Early humans maintained certain beliefs about the nature of the universe and their place in it long before they began etching those beliefs onto the walls of their caves. Our ancestors, Adam and Eve, were not walking around in a nihilistic fog from which they suddenly snapped like prophets racked by revelation. Rather, Adam and Eve inherited their belief system much in the way they inherited their hunting prowess or their cognitive and linguistic skills: gradually, and over the course of hundreds of thousands of years of mental and spiritual evolution.