Stimulating drinks made from exotic plants, like the cocoa tree and a type of southern holly, were consumed much more widely across the prehistoric Southwest than was thought, according to new research.

A recent study — the largest of its kind ever conducted — analyzed nearly 200 samples of pottery from Southwestern archaeological sites, ranging from Colorado to Chihuahua and spanning 650 years of human occupation.

This is the first evidence that the Ancestral Puebloans and other Southwestern cultures consumed the highly caffeinated Ilex drinks.

Until now, the use of ‘black drink’ had mainly been associated with distant cultures in the American Midwest and South, such as the Mississippian metropolis of Cahokia, where it was drunk as part of purging rituals, or for stimulating trance-like states. [Learn about the history of ‘black drink’: “Ancient Americans Pounded ‘Black Drink’ 6 Times Stronger Than Coffee“]

Moreover, making both cocoa and ‘black drink’ required plants that grew in far-off climates, researchers say, indicating that the Southwest was part of an ancient ‘caffeine trade network’ that extended from the foothills of the Rockies to the heart of Mexico.

“There are no known plants in the Southwest or Northwestern Mexico that have caffeine,” said Dr. Patricia Crown, an anthropologist at the University of New Mexico who led the study. The results revealed that more than 20 percent of the ceramics contained traces of either cocoa or a potent concoction known as ‘black drink,’ made from yaupon holly, known to scientists as Ilex vomitoria.

“So these caffeinated drinks required acquiring — through exchange or direct acquisition — materials from a distance: Mesoamerica, for either plant, or perhaps the Gulf Coast for the holly.”

Crown was one of the researchers who, in 2009, first discovered traces of cocoa — or cacao — in pottery excavated from New Mexico’s Chaco Canyon.

It was a striking reminder of the great economic reach of the Ancestral Puebloans, whose sites had already turned up other Mesoamerican items, like copper bells and remains of scarlet macaws. [See recent research into Chaco’s macaws: “Bones of Exotic Macaws Reveal Early Rise of Trade, Hierarchy in Chaco Canyon“]

Following that find, Crown and colleague W. Jeffrey Hurst, senior scientist with the Hershey Company, wanted to learn how widespread the use of cocoa was throughout the pre-contact Southwest.

“We were interested in determining the spatial and temporal extent of cacao use in the Southwest and Mexican Northwest,” she said.

“We began by looking at other contemporaneous sites in Chaco, then sites outside Chaco but related to it, then sites with evidence for exchange in Mesoamerican goods in other areas, and then sites that filled in geographic areas or time periods but didn’t necessarily have other evidence for Mesoamerican exchange.”

In all, the new study analyzed 177 pottery sherds from 18 different sites, ranging in age from the year 750 to 1400. They included monuments like Chaco’s Chetro Ketl, the ancient Hohokam settlement in Arizona known as Snaketown, and more recently studied sites like Windy Knob in southwestern Colorado.

Using liquid chromatography and mass spectrometry, the researchers then analyzed the sherds for traces of chemicals known as methylxanthines — stimulants that include caffeine, theobromine and theophylline, which are found in cacao and Ilex vomitoria, though in different proportions.

The results, Crown said, were surprising.

“When we started getting results … we realized that not all of them were clearly cacao,” she said.

“Many [of the results] had high caffeine [levels], which is not characteristic of cacao, and some had none of the other methylxanthines — theobromine and theophylline — that characterize cacao.

“So we had to determine what else those samples could be if they weren’t cacao.”

After comparing those residues with ones found in pottery fragments from around Cahokia, where Ilex-based beverages were known to have been used, Crown and Hurst determined that the unusual chemical signatures were likely those of ‘black drink.’

“We fully expected to see evidence for cacao — or not — in the samples,” Crown added.

“We were surprised to find results that suggested that some samples had caffeinated drinks that were not cacao.” [Read about a recent cacao discovery: “Earliest Use of Chocolate in America Discovered, Suggesting Ancient Immigrants“]

In addition to showing that holly-based drinks were likely used in the pre-Hispanic Southwest, this new analysis reveals just how widespread the consumption of caffeine was in the region.

Of the 177 pottery samples — 40 of them, or 22 percent — turned up traces of either cacao or Ilex, even in the sherds from communities that were not known to have Mesoamerican artifacts, or other signs of influence from far-flung cultures.

This, Crown noted, indicates that the Ancestral Puebloans, the Hohokam, and other Southwestern groups not only traded with the peoples of Mesoamerica and the Gulf Coast, they had prolonged and sustained contact with them.

“Once made into drinks, these plants were consumed,” she said. “So, unlike some other exchanged items, if they were an important part of life in the Southwest, or Northwestern Mexico, there had to be an ongoing supply, even if they were consumed only sporadically.

“This created social and economic relationships with distant populations,” she added.

“Individuals who served these drinks might have created more local relationships and obligations with the people who drank them in feasts or rituals or political contexts.

“So part of the takeaway is that special drinks of these sorts tell us something about relationships with distant areas, and also within local groups.”

Crown and Hurst report their findings in the Proceedings of the National Academy of Sciences.