Corn cultivation spread from Mesoamerica to what is now the American Southwest by about 4000 B.C., but how and when the crop made it to other parts of North America is still a subject of debate. In a new study, scientists report that corn was not grown in the ancient metropolis of Cahokia until sometime between A.D. 900 and 1000, a relatively late date that corresponds to the start of the city’s rapid expansion.
The findings are published in the journal American Antiquity.
The research team determined the age of charred corn kernels found in homes, shrines and other archaeological contexts in and around Cahokia. The researchers also looked at carbon isotopes in the teeth and bones of 108 humans and 15 dogs buried in the vicinity. Carbon-isotope ratios differ among food sources, with isotope ratios of corn being significantly higher than those of almost all other native plant species in the region. By analyzing the ratio of carbon 12 to carbon 13 in teeth and bones, the team determined the relative proportion of different types of foods the people of Cahokia ate in different time periods.
The corn remnants and isotope analyses revealed that corn consumption began in Cahokia between 900 and 1000. This was just before the city grew into a major metropolis.
Read more at University of Illinois at Urbana-Champaign, News Bureau
Image: Corn cultivation began in the vicinity of the city of Cahokia between A.D. 900 and 1000, researchers report in a new study. Its arrival may have contributed to the abrupt rise of this ancient metropolis in and around present-day St. Louis. (Credit: Graphic by Diana Yates)