The city of Cahokia was deserted and researchers struggle to agree on the explanation for this exodus.
For hundreds of years, Cahokia was a bustling city in Illinois, USA, east of the Mississippi River. Around the middle of the 14th century, when the city was inhabited by more than 50,000 people and spread over more than 1,600 hectares, an exodus took place. How can we explain the sudden abandonment of this otherwise dynamic territory?
The first hypothesis considered is that a major drought has damaged the harvests. However, the new investigation by the United States Bureau of Land Management and Washington University in St. Louis, published in The Holocenehas just put this theory in jeopardy. To do this, scientists analyzed soil samples and looked for carbon isotopes, which are indicators of the types of crops planted. They found that two carbon isotopes were still present during the period when people were leaving the city.
The researchers then assure that the drought could not have driven the entire population away: “Given the diversity of their known food base, the domesticated landscape around Cahokia may have been resilient to climate change and capable of producing more food than the Cahokians needed.” They therefore believe that the Cahokians were probably able to adapt to the drought and were able to set up systems to store food, knowing that they benefited from a diversified diet (fish, birds, fruit, nuts, etc.) allowing them to have more possible resources.
The researchers want to continue their research to learn more about the cultures of these ancient people. “Collecting this information would help us see if people have chosen different crops in response to climate change,” explained archaeologist Natalie Mueller of the University of Washington.
But then why did the population flee the city? Experts have not answered this question, only mentioning “external pressures that pushed them to leave”. “I do not imagine a scene where thousands of people suddenly leave the city. People probably dispersed to be near their families or in front of the prospect of new opportunities,” Natalie Mueller supposed. The site has been a UNESCO World Heritage Site since 1982 and attracts 250,000 visitors a year.