For those of you surprised at how well your cat/dog does on the high protein diets, can I just point out that these are carnivorous species evolved to eat other animals not plants. Cats are more obligate carnivores than dogs, they do not have the enzymes necessary to fully digest starch. Humans on the other hand are evolutionarily omnivores, like pigs, evolved to eat anything available both animal and vegetable in origin. The trick is finding the right balance. And from the little experence I have of anthropology, I don't think paleolithic people necessarily got it right all the time either seeing as many of the remains found show signs of disease, malnutrition, stunted growth...