Why and when human societies shifted from nomadic hunting and gathering to settled agriculture engages the interest of scholars around the world. One of the most fruitful areas in which to study this issue is the North American Southwest, where Late Archaic inhabitants of the Sonoran and Chihuahuan Deserts of Mexico, Arizona, and New Mexico turned to farming while their counterparts in Trans-Pecos and South Texas continued to forage. By investigating the environmental, biological, and cultural factors that led to these differing patterns of development, we can identify some of the...