All right, to answer that question, let's take a look at the advantages and disadvantages of agriculture. Advantage, controllable food supply. You might have droughts or floods, but if you're growing the crops and breeding them to be hardier, you have a better chance of not starving. Disadvantage, in order to keep feeding people as the population grows, you have to radically change the environment of the planet. Advantage, especially if you grow grain, you can create a food surplus, which makes cities, possible, and also the specialization of labor. Like, in the days before agriculture, everybody's job was foraging, and it took about a thousand calories of work to create a thousand calories of food. And it was impossible to create large population centers.