Disposable soma theory of aging

The Disposable Soma theory of aging is a theory of aging and longevity proposed in 1977 by Dr. Thomas Kirkwood. It essentially postulates that, after reproduction, the individual unit becomes "disposable" and so is not evolutionarily selected for continued extension of longevity.

"The idea has been challenged by the Grandmother hypothesis which posits that older individuals past reproductive age can help select for the survival of their grandchildren by assisting in the raising, care, and protection of their grandchildren, making the genes of long-lived individuals more likely to survive than those from individuals that did not live long enough to care for their grandchildren."

http://www.programmed-aging.org/theories/disposable_soma.html