Biomarkers of Ancient Population Change
Coprostanol (5ß-cholestan-3ß-ol) is formed by the microbial breakdown of cholesterol in the guts of many animals. Currently only humans, and to a lesser degree sheep and pigs, make significant quantities that might be measured in lacustrine and/or wetland sediments. Changes in the concentration of coprostanol in sediments over time has been postulated to represent changes in the number of people on the landscape (D'Anjou et al., 2012).
My interest in the molecule is both in its potential for understanding human demography related to climate change and also in refining our interpretation of the molecule by testing other animals to eliminate potential overprints of the human record. We have successfully tested the molecule against a well-studied societal collapse at Cahokia, Illinois. Once one of the largest urban settlements of pre-historic North America, Cahokia underwent a rapid depopulation during the 12th century AD.
The abandonment of the city and its cultural mounds has been an enduring mystery. Our work confirmed that coprostanol mimics population reconstructions based on archaeological features giving validation to its use as a demographic proxy. Subsequent work on the Cahokia site suggests that summer drought was coincident with the decline in population.
- Briles, C, Serenchenko, O, Stevens, L, White, AJ, Huong, M (2019). Late Holocene anthropogenic and climatic impacts on a tropical island ecosystem of Northern Vietnam. Frontiers in Ecology and Evolution: Paleoecology 7, 121. doi: 10.3389/fevo.2019.00121
- White, AJ, Stevens, LR, Lorenzi, V, Munoz, SE, Schroeder, S, Cao, A, Bogdanovich, T. (2019). Fecal stanols show simultaneous flooding and seasonal precipitation change correlate with Cahokia's population decline. Proceedings of the National Academy of Sciences (PNAS) 116, 5461-5466.
- White, AJ, Stevens, LR, Lorenzi, V, Munoz, S, Lipo, C, Schroeder, S. (2018). An Evaluation of Fecal Stanols as Indicators of Population Change at Cahokia, Illinois. Journal of Archaeological Science 93, 129-134.
- 2017 - AJ White: Fecal Stanols as Indicators of Ancient Population Change
- 2016 - Angelica Cao: stable isotope record of drought in Cahokia, Illinois
- 2016 - Taylor Bogdanovich: stable isotope record of drought in Cahokia, Illinois
- 2015 - Leticia Martin: coprostanol analysis of an ancient Vietnamese port, Van Don Island, VN