But cooking also altered the meat itself. It breaks up the long protein chains, and that makes them easier for stomach enzymes to digest. "The second thing is very clear," Wrangham adds, "and that is the muscle, which is made of protein, is wrapped up like a sausage in a skin, and the skin is collagen, connective tissue. And that collagen is very hard to digest. But if you heat it, it turns to jelly."

"Ultimately, of course, what makes us intellectually human is our brain," he says. "And I think that comes from having the highest quality of food in the animal kingdom, and that's because we cook."

"So, as the Neanderthals liked to say around the campfire: bon appetit."