Today nearly all meat comes from animals raised exclusively for that purpose. Mass production methods are dictated by a simple economic imperative: the meat should be produced at minimum cost, which generally means in the shortest possible time. Animals are now confined to minimize the expenditure of feed on unnecessary movement, and they’re slaughtered before they reach adulthood, when the growth of their muscles slows down. Rapid, confined growth favors the production of white muscle fibers, so modern meats are relatively pale. They’re also tender, because the animals get little exercise, because rapid growth means that their connective-tissue collagen is continuously taken apart and rebuilt and develops fewer strong cross-links, and because rapid growth means high levels of the protein-breaking enzymes that tenderize meat during aging. But many meat lovers feel that meat has gotten less flavorful in recent decades. Life intensifies flavor, and modern meat animals are living less and less.