Clearly, the implications for our healthcare systems and for our entire economic structure are immense. Aging populations are already straining Social Security and Medicare in this country. Worldwide, the �potential support ratio� or the number of people age 15 to 64 who are available as workers to support retirees is shrinking. In 1950, the ratio was 12 to 1; in 2000, it was 9 to 1; by 2050, it may dwindle to 4 to 1.