Yale's introductory lecture in the course The Psychology, Biology and Politics of Food opens the term by laying out why eating is never just a biological act. The instructor frames food choice as the product of three overlapping forces: the appetite and metabolism systems shaped by evolution, the psychological drivers of craving and habit, and the policy and industry decisions that determine what ends up on a plate and at what price. Expect early discussion of how the modern food environment, with cheap calories and aggressive marketing, collides with biology built for scarcity, setting up questions the rest of the course will return to. The lecture moves at the pace of a survey session, sketching the territory rather than settling any single debate, and works as an orientation to the interdisciplinary approach the course takes toward obesity, hunger, and food policy.