Received: 30 August 2021
Accepted: 30 June 2022
Published in print: 12 August 2022
We are grateful to the late Sugio Hayama for conceiving and conducting in vivo chimpanzee experiments and for establishing the collection of excised larynges at the Japan Monkey Centre (JMC). We thank the JMC, Nagoya Higashiyama Zoo, Fukuoka City Zoological Garden, Kagoshima City Hirakawa Zoological Park, Yokohama Zoological Gardens, and the Wildlife Research Center, the Laboratory of Physical Anthropology, and the Primate Research Institute (PRI) of Kyoto University for providing samples. We thank T. Udono, Y. Shintaku, K. Matsui, H. Imai, S. Tsubouchi, and A. Kataoka for preparing or scanning the specimens; Y. Nomura and Z. Chen for examining laryngeal anatomy; K. Migimatsu, T. Matsumoto, M. Kanaya, and R. Miyazaki for conducting ex vivo experiments; C. R. Larson for providing suggestions for in vivo experiments of macaques; and T. Miyabe-Nishiwaki, Y. Sawada, B. Bach Andersen, and present and past staff of the PRI and the German Primate Center for help conducting in-vivo experiments and/or daily care of subjects. We appreciate the photograph courtesy of K. Sato at the Kurume University. This research was in part supported by the Kyoto University-University of Vienna Strategic Partnership Program.
Funding: Japan Society for the Promotion of Science grants 16H04848 and 19H01002 (T.N.), 17H06313 and 20K11875 (I.T.T.), and 18H03503 (H.K.) Research Units for Exploring Future Horizons through the Kyoto University Research Coordination Alliance (T.N., C.T.H.) Rhinology and Laryngology Research Fund UK (J.C.D.) Ministry of Education, Culture, Sports, Science and Technology Grant-in-aid for Scientific Research on Innovative Areas no. 4903 (Evolinguistics) grant 17H06380 (H.K.) Ministry of Education, Culture, Sports, Science and Technology Grant-in-aid for Scientific Research on Innovative Areas no. 4903 (Evolinguistics) (W.T.F.) Austrian Science Fund DK Grant “Cognition & Communication 2” grant W1262-B29 (W.T.F.).
Author contributions: Conceptualization: T.N., W.T.F. Methodology: T.N., C.T.H., I.T.T., S.M., J.C.D., U.J., W.T.F., O.N.L. Formal analysis: T.N., I.T.T., W.T.F. Investigation: T.N., W.T.F., I.T.T., S.M., J.C.D., C.T.H., K.I., A.K., Y.K., H.K., J.P.P.S., H.I., T.M., O.N.L., U.J., H.H., S.K. Resources: T.N., A.K., U.J., S.K., O.N.L. Writing - original draft: T.N., I.T.T., S.M., J.C.D., C.T.H., W.T.F. Writing - review and editing: T.N., I.T.T., W.T.F. Project administration: T.N. Funding acquisition: T.N., I.T.T., J.C.D., H.K., W.T.F.
Competing interests: The authors declare that they have no competing interests.
Data and materials availability: Laryngeal specimens from the subjects named Baran, Keiko, Wilie, and Yuri were available from the zoos under a material transfer agreement with the Kyoto University. Some specimens were provided through the Collaborative Research program of the JMC (no. 2018017) and the Great Ape Information Network under the National BioResource Project (NBRP) of Japan. All data are available in the main text or the supplementary materials.