a1 School of Psychology, University of Queensland, Brisbane, Qld 4072, Australia. firstname.lastname@example.org http://www.psy.uq.edu.au/directory/index.html?id=636gh
Human life history incorporates childhood, a lengthy post-weaning period of dependency. This species-specific period provides an opportunity for extensive learning and for sophisticated cultural behaviors to develop, including crucial tool use skills. Although I agree that no individual cognitive trait singularly differentiates humans from other animals, I suggest here that without childhood, the traits that are key to human tool use would not emerge.