Cow's milk is indeed a natural food - for calves! - just as human milk is made for humans, rat's milk is made for rats, and dog's milk is made for dogs. Our consumption of cow's milk is even more absurd when you consider that calves stop drinking cow's milk when they're weaned, and humans stop drinking human milk when they're weaned, but somehow we've all been convinced that humans should continue drinking cow's milk - and never wean.