"Wide adaptation" is an agricultural concept often employed and seldom closely examined. Norman E. Borlaug, while working for the Rockefeller Foundation (RF) on an agricultural project in Mexico in the 1950s, discovered that some tropical wheat varieties could be grown over broad geographic regions, not just in Central and South America but also in the Middle East and South Asia. He called this wide, or broad, adaptation, which scientists generally define as a plant type that has high yields throughout diverse environments. Borlaug soon made wide adaptation as a core pillar of his international wheat program. Borlaug's wheat program rapidly expanded in the 1960s, and he and his colleagues from the RF heavily promoted wide adaptation and the increased use of fertilizers in the Middle East and India. These events led to the green revolution, when several countries rapidly increased their wheat production. Indian wheat cultivation changed radically in the 1960s due to new technologies and policy reforms introduced during the green revolution, and farmers' adoption of 'technology packages' of modern seeds, fertilizer, and irrigation.

Just prior to the green revolution, Indian wheat scientists adopted Borlaug’s new plant breeding philosophy—that varieties should have as wide an adaptation as possible. But Borlaug and Indian wheat scientists also argued that wide adaptation could be achieved by selecting only plants that did well in high fertility and irrigated environments. Scientists claimed, in many cases erroneously, that widely adapted varieties still produced high yields in marginal, or resource poor, areas. Many people have criticized the green revolution for its unequal spread of benefits, but none of these critiques address wide adaptation—the core tenant held by Indian wheat scientists to justify their focus on highly productive land while ignoring marginal and rainfed agriculture. My dissertation describes Borlaug and the RF's research program in wide adaptation, Borlaug's involvement in the Indian wheat program, and internal debates about wide adaptation and selection under favorable environments among Indian scientists. It argues that scientists leveraged the concept of wide adaptation to justify a particular regime of research focused on high production agriculture, and that the footprints of this regime are still present in Indian agriculture.

This study investigates the vulnerability of subsistence agriculturalists to food shortfalls associated with dry periods. I approach this effort by evaluating prominent and often implicit conceptual models of vulnerability to dry periods used by archaeologists and other scholars investigating past human adaptations in dry climates. The conceptual models I evaluate rely on an assumption of regional-scale resource marginality and emphasize the contribution of demographic conditions (settlement population levels and watershed population density) and environmental conditions (settlement proximity to perennial rivers and annual precipitation levels) to vulnerability to dry periods. I evaluate the models and the spatial scales they might apply by identifying the extent to which these conditions influenced the relationship between dry-period severity and residential abandonment in central Arizona from A.D. 1200 to 1450. I use this long-term relationship as an indicator of potential vulnerability to dry periods. I use tree-ring precipitation and streamflow reconstructions to identify dry periods. Critically examining the relationship between precipitation conditions and residential abandonment potentially sparked by the risk of food shortfalls due to demographic and environmental conditions is a necessary step toward advancing understanding of the influences of changing climate conditions on human behavior. Results of this study support conceptual models that emphasize the contribution of high watershed population density and watershed-scale population-resource imbalances to relatively high vulnerability to dry periods. Models that emphasize the contribution of: (1) settlement population levels, (2) settlement locations distant from perennial rivers, (3) settlement locations in areas of low average annual precipitation; and (4) settlement-scale population-resource imbalances to relatively high vulnerability to dry periods are, however, not supported. Results also suggest that people living in watersheds with the greatest access to and availability of water were the most vulnerable to dry periods, or at least most likely to move when confronted with dry conditions. Thus, commonly held assumptions of differences in vulnerability due to settlement population levels and inherently water poor conditions are not supported. The assumption of regional-scale resource marginality and widespread vulnerability to dry periods in this region of the U.S. Southwest is also not consistently supported throughout the study area.