Argument: Humans have always eaten/exploited animals; it has evolved into our DNA
Michael Pollan. "An Animal's Place". The New York Times Magazine. November 10, 2002 - "There is, too, the fact that we humans have been eating animals as long as we have lived on this earth. Humans may not need to eat meat in order to survive, yet doing so is part of our evolutionary heritage, reflected in the design of our teeth and the structure of our digestion. Eating meat helped make us what we are, in a social and biological sense. Under the pressure of the hunt, the human brain grew in size and complexity, and around the fire where the meat was cooked, human culture first flourished. Granting rights to animals may lift us up from the brutal world of predation, but it will entail the sacrifice of part of our identity--our own animality.
Surely this is one of the odder paradoxes of animal rights doctrine. It asks us to recognize all that we share with animals and then demands that we act toward them in a most unanimalistic way. Whether or not this is a good idea, we should at least acknowledge that our desire to eat meat is not a trivial matter, no mere "gastronomic preference." We might as well call sex--also now technically unnecessary--a mere "recreational preference." Whatever else it is, our meat eating is something very deep indeed."