Ancestral Diet

If we want to return to our ancestral diets, the ones we ate when most of the features of our guts were evolving, we might reasonably eat what our ancestors spent the most time eating during the largest periods of the evolution of our guts. If that is the case, we need to be eating fruits, nuts, and vegetables—especially fungus-covered tropical leaves.

Rob Dunn - http://blogs.scientificamerican.com/guest-blog/2012/07/23/human-ancestors-were-nearly-all-vegetarians/