An advancement of the challenging theory that, along with growth and puberty, aging also unfolds “on a schedule programmed into the regulatory portion of our DNA.”
At first glance, this would appear to contradict “the fundamental premise of Darwinian evolution,” survival of the fittest, the principle of natural selection epitomized by the “selfish gene,” a term coined by Richard Dawkins in The Selfish Gene (1976). Theoretical biologist Mitteldorf and ecological philosopher Sagan (Cosmic Apprentice: Dispatches from the Edges of Science, 2013, etc.) make a convincing case for broadening the generally accepted neo-Darwinian framework, which incorporates the role of the genome in shaping the individual, to include species evolution and the relationship between individual survival and survival of the ecosystem on which it depends. They address the seeming paradox that “genes for aging have been fixed in the genome, despite the fact that these genes work against themselves.” By limiting the reproductive potential of the aging individual, they play an important role in evolution. The authors contend that death and aging are crucial to the existence of “stable ecosystems in nature.” Without them, unchecked reproduction would lead to major extinction events and the destruction of ecosystems. Mitteldorf and Sagan suggest that aging and death have evolved to moderate what might otherwise be untrammeled reproduction by predators, leading to the destruction of their prey and their own extinction. Natural selection operates to create a balance between longer life expectancy and greater fertility. Death and aging play a necessary role by regulating population growth in order to create the space for “populations of living things to evolve rapidly and efficiently.” This leads the authors to the provocative conclusion that if we accept the goal of increasing longevity and the long-term survival of the human species, we must also accept the idea of zero population growth.
A thoughtful examination of the role of aging and death in supporting life.