Longevity may be a consequence of grandmothering. Continued life after reproduction may be adaptive when post-reproductive individuals increase the reproductive success of their extended kin. As Kristen Hawks suggests ‘grannies have a lot to offer their grandchildren” (Hawkes 2004). By subsidizing grandchildren, grandmothers enhance the fertility of their daughters. In other words, more robust elders left more descendants (Hawkes, Smith 2010).
Hawkes, K. 2004. The grandmother effect. Nature 428 (6979):128-129.
Hawkes, K., K. R. Smith. 2010. Do women stop early: SImilarities in fertility decline in humans and chimpanzees. Annals of the New York Academy of Sciences 1204:43-53.