Here, used as a proxy, temperature variability. It was a jumpy ride. 80,000 years back in a crisis, we leave Africa, we colonize Australia in another crisis, 60,000 years back, we leave Asia for Europe in another crisis, 40,000 years back, and then we enter the remarkably stable Holocene phase, the only period in the whole history of the planet, that we know of, that can support human development. A thousand years into this period, we abandon our hunting and gathering patterns. We go from a couple of million people to the seven billion people we are today. The Mesopotamian culture: we invent agriculture, we domesticate animals and plants. You have the Roman, the Greek and the story as you know it. The only phase, as we know it that can support humanity.