Adapting animals for use as food or for work such as pulling vehicles is called domestication. The first animals to be domesticated were dogs; these were followed by sheep, pigs, goats, and cows. Some animals, for example rabbits were not domesticated until the modern era. In the book Guns. Germs, and Steel, author Jared Diamond discusses which sorts of animals can be domesticated. First, he suggests, they must be able to eat a broad diet, and it is especially useful if they do not consume the food humans eat. They must also have a fast growth rate. Slow-growing animals need too much care before they reach a useful size. Next, they must be able to be bred in captivity. Some animals, such as the panda, are difficult to breed in captivity. In addition, they must be able to live alongside humans and not be aggressive: lions or hyenas are clearly not suitable for this reason. As more and more animals were domesticated over time, farms developed. Animals were captive, but their existence was mostly unchanged from the wild state. Domesticated