Aging is any change in an organism over Aging refers to a multidimensional process of physical， psychological， and social change (Hultsch and Deutsch) Some dimensions of aging grow and expand over time， while others Reaction time， for example， may slow with age， while knowledge of world events and wisdom may expand (Schaie) Research shows that even late in life potential exists for physical， mental， and social growth and Aging is an important part of all human societies reflecting the biological changes that occur， but also reflecting cultural and societal Age is usually measured in full years — and months for young A person's birthday is often an important The term "aging" is somewhat Stuart-Hamilton (1994) notes how distinctions may be made between "universal aging" (age changes that all people share) and "probabilistic aging" (age changes that may happen to some， but not all people as they grow older， such as the onset of Type Two diabetes) Chronological aging， referring to how old a person is， is arguably the most straightforward definition of aging and may be distinguished from "social aging" (society's expectations of how people should act as they grow older) and "biological aging" (an organism's physical state as it ages) Stuart-Hamilton also notes distinction between "proximal aging" (age-based effects that come about because of factors in the recent past) and "distal aging" (age-based differences that can be traced back to a cause early in person's life， such as childhood poliomyelitis)Differences are sometimes made between populations of adults; as McFadden (2005) points out， divisions are sometimes made between the young old (65-74)， the middle old (75-84) and the oldest old (those aged 85 and above) However， as McFadden notes， problematic in this is that chronological age does not correlate perfectly with functional age， two people may be of the same age， but differ in their mental and physical Population ageing is the increase in the number and proportion of older people in Population aging has three possible causes: migration， longer life expectancy (decreased death rate)， and decreased birth The societal effects of age are Young people tend to commit most crimes， they are more likely to push for political and social change， to develop and adopt new technologies， and to need Older people have different requirements from society and government as opposed to young people， and frequently differing values as Older people are also far more likely to vote， and in many countries the young are forbidden from voting， and thus the aged have comparatively more political 具体的你看 吧
