Health, Wealth, and Welfare

coupled with a wider perspective suggest sizable economic returns to better health Living longer THE LAST 150 years has witnessed a global transformation in human health that has led to people living longer, healthier, more productive lives. While having profound consequences for population size and structure, better health has also boosted rates of economic growth worldwide. Between the 16th century and the mid-19th century, average life expectancy around the world fluctuated but averaged under 40 years, with no upward trend. Life spans slowly but steadily increased in the second half of the 19th century and then jumped markedly in the 20th century, initially in Europe and then in the rest of the world (see table). Economic historians and demographers still debate the genesis of these changes, but they increasingly point to rising incomes (and resulting improvements in sanitation and food availability) as the major cause of declines in 19th-century mortality rates. For the 20th century, however, they believe technical improvements were the catalysts— particularly the discovery of the germ theory of disease, a better understanding of Life expectancy rose sharply around the world in the second half of the 20th century, but AIDS is undermining progress in Africa and elsewhere.