[Active mechanisms of dysfunction in the process of aging]

Current views on the causes and mechanisms of aging are discussed. Evidence for active mechanisms which are regulatory in their origin and operate at the body and its systemic levels is presented. These mechanisms are believed to be capable of inducing changes in the organism thus bringing its functioning to the level which is characteristic of old age. Such phenomena have been observed in the immune and reproductive systems, connective tissue, skin, and liver. Examination of heterochronic parabionts revealed that these mechanisms affect the general viability of a young organism paired to an old one causing a marked reduction of the young parabiont's life-span up to the life limit of his old partner. This suggests a possible role played by aging in a species' adaptation to the environmental conditions.