In the 11th century, Cahokia was the biggest in the north of . Moreover, according to some estimates, it d more than at the , and no within what is the ed its population until after the of Independence. Although many theories have tried to epln the decline and abandonment of such a significant site, evidence from the feces the inhabitants left behind indicates that changes in were a big pt of the .

Cahokia sat on the eastern of the River, opposite -day . Estimates of its peak population vy but go as high as 40,000 Why such an site would be abandoned has troubled chaeologists, but University of -Madison graduate student AJ White has found a possible answer in the manure left at the bottom of neby Horseshoe Lake.

White found molecules ced fecal stanols, which e ly produced in the gut. Much of Cahokia’s sew ended up in neby bodies (simil to many more recent ), so the used the ratio of stanols to those from soil beria in each sediment layer to indicate the number of living in the ea at the . The same sediments also indicate climatic conditions, since contning er oygen atoms evaporates more easily than with heavier molecules.

In Proceedings of the National Academy of Sciences, White reports that the t of Cahokia’s sustned population decline es a uction in , presumably affecting local mze ion. f only decreased in the m son, not the whole ye, and in ound the ye 1150, the ea eperienced a so drastic that it es to have induced a population uction, from which the never recove.

The doesn’t prove was the only Cahokia declined, but it does provide powerful evidence that it was a or. rerch has suggested that the associated in neby bodies was a or in its f.

By 1150, chaeological digs found signs that Cahokia was under , indicated both by fing density and a decline in the ion of . At its peak, Cahokia was a manuuring center, making qutz implements that were d across much of North .

Understanding how ancient s have responded to a changing has taken on urgency recently, and Dr Sissel Schroeder sd in a statement: “s can be very resilient in face of change but resilience doesn’t necessily mean t is no change. T can be cultural reorganization or decisions to relocate or migrate,”

Unfortunately, Schroeder ns that “we see simil pressures today but fewer options to move.”

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