The collapse of Classic Maya society in the 8th and 9th Centuries CE is often referenced as a typical preindustrial case of “ecocide.” Many scholars and popular writers argue that the Prehispanic Maya contributed to their own demise by overexploiting their natural resources. My research on burnt lime production provides a different way to look at the Maya: not as clueless exploiters marching themselves off of a cliff, but instead as conscious would-be conservationists that were ultimately overwhelmed by forces beyond their control (no, not aliens).

As a graduate student in the Archaeology section of the Department of Anthropology at UW-Madison, I have been conducting field research at the Prehispanic Maya site of Kiuic in the Northern Yucatan Peninsula of Mexico every summer for the past five years. In addition to the incredible feeling of uncovering artifacts and piecing together information about our collective human past, my fieldwork allows me a much-appreciated change of cultural and natural environment for a few months every year. My current project focuses on Prehispanic Maya burnt lime production technology and its effects on socioeconomic and resource management issues. The funding for this project was generously provided by a National Science Foundation Doctoral Dissertation Improvement Grant, by the Anthropology Department at UW-Madison, and by the Bolonchén Regional Archaeological Project (BRAP).

The Classic Maya civilization flourished in the tropical lowlands and volcanic highlands of southeastern Mesoamerica between 250-900 CE. Contrary to popular belief, there was no “Mayan Empire.” Instead, divine kings and queens ruled over numerous city-states that were organized into constantly shifting systems of alliances and antagonisms. Beginning in the 8th century CE, sociopolitical organization in many of the southern and central lowland polities began to break down and many polity centers were abandoned.

The timeline and specific causes of this breakdown, often referred to as the “Classic Maya Collapse,” varied between different city-states. Archaeologists have offered several explanations for collapse including inter-polity warfare, intra-polity civil strife, mega-droughts, and overexploitation of environmental resources, among others. While it was most likely a combination of several of these factors that led to the breakdown of the Classic Period system, the environmental exploitation theory has drawn much attention from both scholars and popular writers. Books like Jared Diamond’s Collapse use the Classic Maya as an example of wanton overuse of environmental resources and as a warning to modern society. While environmental changes may have indeed played an important role in the breakdown of Classic Maya city-states, my research suggests that the Maya were not unaware of the dangers of environmental mismanagement and actually took steps to conserve their resources.

Aside from clearing forests for slash-and-burn agriculture, archaeologists theorize that one of the main reasons for resource depletion was the need for wood fuel for burnt lime production. The Prehispanic Maya, like other Mesoamerican cultures past and present, used burnt lime for a variety of functions. They used it to make the mortar that held together everything from monumental pyramids and plazas to everyday residences. Unlike the Classic Roman Arch, the Maya arch required the use of much stone and mortar fill in the roof to hold the arch stones in place within stone-vaulted structures. Burnt lime was a key ingredient in the plaster that decorated structures and coated plazas to provide a sanitary alternative to performing daily activities directly on the soil. Burnt lime was also used for the nixtamalization process, by which maize was soaked in lime-infused water to release nutrients such as niacin that would otherwise have not been available for absorption into the body. Without the burnt lime treating process, maize-based diets would have led to the vitamin deficiency disease known as pellagra. Based on these factors alone it is easy to see how significant burnt lime was to the everyday life of the Prehispanic Maya.

How could the Classic Maya’s burnt lime consumption have been so great that it led to significant deforestation? Burnt lime is produced by cooking limestone at high temperatures (at least 800 degrees Celsius) for a long enough duration that the chemical composition of the stone itself changes. The traditional method used during the Colonial Period (1520-1821 CE) involves constructing a massive wooden pyre and placing fist-sized pieces of crushed limestone on top. The relative lack of identified Prehispanic lime kilns suggests that the traditional method would have been used during the Prehispanic Period as well (prior to 1520 CE).

Studies have shown that an average of five cubic meters of wood are burned for every cubic meter of burnt lime produced using this aboveground pyre technique. Based on the importance of burnt lime for so many aspects of Prehispanic Maya life, one can imagine the amount of forestland that would have been cleared to produce the fuel necessary for making burnt lime. I estimate that at least three square kilometers of forest were felled annually to supply the lime production needs of Kiuic, while 196 square kilometers of forest may have been required to build the gigantic El Tigre pyramid complex at the Preclassic site of El Mirador.1 The demand for burnt lime can be seen in a similar way to the demand for fossil fuels today, with the production and consumption of both arguably leading to deteriorating environmental conditions. However, while the Maya were contributing to rapid deforestation, they were also attempting to mitigate the negative effects of burnt lime production.

Recreating Maya Conservation Techniques

For the past two summers I have conducted burnt lime research at the Prehispanic Maya site of Kiuic as a member of the Bolonchén Regional Archaeological Project (BRAP), which is directed by Tomás Gallareta Negrón of the Mexican National Institute of Anthropology and History, George J. Bey III of Millsaps College, and Bill Ringle of Davidson College. Kiuic is located in the Puuc Region of the northern Yucatán Peninsula of Mexico, about two hours south of the closest large city of Mérida, and about five hours west of Cancun. It was first inhabited in the 9th century BCE but reached its heyday along with other Puuc sites during the 9th and 10th centuries CE, when larger polities to the south such as Tikal and Palenque were already in decline. Puuc means “hill” in Yucatec Maya (the local language that is still spoken by the majority of the region’s residents and is taught here at the University of Wisconsin). This reflects the region’s hilly topography that places it in stark contrast to the rest of the Yucatán’s endlessly flat landscape.

In the 8th century CE, many of the larger Classic Period sites further to the south were abandoned, but Kiuic and other sites in the Puuc were experiencing both a population and a construction boom. This population growth led to even more clearing of land for agricultural production. The larger population and greater maize output required increased burnt lime production for construction and nixtamalization purposes, which would have taxed the natural resources of the region. And this is exactly what appears to have happened. My colleagues and I have identified what appear to be Prehispanic Maya lime production kilns in and around Kiuic.

The ring structures we identified appear in the archaeological record as low mounds with a circular depression in the middle. Many are capped on top by a single or double ring of large stones surrounding the central pit. There have only been a few potential Prehispanic Maya pit-kilns identified elsewhere in the Maya lowlands. They look nothing like the Kiuic ring structures, nor do they appear with such frequency (50+ identified thus far at Kiuic!). If it turned out that the Kiuic structures were used as burnt lime pit-kilns, this potentially represented the invention of a more resource-efficient lime production technology than was in use elsewhere in the Maya area.

Over the course of 20 weeks spread over two field seasons, I directed the excavation of a sample of nine of these ring structures. The evidence that I recovered within and around these structures strongly pointed to their use as Prehispanic lime pit-kilns. Furthermore, the radiocarbon dates recovered from the structures pointed to their use starting in the late 7th century CE, right around the time that the Kiuic polity would have first been experiencing drastic increases in population and construction.

In order to test the potential fuel-conservation benefits of the kilns, I oversaw the construction of a pit-kiln modeled on the ancient structures and fired a bunch of limestone. Comparing the fuel-to-product ratio from this experimental pit-kiln firing with the aboveground pyre technique, I found that the pit-kiln required approximately 20 percent less fuel. While this may not seem like a drastic improvement, when multiplied by the amount of lime firings that would have been taking place during the heyday of Kiuic, these pit-kilns would have saved the Prehispanic Kiuicanos a good deal of fuel over time.

The fact that this technology was developed at the beginning of the population and construction boom suggests that lime producers in the Puuc had the foresight to develop a more resource-efficient method of lime production before overexploitation became too rampant. The Kiuic polity continued to expand for at least another 250 years after the inception of the lime pit-kiln technology, even as more and more arable land was cleared for agricultural purposes. Eventually, Kiuic went the way of the other Classic Maya city-states. It was ultimately abandoned at the beginning of the 11th Century CE, most likely due to the effects of prolonged mega-droughts. However, without the fuel-conserving measures of the pit-kiln technology Kiuic and the other Puuc sites’ demise might have come about a lot sooner than it did. There were in fact environmental stewards among the Classic Maya. To describe the Classic Maya “collapse” as a result of widespread overexploitation is both an oversimplification and a mischaracterization.

Featured Image: The experimental pit-kiln loaded with fuel and crushed limestone ready to burned. Photo by Ken Seligson.

Ken Seligson is a graduate student in the Archaeology section of the Anthropology Department at UW-Madison. He is studying Prehispanic Maya burnt lime technology for his dissertation and plans to receive his PhD in May 2016. He is also a part-time artist and some of his work is currently on display at the Espresso Royale Caffe on the campus end of State St. from Feb 18-March 17, 2016. Contact.