About the Authors

Hani D. Freeman

hani.freeman@gmail.com

Affiliations Language Research Center, Georgia State University, Atlanta, Georgia, United States of America, Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois, United States of America

Jennifer Sullivan

Affiliation Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin, United States of America

Lydia M. Hopper

Affiliations Language Research Center, Georgia State University, Atlanta, Georgia, United States of America, Lester E. Fisher Center for the Study and Conservation of Apes, Lincoln Park Zoo, Chicago, Illinois, United States of America, Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, Bastrop, Texas, United States of America

Catherine F. Talbot

Affiliation Language Research Center, Georgia State University, Atlanta, Georgia, United States of America

Andrea N. Holmes

Affiliation Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, Bastrop, Texas, United States of America

Nancy Schultz-Darken

Affiliation Wisconsin National Primate Research Center, University of Wisconsin, Madison, Wisconsin, United States of America

Lawrence E. Williams

Affiliation Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, Bastrop, Texas, United States of America

Sarah F. Brosnan

Affiliations Language Research Center, Georgia State University, Atlanta, Georgia, United States of America, Michale E. Keeling Center for Comparative Medicine and Research, UT MD Anderson Cancer Center, Bastrop, Texas, United States of America, Department of Psychology, Philosophy & Neuroscience Institute, Georgia State University, Atlanta, Georgia, United States of America

Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

Conceived and designed the experiments: SFB NS-D LEW. Performed the experiments: HDF JS LMH CFT ANH. Analyzed the data: SFB HDF LMH NS-D CFT. Contributed reagents/materials/analysis tools: NS-D LEW. Wrote the paper: HDF SFB LMH JS CFT LEW NS-D ANH.