3.1Â Explain the four biological theories of aging
Biological aging, or senescence, is the normal process of alterations over time in the body and its organ systems that eventually affect our functioning but do not necessarily result in disease or death. Yet aging and disease are often linked in our minds, because declines in organ capacity and our immune system make us more vulnerable to illness, such as dementia, arthritis, and heart attacks that increase in incidence with age. However, a more accurate conception of the aging process is a gradual accumulation of irreversible functional losses to which the average person adapts—often in very creative ways.
One way of understanding variations in biological aging is to examine the major theories to explain cellular- and organ-level alterations, which can only be inferred from tests of physiological function. And scientific discoveries of the cause of a physiological process or disease can, in some instances, point to ways to prevent it.
Most biological theories of aging have one of two general orientations:
Aging occurs due to random genetic mutations and oxidative stress, or
Aging is a result of programmed senescence (Bengtson, Gans, Putney, & Silverstein, 2009).
We briefly discuss four primary theories of biological aging: