Shade

A wolf has a stomach at pH 1, a short simple gut and no fermentation chamber anywhere in it. It eats meat. A lion has an intestine about 4 times its body length, where a grazer runs 20, and sleeps 20 hours a day between kills. It eats meat. A cat cannot make its own taurine and cannot turn carotene into vitamin A. Denied animal tissue it goes blind and its heart gives out. It eats meat. A crocodile has the strongest stomach acid ever measured in a vertebrate, strong enough to take bone and horn apart. It eats meat. A ferret moves food from mouth to exit in about 3 hours. There is no time in that gut to ferment anything. It eats meat. An eagle has forward-facing eyes, a hooked beak, talons, and coughs up the parts it cannot dissolve. It eats meat. A polar bear stores so much vitamin A in its liver that one meal of it would poison a man. It eats meat. Not one of them was ever told. The body was the instruction. The human has stomach acid at pH 1.5, as strong as animals that eat things they find already dead. A small intestine running two thirds of the gut and a colon under a quarter, the carnivore's proportion, upside down from every leaf-eater alive. No cellulase. No rumen. A caecum so useless we take it out when it complains. B12 in no plant on earth. Haem iron absorbed at 25 to 35%, against 2 to 10 for the plant kind. Forward-facing eyes. A shoulder built to throw. Skin that sweats, so we can run something faster than us into the ground by mid-afternoon. Our tapeworms split from the ones in lions and hyenas 1.7 million years ago, because we were standing at the same carcass. Stone tools were stripping meat off bone 2.6 million years back. Same acid. Same gut. Same eyes. The only animal on earth that can read its own biology is the only one arguing with it.