Today, Tikal is a national park and a UNESCO World Heritage site. Researchers believe a combination of economic, political and social factors prompted people to leave the city and its adjacent farms. But the climate no doubt played a role, too, Lentz said.
“They have a prolonged dry season. For part of the year, it’s rainy and wet. The rest of the year, it’s really dry with almost no rainfall. So they had a problem finding water,” Lentz said.
Co-author Trinity Hamilton, now an assistant professor of biology at the University of Minnesota, worked on the analysis of ancient DNA from cyanobacteria that sank to the reservoir bottom and was buried by centuries of accumulated sediment.
“Typically, when we see a lot of cyanobacteria in freshwater, we think of harmful algal blooms that impact water quality,” Hamilton said.