1. Department of Anthropology, University at Buffalo, Buffalo, NY 14261, USA
2. Evolution, Ecology, & Behavior Program, Department of Environment and Sustainability, University at Buffalo, Buffalo, NY 14260, USA
3. German Primate Centre, Endocrinology Laboratory, Leibniz Institute for Primate Research, 37077 Goettingen, Germany
4. Faculty of Veterinary Medicine, Bogor Agricultural University, Bogor 16680, Indonesia
5. School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool L3 3AF, UK