Evidence disputing deforestation as the cause for the collapse of the ancient Maya polity of Copan, Honduras

Abstract

Archaeologists have proposed diverse hypotheses to explain the collapse of the southern Maya lowland cities between the 8th and 10th centuries A.D. Although it generally is believed that no single factor was responsible, a commonly accepted cause is environmental degradation as a product of large-scale deforestation. To date, the most compelling scientific evidence used to support this hypothesis comes from the archaeological site of Copan, Honduras, where the analysis of a sediment core suggested a dramatic increase in forest clearance in the Late Classic period (A.D. 600–900). By contrast, in the work presented here, the authors’ analysis of a longer sediment core demonstrates that forest cover increased from A.D. 400 to A.D. 900, with arboreal pollen accounting for 59.8–71.0% of the pollen assemblage by approximately A.D. 780–980. The highest levels of deforestation are found about 900 B.C. when, at its peak, herb pollen made up 89.8% of the assemblage. A second, although less pronounced, period of elevated deforestation peaked at approximately A.D. 400 when herb pollen reached 65.3% of the assemblage. The first deforestation event likely coincided with the widespread adoption of agriculture, a pattern found elsewhere in Mesoamerica. The second period of forest clearance probably was associated with the incursion of Maya speakers into the Copan Valley and their subsequent construction of the earliest levels of the Copan Acropolis. These results refute the former hypothesis that the ancient Maya responded to their increasingly large urban population by exhausting, rather than conserving, natural resources.

The Maya Forest: Destroyed or cultivated by the ancient Maya?

“…The pollen analysis presented and interpreted by McNeil et al (2) does not imply that the ancient Maya were perfect stewards of the forest. We now have many documented cases of apparently human-induced local environmental degradation, particularly for the Preclassic period (e.g., refs.…”

“…In the pollen diagram developed from the Copan sediment core (2), nearly all of the broad taxonomic categories of plants used as indicators of both disturbance and forestation could include species known to have been used as food by the Maya and were likely to have been managed as subsistence resources. The pollen record, however, has severe limitations when we try to evaluate the contribution of forest management and polycultural home gardening to ancient Maya subsistence.…”

“…The results of this study demonstrate how refinement of methods and extension of time frames can provide dramatic reinterpretations of scenarios that have become engrained in both academic and popular perceptions about the Maya. Whereas the pollen analysis presented and interpreted by McNeil et al (2) cannot be expected to provide a full picture of the Maya Forest and how it may have been managed, it does provide sound and convincing evidence that the Late Classic Maya at Copan did not foolishly strip away the forest and destroy their environment as portrayed in Jared Diamond's best-selling book (3) and taught in our children's classrooms. Among academics, we generally recognize that the results of our research represent what we hope to be the best interpretation of currently available data, and that our interpretations will be subject to modifications as new data and methods are developed.…”

“…This lesson was based in large part on the earlier interpretation of a sediment core from Copan (4). Dramatic swings in our interpretations concerning the historical ecology of the Maya Lowlands will continue, at least until enough studies, such as the one presented by McNeil et al (2), are conducted and published.…”

“…The analysis of a sediment core from a pond located near the ancient Maya city of Copan, Honduras, interpreted by McNeil et al (2) in this issue of PNAS, offers a unique perspective on long-term interactions between the Maya and their environment. The results of this study demonstrate how refinement of methods and extension of time frames can provide dramatic reinterpretations of scenarios that have become engrained in both academic and popular perceptions about the Maya.…”