Im not sure that humans can exist without some form of social ethical structure considering our upper brain function and reasoning skills. It in the animal nature to socialize, hunt, communicate, congregate, dominate and recreate. The upper brain always gets in the way with thought, conception, rationalization, tinkering and whatnot. The rational mind seeks answers that arent easy and may just simply be unanswerable considering the facts and suppositions at hand. Eating animals is half animal half rational. Eating is eating... eating anything that isnt tied down when hungry is simple base animal instinct. It falls along the same lines as linguistics. Little minds imprint like sponges. You learn to speak what you hear every day. Our forebears who taught us to hunt and gather have shown us what is and isnt safe to eat... how to herd it, sow it, harvest, store, control, brew, barter, stalk. Until less than a century ago our forebears were rather spotty on total caloric intake. You get what you can get when you can get it. Its self protection. The human mind sees animals as food ... the rational mind tells us not to eat the ones we have been conditioned against: other man, dogs, cats and the like... but still.. even then... put a human in the right place with sheer survival on the line, you will see the high brain conditioning go down the loo and find someone gobbling on someones elses leg.