Inherited Evil

The event that hung like the sword of Damacles over the head of a sleeping, unprepared and complacent civilization, and which was known to happen at any time, destroyed everything that made it a civilization. The old Latin saying, Homo homini lupus, soon proved to be correct.
Was this evil the result of an unfortunate sequence of events, or was the evil just dormant and waiting for the moment to emerge. If the latter, where does this evil in us come from?