I missed this story back in December about menopause in captive gorillas:
Many biologists believe menopause evolved because it gave human grandmothers more time to help care for their grandchildren, said Steve Austad, a researcher at the University of Texas Health Science Center in San Antonio who was not involved in the study.
The new findings argue against the so-called "grandmother hypothesis," because female gorillas in the wild migrate away from their family groups and don't hang around to care for the grandkids.
Instead of an evolutionary adaptation, menopause could result merely from humans -- and captive gorillas -- living longer, Austad said.
"It's going to make evolutionary biologists think long and hard about what this suggests for humans," Austad said. "Right now, they're saying humans are unique. It may turn out you can get gorillas to live 75 years, and 25 years of that is post-menopausal."
This isn't entirely new, but it is apparently a nice survey of older known-age gorillas, which is the best sample available for it. According to the article, the average age of the post-menopausal gorillas is 44.