Over the past forty years life expectancy has im- proved more than during the entire previous span of human history. In 1950 life expectancy in devel- oping countries was forty years; by 1990 it had increased to sixty-three years. In 1950 twenty-eight of every 100 children died before their fifth birth- day; by 1990 the number had fallen to ten. Small- pox, which killed more than 5 million annually in the early 1950s, has been eradicated entirely. Vac- cines have drastically reduced the occurrence of measles and polio. Not only do these improve- ments translate into direct and significant gains in well-being, but they.
