Antonio Cano
Professor of Obstetrics and Gynaecology in the Department of Paediatrics, Obstetrics and Gynaecology
This is a solid study, supported by sound methods and with few limitations. Isolated cases had been described, but not a whole population consisting of groups of chimpanzees in the wild. This study also shows that in chimpanzees, a species close to humans, the life span beyond the end of reproductive capacity also occurs naturally.
[The 'grandmother hypothesis'] seeks to justify an evolutionary advantage in that [older females] could contribute to the care of offspring while the mothers provide food and other benefits required for survival. That advantage, which has been used to justify [menopause] in killer whales, is not confirmed in this study.
The study does not confirm that it is a group survival advantage, because female chimpanzees leave the colony when they reach adult reproductive age. It could be a marker of good, or at least minimal nutritional status.