Primate reproductive aging: from lemurs to humans.

Abstract

The scope of data now available for primates from long-term field and captive studies has opened up exciting possibilities for investigating age-related patterns of reproduction. Valuable information on the aging process can be gleaned through broad cross-taxonomic comparative studies that include lemurs, monkeys, apes and humans. Thus, across all taxa discussed in this volume, female reproduction was found to be complex and dynamic, affected by the interplay of multiple exogenous and endogenous factors. Throughout their lives, females differ in their individual reproductive output. As they age, a period of reproductive instability is common among female primates and perimenopausal- like hormonal changes have been noted in many species. Available data from lemurs and callitrichids indicate that at least in some species, age-related declines in reproduction are manifested as diminished success of females to rear their young to weaning age. Few data are available for New World primates, but the same observation holds true for Old World monkey females, who also are characterized by declines in sexual activity and decreased birth rates. In apes, captive data suggest the presence of an appreciable postreproductive lifespan but this has not been confirmed in the wild. Menopause may be manifested as an evolutionary continuum across primate taxa with the potential for an extended postreproductive lifespan evident in cercopithecines and apes.