A team of researchers studying the Ngogo community of wild chimpanzees in western Uganda’s Kibale National Park for two decades has published a report in Science showing that females in this population can experience menopause and postreproductive survival.
Prior to the study, “Demographic and hormonal evidence for menopause in wild chimpanzees,” these traits had only been found among mammals in a few species of toothed whales, and among primates — only in humans. These new demographic and physiological data can help researchers better understand why menopause and post-fertile survival occur in nature, and how it evolved in the human species.
“In societies around the world, women past their childbearing years play important roles, both economically and as wise advisors and caregivers,” said Brian Wood, UCLA associate professor of anthropology. “How this life history evolved in humans is a fascinating yet challenging puzzle.”
Wood, first author of the paper, worked closely with Kevin Langergraber from Arizona State University, Jacob Negrey of University of Arizona, and Ngogo Chimpanzee Project founders and co-directors John Mitani and David Watts.
“The (study) results show that under certain ecological conditions, menopause and post-fertile survival can emerge within a social system that’s quite unlike our own and includes no grandparental support,” Wood said, referring to the grandmother hypothesis.
That hypothesis, which has been used to explain the existence of human postmenopausal survival, proposes that females in their postreproductive years may be able to pass on more of their genes by helping to raise the birth rates of their own children or by caring directly for grandchildren, thereby increasing grandchildren’s odds of survival.
And indeed, several studies of human grandmothers have found these positive effects. But chimpanzees have very different living arrangements than humans. Older female chimpanzees typically do not live near their daughters or provide care for grandchildren, yet females at Ngogo often live past their childbearing years.
Do female chimpanzees have menopause?
We conclude that menopause occurs near 50 years of age in chimpanzees as it does in women. Our finding identifies a basic difference between the human and chimpanzee aging processes: female chimpanzees can remain reproductively viable for a greater proportion of their life span than women.
Which 5 animals are known for the females to experience menopause?
Age-related changes in mothering behavior could drive evolutionary pressures. As far as we know, only four species experience menopause: humans, killer whales, short-fin pilot whales, and false killer whales. So how did this rare biological process, which leaves females unable to bear children, evolve?
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