K.D. Nelson Lecture Series – Dr. Peter Douglas

The Department of Earth & Environmental Sciences in the College of Arts and Sciences presents the K.D. Nelson Lecture Series featuring speaker Dr. Peter Douglas of McGill University. His talk is titled: Earth, Fire, Water, Waste: Using multiple biomarker proxies to understand human-environment interactions in the Maya Lowlands

The Lowland Maya civilization provides an important example of both early human environmental impacts and the effects of climate change on ancient societies. Our understanding of the environmental history of the Lowland Maya remains patchy, with limited data for key environmental variables. I will discuss the use of multiple lipid biomarker proxies to develop integrated histories of environmental change in the Maya Lowlands, including leaf wax hydrogen isotopes (dD) for hydroclimatic change, leaf wax stable carbon isotopes (d¹³C) for C₄ plant agriculture; leaf wax radiocarbon for soil carbon storage, fecal stanols for human waste and population change, and polycyclic aromatic hydrocarbons for fire history. I will also discuss challenges associated with interpreting these proxies in tropical lake sediment cores. Key findings include: 1) widely varying regional climate histories, complicating the inferred role of drought in causing societal collapse; 2) evidence for major early land use impacts on the tropical forest environment that precede archaeological evidence for large populations; and 3) a shift to reduced fire and C₄ agriculture during later archaeological periods with more established populations, implying a more complex and specialized land use strategies.