Drawing on the collaboration of several archaeologists, paleogeographers, ecologists, and computational modelers, a consortium of scientists is reexamining the Central American Maya Lowlands–the 250,000 km2 of the Yucatan Peninsula–from the rise of Maya complex society to its demise (400 BCE-900 CE).
Drawing on the collaboration of several archaeologists, paleogeographers, ecologists, and computational modelers, a consortium of scientists is reexamining the Central American Maya Lowlands–the 250,000 km2 of the Yucatan Peninsula–from the rise of Maya complex society to its demise (400 BCE-900 CE). Working under the umbrella of IHOPE [Integrated History (and Future) of the People on Earth], our charge is to discern the interplay between societal decision making and environmental change during this long-lived civilization (1, 2). The IHOPE-Maya area is one of several past, resilient cultural groups that are undergoing novel reevaluation by similarly composed teams aimed at comparing and contrasting complex adaptive systems of past societies and the manner by which they acted and reacted to environmental processes. The ultimate goals of IHOPE-Global are to: (i) contextualize recent millennial time since the advent of agriculture and urbanism, (ii) evaluate the socioeconomic and sociopolitical processes undergirding complexity, and within society’s historical precedence and (iii) quantify and qualify ecological processes and their effects on environments of the past as a model for our present. As Faulkner notes, “The past is never dead. It’s not even the past” (3); and with these directives, we bring modeling efforts today in line with what is known of the past–or “actionable” research.
A Synthesis: Currently, we are proposing to a series of four workshops designed to address the interpretive distance between what is climatically produced on a landscape, as opposed to what is a consequence of human modifications. Our point of departure is the foundational experience and outcomes from the IHOPE-Maya group to date (4). If we are to understand the impact of climate change on society and its well being today, we need to examine this separation to best control for the kinds and degrees of environmental changes on the landscapes that humans effect; both to enhance productivity and social welfare (e.g., infrastructural adjustments like roads, reservoirs, terracing, canalization, etc.) as well as cope with deleterious, unintended consequences (elevated erosion rates and corresponding sedimentation loads, mineral pollutant release, uncontrolled forest ignitions, etc.). Climate has surely stimulated social action in the past, a topic that has been a part of the archaeological literature for nearly a century, and a concept that has by now introduced to the semi-popular literature (5). However, our charge is to:
(i) examine in detail regional climatic influence on the environment independent of human action or reaction,
(ii) draw upon our earlier IHOPE-Maya work in identifying the controlled temporal development of the engineered landscape constructed by the ancient Maya, and
(iii) assess the actual impact of climate change on social change.
We are aware that climate can be affected regionally by the actions of ancient societies through destructive events such as deforestation, but our proxies indicate that we can separate causality (see below). Furthermore, some climatologists have argued that in the last 3000 years humans have significantly altered our global carbon footprint by methane generation via spiking domesticated animal use and rice paddy food production. The result has been a Holocene warm period that has extended far beyond what planetary rotation and the earth’s changing relationship to the sun should allow (6). Nevertheless, our concern is not human impact at this scale, a level now a focus of the IPCC. Rather, we wish to identify the suite of immediate landscape signatures indicative of regional climate change as distinguishable from (or interacting with) human alterations across the Yucatan Peninsula (cf. 7). Once this separation is accomplished, our product goal is to (i) identify how the ancient Maya adjusted to climate change (both material and ritualized responses) by way of (ii) controlled dating methods for when societal correctives occurred as climate oscillated (societal lag) as well as (iii) spatially positioning where in the Maya lowlands both climate change and social adjustments occurred most dramatically.
A Contribution: Because we view the ancient Maya as our best studied, deep-time bellwether of tropical society today (8, 9), a society without our technological advancement but institutionally and structurally organized as a hierarchical state, it suggests a highly simplified model of human-nature couplings. Our approach allows a transparent assessment of significant aspects of present-day, extremely convoluted and nonlinear complexity reduced to a scale manageable for holistic evaluating long-term environmental and social change. Because the tropics are the seat for perhaps half of all biodiversity on the planet (10), an evaluation of past effects of climate variability on plant communities and geomorphological processes has immediate resonance. When combined with an understanding of societal development and our focused knowledge of how the ancient Maya exploited and harvested their ecology, we are in a position to project measurable trends in the utilization of ecosystem services–their availability, extraction, allocation and consumption rates. Although we have no illusions that our outcomes can be projected beyond the Maya area, we do suggest that our methods and computational modeling approach will be of significance to others interested in capturing a global assessment beyond “the past can inform the future” platitudes.
Three hypotheses we wish to address are:
H1: Using the wealth of environmental data now identified from the Maya area, we posit that drought conditions near the end of the Late Preclassic Period (AD 200) and again at the close of the Late Classic Period (AD 800) occurred and were a sole consequence of external climatic forcings.
H2: The ancient Maya suffered severe socioeconomic and sociopolitical disruptions internally precipitated by social institutional and structural flaws resulting from the overexploitation of natural resources, especially manifest during the end of the Late Preclassic Period and again by the close of the Late Classic Period.
H3: We can causally isolate the processes implicated in H1 and H2 by determining their landscape signatures.
Supporting H1 are environmental data from lake cores that reveal significant climatic swings. These are measured by O18/16 ratios in lake sediments as well as sedimentation rates (11-13). Recent speliothem assessments from the peninsula (15, 16) also provide support for climatic oscillations from non-urbanized zones. To attribute cause, charcoal ash can be divided between natural wild fires from long-term drought as opposed to slash-and-burn agriculture (cf. 14). Other climatic proxies exist, such as reservoirs (17) coterminous with drought cycles, but these data are construed as circular logic given H2.
Expectations for H2 are that the numerous engineered landscape signatures found throughout the Maya lowlands were built to enhance human productivity, longevity, and social welfare (18). But terraces fail, dams break, and short-fallowed fields erode leading to exhausted and unintended parched or flooded landscapes. Such unanticipated consequences may suggest the effects of climate change, if not carefully separated as to processes of creation and maintenance.
Novel with High Rewards: H3 posits that the effects of engineered landscapes today may be confused with climate change alterations resulting in evaluations that over- or under-estimates climate’s true impacts. Is climate-induced sea-level rise solely responsible for increased sedimentation in delta sediments, or is accelerating erosion resulting from spiking agricultural production the principal cause? Are extended climatic droughts the reason for generational deforestation or is agricultural overexploitation the culprit? These are big questions that require careful parsing of human and natural systems.
Clearly, causal factors are a complex mix with most ecological modeling emphasizing their dynamic interplay. Nevertheless, if we can examine a much simpler set of ancient human/natural systems, we anticipate the ability to weigh the impact of climate vs. human alteration. Learning how a past civilization was affected by these dichotomous forces will introduce a methodology to best plan a corrective future.
Our interest in this program of workshops is to show that a separation between anthropogenic and climatic changes on a landscape can be identified, measured and weighted as to their influence on societies. We anticipate providing a range of parameters suggestive of the impact that climate may have created today vs. what humans may have induced on our landscapes.
1.Costanza R, Graumlich L, Steffen W (2007) Sustainability or Collapse? Integrated History and Future of People on Earth (IHOPE) (MIT Press, Cambridge, MA)
2.Costanza, R., et al. (2012) Developing an Integrated History and future of People on Earth (IHOPE). Cur Op Environmental Sustainability 4:106-114.
3.Faulkner, W (1950) Requiem to a Nun (Random House, NY).
4.Chase AF, Scarborough VL (in press) The Resilience and Vulnerability of Ancient Landscapes: Transforming Maya Archaeology through IHOPE. Archaeol Papers Am Anthropol Assn, no. 22 (Wiley, Hoboken, NJ).
5.Fagan, B (2004) The Long Summer: How Climate Changed Civilization (Basic Books, NY).
Major collaborators and affiliated institutions
Our group is representative of 13 universities, one company, three women, and one latina. Our intellectual traditions span anthropology, archaeology (var.), botany, economics, geography, and climatic modeling. Most of our participants are senior full professors at Research I Institutions, though one is an assistant professor and two others are associate professors. They are all highly energetic and accomplished professionals. All participants are past IHOPE-Maya contributors, most of who have met at least twice a year since 2008 in groups of 15.
Beach,Timothy, Georgetown University
Brewer,Simon, University of Utah
Chase,Arlen, University of Central Florida
Chase,Diane, University of Central Florida
Cobos, Rafael, Universidad Autónoma de Yucatán
Dunning, Nicholas, University of Cincinnati
Fialko, Vilma, Instituto de Antropologia e Historia, Guatemala City
Fedick, Scott, University of California Riverside
Gunn, Joel, University of North Carolina, Greensboro
Heckbert,Scott, Alberta Innovates Technology Futures
Iannone, Gyles, Trent University
Isendahl, Christian, Uppsala University
Lentz, David, University of Cincinnati
Liendo, Rodrigo, Ciudad Universitaria, Universidad Nacional Autònoma de México
Lucero, Lisa, University of Illinois
Luzzadder-Beach, Sheryl, George Mason University
Prufer, Keith, University of North Mexico
Sabloff, Jeremy, Santa Fe Institute
Scarborough, Vernon, University of Cincinnati
Valdez, Fred, University of Texas
Van der Leeuw, Sander, Arizona State University’s School of Sustainability