After millions of years of being forced to use our wits to survive combined with periods of inbreeding (resulting in a relatively narrow genome), humans are now a super-race of genetic mutants ahead of our time on the evolutionary scale. It wouldn't surprise me one bit if being too smart for our own good contributed to our demise.<p>Edit: By "inbreeding" I mean - if the human population were reduced to a few thousand breeding individuals, and those individuals were also spreading or migrating into different areas of Africa, the middle East, Europe, etc. at the same time, that would mean much smaller groups of people who breed within their "community." It may have been thousands or tens of thousands of years before those different communities met up with each other and combined genetic material again.