(December 2002) The Census Bureau projects life expectancy in the United States to the year 2050, based on lowest-, middle-, and highest-series assumptions. The Census Bureau’s middle series projects life expectancies of 87 years for females and 81 years for men in 2050. Under this scenario, it would take over 15 years for American men to achieve the life expectancy of Japanese men in 1995 (77 years), and American women would not achieve the life expectancy of Japanese women (83 years) until 2020. Japan has been one of the world’s leaders in life expectancy in recent years.

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Demographer Ronald Lee and his colleagues have argued that the usual practice of publishing lowest-, middle-, and highest-series projections does not adequately represent the real uncertainty surrounding these projections. There is a chance, in other words, that life expectancy will improve faster than the highest-series or slower than the lowest-series projections.

Some analysts believe that life expectancy in the United States and other rich nations is approaching a biological limit, and that we should therefore expect its rate of improvement to slow or stop in the coming decades. However, no slowdown is apparent yet, even in countries with life expectancies well above those in the United States. The completion of the first phase of the Human Genome Project (an effort to decode human DNA) and other advances in research make many researchers optimistic that the pace of discovery will quicken and that mortality rates will decline more rapidly than expected. Some biologists and demographers who study centenarians believe that their longevity is not the result of any unique or rare factors, and that whole populations could live past 100 years on average in the future.

Others argue that the aging process leads to multiple failures of organs and organ systems, and new diseases or drug-resistant strains of old ones are constantly appearing. Conquering childhood diseases in the 20th century added many years to life expectancy, but there is no guarantee of continued success against the major killers of older people, such as heart disease, cancer, and stroke.

References

[1999, 2025, 2050, and 2100 data] U.S. Census Bureau, “Projected Life Expectancy at birth by Race and Hispanic Origin, 1999 to 2100,” accessed online at www.census.gov/population/documentation/twps0038/tabC.txt, on October 26, 2000; [2000 data] A.M. Minino et al., “Deaths: Final Data for 2000,” National Vital Statistics Reports 50, no. 15 (2001); [Data for Japan] Ministry of Health, Labour and Welfare of Japan, “International Comparison of Life Expectancy at Birth,” accessed online at http://web-japan.org/stat/stats/02VIT25.html, on July 31, 2002.