Abstract # 96:

Scheduled for Friday, June 22, 2007 11:00 AM-11:15 AM: Session 9 (North Main Hall F/G) Symposium

Stone Handling as a Behavioral Tradition in Japanese Macaques (Macaca fuscata): Charting Inter- and Intra-group Diversity and Investigating Ecological and Socio-demographic Contexts of Transmission

J. B. Leca1, N. Gunst2, C. A. Nahallage3 and M. A. Huffman3
1Equipe d’Ethologie des Primates, Institut Pluridisciplinaire Hubert Curien, Département Ecologie, Physiologie et Ethologie, UMR 7178 CNRS-ULP, Strasbourg 67087, France, 2Institute of Ecology, University of Georgia, Athens, USA, 3Section of Ecology, Primate Research Institute, Kyoto University, Inuyama, Japan
     How can we explain inter- and intra-group differences in stone handling (SH), a form of solitary object play, consisting of manipulating stones by performing various behavioral patterns? SH is presumably socially transmitted across generations, as a behavioral tradition in Japanese macaques. We tested hypotheses proposing that SH variability reflects ecological, socio-demographic, and developmental constraints. From 2003 to 2005, we systematically compared SH occurrence and form in four captive troops of Japanese macaques, and six free-ranging troops living at five geographically isolated sites in Japan (Arahiyama, Koshima, Shodoshima, and Takasakiyama). We used a standardized observation procedure to collect 1117 hours of video-recorded focal samples (including 1280 SH bouts), interspersed with 4821 group activity scans, and complemented by the quadrat method for stone sampling. Most of the 45 SH patterns showed geographically patchy distributions, referred to as local variants or SH traditions, and clustered into three levels of SH cultures, based on behavioral complexity. Nonparametric statistics [Mantel Test for Independence, Spearman Rank Correlations and Wilcoxon Signed Rank Tests; a=0.05] showed geographic proximity was significantly related to cultural similarity. SH occurrence was significantly better explained by food provisioning than stone availability. The significant positive effect of troop size on the synchronized performance of SH may reveal the contagious nature of play activities. Age-related differences explained most intra-group variation in SH. Our findings highlight the constraints on the innovation, diffusion, and maintenance of this behavioral tradition. Sponsor: Lavoisier grant.