I think we do need to worry about a food shortage, but we also need to worry about the quality of the food. A lot of the stuff that's marketed to us tastes delicious because it fools our bodies. It fools our bodies into thinking that a particular mix of fat and salt and sugar is good for us. In fact, it isn't. That's why you're seeing in the United States life expectancies are declining, particularly in rural areas. You're seeing life expectancies falling in part because of diet.

We kind of know that food is necessary to survive. But our ways of connecting with food have been, in many ways, taken over by capitalism - certainly taken over by the influence large corporations have on the way that we eat and the way that we think about food. That's why kids these days are more prepared to take nutritional advice from Ronald McDonald than they are from their parents or their teachers or from scientists. And particularly in urban areas, you'll see kids who honestly believe tomatoes come from the supermarket rather than from a plant.

A recent review of different agricultural options for the future was conducted by a panel of experts. The scientists posed the question: How are we going to feed the world when there are nine billion people on it, as there will be by 2050? And the answer they came up with was industrial agriculture won't work and genetic engineering won't work and the solution is going to be sustainable, and going to ecological kinds of farming that are based on local environmental conditions that work with local ecosystems available to develop a richer kind of farming technology.

Agricultural sustainability doesn't depend on agritechnology. To believe it does is to put the emphasis on the wrong bit of 'agriculture.' What sustainability depends on isn't agri- so much as culture.

Exporters monitor economic and political policies to the developing world, but the consequences of that have been to make developing countries far more sensitive to the constant fluctuations. Developing countries are not always allowed to support their farmers in the same way as the U.S. or Europe is. They're not allowed to have tariff barriers. They're forced, more or less, to shrink their social programs. The very poorest people have fewer and fewer entitlements. The consequence of this has been that there's been a chronic increase in the vulnerability of those economies to price shocks.

When you have weird policy decisions in the United States that then ripple out throughout the world, the rest of the world really takes it on the chin. When the U.S. decides to set their corn on fire rather than to eat it, which is what the biofuels policy basically is - then that drives up the price of corn. It drives up the price of substitutes. And all of a sudden you have a sort of spiral of food prices. And other countries don't have the resources, because they're not allowed to, to weather the storm.

I do think we have a food problem. In 2006, which is the year for which we have the latest data, 35.5 million Americans were food insecure. That means there are 35.5 million Americans who are so hard up at some point during the year that they didn't know where their next meal was coming from. That's a lot of Americans. They don't get reported very much because there's nothing spectacular about people skipping a meal because they're poor. The media tends to ignore that, just as it ignores the sort of chronic food shortages elsewhere in the world.