In On Deep History the author, who is by trade actually a historian of medieval France, argues that the discipline of history has unnecessarily self-limited to the study of "documents"--broadly speaking, history has been the history of "civilization," i.e. the 5000 or so years since the invention of writing. Smail wants history to think wider, and longer, and incorporate more ideas from anthropology, evolutionary biology, linguistics, and neurology (at a minimum!). After explaining the source of this perceived self-limitation, Smail finally opens up to the ideas he wants to pursue: that a major driving force for individuals is the modulation of our neurochemistry, sometimes consciously and directly (caffeine, nicotine, sex, &c.) and sometimes through complex behavioral patterns (ritual, gossip, &c.).
I want to hear more, though I should say I have discussed this with a recent medieval history Ph.D. whose initial reaction was, "Those aren't new ideas!" and that (as an analogy) I once had a Mesopotamian history professor who absolutely despised the work of Jared Diamond as speculations of a rank amateur.
[P.S. Altough I cannot unequivocally recommend the sequel, Olympos, that book has one of the best first lines around.]
On one hand, I do wish I could see it again, for the beauty of the craftsmanship--acting, visualizing, story-telling, and on and on. But I don't think I could emotionally handle being enmeshed again in those characters' suffering.
It's intense. Be amazed, but also try to know your limits.