NEW YORK, NY.- In 2011, archaeologists in the Netherlands discovered an ancient pit filled with 86,000 animal bones at a Roman era farmstead near the city of Utrecht. It fell to Martijn van Haasteren, an archaeozoologist at the Cultural Heritage Agency of the Netherlands, to sort through them.

Deep into the cataloging process, van Haasteren was cleaning the mud from yet another bone when something unexpected happened: Hundreds of black specks the size of poppy seeds came pouring out from one end.

The specks turned out to be seeds of black henbane, a potently poisonous member of the nightshade family that can be medicinal or hallucinogenic depending on the dosage. The bone — hollowed-out and sealed with a tar plug — was an ancient stash pouch that had kept the seeds safe for some 1,900 years.

Researchers determined that the bone was deposited in the pit somewhere between A.D. 70 and 100 — a time when the Netherlands represented the Roman Empire’s northern border. Parts of the container were smooth, suggesting frequent handling.

This “very special” discovery provides the first definitive evidence that Indigenous people living in such a far-flung Roman province had knowledge of black henbane’s powerful properties, said Maaike Groot, an archaeozoologist at the Free University of Berlin and a co-author of a paper published in the journal Antiquity last month describing the finding.

At the time that the original owner stuffed the container full of seeds, the properties of black henbane were already well known in Rome. Writings by Pliny the Elder and others testify to the medicinal use of black henbane seeds and leaves, but warn that an overindulgence will result in mind-altering effects.

The plant was mostly used during Roman times as an ointment for pain relief, although some sources also reference smoking its seeds or adding its leaves to wine. It seems its psychedelic effects came to the fore in the Middle Ages, when black henbane became associated “with witches and summoning demons,” said van Haasteren, who is a co-author of the paper.

Whether Roman knowledge of black henbane’s special properties traveled to the empire’s more distant corners — or whether this knowledge might have been developed independently by local communities — has been a difficult question for scholars to answer.

Black henbane has been found at archaeological sites in the Netherlands that date back to the Neolithic period. But because it is a wild plant that readily grows in the disturbed soil near settlements, experts have been unable to ascertain whether it was used by people or was just part of the environment.

In 2008, for example, archaeologists found a Roman-Era ceramic beaker in Voorburg that had been filled with dirt over time. In the dirt, they found one black henbane seed along with 26 hazelnuts and a single grain each of corn, barley, wheat and various other seeds. “The overall composition of the seeds seemed to point at the intentional use of black henbane as some kind of medicine or hallucinogen,” said Jasper de Bruin, curator of the “Netherlands in Roman Times” collection at the National Museum of Antiquities in Leiden, who was not involved in the new research.

However, according to Laura Kooistra, a retired archaeobotanist and a co-author on the latest findings, a single seed embedded in soil does not provide the degree of certainty needed to draw conclusions about whether black henbane was used by people. “One swallow does not make a summer,” she said.

The bone container, on the other hand, does provide that level of smoking-gun evidence. “It shows, for the first time in Western Europe, the deliberate collection of seeds of the poisonous black henbane during the Roman Period,” said Otto Brinkkemper, an archaeobotanist at the Cultural Heritage Agency of the Netherlands, who was not involved in the research.

Experts can only guess, though, what purpose the seeds might have served.

The authors of the new study refer to black henbane as a medicinal plant, said Astrid Van Oyen, an archaeologist at Radboud University in Nijmegen, who was not involved in the research. But it is also possible that black henbane was used by people “actively seeking psychoactive experiences” for spiritual, therapeutic or recreational purposes, she said.

“This find shows us a rare glimpse of a possible way in which people navigated and mediated the anxieties, stresses, hopes and aspirations of daily life,” Van Oyen said. “Whoever collected all these seeds in this makeshift container did this deliberately and skillfully — they knew what they were doing.”

This article originally appeared in The New York Times.