Dump heaps were well fertilized, cultivated seeds, tubers of foods that were gathered grew here. Accidental discovery that led to better life and therefore maintained. Cohen's population pressure hypothesis. Necessity-people were starving, didn't like change but no other choice Heiser's Planting as Religion . Grows well such that each day, each leaf produces another new leaf.
People admire lily pads, and fish in pond.
Then 29 days later, someone notices that pond is half full of lily pads. People start to wonder if they need to be concerned. We'll come back to trends in human populatoin sizes, but first we need to get some basic concepts.