Jeffery J. Clark

Prehistoric demography in the Southwest: Migration, coalescence, and Hohokam population decline

One of the most prominent but least understood demographic phenomena in the precontact Southwest is the disappearance of the Hohokam from the valleys of southern Arizona. Despite extensive research, no widely accepted explanation has been offered. We argue that the failure to identify a satisfactory cause is due to excessive focus on catastrophic phenomena and terminal occupations, and a lack of attention to gradual demographic processes. Based on a combination of macro-regional population studies and local research in the lower San Pedro River valley, we present an explanation for gradual population decline precipitated by social and economic coalescence beginning in the late A.D. 1200s. In the southern Southwest an influx of immigrants from the north led to a shift from a dispersed, extensive settlement/subsistence strategy to increased conflict, aggregation, and economic intensification. This shift resulted in diminished health and transformation from population growth to decline. Over approximately 150 years gradual population decline resulted in small remnant groups unable to maintain viable communities. Small, terminal populations were ultimately unable to continue identifiable Hohokam cultural traditions and consequently disappeared from the archaeological record of southern Arizona, either through migration or a shift in lifestyle that rendered them archaeologically invisible.

Transformation of social networks in the late pre-Hispanic US Southwest.

The late pre-Hispanic period in the US Southwest (A.D. 1200–1450) was characterized by large-scale demographic changes, including long-distance migration and population aggregation. To reconstruct how these processes reshaped social networks, we compiled a comprehensive artifact database from major sites dating to this interval in the western Southwest. We combine social network analysis with geographic information systems approaches to reconstruct network dynamics over 250 y. We show how social networks were transformed across the region at previously undocumented spatial, temporal, and social scales. Using well-dated decorated ceramics, we track changes in network topology at 50-y intervals to show a dramatic shift in network density and settlement centrality from the northern to the southern Southwest after A.D. 1300. Both obsidian sourcing and ceramic data demonstrate that long-distance network relationships also shifted from north to south after migration. Surprisingly, social distance does not always correlate with spatial distance because of the presence of network relationships spanning long geographic distances. Our research shows how a large network in the southern Southwest grew and then collapsed, whereas networks became more fragmented in the northern Southwest but persisted. The study also illustrates how formal social network analysis may be applied to large-scale databases of material culture to illustrate multigenerational changes in network structure.

Multiscalar perspectives on social networks in the late Prehispanic Southwest

Abstract Analyzing historical trajectories of social interactions at varying scales can lead to complementary interpretations of relationships among archaeological settlements. We use social network analysis combined with geographic information systems at three spatial scales over time in the western U.S. Southwest to show how the same social processes affected network dynamics at each scale. The period we address, A.D. 1200–1450, was characterized by migration and demographic upheaval. The tumultuous late thirteenth-century interval was followed by population coalescence and the development of widespread religious movements in the fourteenth and fifteenth centuries. In the southern Southwest these processes resulted in a highly connected network that drew in members of different settlements within and between different valleys that had previously been distinct. In the northern Southwest networks were initially highly connected followed by a more fragmented social landscape. We examine how different network textures emerged at each scale through 50-year snapshots. The results demonstrate the usefulness of applying a multiscalar approach to complex historical trajectories and the potential for social network analysis as applied to archaeological data.

Evaluating Chaco migration scenarios using dynamic social network analysis

Migration was a key social process contributing to the creation of the ‘Chaco World’ between AD 800 and 1200. Dynamic social network analysis allows for evaluation of several migration scenarios, and demonstrates that Chaco’s earliest ninth-century networks show interaction with areas to the west and south, rather than migration to the Canyon from the Northern San Juan. By the late eleventh century, Chaco Canyon was tied strongly to the Middle and Northern San Juan, while a twelfth-century retraction of networks separated the Northern and Southern San Juan areas prior to regional depopulation. Understanding Chaco migration is important for comprehending both its uniqueness in U.S. Southwest archaeology and for comparison with other case studies worldwide.

The "Collapse" of Cooperative Hohokam Irrigation in the Lower Salt River Valley

Buried beneath Phoenix, Arizona, are the remains of a once prosperous irrigation society known to archaeologists as “Hohokam” and to local Native peoples (the Akimel O’odham [formerly Pima] and the Tohono O’odham [formerly Papago]) as “Huhugkam.”1 Phoenix is the largest American city north of Mexico underlain by such extensive remains predating European contact, and was so named in hopes that a new civilization would “rise from the ashes” of the ancient. Phoenix and its suburbs are rapidly growing cities with looming social and environmental concerns. These include the destruction of the archaeological record that holds clues to similar problems in the past. Despite generations of research, understanding the decline of Classic period (A.D. 1200–1450) Hohokam society remains a challenge for anthropologists. Multiple hypotheses have been proposed with varying levels of support, but all have been plagued by contradictions, or fail to offer adequate explanation of the broad phenomena at issue. The Hohokam case has been invoked in prominent discussions of collapse (Diamond 2005; Krech 2000; Lawler 2010; Redman 1999; Tainter 1988; Wilcox 2010), and our own research is mischaracterized

VILLAGE GROWTH, EMERGING INFECTIOUS DISEASE, AND THE END OF THE NEOLITHIC DEMOGRAPHIC TRANSITION IN THE SOUTHWEST UNITED STATES AND NORTHWEST MEXICO

In the final centuries prior to the arrival of the Spanish, the southwest United States and northwest Mexico underwent two major sociodemographic changes: (1) many people coalesced into large villages, and (2) most of the villages were depopulated within two centuries. Basic epidemiological models indicate that village coalescence could have triggered epidemic diseases that caused the observed demographic decline. The models also link this decline to a global phenomenon, the Neolithic Demographic Transition. En los últimos siglos antes de la llegada de los españoles, el suroeste de los EE. UU. y el noroeste de México experimentaron dos transformaciones sociodemográficas: (1) una gran parte de la población se incorporó en aldeas grandes; y (2) la mayoría de las aldeas se despoblaron en menos de dos siglos. Modelos básicos de la epidemiología indican que la formación de aldeas grandes pudo haber provocado epidemias que causaron una disminución demográfica. Los modelos también proporcionan un enlace teórico entre los cambios regionales y un fenómeno global, la Transición Demográfica del Neolítico.