AP Photo

For one billion people around the world, the daily effort to grow, buy or sell food is the defining struggle of their lives. This matters to them, and to all of us.

Consider the daily life of the world's typical small farmer. She lives in a rural village in sub-Saharan Africa, Asia or Latin America, and farms a piece of land she does not own. She works all day in a field. If she's lucky, drought, blight or pests don't destroy her crops, and she raises enough to feed her family. She may even have some left over to sell. But there's no road to the nearest market and no one there who can afford to buy from her.

Now let's consider the life of a young man in a crowded city 100 miles from that farmer. He has no job -- or a job that pays pennies. He goes to the...