This article by Southern Louisiana U. professor Matt Rossano, published in the Cambridge Archaeological Journal in 2007, has an awesome premise:
Imagine you travelled back in time 100,000 years and happened upon a group of our ancestors gathered around an evening fire. Would anyone be surprised to find them chanting, clapping, dancing in unison, or maybe just sitting mesmerized before the flickering flame? The thesis of this article is that this commonplace activity, which I will call campfire rituals of focused attention, created an important selective pressure in the evolution of the modern human mind. Ritualized gatherings before an open fire — repeated night after night, generation after generation for thousands of years — contributed significantly, though not necessarily exclusively, to the evolution of the enhanced working memory capacity required for symbolic thinking.
Makes sense to me!
I really want to write a book about the history of consciousness and contemplative practices. It would be an awesome way to write a grand history of everything in drag, and it's an obvious sequel to the contemplative computing book.
You can find a PDF of the article on Rossano's site here.