Human faeces in lake reveal climate change-related fate of Cahokia, a once bustling settlement by the Mississippi River

Cahokia was once a thriving, cosmopolitan settlement, located across the Mississippi River from the modern town of St Louis. ... While it housed a population that numbered in the tens of thousands at its peak, those who lived there appear to have abandoned the site by the time Europeans arrived on the continent.

Scientists tracked the history of the area using samples taken from the nearby Horseshoe Lake in Illinois, using them to follow both historical human population changes and weather patterns.

They concluded that a period of climate change accompanied by both droughts and floods had driven people in their thousands from the city.

“When we see correlations with climate, some archaeologists don’t think climate has anything to do with it, but it’s difficult to sustain that argument when the evidence of significant changes in the climate show people are facing new challenges,” said Professor Sissel Schroeder, an anthropologist at the University of Wisconsin-Madison.

The study was based on faecal stanols – molecules produced in the human gut that can persist in the environment for thousands of years.