I recently read Born to Run: a hidden tribe, superathletes and the greatest race the world has never seen by Chris McDougall--highly recommended for all runners! I also read The Jungle Effect by Daphne Miller. It's all about indigenous diets (from several different parts of the world, including the Copper Canyons in Mexico which is where a lot of Born to Run is about) and how to incorporate them into our lifestyle to be healthier.