To survive, animals must select, from among myriad nonnutritive and toxic items they could ingest, those few that are both nutritious and relatively toxin-free. Humans are, of course, animals, and many of the behavioral processes that guide the food choices of other animals influence humans' food choices as well. However, diet selection by humans is unusual in at least two ways. First, most human knowledge about foods comes secondhand, either directly or indirectly from others. Second, the feeding environment of humans living today in the developed world is dramatically different from that in which humans evolved their abilities to choose foods. We experience food excess, rather than food shortage, extraordinary variety in available foods, rather than restricted food choices, and we are exposed to foods with artificially enhanced palatability. Consequently, our evolved mechanisms of food choice...