Changes in the Physiology of Aging during the Twentieth Century
One way to demonstrate how remarkable changes in the process of aging have been is to compare health over the life cycles of 3 cohorts. For the first cohort, born between 1835 and 1845 (the Civil War cohort), life was short and disabilities were common even at young ages. Other factors contributing to lifelong poor health were widespread exposure to severely debilitating diseases and chronic malnutrition. Fewer of the World War II cohort, born between 1920 and 1930, died in infancy and most of the survivors have lived past age 60 without developing severe chronic diseases. Members of this cohort have experienced better health throughout their lives largely due to their lower exposure to environmental hazards before birth and throughout their infancy and early childhood. Members of the cohort born between 1980 and 1990 have a 50-50 chance of living to age 100. The average age at onset of disabilities has continued to rise, so members of this cohort can expect to remain healthy at later ages. Adopting a healthy life style early can help to prevent or postpone disability at older ages.