In 1994 Epstein went back to the Santa Fe Institute, this time to lecture on Sugarscape. He told me, "I came to a run in the Sugarscape that we called the Protohistory, which was really this made-up toy history of civilization, where it starts with some little soup of agents and they go to peaks on the Sugarscape and coalesce into tribes and have lots of kids and this forces them down in between the peaks and they smash into the other tribe and they have all this assimilation and combat and all this other stuff. And I showed that toy history to this typically unlikely Santa Fe collection of archaeologists and biologists and physicists, and I said, 'Does this remind anyone of anything real?' And a hand shot up, and it was George Gumerman's hand. I had never met George. And he said, 'It reminds me of the Anasazi.' I said, 'What the heck is that?' And he told me the story of this tribe that flourished in the Southwest and suddenly vanished. And why did they suddenly vanish? I thought, That's a fascinating question."