Around 1,000 years ago, Native Americans in the Midwest built large settlements, like Cahokia near St. Louis and Angel Mounds in southwest Indiana.
Indiana University-Purdue University Indianapolis scientist Broxton Bird says the growth came with warmer, wetter weather.
“And it’s at that point that they adopted corn and their populations expanded,” Bird says.
Fast forward 500 years and the researchers found a colder, drier climate. That’s bad for corn, says Jeremy Wilson, another IUPUI scientist who co-led the study.