It is not how we breed, keep and kill animals for human consumption that has been the impetus for vegetarianism for thousands of years. It is that we breed, keep and kill animals for human consumption. Throughout the centuries the common thread in the arguments against eating animals is the fact that since we have no nutritional requirement for the flesh or fluids of animals, killing them to simply satisfy our taste-buds or habits or customs amounts to senseless slaughter, and senseless slaughter is no small thing.