By MICHAEL HAEDERLE
Published: February 3, 2009
ALBUQUERQUE — For years Patricia Crown puzzled over the cylindrical clay jars found in the ruins at Chaco Canyon, the great complex of multistory masonry dwellings set amid the arid mesas of northwestern New Mexico. They were utterly unlike other pots and pitchers she had seen.
Some scholars believed that Chaco’s inhabitants, ancestors of the modern Pueblo people of the Southwest, had stretched skins across the cylinders and used them for drums, while others thought they held sacred objects.
But the answer is simpler, though no less intriguing, Ms. Crown asserts in a paper published Tuesday in The Proceedings of the National Academy of Sciences: the jars were used for drinking liquid chocolate. Her findings offer the first proof of chocolate use in North America north of the Mexican border.
How did the ancient Pueblos come to have cacao beans in the desert, more than 1,200 miles from the nearest cacao trees? Ms. Crown, a University of New Mexico anthropologist, noted that maize, beans and corn spread to the Southwest after being domesticated in southern Mexico. Earlier excavations at Pueblo Bonito, the largest structure in the Chaco complex, had found scarlet macaws and other imported items.
Dorie Reents-Budet, a curator at the Museum of Fine Arts in Boston and a Smithsonian Institution research associate specializing in Mayan cylinder vases, said that a sophisticated Mesoamerican trade network extended to Chaco in the north and as far south as Ecuador and Colombia.
The Mayan vessels, decorated with court scenes and hieroglyphics, were used to ceremonially consume chocolate at sumptuous feasts, Ms. Reents-Budet said. An expensive luxury, the cacao beans were fermented, roasted and ground up, then mixed with water and flavorings before being whipped into froth. It made sense to present the beverage in a special vessel, she said.
“It’s as if you were having a dinner party and serving Champagne,” said Ms. Reents-Budet. “You serve Champagne in really nice glasses.”
After an exchange with Ms. Reents-Budet in October 2007 about the resemblances between the Chacoan and Mayan earthenware, Ms. Crown said she thought about having the Chacoan cylinders checked for cacao residue.
Ms. Crown turned to W. Jeffrey Hurst, a senior bioanalytical chemist for the Hershey Company, the giant chocolate maker, whose bosses have been allowing him to test Mesoamerican ceramics for cacao for two decades. In 2002, he co-published a paper in Nature showing that early Maya were using cacao by 600 B.C., pushing back the earliest chemical evidence for their cacao use by 1,000 years.
Ms. Crown submitted five fragmentary shards to Mr. Hurst’s laboratory, which subjected the samples to high performance liquid chromatography and mass spectrometry testing, which confirmed the presence of theobromine — a bio marker for cacao — in three shards.
“The results were unequivocal,” said Mr. Hurst, who wrote the new paper with Ms. Crown.
The shards were among 200,000 artifacts excavated from trash heaps next to the 800-room Pueblo Bonito. They date from 1000 to 1125, when Chaco civilization was at its height.
An earlier expedition had uncovered 111 cylinder jars beneath a room in Pueblo Bonito. The jars, of native clay, are about 10 inches high with black geometric designs over a white background, said Ms. Crown, an expert on Pueblo ceramics.
Ms. Crown speculated that the Chacoans might well have followed Mayan ritualized chocolate drinking practices, given the similarity of the drinking vessels.
“It’s likely that this was not something everybody consumed,” she said. “It’s likely it was intended for only this one segment of society.”
She next plans to look for implements that might have been used in the ritual preparation of the beverage and determine whether it was enjoyed elsewhere in the Southwest. For now, she is gratified to have added to the store of knowledge about Chaco’s long-ago residents.
“Most of what we do in archaeology is interpretive, and the interpretations can change,” she said. “It’s rare that you get to find anything this definite and answer a question. It felt great.”