Reproduce and die! Why aging? Part II.
Whilst in part I of this diptych on aging the question why aging exists at all is discussed; this part deals with the question which mechanisms underly aging and, ultimately, dying. It appears that aging is not just an active process as such--although all kinds of internal (e.g., oxigen-free radicals) and external (e.g., UV radiation; disease) actively damage the organism--but more a passive one: it is mainly the result of a diminishing capacity to resist damaging internal and external influences, notably the capacity to repair the ensuing damage of DNA, until, indeed, the genome is entirely beyond repair and all kinds of vital functions detoriate with as a result that, in the end, the body collapses due to some final internal (e.g., a neoplasm or a CVA) or external (e.g., some infection, accident or attack) push. The time-course with which the capacity to repair DNA diminishes, however, is genetically fixed, and is associated with (even determined by) the reproductive strategy of the species in question: once the phase of reproduction is over, the reins are loosened and all kinds of genetic and physiological errors accumulate, giving rise to a large variety of pathology which ultimately carries the pertinent individual to the grave.
Schuiling
Gerard A
GA
Division of Human Biology, Faculty of Medical Sciences, University of Groningen, Groningen, The Netherlands. g.a.schuiling@med.ug.nl
D000375:Aging / Q000502:physiology*; D000533:Altruism; D004260:DNA Repair / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics; D003643:Death; D005260:Female; D006801:Humans; D043762:Reproductive Behavior / Q000502:physiology*
D004272:DNA, Mitochondrial