About the Authors

Serge A. Wich

sergealexander.wich@uzh.ch

Affiliations Anthropological Institute, University of Zurich, Zurich, Switzerland, Sumatran Orangutan Conservation Programme (PanEco-YEL), Medan, Sumatra, Indonesia

Erin R. Vogel

Affiliation The Center for the Advances Study of Hominid Paleobiology, The George Washington University, Washington D. C. United States of America

Michael D. Larsen

Affiliation Department of Statistics, The George Washington University, Washington, United States of America

Gabriella Fredriksson

Affiliation Institute for Biodiversity and Ecosystem Dynamics/Zoological Museum, University of Amsterdam, Amsterdam, The Netherlands

Mark Leighton

Affiliation Great Ape World Heritage Species Project, Babson Park, Massachusetts, United States of America

Carey P. Yeager

Affiliation Zoology Department, University of Florida, Gainesville, Florida, United States of America

Francis Q. Brearley

Affiliation School of Science and the Environment, Manchester Metropolitan University, Manchester, United Kingdom

Carel P. van Schaik

Affiliation Anthropological Institute, University of Zurich, Zurich, Switzerland

Andrew J. Marshall

Affiliation Graduate Group in Ecology, and Animal Behaviour Graduate Group, Department of Anthropology, University of California Davis, Davis, California, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: SAW CPvS AJM. Performed the experiments: SAW GF ML CPY FQB CPvS AJM. Analyzed the data: SAW AJM EV MDL. Contributed reagents/materials/analysis tools: SAW AJM EV MDL. Wrote the paper: SAW EV MDL AJM.