In a groundbreaking revelation, female chimpanzees living in an East African woodland have been observed to undergo menopause and then continue living for years or even decades after becoming biologically incapable of reproduction. This discovery challenges previous understandings of menopause and sparks questions about its evolutionary significance.

These chimpanzees, which represent the first known instances of wild, nonhuman primates experiencing menopause and outlasting their reproductive years, were the subjects of research conducted by Brian Wood, a UCLA evolutionary anthropologist.

 Published in the journal Science on October 27, this research highlights a close genetic relationship between humans and chimpanzees, implying that both species are inclined toward post-reproductive survival.

The study focused on 185 females in the Ngogo community of wild chimpanzees in Uganda. The results revealed that hormonal indicators of fertility declined after reaching the age of 30, with no recorded births in chimpanzees aged over 50. Nevertheless, 16 Ngogo females lived beyond the age of 50, with some even reaching their 60s. These findings suggest that females in this community experience approximately 20% of their adult years after losing their capacity to reproduce.

According to anthropologist Kristen Hawkes from the University of Utah in Salt Lake City, some evidence indicates that the age at which female fertility declines is similar in humans and chimpanzees (Pan troglodytes), provided that our primate relatives have a sufficiently long lifespan. However, in other research, female chimpanzees, including those observed by Jane Goodall at Tanzania’s Gombe National Park, aged rapidly and often didn’t live past their early 30s, even though they continued to have menstrual cycles.

Hawkins claimed that “What’s surprising is so many females living so long after menopause”.

This study challenges previous theories concerning the evolution of human menopause, which posited that grandmothers played a vital role in caring for their grandchildren. In the case of chimpanzees, this theory does not hold, as females move to new communities during adolescence, leaving no breeding daughters nearby to provide assistance.

An alternative explanation is that older female chimpanzees may possess the experience and knowledge required for group survival, a trait observed in certain other mammals, such as killer whales. Alternatively, factors like reduced predation by leopards, access to ample food, and competition with other chimpanzee groups may have contributed to the extended female longevity in the Ngogo community.

It’s important to acknowledge that these findings are specific to the Ngogo chimpanzee population inhabiting an undisturbed forest environment, and may not be universally applicable to other chimpanzee populations.

This research also prompts the question of whether menopause might be an inherent characteristic in primates that becomes more apparent as mortality rates decrease.

In summary, this discovery challenges our existing knowledge of menopause in nonhuman primates and opens up new avenues for researching the evolution of this phenomenon.

Surprisingly long-lived wild female chimps go through menopause