A history of how chickens went from the jungle to dinner tables all around the world:
Europeans arriving in North America found a continent teeming with native turkeys and ducks for the plucking and eating. Some archaeologists believe that chickens were first introduced to the New World by Polynesians who reached the Pacific coast of South America a century or so before the voyages of Columbus. Well into the 20th century, chickens, although valued, particularly as a source of eggs, played a relatively minor role in the American diet and economy. Long after cattle and hogs had entered the industrial age of centralized, mechanized slaughterhouses, chicken production was still mostly a casual, local enterprise. The breakthrough that made today’s quarter-million-bird farms possible was the fortification of feed with antibiotics and vitamins, which allowed chickens to be raised indoors. Like most animals, chickens need sunlight to synthesize vitamin D on their own, and so up through the first decades of the 20th century, they typically spent their days wandering around the barnyard, pecking for food. Now they could be sheltered from weather and predators and fed a controlled diet in an environment designed to present the minimum of distractions from the essential business of eating. Factory farming represents the chicken’s final step in its transformation into a protein-producing commodity. Hens are packed so tightly into wire cages (less than half a square foot per bird) that they can’t spread their wings; as many as 20,000 to 30,000 broilers are crowded together in windowless buildings.