A new study supports the hypothesis that menopause and female life span beyond the ability to have children evolved because the advantage of helping daughters reproduce and raise their children outweighed the advantages of continuing to give birth. In other words, natural selection favored menopause, long life and perhaps even close family ties, because only grandmothers who are not busy feeding their own children have time to help with grandchildren. The study, which concluded that grandmothers are key to raising children, found:
- In the families where the grandmother was still living when their children started to have children, there were more children born compared with families where the grandmother was no longer living
- More children survived when the grandmother was around than when she wasn't
- The grandmother had to be nearby and available to help in raising her grandchildren in order for the beneficial effect to be seen
- Grandmothers were more likely to die when their own children reached menopause and could no longer have children
Health Day March 10, 2004