Traces of hallucinogenic plants and chile peppers found at Maya ball court suggest rituals took place there

A bundle of botanicals buried at an ancient Maya ball court in Mexico may have been placed there as part of a ritual, according to a new study.

Archaeologists made the discovery while conducting fieldwork in what was once the ancient Maya city of Yaxnohcah, on the Yucatán Peninsula. During excavations, they noticed a dark stain in the soil and collected samples of it, the team reported in the study, which was published Friday (April 26) in the journal PLOS One.

Back in the lab, researchers conducted an environmental DNA analysis of the soil, using a method they developed that involves collecting specimens in sealable, cryogenic tubes and preserving the samples as they are transported from the field to the lab. To preserve the samples, the researchers applied a solution called RNAlater, which helps to inhibit bacterial growth in the soil.

"It keeps the bacteria from eating DNA in there," lead author David Lentz, a professor of biological sciences at the University of Cincinnati, told Live Science.

The analysis revealed that the stain was actually the remnants of four types of plants, all of which have known "religious associations and medicinal properties" and were often used by the Maya, according to a statement from the University of Cincinnati. The botanicals included a morning glory known as xtabentun, which has hallucinogenic properties, as well as lancewood and chile peppers. The plants were then wrapped in the leaves of the jool plant — a common step in Maya rituals.

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"For the Maya, chile peppers were more than just a condiment and were often used in rituals and had medicinal applications," Lentz said. "Xtabentun has similar physiological effects as LSD, and we've seen evidence of its use in a ceremonial context. It turns out that this was a ceremonial bundle."