The party comes across a nice hermit in the woods. He gives them food and lodging for the night. They awaken to his terrified screams. "East! It's east! Stop it! It'll kill us all!" The poor horror-stricken hermit dies thrashing in agony, one boney arm outstretched, his finger pointing to the east.
A certain patch of forest is well known for causing anyone who ventures into it to suddenly go blind. Once they leave the area their vision returns. Rumors of treasure hidden within.
As population increases, animal souls are promoted to human before they are spiritually advanced enough in terms of impulse control, etc.: this shouldn't have happened, but karmic progression is automatic, after all--it's a force of nature. But the 'animalization' of humankind bodes ill for civilization.
No doubt the same goes for elves, dwarves, and so on.