Consider life expectancy. Last week, the UN issued a report on world aging. Today roughly 10% of the world’s population is 60 or older. By 2050, that percent will double. In developed nations, people over 60 now account for one-fifth of the population, by 2050, they will account for one-third. During the same period, the number of people over 60 in developing regions will more than double from 8% to 20%. (The fastest growing age group is people over 80, which is increasing 3.8% annually.) These changes are not paralleled in any prior century.