The price of grain is now directly tied to the price of oil. We used to have a grain economy and a fuel economy. But now they're beginning to fuse.

Mexicans have long been known as the Corn People, but that label perhaps provides a better fit for modern day Americans. The simple seeds of corn play a fundamental role unprecedented in the history of human agriculture. Corn now underpins two major sectors--arguably the two most important sectors--of our modern economy: food supply and energy supply. How we choose to consume this seed has far-ranging consequences for pressing issues as far apart as climate change and diabetes, energy policy and immigration, tropical deforestation and food riots.

Recent years have brought surging interest in both the food we eat and the energy we use. The growth of farmers' markets around the country, the decision of major retailers such as Walmart to sell organic produce, and the popularity of grocery chains such as Whole Foods all bear witness to the fact that Americans care more and more about where their food comes from and how it was grown. The recent popularity of compact fluorescent light bulbs, hybrid cars such as the Toyota Prius, and voluntary carbon offsets similarly demonstrates that individuals see a connection between their behavior and climate change, and care enough to do something about it.