His research is centered around important questions in anthropology that investigates the adoption and spread of farming. He considers the development of a plant producing economy as fundamental to many later cultural changes in societies. He pursues related issues in Northern Mexico, the American Southwest, and Texas, which contain a diversity of ecological settings and archaeological records of past hunter-gatherer and early farming societies. Him and his colleague, John Roney, have conducted work in northwest Chihuahua, Mexico that has documented rapid and early adoption of farming in the form of a hilltop defensive settlement known as Cerro Juanaqueña. In contrast, on the Texas Coastal Plain, their stable isotope studies have demonstrated a long record of hunter-gatherer adaptations involving the intensive use of aquatic resources. Currently, both researchers are working in southern Chihuahua attempting to understand the adoption of farming in this little known region that lies near northern boundary of Mesoamerica.