The spread of democracy, moreover, carries the hope of a more peaceful world. Democracies do not generally go to war with one another. This generalization can of course be overdone, if only because formal democracies can be unstable, as in Weimar Germany and perhaps Russia today. Rising abundance will also make more destructive weapons available to more nations. But if democratic institutions spread and deepen, it is surely a good thing for peace on earth.
Prosperity also has profound effects on demographics.
In many prosperous nations, the population today is actually declining as birth rates sink below replacement levels. There is every reason to believe as the rest of the world develops population growth will slow naturally, even without the extremes of China's one-child policy. World population is now about six billion, and a century from now is likely to be around 10 billion and growing only slowly. This will of course mean a much more elderly population. In the U.S., the Census Bureau predicts that the over-85 population will grow to 18 million in 2050 from five million today.