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An international team of scientists discovered that the high Amazon had given birth to the farmer Theobroma cacao, the plant from which chocolate is made.
Zarrillo et al bring back the oldest evidence of cocoa use in the Americas and the first archaeological example of its pre-Columbian use in South America. Image credit: Stana.
Theobroma cacao It was a culturally important culture in Pre-Columbian Mesoamerica, a historical region and North American cultural area that extends from central Mexico to Belize, Guatemala, El Salvador, Honduras, Nicaragua and the north. from Costa Rica.
Cocoa beans were used both as currency and to make chocolate beverages consumed at parties and rituals.
Archaeological evidence of cocoa use, dating back to 3,900 years ago, had already led to the belief that cocoa was domesticated for the first time in Central America.
However, genomic research shows that the greatest diversity of cocoa is found in the Upper Amazon region of northwestern South America, making it the center of origin.
"Our study shows us that people in the upper reaches of the Amazon basin, extending to the foothills of the Andes, in southeastern Ecuador, were harvesting and consuming cocoa, which seems to be a close relative to the type of cocoa used later in Mexico – and they did it 1,500 years ago, "said Professor Michael Blake of the University of British Columbia, corresponding author of the study.
"They also used elaborate pottery earlier than found in Central America and Mexico."
"This suggests that the use of cocoa, probably as a drink, was something that was successful and that was most likely spread to the north by farmers who were growing cocoa in present-day Colombia and then in Panama. and in other parts of Central and South America. "
For the study, Professor Blake and his co-authors studied ceramic artifacts from Santa Ana-La Florida, Ecuador, the oldest known site of Mayo-Chinchipe culture, occupied for at least 5,450 years .
They used three data sources to show that Mayo-Chinchipe culture used cocoa between 5,300 and 2,100 years ago:
(i) the presence of cocoa-specific starch grains inside ceramic containers and broken pieces of pottery;
(ii) residues of theobromine, a bitter alkaloid found in the cocoa tree, but not its wild relatives;
(iii) old DNA fragments with sequences unique to cocoa.
"The evidence for the use of cocoa was found by badyzing the characteristic starch grains of the genus theobroma, traces of theobromine, a biochemical compound specific to ripe cocoa beans, and ancient cocoa DNA found in ceramic vases, some dating back more than 5,300 years, "said the co-author, Dr. Claire Lanaud, researcher at CIRAD, France.
The results suggest that Mayo-Chinchipes domesticated cocoa at least 1,500 years before the use of the crop in Central America.
With some artifacts from Santa Ana-La Florida having links to the Pacific coast, researchers suggest that trade in goods, including culturally important plants, could have begun the journey of cocoa to the north.
"For the first time, three independent sources of archaeological data have documented the presence of ancient cocoa trees in the Americas: starch grains, chemical biomarkers, and old DNA sequences," said the first author , Dr. Sonia Zarrillo, from the University of Calgary.
"These three methods combine to definitively identify a plant that is notoriously difficult to locate in archaeological archives because seeds and other parts are rapidly degrading in humid, warm tropical environments."
The study appears in the newspaper Nature Ecology & Evolution.
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Sonia Zarrillo et al. The use and domestication of Theobroma cacao during the Holocene in the Upper Amazon. Nature Ecology & Evolution, published online October 29, 2018; doi: 10.1038 / s41559-018-0697-x
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