La Brea Tar Pits once trapped prehistoric mammals. Today that killer has a chemical cousin in the Athabasca oil sands of Alberta, Canada--immense deposits of natural asphalt destined for upgrading to synthetic crude oil. If the harvesting of this natural asphalt continues unabated, we might find ourselves stuck in a muck of a different kind. Humanity has used asphalt for thousands of years. This humble hydrocarbon may have glued the first...