Hazard rates and causes of death in a captive group of crab-eating monkeys (Macaca fascicularis).

ABSTRACT

In an attempt to examine possible associations between stages of agespecific mortality and various causes of death, vital records of 159 male and 192 female crab-eating monkeys (Macaca fascicularis), housed as a single group, were analyzed. Survival and hazard rates associated with each of five distinct categories of causes of death were estimated for males and females, using the nonparametric kernel method. The obtained overall survival and hazard functions were similar to those reported previously for rhesus monkeys. Among two stages identified in age-specific mortality, the first stage, characterized by rapidly decreasing hazard rates up to about 1.5-2 years of age, was discriminated by the occurrence of deaths due to unfitness for postnatal life. The second stage lasted up to the age of 10-15 years and was largely characterized by a high incidence of violent deaths. The respective hazard rates in males and females attained peaks during the early reproductive period of life and markedly decreased thereafter. This pattern was interpreted to indicate that second stage mortality is unlikely related to senescence, but rather, seems to depend on extrinsic environmental factors. Thus, when considering overall hazard rates in Macaca fascicularis, the onset of senescence, as a result of the specific aspects of simian reproduction, may be hidden from view, and mortality due to aging may only be appreciable after 10 to 15 years of age. © 1993 Wiley-Liss, Inc.