One of the great mysteries of histories is “What happened to the Mayas?” The quick answer, of course, is nothing. They’re still there, right where they always were. Okay, not so much around Tikal and the other classic jungle centers in Peten, but definitely not far from the Yucatan and Guatemalan highland centers where the Spanish found them. The question then is: “What happened to the Mayan cities and high civilization?” The cities were probably never cities in the Western sense, but more like ceremonial centers, where people gathered and then dispersed periodically, just as they do now on market and festival days. Civilization itself seems to go through phases, possibly in some predictable order, but the concept is so new that it’s hard to generalize. The era of civilization occupies only a very small fraction of man’s total time as a creative, speaking, tool-using animal. Certainly civilizations don’t just go through an early, classic, and late phase, and then just disappear. Something else comes along. Greece, Egypt, and Mesopotamia are still here long after their classic eras. As for the cause of cataclysmic changes, disease is a good guess. Cities were a major breakthrough for bacteria.