So the first transition, they say, was about 10,500 years ago with the beginning of agriculture. Some have said farming was our biggest mistake: it supported more of us, but at the cost of more disease, poor nutrition, grinding labour, and hierarchical societies that turned into warring empires. But we gained more energy from domesticating animals, and more information by the invention of writing. “Serendipitously,” the authors write, “farming created environmental conditions across our home planet that were unusually stable. This gave time for large-scale civilizations to develop.” That is, humans launched global warming not in the 1800s but with the first agriculture. By burning off forests to make farmland, we began to pump carbon dioxide into the atmosphere — coincidentally, just as the earth was moving on schedule back into another glacial period. Over the next few thousand years farming spread across Asia, Africa, Europe, and much of the Americas, keeping the planet just a little too warm for a return of the glaciers.