1. Department of Anthropology, Durham University , Durham, County Durham, DH1 3LE , UK
2. Department of Psychology, College of Sciences, San Diego State University, Imperial Valley Campus , Calexico, CA 92231-09021 , USA
3. Independent Researcher , Dar Es Salaam, Tanzania
4. Independent Researcher , Yaida, Tanzania
5. Department of Psychology, Center for Applied Cognitive Science, University of Texas at Austin , Austin, TX 78712 , USA
6. Department of Psychology, University of Pennsylvania , Philadelphia, PA 19104 , USA