The modern broiler chicken was only bred in the late 1940s. Undoubtedly, the breeds that create it mated many times in the past, but the farmers thought it was a useless defective monster. Chickens used to be expected to forage around the barnyard, and cornish cross broiler chickens aren't capable of it. They need to be kept in a highly regulated environment, they're constantly hungry and incredibly lazy. They reach maturity in 60-90 days and die of heart failure around one year.

Traditional chickens have about half the meat of a modern broiler. Roosters don't produce eggs, and they to destroy each other through combat, but testosterone makes the meat tough, so they would only be used for slow cooked stew. The really desirable meat was capon, produced from a castrated male chicken, but the testes are internal and the procedure had a high fatality rate.