For anyone curious the idea that we make slow, discrete progress and that the idea that a few brilliant souls are responsible for most of the advances in human hostory is a bunch of hogwash, Matt Ridley has written an excellent book on the subject, The Evolution Of Everything (amazon.com/Evolution-Everything-How-Ideas-Emerge/dp/0062296000). Coincidentally he's also written a fabulous book on the human genome, either way it's great stuff and absolutely critical to understanding how to we can (as a species) progress most effectively.