A UCLA researcher reports the first solid evidence of menopause in wild chimpanzees. The findings, published in a peer‑reviewed journal, indicate that humans are not the only primates with lifespans that extend well beyond childbearing years. The study underscores a significant biological milestone in chimpanzee evolution and aging.
Biologist Brian Wood identified menopause in female chimpanzees from the Ngogo community in Uganda. He observed a clear decline in the ability to conceive after the age of 30, with reproductive activity stopping as they passed 50. In practical terms, a female chimpanzee spends roughly twenty percent of her adult life in a post‑reproductive phase.
To reach these conclusions, researchers analyzed birth and death records for 185 female chimpanzees, drawing on demographic data spanning 1995 to 2016. They also quantified hormone concentrations in urine samples from 66 females aged 14 to 67, providing a hormonal context to the observed reproductive changes.
Prior to this work, signs of menopause in mammals were recognized in only a few dolphin species, and among primates, menopause had been documented mainly in humans. These new results shed light on the biological meaning of menopause and how it manifests in nonhuman great apes. One widely discussed theory proposes that women beyond reproductive age can increase their genetic contribution by supporting their grandchildren, thereby aiding the survival of their kin. Yet among chimpanzees, older females typically do not reside with or actively care for their offspring, suggesting different social dynamics at play.
Scientists propose that the onset of menopause in Ngogo chimpanzees might reflect a temporary response to unusually favorable environmental conditions. The population enjoys steady, abundant food and faces low predation risk, factors that could influence aging patterns. Conversely, it remains possible that the long lives of older females have not been fully observed before because some infections in wild settings pose severe risks, and researchers have only recently developed methods to minimize disease outbreaks during long-term studies.
A separate, unrelated observation from Brazil notes the discovery of a new “iron” centipede species with intricate reproductive organs, highlighting ongoing discoveries across diverse ecosystems and the complexity of animal reproduction.