Vernon L. Scarborough

Arising from the Bajos: The Evolution of a Neotropical Landscape and the Rise of Maya Civilization

The conjunctive use of paleoecological and archaeological data to document past human-environment relationships has become a theoretical imperative in the study of ancient cultures. Geographers are playing leading roles in this scholarly effort. Synthesizing both types of data, we argue that large karst depressions known as bajos in the Maya Lowlands region were anthropogenically transformed from perennial wetlands and shallow lakes to seasonal swamps between 400 bc and ad 250. This environmental transformation helps answer several questions that have long puzzled scholars of Maya civilization: (1) why many of the earliest Maya cities were built on the margins of bajos, (2) why some of these early centers were abandoned between 100 bc and ad 250, and (3) why other centers constructed elaborate water storage systems and survived into the Classic period (ad 250 –900). The transformation of the bajos represents one of the most significant and long-lasting anthropogenic environmental changes documented in the pre-Columbian New World.

A water storage adaptation in the maya lowlands.

Prehispanic water management in the Maya Lowlands emphasized collection and storage rather than the canalization and diversion accentuated in highland Mexico. Reexamination of site maps of the ancient Maya city of Tikal, Guatemala, has revealed an important, overlooked factor in Maya centralization and urban settlement organization. In a geographical zone affected by an extended dry season and away from permanent water sources, large, well-planned reservoirs provided resource control as well as political leverage.

Temple mountains, sacred lakes, and fertile fields: ancient Maya landscapes in northwestern Belize

Forty-three years later these words still ring true, but are too seldom followed (Fedick 1996). For several years, we have been engaged in a multidisciplinary programme of research in northwestern Belize and neighbouring areas of Guatemala, eliciting a comprehensive, integrated picture of changing ancient Maya landscapes (Scarborough & Dunning 1996; Valdez et al. 1997). Our goals include a reconstructive correlation of environmental and cultural history, including the relationship between changes in water and land management and political economic organization. This work is still in progress and our understanding is far from complete (Dunning & Scarborough 1997).

Water and sustainable land use at the ancient tropical city of Tikal, Guatemala

The access to water and the engineered landscapes accommodating its collection and allocation are pivotal issues for assessing sustainability. Recent mapping, sediment coring, and formal excavation at Tikal, Guatemala, have markedly expanded our understanding of ancient Maya water and land use. Among the landscape and engineering feats identified are the largest ancient dam identified in the Maya area of Central America; the posited manner by which reservoir waters were released; construction of a cofferdam for dredging the largest reservoir at Tikal; the presence of ancient springs linked to the initial colonization of Tikal; the use of sand filtration to cleanse water entering reservoirs; a switching station that facilitated seasonal filling and release; and the deepest rock-cut canal segment in the Maya Lowlands. These engineering achievements were integrated into a system that sustained the urban complex through deep time, and they have implications for sustainable construction and use of water management systems in tropical forest settings worldwide.

Complexity and Sustainability: Perspectives from the Ancient Maya and the Modern Balinese

Complexity is both a buzzword and a paradigm in the biophysical sciences and, increasingly, the social sciences. We define “social complexity” as the nonlinear escalation of costs and emergent infrastructure with rising energy use and concentrated power as societies develop. Two paths to social complexity are technotasking, which relies on technological break-throughs and is often politically hierarchical, and labortasking, which relies on skilled labor pools and is often heterarchical. We suggest several pathways to greater degrees of complexity and present two case studies emphasizing the role of labor-tasking; an in-depth review of the ancient Maya and a shorter introduction to the recent Balinese. Both of these complex societies used labortasking to adapt to local ecological limitations in semitropical settings. These societies used heterarchical organizations to accretionally engineer and manage their environments, strategies that promoted long-term resilience. Case studies such as these provide a nuanced picture of different paths to social complexity and highlight their relative costs, benefits, and potential for long-term sustainability.

How to interpret an ancient landscape

Perhaps as a foil to postmodern anthropology and geography, a seemingly increased percentage of publications examining material-grounded human ecological relationships have championed a highly deterministic view of the environment (1, 2). Rather than evolving with newly accessed data and methods for their retrieval, several pioneers of human ecology and their students continue to argue for an altered biophysical environment without assessing the changes, sometimes subtle, in societal structures (3, 4). The article by Fisher et al. (5) in this issue of PNAS takes on that tired perspective of human ecology and implicitly demonstrates the necessity of economy: how humans make a living and structure their activities to achieve that living (6). Although the report focuses on a relatively small ancient west-Mexican society, it sets the stage for deconstructing the determinism of human ecology, the view that human society both impacts and is impacted by the environment based on the same suite of physical forces that dictate changes in the natural world, a biophysical environment less subject to the different socioeconomic and sociopolitical organizational strategies practiced by humans. Although the biophysical environment remains fundamental, it is necessarily contextualized by culture.

The Pre-Hispanic Maya Reservoir System at Kinal, Peten, Guatemala

The southern Lowland Maya hilltop center of Kinal is shown to be a human-modified watershed. The broad paved surfaces of the elevated central precinct acted as runoff-catchment areas directing precipitation into gravity-fed channels and reservoirs. In a geographical zone affected by an extended dry season and away from permanent water sources, Kinal demonstrates the components of a rainfall-dependent water-management system characteristic of other large sites in the region.

Forests, fields, and the edge of sustainability at the ancient Maya city of Tikal

Significance The rise of complex societies and sustainable land use associated with urban centers has been a major focus for anthropologists, geographers, and ecologists. Here we present a quantitative assessment of the agricultural, agroforestry, and water management strategies of the inhabitants of the prominent ancient Maya city of Tikal, and how their land use practices effectively sustained a low-density urban population for many centuries. Our findings also reveal, however, that the productive landscape surrounding Tikal, managed to the brink of its carrying capacity during the Late Classic period, did not have the resilience to withstand the droughts of the 9th century. These results offer essential insights that address the question of why some cities thrive while others decline. Tikal has long been viewed as one of the leading polities of the ancient Maya realm, yet how the city was able to maintain its substantial population in the midst of a tropical forest environment has been a topic of unresolved debate among researchers for decades. We present ecological, paleoethnobotanical, hydraulic, remote sensing, edaphic, and isotopic evidence that reveals how the Late Classic Maya at Tikal practiced intensive forms of agriculture (including irrigation, terrace construction, arboriculture, household gardens, and short fallow swidden) coupled with carefully controlled agroforestry and a complex system of water retention and redistribution. Empirical evidence is presented to demonstrate that this assiduously managed anthropogenic ecosystem of the Classic period Maya was a landscape optimized in a way that provided sustenance to a relatively large population in a preindustrial, low-density urban community. This landscape productivity optimization, however, came with a heavy cost of reduced environmental resiliency and a complete reliance on consistent annual rainfall. Recent speleothem data collected from regional caves showed that persistent episodes of unusually low rainfall were prevalent in the mid-9th century A.D., a time period that coincides strikingly with the abandonment of Tikal and the erection of its last dated monument in A.D. 869. The intensified resource management strategy used at Tikal—already operating at the landscape’s carrying capacity—ceased to provide adequate food, fuel, and drinking water for the Late Classic populace in the face of extended periods of drought. As a result, social disorder and abandonment ensued.

An Alternative Order: The Dualistic Economies of the Ancient Maya

Harkening back to the debates associated with “dualistic economies” in addressing emerging nation states, we examine aspects of the ancient economy of the lowland Maya. Resource-specialized communities were knit together in a network of interdependencies that allowed high degrees of self-sustaining separation from the large monumental centers about which we know most. The social and biophysical environs of the ancient Maya permitted multiple economic spheres that influenced their political organization and affected their lack of developed hegemonic controls. Evidence is presented from the present-day ecological set aside of the Programme for Belize in northwestern Belize.

A Preclassic Maya Water System

The late preclassic Maya center of Cerros, northern Belize, 300 BC to 150 AD, has revealed evidence of a sophisticated water control system. Canals and raised field platforms have been examined inside the comunity center. An underlying limestone caprock was systematically removed during the quarrying of monument fill to maintain adequate drainage in the community. The result was a man-made relief or a watershed across the entire core site area. The role of present and past microenvironments at Cerros is addressed.