DURHAM, N.C. -- A study of mortality and fertility patterns among seven species of wild apes and monkeys and their relatives, compared with similar data from hunter-gatherer humans, shows that menopause sets humans apart from other primates.
Nonhuman primates aren't immune to the fading female fertility that comes with age, the researchers say. But human females are unique in living well beyond their childbearing years.
"Unlike other primates women tend to have a long post-reproductive life. Even before modern medicine, many women lived for 30 to 35 years after their last child was born," said co-author Susan Alberts of Duke University and the National Evolutionary Synthesis Center.
In a study appearing the week of July 29 in the Proceedings of the National Academy of Sciences, Alberts and colleagues compared mortality and fertility data for seven species of wild primates to similar data for the !Kung people of Southern Africa, a human population of hunter-gatherers with limited access to modern medicine or birth control.
The nonhuman primate data were based on long-term observations of 700 adult females, including capuchins in Costa Rica, muriqui monkeys in Brazil, baboons and blue monkeys in Kenya, chimpanzees in Tanzania, gorillas in Rwanda and sifakas in Madagascar.
This is the first study to compare humans with multiple primate species living in the wild.
For each species, the researchers estimated the pace of reproductive decline -- measured as the probability, at each age, that a female's childbirth will be her last -- and compared it with the rate of decline in overall health, measured as the odds of dying with each passing birthday. "This way we were able to compare the rate of aging in the reproductive system with the rate of aging in the rest of the body,' Alberts said.
The results suggest that in nonhuman primates, reproductive decline is surpassed by declines in survival,
|Contact: Robin Ann Smith|