Kazuhiko Hosaka is Associate Professor at Kamakura Women's University, Japan. His research focuses on the social interactions, hunting and meat-eating behaviour of chimpanzees in relation to human evolution.

Noriko Itoh is a researcher in the Wildlife Research Center, Kyoto University, Japan. She has studied the Mahale chimpanzees since 1995, focusing on grouping behaviours and related environments.

Koichiro Zamma is a researcher in the Graduate School of Asian and African Area Studies and in the Wildlife Research Center, both at Kyoto University, Japan. His research focuses on the impact of ectoparasite infections on grooming and on the sleep-related behaviours of chimpanzees.