For me personally, I believe that something similar to the symbol God was erected by mind as soon as mind realized that existence was finite. In the modern world all human groups have attempted to cope with finite consciousness, and all have employed the same mechanism: a form of conscious infinity. Pinpointing exactly when our ancestors started to do this would, in a sense, be finding the origins of religion because all religions share a similar understanding of super-nature. But since we can’t study the behaviour of early Homo (or even the australopithecines) we may never really know how this belief manifested and developed over evolutionary time. I also believe explanation and scarcity play a role in the creation of symbol God. For more: http://theadvancedapes.com/religion-and-our-evolution/