By Elizabeth Norton

In the 1600s, Europeans exploring the American southeast wrote of a purification ritual practiced by the native people, involving dancing, vomiting, and large amounts of what the travelers called black drink. Served from shell cups, the highly caffeinated tea was brewed from the shrub Ilex vomitoria, a species of holly. In a new study, researchers have found the first direct evidence of black drink—not in shells from Florida or Mississippi, but in ceramic beakers at the ancient city of Cahokia outside what’s now St. Louis, Missouri. The finding hints at a trade network that flourished centuries before Christopher Columbus landed in the New World, in which caffeinated drinks had Starbucks-like importance and possibly religious significance.

Cahokia sprang up almost overnight around 1050 C.E. and vanished almost as abruptly 300 years later. In the meantime, it was the largest and most sophisticated metropolis north of Mexico. According to archaeological evidence, the central part of the city covered about 14 square kilometers, making it larger than London was then. The 15,000 inhabitants built a wooden version of Stonehenge that charted eclipses; a stockade surrounding the city could be dismantled and rearranged according to an invader’s position. Excavation sites also yielded distinctively patterned, mug-shaped beakers.

Archaeologist Patricia Crown of the University of New Mexico, Albuquerque, and her colleagues were analyzing fragments of these beakers sent by Thomas Emerson and Timothy Pauketat, two archaeologists from the University of Illinois, Urbana-Champaign, who were working at Cahokia. The beakers contained residues presumed to be chocolate—a prized drink that made its way up from Central America. But although the chemical signatures showed traces of caffeine, they didn’t match up with those of cacao, chocolate’s main ingredient. The Cahokia team wondered whether the beakers had contained black drink instead. Since shell cups like those in the southeast had been found in Cahokia, some archeologists suspected that traders might have brought the purifying brew to the city as well. But because holly leaves don’t survive to be found in archaeological digs, and analytical methods couldn’t distinguish among sources of caffeine, it wasn’t clear just what the Cahokians had been drinking.

To find out, Crown teamed up with biochemist and chocolate expert W. Jeffrey Hurst of the Hershey Foods Technical Center in Pennsylvania. Hurst had previously identified a chemical called theobromine that is found in chocolate. Research had also shown that holly plants contain a compound called ursolic acid, which isn’t found in chocolate.

In the new study, which appears online today in the Proceedings of the National Academy of Sciences, Crown and Hurst analyzed the Cahokian samples to look for each compound. They found that the holly-based drink had a characteristic ratio of caffeine to theobromine, plus the presence of ursolic acid, which distinguished it from cacao. Using this profile, they showed that the beakers of Cahokia had indeed contained black drink—400 kilometers from the nearest Ilex vomitoria plant and 500 years before the Europeans described the brew in their journals.

Crown explains that because the bushes weren’t native to Cahokia but to the coastal region between eastern Texas and Florida, the leaves must have been brought to the inland city through trade routes connecting the two areas, which suggests the drink had huge cultural importance. Whether the Cahokians used black drink ritually isn’t known, but its appearance in fine-quality beakers suggests it was highly prized, if not sacred.

"We haven’t yet analyzed other types of pottery, so we can’t say that these beakers were for black drink exclusively," Crown says. But the beakers were found at sites thought to be ritual gathering or burial places, and the distinctive handles, straight sides, and patterns are seen in pottery as far north as Wisconsin. If the beakers and black drink do go hand in hand, Crown and colleagues propose, it might signify wide-ranging Cahokian religious influence between the 11th and 13th centuries.

Paleoethnobotanist Gayle Fritz of Washington University in St. Louis says it’s exciting to have such an exact way of analyzing plant remains. "Usually it’s only charred remains of larger plant parts, such as corncobs, nuts, or seeds that show up in excavations."

ScienceNOW, the daily online news service of the journal Science

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  • "Younger Brother Obsidian," as labeled on the north wall of the Maya city's house by an unknown hand, was painted in the 9th century A.D. Archaeologist William Saturno of Boston University excavates the house in the ruins of the Maya city of Xultún. Younger Brother Obsidian may have been the town scribe. Excavation and preservation of the site were supported by the National Geographic Society. Photo by Tyrone Turner © 2012 National Geographic

  • Trees grow atop a newly discovered mound over a house built by the ancient Maya that contains the rendering of an ancient figure, possibly the town scribe. The house sits at the edge of the ancient site of Xultún in Guatemala, a city that once housed tens of thousands of people. Excavation and preservation of the site were supported by the National Geographic Society. Photo by Tyrone Turner © 2012 National Geographic

  • Three male figures, seated and painted in black. The men, wearing only white loincloths and medallions around their necks and a head dress bearing another medallion and a single feather, were uncovered on the ruined house's west wall. The painting recreates the design and colors of the original Maya mural. Excavation and preservation of the site were supported by the National Geographic Society. Painting by Heather Hurst

  • A Maya king, seated and wearing an elaborate head dress of blue feathers, adorns the north wall of the ruined house discovered at the Maya site of Xultún. An attendant, at right, leans out from behind the king's head dress. The painting by artist Heather Hurst recreates the design and colors of the original Maya artwork at the site. The excavation and preservation of the site were supported by the National Geographic Society. Painting by Heather Hurst

  • A vibrant orange figure, kneeling in front of the king on the ruined house's north wall, is labeled "Younger Brother Obsidian," a curious title seldom seen in Maya text. The man is holding a writing instrument, which may indicate he was a scribe. The painting recreates the design and colors of the figure in the original Maya mural. Excavation and preservation of the site were supported by the National Geographic Society. Painting by Heather Hurst

  • Four long numbers on the north wall of the ruined house relate to the Maya calendar and computations about the moon, sun and possibly Venus and Mars; the dates may stretch some 7,000 years into the future. These are the first calculations Maya archaeologists have found that seem to tabulate all of these cycles in this way. Although they all involve common multiples of key calendrical and astronomical cycles, the exact significance of these particular spans of time is not known. Illustration by William Saturno and David Stuart © 2012 National Geographic

  • The painted figure of a man -- possibly a scribe who once lived in the house built by the ancient Maya -- is illuminated through a doorway to the dwelling, in northeastern Guatemala. The structure represents the first Maya house found to contain artwork on its walls. The research is supported by the National Geographic Society. Photo by Tyrone Turner © 2012 National Geographic

  • Conservator Angelyn Bass cleans and stabilizes the surface of a wall of a Maya house that dates to the 9th century A.D. The figure of a man who may have been the town scribe appears on the wall to her left. Excavation and preservation of the site were supported by the National Geographic Society. Photo by Tyrone Turner © 2012 National Geographic

  • Never-before-seen artwork -- the first to be found on walls of a Maya house -- adorn the dwelling in the ruined city of Xultún. The figure at left is one of three men on the house's west wall who are painted in black and wear identical costumes. Excavation and preservation of the site were supported by the National Geographic Society. Photo by Tyrone Turner © 2012 National Geographic

  • Archaeologist William Saturno of Boston University carefully uncovers art and writings left by the Maya some 1,200 years ago. The art and other symbols on the walls may have been records kept by a scribe, Saturno theorizes. Saturno's excavation and documentation of the house were supported by the National Geographic Society. Photo by Tyrone Turner © 2012 National Geographic