Abstract # 2772 Event # 217:

Scheduled for Monday, September 21, 2009 02:15 PM-02:25 PM: Session 23 (Mission Bay Ballroom AB) Oral Presentation


J. P. Higham1, G. Nodza2, U. Buba2, M. Heistermann3, C. Ross4 and A. M. MacLarnon4
1Institute for Mind and Biology, University of Chicago, Chicago, Illinois 60637, USA, 2Gashaka Primate Project, Taraba State, Nigeria, 3Department of Reproductive Biology, German Primate Centre, Göttingen, Germany., 4Centre for Research in Evolutionary Anthropology, Roehampton University, London, UK.

Recent studies of the reproduction of two baboon troops at Gashaka, Nigeria, identified a pattern of seasonal progestogen excretion from all females, regardless of reproductive state. This was correlated with consumption of Vitex doniana, which contains progestogen-like compounds. Our evidence suggested that V.doniana acts as a seasonal physiological and social contraceptive, suppressing ovulation via high progestogen levels, and reducing male mating interest via sexual swelling inhibition. To search for more direct evidence of this, and to address questions related to selectivity, we collected new field data. From August 2007-June 2008 we sampled V.doniana twice monthly to assess seasonal availability of hormone-mimics. In January-March 2008 (during V.doniana new leaf availability) we collected 220 fecal samples from one group, and undertook focal feeding observations on 5 females and 2 males. Progestogen levels of both plant and fecal samples were assessed by response to a 5?-pregnane-3alpha20alpha-diol (PdG) enzyme-immuno-assay. Using non-parametric analyses, we show: 1) direct links between V.doniana leaf consumption and increased progestogen excretion, providing direct evidence for our previous correlative result; 2) no differences in V.doniana consumption between males and females in different reproductive states, indicating no targeting of the plant for specific reproductive effects; 3) that consumption was related to plant part stage (e.g. fruit ripeness) rather than hormone-mimic availability. These results suggest that the observed seasonal consumption of phyto-hormones is incidental rather than targeted.