Eight centuries ago, the Four Corners region of the US Southwest was bustling. Regular rainfall coaxed crops from healthy soil, and the abundance of cottontails, jackrabbits, and mule deer made for choice meals. Tens of thousands of Ancestral Puebloans lived in adobe houses and cliff dwellings spread across an area the size of Napa County. Then, in the final decades of the 1200s, most everyone left. Drought, crop failure, and conflict all contributed to the society’s collapse. But we don’t exactly how the migration