About the Authors
- Matthew W. Campbell, Frans B. M. de Waal
- Living Links Center, Yerkes National Primate Research Center, Emory University, Atlanta, Georgia, United States of America
The authors have declared that no competing interests exist.
Conceived and designed the experiments: MWC FBMW. Performed the experiments: MWC. Analyzed the data: MWC. Wrote the paper: MWC FBMW.