[1] Boston Coll, Dept Psychol & Neurosci, Chestnut Hill, MA 02467 USA
[2] Harvard Univ, Dept Organism & Evolutionary Biol, Cambridge, MA 02138 USA
[3] Tufts Univ, Dept Anthropol, Medford, MA 02155 USA
[4] Kibale Forest Sch Program, Kabarole, Uganda
[5] Kasiisi Project, Lexington, MA 02143 USA