Archaeologists uncover ancient pottery revealing early traces of chocolate

"The Indigenous world of the Southeast was an international world, where people were very connected," says Adam King, an archaeologist at the University of South Carolina.

Cacao - the source of chocolate after its beans are fermented and roasted - has its origins in Mesoamerica, with domestication evidence stretching back roughly 5,300 years to Ecuador.

Fermented chocolate beverages were being produced by the Olmecs of southern Mexico as early as 1500 BCE, and the Maya later employed cacao beans as currency during the Classic Period.

By 1050 BCE, chocolate had become ubiquitous across the region, yet proof of its presence in North America remained scant.

Located just to the northwest of Atlanta, Etowah features six earthen monuments constructed by Native Americans during the pre-Columbian Mississippian era.

The loftiest of these structures once stood around 64 feet tall, according to Mr King, fashioned from red clay between 1000 and 1550 CE.

Comparable pyramid-style mounds were erected at Cahokia in southern Illinois, home to the celebrated 100-foot Monks Mound.

Cacao - the source of chocolate after its beans are fermented and roasted - has its origins in Mesoamerica

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Mr King believes the construction process at Etowah was deeply ceremonial, with the mounds potentially representing the Earth itself.

"They are actually re-enacting the creation of the Earth," he said.

During the 1950s, archaeologists uncovered remnants of one such celebration - including animal bones and pottery sherds - dating to between 1050 and 1150 CE.

These artefacts had been deposited in a borrow pit, a cavity left behind after red clay was extracted for mound construction.

The pottery was cleaned and placed in storage for decades, yet crucially retained residual traces of its former contents.

Their new study identified cacao DNA in two of the pottery sherds

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Roughly 10 years ago, Mr King and colleague Terry Powis, a specialist in Mesoamerican cacao use, sought permission from the Muscogee people - for whom Etowah is sacred - to test the sherds.

Their initial analysis detected four organic compounds associated with cacao, with caffeine appearing in all 31 fragments examined.

However, caffeine is also present in several American holly species, including the yaupon holly, traditionally brewed as tea by Indigenous peoples of the south-eastern United States.

The researchers could not definitively distinguish between the two sources and initially favoured yaupon holly as the likelier explanation.

To resolve this ambiguity, they collaborated with French scientists to conduct DNA analysis on the artefacts.

How the ancient cacao made its way to Georgia remains a mystery

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Their new study identified cacao DNA in two of the pottery sherds.

The team took considerable precautions to rule out modern contamination - the DNA had degraded in a manner consistent with material roughly a millennium old.

Barbara Mills, a professor emerita of archaeology at the University of Arizona, said: "They take a lot of care to talk about why they don't think it's modern contamination, which you have to worry about with DNA. I thought they did a really great job."

The distance between Etowah and the nearest cacao-growing regions - tropical lowlands such as southern Mexico - makes the discovery particularly shocking.

How the beans reached Georgia remains uncertain - but Mr King suggests they may have been carried directly by a traveller or passed along through successive exchanges.

Cacao residue previously identified in ceramic vessels at Pueblo Bonito in New Mexico's Chaco Canyon dates to a similar period, raising the prospect that continent-spanning trade routes linked these distant communities.

"There are continental scale trade networks," Mr Mills said.