The more science, the better. Apparently, he saw on tv we ate no meat. I asked him how that is possible, if there's only 30kcal in every 100g of herbs/vegetables. He said that if cows can do that, we can. It turned into an endless discussion, and I just don't know how to prove it to him. What I need is some steady batch of scientific studies that show him why eating paleo is the right thing to do. That show him humans ate meat.
I have almost no experience with scientific studies about diet, so I really don't know where to start searching.