by Roger Bourke White Jr., for Anthropology 1020, Jennifer Campbell, copyright June 2014
One version of the Grandmother Hypothesis contends that human lifespan extended when grandmothers started helping to feed children. This 24 Oct 12 Sci-News.com article, New Study Supports ‘Grandmother Hypothesis’ by Enrico de Lazaro (http://www.sci-news.com/othersciences/anthropology/article00678.html), describes this hypothesis as it is presented by Kristen Hawkes, a professor of anthropology with the University of Utah and co-author of the ‘grandmother hypothesis,’ a theory that humans evolved longer adult lifespans than apes because grandmothers helped feed their grandchildren.
In Hawkes's version the feeding of grandchildren favored genes that allow females to live well beyond menopause. “Grandmothering was the initial step toward making us who we are,” said Prof. Hawkes.
I agree that something changed for humans that made longer life a valuable trait. I disagree on what the change was. I see the change as being strong language skill, not feeding grandchildren.
The reason strong language skill favored having older people in the community is because it allowed teaching to happen. This ability to pass on information from one generation to the next was a huge benefit, and it promoted many changes in the human genotype and phenotype. One of those was larger brains and another was longer lifespans.
Strong language skill favored living longer because older beings became repositories of knowledge that could then be passed on to the children and grandchildren.
Two of my books discuss the ramifications of strong language skill: Evolution and Thought (Authorhouse, 2010, ISBN 978-1-44904-200-4)and How Evolution Explains the Human Condition (Authorhouse, 2013, ISBN 978-1-47727-391-3).
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