Metaphysical / Paranormal event
Mythological creature crusades occur, capturing and releasing most in Haven.
Per the Earth Abandonment Treaty of 1550 CE and it's Earth Abandonment Crusade Amendment of 1650, mythological beings are transported to Haven. This leaves only humans and non-magical animals (some spirits, water, and air-based creatures are left on Earth—too hard to capture) which stops divine evolution on Earth.