Chocolate may have arrived early to U.S. Southwest

Americans liked their chocolate drinks tall and frothy long before Starbucks. People were making cacao beverages in the American Southwest as early as 1000 A.D., suggests a new chemical analysis of ancient jars.

The findings, published online February 2 in Proceedings of the National Academy of Sciences, report the earliest known use of cacao north of the U.S.–Mexico border and may stir up debate regarding the Chaco Canyon culture and its relationship with Mesoamerican societies to the south.

Scientists have long puzzled over the purpose of tall, cylindrical jars found in the northwest New Mexico site known as Pueblo Bonito in Chaco Canyon. Speculations range from vessels for corn beer or, with skin stretched over the tops, for drums.

Excavations in the late 1800s and 1920s uncovered 166 of the ceramic jars (fewer than 200 are known from all of the American Southwest) from Pueblo Bonito, a multistory pueblo with an estimated 800 rooms, dating to roughly A.D. 860 to 1128. Much remains unknown about the people who dwelled there and their culture.

The jars may have been used for drinking a cacao beverage, perhaps as part of a specialized ritual, proposes Patricia Crown of the University of New Mexico in Albuquerque. Among the artifacts excavated were a stone that could have been used for grinding the cacao beans, and stirring sticks. Frothing a beverage with stirring sticks or by pouring it from on high was not uncommon in some Mesoamerican cultures.

That the jars were for cacao beverages “really did seem like a stretch,” says Crown, who led the new work and has been studying the Chaco Canyon artifacts for years. When Crown discussed the idea with colleagues “some people thought it was an interesting and great idea, and some people thought it was a joke.”

Cacao use become widespread about 400 years later, when the Spanish arrived.

Crown had learned of similarly sized jars from some Maya sites that researchers knew were specialty vessels for cacao drinks. (When the symbols on the Maya jars were finally deciphered, they read the equivalent of, “This is Bill’s cacao vessel”). Crown sent shards from several jars and a pitcher to paper coauthor Jeffrey Hurst, a specialist in analysis of cacao remains with the Hershey Center for Health and Nutrition in Hershey, Pa.

Using mass spectrometry and high performance liquid chromatography , Hurst analyzed the traces of residue on the jar shards. Cacao has more than 500 compounds, but theobromine gives it away. The chemical could have only come from the cacao plant, a neotropical tree that doesn’t grow north of Mexico. Three of the five shards had traces of theobromine; the pitcher shards did not, Crown says.

The findings are likely to renew debate over the people of Chaco Canyon, comments Bruce Smith of the Smithsonian Institution National Museum of Natural History. “There will be a kerfuffle,” he says. One view sees Chaco Canyon as a mere outpost of Mesoamerica, where all the real cultural action was happening. Another sees it as a society in its own right — it may have borrowed items, such as cacao, from Mesoamerica, but it put its own stamp on them.

Crown has erred on the side of Chaco Canyon being relatively isolated. The amount and variety of Mesoamerican items in these Southwest sites isn’t much, Crown says: evidence of macaws (likely kept for their feathers), some pyrite iron mirrors, copper bells, a few other things and now cacao. Now, she says, she’s not sure about how isolated the Chaco people were.

Another arena of debate concerns how the cacao was being used. Unlike many of the Mesoamerican cultures to the south, no evidence of a rigid societal hierarchy has been found at the Chaco site — there isn’t evidence of chieftains, or distinct classes, says Smith. Yet cacao was probably too valuable and scarce to have been used by everybody, says archaeobotanist Cameron McNeil of Queens College in Flushing, N.Y.

Cacao “is going to have been phenomenally expensive,” McNeil says. “When you think about how far this had to travel — it would have been an extremely important trade item.”