The wonderful thing about food is you get three votes a day. Every one of them has the potential to change the world.

If you're a politician it's very useful to say that we can have economic growth and at the same time green the economy, but writers just have to face up to the fact that there are some fundamental tensions between the economic order and the biological order.

Originally, the atoms of carbon from which we're made were floating in the air, part of a carbon dioxide molecule. The only way to recruit these carbon atoms for the molecules necessary to support life-the carbohydrates, amino acids, proteins, and lipids-is by means of photosynthesis. Using sunlight as a catalyst the green cells of plants combine carbon atoms taken from the air with water and elements drawn from the soil to form the simple organic compounds that stand at the base of every food chain. It is more than a figure of speech to say that plants create life out of thin air.

Wrangham cites several studies indicating that in fact humans don't do well on raw food: they can't maintain their body weight, and half of the women on a raw-food regimen stop menstruating. Devotees of raw food rely heavily on juicers and blenders, because otherwise they would have to spend as much time chewing as the chimps do. It is difficult, if not impossible, to extract sufficient energy from unprocessed plant matter to power a body with such a big, hungry brain.

The human animal is adapted to, and apparently can thrive on, an extraordinary range of different diets, but the Western diet, however you define it, does not seem to be one of them.

The shared meal elevates eating from a mechanical process of fueling the body to a ritual of family and community, from the mere animal biology to an act of culture.

When you're cooking with food as alive as this -- these gorgeous and semigorgeous fruits and leaves and flesh -- you're in no danger of mistaking it for a commodity, or a fuel, or a collection of chemical nutrients. No, in the eye of the cook or the gardener ... this food reveals itself for what it is: no mere thing but a web of relationships among a great many living beings, some of them human, some not, but each of them dependent on each other, and all of them ultimately rooted in soil and nourished by sunlight.