Explorers mapped the world. Cartographers gave us details. But we still do not know what we eat, the biochemical compounds in our food. Or in other plants, animals or microbes. Which metabolites are exclusively found in which species? How does human metabolism differ from apes and other primates? Which compounds should we expect in organs, and at which levels? How does metabolism change when we age? What is ‘normal’ or ‘healthy? And how much will metabolism be impacted by diets, exercise or disease?