If you're cooking food, you don't have to count calories.

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 longer I've looked at these questions, of the American diet and the public health crisis that we face because of that diet, the more I've come to the conclusion that the collapse of cooking is a big part of the problem.

The ninety-nine cent price of a fast-food hamburger simply doesn't take account of that meal's true cost--to soil, oil, public health, the public purse, etc., costs which are never charged directly to the consumer but, indirectly and invisibly, to the taxpayer (in the form of subsidies), the health care system (in the form of food-borne illnesses and obesity), and the environment (in the form of pollution), not to mention the welfare of the workers in the feedlot and the slaughterhouse and the welfare of the animals themselves.

The growth of the American food industry will always bump up against this troublesome biological fact: Try as we might, each of us can only eat about fifteen hundred pounds of food a year. Unlike many other products - CDs, say, or shoes - there's a natural limit to how much food we each can consume without exploding. What this means for the food industry is that its natural rate of growth is somewhere around 1 percent per year - 1 percent being the annual growth rate of American population. The problem is that [the industry] won't tolerate such an anemic rate of growth.

The correlation between poverty and obesity can be traced to agricultural policies and subsidies.

A natural historian is somebody who looks at something in terms of its relationship to the rest of the natural world. You look at things ecologically. When you see a cow on a feedlot, you don't just see a cow; you see a cow that is eating certain food. You follow that food and that food takes you back to a corn field.