The dynamics of life: aging.

Biologic aging arises from various causes, including deterioration of cells by mutations, destruction of the cells in organs through infections, aging by failure to eliminate harmful waste products, poisoning from external sources, and by radiation damage. All of these processes lead to equations of the kind observed experimentally for the aging process, so that a proper assessment of the various factors contributing to aging is especially complicated. Many nonbiological processes in which the products of reaction speed up the aging reaction lead to the familiar equation for the rate of aging. Corrosion of metals is exhibited as a typical example of this; many other examples could be given. The general equation for depth of anesthesia brought about by lipid-soluble materials and how this effect can be mimicked by accumulation of waste products is shown to simulate the typical aging curve; it is well known that such waste products are a frequent cause of death.