BYU researchers gauge ancient Mayan populations by studying soil

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PROVO, Utah – Researchers at Brigham Young University are making discoveries about the ancient Mayans by analyzing soil samples in the areas where they once lived.

Soil scientist Richard Terry, BYU, said they have been analyzing dirt from Guatemala to determine how many Mayans lived in certain places. The idea is to track where corn was grown and how much was produced.

He said: “But the question has always been: Well, how many people would the land actually have sustained?”

Terry takes a group of BYU students to Central America each year to do research on the Mayans. This group took 185 soil samples from the area around Tikal.

"In the ancient corn fields of the Maya there is this history that's recorded in the carbon isotopes,” he said.

In addition to the samples, Terry’s team used satellite views, geographic information and computer modeling to determine where the corn fields were. He said they believe Tikal had a population of between 30,000 and 62,000 people. But he said one day, the Mayans all disappeared.

“And each of these cities in the Maya area, starting in about 800 AD, one city after the next after the next collapsed,” he said.

Researchers don’t know whether the disappearance was caused by a lack of water or by a religious or political event, like a war. Terry said he is certain the Mayans intended to come back though.

"In fact, we'll sometimes see their corn grinding equipment stacked up against the walls, as if they're protecting it from the weather because they're going to come back and use this, and yet, 1,200 years later nobody ever came back,” he said.

Terry said the Mayans used advanced techniques and grew their crops in terraces against hillsides. He also said they even produced their own soils.

“Those soils are very high in organic matter, they're very dark in color, and may have been quite productive, even though they're very high in rock,” he said.

Terry said water is another key part of the mystery, as modern-day Tikal doesn’t have rivers, streams or lakes nearby.

"Well, how did they support a large population of people when they had no water? And it becomes apparent that they harvested water, and they stored it,” he said.

Terry said learning about the Mayans has opened up his students to a whole new world.

“The thing that's most exciting and stimulating in this work that we've done is the development of these techniques to find those invisible artifacts,” he said.