And I didn't choose this time span arbitrarily. 200,000 years is about how long we believe anatomically modern humans have been on our planet, our subspecies of Homo sapiens sapiens. Now the reason why I show these stone tools is because the ages, the periods of modern humanity, or even pre-modern humanity, are named after the types of tools that have been found in archeological digs. So most of even pre-human, or near pre-human, and human history has been the Paleolithic period, or Old Stone Age. Paleo, paleo for old, lithic coming from lithos for stone. So Paleolithic. The Old Stone Age is the great bulk of human history.