I recently had a birthday. It happens every year: I get older. And I'm not the only one. The average age of people in the industrialized countries, China, and India is on the rise. Which means that by 2050-when some projections hold that the world's population will peak at about nine billion, then start declining-there will not only be far more people, but also proportionately more elderly and fewer young people to care for them. Life expectancy is increasing around the globe, too.

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