Food For Thought: Meat-Based Diet Made Us Smarter Our earliest ancestors ate their food raw — fruit, leaves, maybe some nuts. When they ventured down onto land, they added things like underground tubers, roots and berries. It wasn't a very high-calorie diet, so to get the energy you needed, you had to eat a lot and have a big gut to digest it all. But having a big gut has its drawbacks. "You can'…