Did you know that we currently get two-thirds of our calories from only four crops: corn, soybeans, wheat, and rice?

When you consider that humankind has historically consumed some 80,000 edible species, and that 3,000 of these have been in widespread use, this represents a radical simplification of the food web. Why should this matter? Because humans are omnivores, requiring somewhere between 50 and 100 different chemical compounds and elements to be healthy. It’s hard to believe that we can get everything we need from a diet consisting largely of processed corn, soybeans, wheat and rice.

Source: Pollan, Michael, Unhappy Meals, The New York Times, January 28,2007.