Reproductive and behavioral characteristics of aging in female Asian colobines

Data from four Asian colobine populations, wild (Ramnagar) and provisioned (Jodhpur) Hanuman langurs, wild Phayre's leaf monkeys (Phu Khieo Wildlife Sanctuary), and captive silvered langurs (Wildlife Conservation Society's Bronx Zoo) were analyzed with respect to reproductive and behavioral trends of aging. All but one female (from a total of seven) became menopausal 1.8 to 5+ years prior to death with a lag time between last parturition and death ranging from 3.0 to 9.0 years (n=8). Hormonal analysis revealed constantly low and acyclic levels of immunoreactive pregnanediol-3-glucuronide (iPdG) in one old, wild female supporting the notion of true menopause. Nonsexual behavior was analyzed based on quantitative data collected for 6 old and 26 younger, adult females simultaneously (1,378.5 h). No support was found for social disengagement, but old females were more inactive and spent less time feeding. Altogether the data support earlier claims of menopause and extended postreproductive life spans in colobine monkeys. Future behavioral studies should aim at longitudinal assessments of behavioral changes and incorporate energetic data as well as testing of social continuity and selectivity.