ÜDS-Sağlık 2006-2 Soru=35

(I) At one time, scientists believed aging to be not just deterioration but an active continuation of an organism's genetically programmed development. (II) Once an individual achieved maturity, “aging genes” began to direct its progress toward the grave. (III) If they remain active long enough, they can also dramatically enhance the organism's health and extend its life span. (IV) This idea has been discredited, and conventional wisdom now holds that aging really is just wearing out over time because the body's normal maintenance and repair mechanisms simply wane. (V) Evolutionary natural selection, the logic goes, has no reason to keep these mechanisms working once an organism has passed its reproductive age.