DNA testing helps push back the origins of chocolate

This Halloween as revelers prepared to feast on chocolate, a new study used DNA testing to prove that cacao actually originated 1500 years earlier than previously thought.

The international team of researchers suggests that cacao – the plant from which chocolate is made – was domesticated, or grown by people for food, much earlier than previously thought. In addition, the researchers found cacao was originally domesticated in South America, rather than in Central America.

Cacao beans were used both as currency and to make chocolate drinks consumed during feasts and rituals. The drinking of cacao is thought to have caught on and was very likely spread northwards by farmers growing cacao in what is now Colombia and eventually Panama and other parts of Central America and southern Mexico.

DNA testing

Researchers studied ceramic artifacts from Santa Ana-La Florida, in Ecuador, the earliest known site of Mayo-Chinchipe culture, which was occupied from at least 5450 years ago. They found three forms of evidence to show that the Mayo-Chinchipe culture used cacao between 5300 and 2100 years ago. These were fragments of ancient DNA with sequences unique to the cacao tree; the presence of starch grains specific to the cacao tree discovered inside ceramic vessels and pottery; and residues of theobromine, a bitter alkaloid found in the cacao tree.

The findings published in Nature Ecology & Evolution [1] suggest that the Mayo-Chinchipe people domesticated the cacao tree at least 1500 years before the crop was used in Central America.

“For the first time, three independent lines of archaeological evidence have documented the presence of ancient cacao in the Americas: starch grains, chemical biomarkers, and ancient DNA sequences”, said Sonia Zarrillo, the study’s lead author and adjunct assistant professor at the University of Calgary.

“Today we all rely, to one extent or another, on foods that were created by the Indigenous peoples of the Americas”, said Michael Blake, study co-author and professor in the University of British Columbia department of anthropology. “And one of the world’s favorites is chocolate.”

[1] Zarrillo S, Gaikwad N and Lanaud C et al. Nature Ecology & Evolution 2018; DOI: 10.1038/s41559-018-0697-x

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