Is aging programed?
Development and morphogenesis may easily be thought of as programed, in the sense that they result from a sequence of cellular and molecular events designed by natural selection to produce a given adult phenotype. Aging, except in exceptional cases such as the rapid decay and death of Pacific salmon, is not design but decay. The decay of senescence is not due to natural selection's designing hand, but to its absence. The empirical difference between programed and nonprogramed senescence becomes evident when comparing the stereotypical steps leading to death in salmon contrasted with the lack of such stereotypy in most organisms such as humans and mice. Understanding the distinction between programed development and nonprogramed senescence helps focus attention on the phenotypic performance of adults, which is the focus of natural selection, and therefore be attentive to any unwanted pleiotropic side-effects of genetic or environmental treatments which retard aging.
Austad
Steven N
SN
Department of Cellular & Structural Biology, University of Texas Health Science Center, STCBM Bldg., Room 3.100, Barshop Center for Longevity & Aging Studies, 15355 Lambda Drive, San Antonio, TX 78245, USA. austad@uthscsa.edu
D000375:Aging / Q000502:physiology*; D000818:Animals; D002454:Cell Differentiation / Q000502:physiology*; D016922:Cellular Senescence / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000502:physiology*; D008017:Life Expectancy; D017683:Oncorhynchus / Q000502:physiology*
D006854:Hydrocortisone