Evolution of Ageing - History

History

August Weismann was responsible for interpreting and formalizing the mechanisms of Darwinian evolution in a modern theoretical framework. In 1889, he theorized that aging was part of life's program because the old need to remove themselves from the theatre to make room for the next generation, sustaining the turnover that is necessary for evolution. This theory again has much intuitive appeal, but it suffers from having a teleological or goal-driven explanation. In other words, a purpose for aging has been identified, but not a mechanism by which that purpose could be achieved. Aging may have this advantage for the long-term health of the community; but that doesn't explain how individuals would acquire the genes that make them get old and die, or why individuals that had aging genes would be more successful than other individuals lacking such genes. (In fact, there is every reason to think that the opposite is true: aging decreases individual fitness.) Weismann disavowed his own theory before his life was over.

Theories suggesting that deterioration and death due to aging are a purposeful result of an organism's evolved design (such as Weismann's "programmed death" theory) are referred to as theories of programmed aging or adaptive aging. The idea that the aging characteristic was selected (an adaptation) because of its deleterious effect was largely discounted for much of the 20th century, but is now experiencing a resurgence because of new empirical evidence as well as new thinking regarding the process of evolution.