Abstract # 147:

Scheduled for Friday, August 18, 2006 03:05 PM-03:25 AM: Session 15 (Regency East #3) Oral Presentation

Patterns of aging in colobine monkeys

C. Borries and A. Koenig
Stony Brook University, Department of Anthropology, Stony Brook 11794-4364, USA
     Similar to humans, old monkeys become far-sighted, slow, and disengaged. The signs of aging seem universal and wild colobine monkeys are no exception. In provisioned Hanuman langurs (Semnopithecus entellus) in India, aging females dropped to the bottom of the hierarchy. Reproductive rates declined but were compensated for by a better rearing success. Post-menopausal periods exceeding three years have been documented. Older females were significantly less social although some became protective grandmothers. They stayed more at the group’s periphery seeming watchful while in fact asleep. Similar trends were found in a wild population of the same species in Nepal as well as in another wild colobine monkey (Phayre’s leaf monkeys, Trachypithecus phayrei) in Thailand. In these two populations the percentage of old individuals was, however, much lower. Due to higher mortality risks and reduced growth and reproductive rates caused by lower food abundance, wild monkeys rarely lived long enough to have an adult offspring in the group. This does not leave much room for kin-biased social interactions in adults. Here we touch upon a dilemma inherent in the topic of aging in wild animals. While the symptoms of aging are similar to captive conditions, in wild populations only very few individuals live long enough to become old. If old monkeys are present at all, they are often peripheral. Supported by DAAD, DFG, NSF.