How much food could you actually find? You would have to walk miles and miles per day if you're trying to hunt. You would have to walk miles and miles per day to get whatever wild grains or berries or whatever, or mushrooms or whatever, or insects that you might consume. But then with the advent of agriculture, it allowed for a much, much higher density population. In fact, going from the birth of agriculture, which happens in the Neolithic period, the dawn of agriculture coincides with the Neolithic period. They're often used somewhat interchangeably. Going from that period 10, 15,000 years ago to the time of ancient Rome, so we're talking on the order of 10,000 years, the world population with agriculture exploded from 10 million to roughly 250 million.