“Aging is inexorable, but senescence, the deterioration of function associated with advancing years, correlates much less strongly with age. Instead, senescence is also influenced strongly by environmental factors like diet, physical activity, or radiation, and thus can be slowed, sometimes prevented, and even partly reversed. The distinction between aging and senescence may seem obvious, but the two processes are frequently confused. Many conditions occur more commonly with advancing age, but only some are actually caused by age. Menopause, for example, is a normal consequence of aging that happens when a woman’s ovaries run out of eggs. In contrast, type 2 diabetes occurs among some older people for reasons not intrinsic to the aging process itself but instead from factors like obesity and physical inactivity whose damaging effects accumulate with age.”