Aging is the accumulation of changes that increase the risk of death. Aging changes can be attributed to development, genetic defects, the environment, disease, and the inborn aging process. The latter is the major risk factor for disease and death after age 28 in the developed countries. In these countries, average life expectancies at birth (ALE-B) now range from 76-79 years, 6-9 years less than the limit of about 85 years imposed by aging. Aging changes may be caused by free radical reactions. The extensive studies based on this possibility show promise of increasing the ALE-B to 85 years and beyond.