Aging and Death (Encyclopedia of Science)
Aging is a series of biological changes that follow a natural progression from birth through maturity to old age and death. For most people, advancing age is characterized by graying or thinning hair, loss of height, wrinkling of the skin, and decreased muscular strength. Still, an active lifestyle, including both exercise and sound nutrition, can contribute greatly to achieving a long and productive life. Genetics (inherited physical characteristics) also appears to play a role in the process of aging and death. People whose parents or grandparents live to old age seem to have a better chance of living long lives themselves.
Great strides have been made in increasing the average life expectancy in humans in the United States. This is due largely to the elimination of many diseases of early childhood and young adulthood and to the advanced methods of treating diseases that in the past would have resulted in early death. However, the maximum potential life span (how long an organism can exist) of humans appears to remain the samebout 85 yearsegardless of efforts to expand it.
Every species has a different normal life span. In most species, death occurs not long after the reproductive phase of life ends. This is obviously not the case for humans. However, women do experience physical changes when they are past their childbearing years. Levels of the hormone estrogen begin to...
(The entire section is 1222 words.)
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