New Evidence That Grandmothers Were Crucial for Human Evolution [View all]

For years, anthropologists and evolutionary biologists have struggled to explain the existence of menopause, a life stage that humans do not share with our primate relatives. Why would it be beneficial for females to stop being able to have children with decades still left to live?

According to a study published today in the journal Proceedings of the Royal Society B, the answer is grandmothers. “Grandmothering was the initial step toward making us who we are,” says senior author Kristen Hawkes, an anthropologist at the University of Utah. In 1997 Hawkes proposed the “grandmother hypothesis,” a theory that explains menopause by citing the under-appreciated evolutionary value of grandmothering. Hawkes says that grandmothering helped us to develop “a whole array of social capacities that are then the foundation for the evolution of other distinctly human traits, including pair bonding, bigger brains, learning new skills and our tendency for cooperation.”

The new study, which Hawkes conducted with mathematical biologist Peter Kim of the University of Sydney and Utah anthropologist James Coxworth, uses computer simulations to provide mathematical evidence for the grandmother hypothesis. To test the strength of the idea, the researchers simulated what would happen to the lifespan of a hypothetical primate species if they introduced menopause and grandmothers as part of the social structure.

http://blogs.smithsonianmag.com/science/2012/10/new-evidence-that-grandmothers-were-crucial-for-human-evolution/