Kristen Hawkes uses a mathematical simulation to show how grandmother nurturing of a daughter's children was sufficient over 60,000 years, to kick start evolution from primate ancestor to human.
Computer simulations provide new mathematical support for the "grandmother hypothesis" -- a famous theory that humans evolved longer adult lifespans than apes because grandmothers helped feed their grandchildren.
"Grandmothering was the initial step toward making us who we are," says Kristen Hawkes, a distinguished professor of anthropology at the University of Utah and senior author of the new study published Oct. 24 by the British journal Proceedings of the Royal Society B.
By allowing their daughters to have more children, a few ancestral females who lived long enough to become grandmothers passed their longevity genes to more descendants, who had longer adult lifespans as a result.
Not mentioned in this article is the study which showed having a grandfather in the household significantly decreased the survival of grandchildren.
Interesting! Where can I read about the connection between grandfathers in the household and decreased survival?
And I stumbled across this meta-analysis from last year: "Alternatives to the grandmother hypothesis"
(full text: http://www.springerlink.com/content/w43135024165575q/fulltext.pdf )
which found that "the survival of the maternal grandmother and grandfather, but not the paternal grandmother and grandfather, was associated with decreased grandoffspring mortality. ... In patrilineal and predominantly patrilocal societies, the grandparents who are most likely to live with the grandchildren have a less beneficial association than those who do not."
But the authors acknowledge that the source studies were limited, "including the use of retrospective designs and inadequate controls for confounding variables such as wealth."