What they knew was that it was easier to hunt and forage in forests after fire had removed the underbrush. They knew that they would be back next year chasing

What they knew was that it was easier to hunt and forage in forests after fire had removed the underbrush. They knew that they would be back next year chasing dear, so they decided to light a fire on the way out to make it easier. No advanced knowledge needed. As time went on, the practice became a ritual.