Probably an adaptation to reality overload, Ned. When you can`t make sense of everyday life, let your imagination roam. When your new approach to reality coincided with a lapse in external pressures, you knew you were on a hot track. Wonder if shamans led the charge?
Weapons that require the victim (as it were) to put in effort before they become effective are pretty much useless, in my opinion. (OK a pretty s**t metaphor, i know, but its late).
Hypothetically, when God exterminated the human race (Great Shades of Hitler)by a world-wide Flood, the survivors apparently did a diaspora to the four corners of the world (hypothetically). How come we don`t find echoes of Noah and Co.'s beliefs in all races? Where are the lingering traces of a mono god? Where are the talking snakes? The ribless man? Please don`t bother about legends of floods, etc.