The growing role of grandparents in raising children is right in line with human biology.
Old people—too old to reproduce, too young and healthy to kick the bucket—are highly biologically relevant.
The Grandmother Hypothesis helps make sense of a recent and intriguing finding: A particular variant of the immunoregulatory receptor gene known as CD33 has been adjusted in human beings (compared with chimps) to be protective against late-onset Alzheimer’s disease.
Old people can make a contribution to their own fitness by enhancing that of their offspring, via their grandchildren.
By the same token, the fact that our species has apparently experienced selection that is at least somewhat protective against the ravages of old age suggests that even the elderly are valuable enough—purely in evolutionary terms—to warrant keeping them functional.
( from an article by David P Barash -in Nautilus)
The Vibrant Channeled Creator 