JAPANESE TOP Message from the Director Information Faculty list Research Projects International Conference Entrance Exam Visitors Publication Job Vacancy International Partnerships Links Access HANDBOOK FOR INTERNATIONAL RESEARCHERS Map of Inuyama
TOPICS
BONOBO Chimpanzee "Ai" Crania photos Itani Jun'ichiro archives Guidelines for Care and Use of Nonhuman Primates(pdf) Study material catalogue/database Guideline for field research of non-human primates Primate Genome DB

Primate Research Institute, Kyoto University
Inuyama, Aichi 484-8506, JAPAN
TEL. +81-568-63-0567
(Administrative Office)
FAX. +81-568-63-0085

Copyright (c)
Primate Research Institute,
Kyoto University All rights reserved.

Contact

Japanese

Prolonged maximal sexual swelling in wild bonobos facilitates affiliative interactions between females

Heungjin Ryu, David A. Hill, Takeshi Furuichi

Perineal sexual skin swelling in relation to menstrual cycle occurs in a variety of primate taxa. However, sexual swelling with exaggerated size and colour is found only in some Old World monkeys and the two Pan species. Although several hypotheses have been proposed (e.g., reliable indicator hypothesis and graded signal hypothesis), it seems unlikely that a single explanation can account for the significance of the sexual swelling in all of these species. Bonobos (Pan paniscus) provide an excellent opportunity for studying sexual swelling since they have the most prolonged maximal swelling periods among primates. In this study we propose a new hypothesis that sexual swelling in female bonobos increases their attractiveness to other females and thereby facilitates affiliative social interaction with them. We found that free-ranging female bonobos with maximal sexual swelling engaged in affiliative social interactions with other females, including genito-genital rubbing, staying in close proximity and grooming, more frequently than females without maximal swelling. These tendencies suggest that females with maximal swelling were attractive to other females. The results also suggest that the benefits of maximal swelling might vary among females depending on their life-history stage. In particular, young females may get more benefits from prolonged maximal swelling through increased grooming reciprocity and staying in close proximity to other females. Thus our study supported the hypothesis that one function of prolonged maximal swelling in bonobos is to increase attractiveness to other females, thereby enhancing affiliative relationships between females in a male-philopatric social system.

Behaviour doi 10.1163/1568539X-00003212

JUL/4/2014

Copyright(C) 2012 PRI (). All rights reserved.