying levels of intercommunication. Recent theoretical developments in human evolutionary ecology have shifted away from description of the normative characteristics of childhood across societies towards exploration of the evolutionary history of primate ontogeny and the fitness consequences of a life history that has childhood as a component (Blurton Jones 1993; Blurton Jones et al. 1989, 1997, 1999; Bogin and Smith 1996; Charnov 1993; Charnov and Berrigan 1993; Hawkes et al. 1997, 1998; Janson and van Schaik 1993; Kaplan et al. 2000). Leigh (2001) has identified four models based in life history theory that have recently been used to explain the slow growth and extended juvenility of primates in general and humans in particular. The brain growth model asserts that slow growth is a consequence of the amount of learning-based knowledge necessarily acquired by adulthood. Essentially, slow growth provides the time needed to fully program the brain with the information needed for adult competence (Bogin 1999). The pleiotropic model developed by Charnov and colleagues (Charnov and Berrigan 1993) argues that among primates the benefits of continued growth to the