Interesting article by a vegetarian saying that humans are omnivores physiologically, like the Great Apes, and that as such we have choice, including being vegetarian for ethical and ecological reasons. This topic comes up often at potlucks I attend and I enjoy sharing my dietary history and hearing others, often quite different from mine. I'm healthiest by far as an omnivore but I meet folks glowingly healthy as vegans (some do best on raw, some on cooked), ovo-lacto vegetarians, some who eat fish now and then, and some folks who react poorly to grains or legumes. A few vegans I've met feel best on a diet composed largely of raw fruits. Human physiology and history make pretty clear that there is no "one size fits all diet" for humans whereas it is very difficult to imagine a cow adapting to an all meat diet like that of the Innuits, who, if true herbivores, would have died out centuries ago.

http://www.vrg.org/nutshell/omni.htm