William Calvin on the Mind's Big Bang

Some 50,000 years ago a burst of technological and artistic activity erupted in Africa and soon become a great profusion of art, trading, body decoration, and new tools. The material evidence of that creative explosion is taken as an indicator of the mind's "big bang": the time after which Homo sapiens did things from which we infer that, for the first time, people could think long, complicated thoughts, much as we do today.

William H. Calvin. 2004. The Fate of the Soul. Natural History 113(5):52-56.