The shape of things to come

WHEN the world was a simpler place, the rich were fat, the poor were thin, and right-thinking people worried about how to feed the hungry. Now, in much of the world, the rich are thin, the poor are fat, and right-thinking people are worrying about obesity.

Evolution is mostly to blame. It has designed mankind to cope with deprivation, not plenty. People are perfectly tuned to store energy in good years to see them through lean ones. But when bad times never come, they are stuck with that energy, stored around their expanding bellies.