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ABSTRACT
Island people have long been associated with longevity. In the second century BC, the Chinese emperor Ch'in Shih Huang-ti sent a legion of ships and several thousand men in search of fabled islands of longevity in the seas to the south of China. They never returned with news of discovery. Two millennia later, island people are again of interest to longevity researchers. Iceland, Sardinia, Okinawa, and Hawaii are among several islands or island chains that lay claim to long-lived people. In particular, the Japanese island prefecture (state) of Okinawa and the American island state of Hawaii offer some interesting similarities and contrasts in the study of human aging and longevity. Health span and life span appear longer than most of the populations of Japan and the United States, respectively. Both populations have undergone recent generational changes in health and associated risk factors (such as obesity), which are diminishing previous health span and life span advantages. However, there is still persistence of this healthy aging and longevity phenomenon in older generations. The environmental and genetic epidemiology of this healthy aging phenomenon has been explored in two collaborative studies-the Okinawa Centenarian Study (OCS) and the Honolulu Heart Program (HHP). This chapter indicates how healthy human aging and longevity are influenced by both genetic and environmental factors and how particular factors may influence odds of living to oldest old ages in good health.
INTRODUCTION
The world is aging and that has important consequences for all of us. The United States, although aging at a moderate pace compared to rapidly aging countries such as Japan, will nonetheless undergo dramatic changes over the next decade as many of America's near 80 million baby boomers become seniors (Anderson & Hussey, 2000). For example, the rapid graying of America risks overwhelming health and social support systems. U.S. Medicare costs are projected to increase from 3.2% of GDP in 2008 to 11.4% by 2083 (U.S. National Research Council, 2010). The sheer number of older adults will have implications for seniors' quality of life and that of their families. A case in point-80% of U.S. seniors have at least one chronic age-related disease (Wenger et ah, 2003). Osteoarthritis, one of the most common age-related diseases, can cause years of pain, disability, and...