In the late thirteenth century, drought ravaged the American Southwest, withering the corn, squash, and beans upon which ancient inhabitants relied for survival. Across the region people abandoned their homes in a desperate search for arable land. Some were lucky enough to find a moist Arizona valley where they built a settlement now known as Grasshopper Pueblo.
At its peak, the pueblo consisted of 500 rooms housing hundreds of families. Archaeologists were puzzled by the differing architecture, pottery styles, and burial traditions within the pueblo, leading them to speculate that the drought must have been so severe that people from several different cultures were forced to live together in one of the few places where food would still grow. While the pottery strongly hinted at the disparate origins of the population, there was no way to test that idea.
Enter archaeologist T. Douglas Price, geochemist Jim Burton, and their colleagues from the Laboratory of Archaeological Chemistry at the University of Wisconsin in Madison. In the late 1980s, Price and Burton learned of a new technique that measured the ratio of strontium isotopes in human bone, revealing how an individual had migrated. One of Price’s students, Joseph Ezzo, had worked at Grasshopper Pueblo and was eager to try the new technique there.