The mystery of the spread of cocoa across South America, more than 5,000 years ago, finally solved

2024-03-07 16:26:00
A cocoa tree in Ecuador, July 2014. C. LANAUD / CIRAD

Chocolate, food of the gods. The formula inspired the clever name of the cocoa tree, Theobroma cacao (Greek theos“god” and joke« aliment »). The Mayans, in fact, associated this divine nectar with their god of fertility and the Aztecs, after them, with their goddess of fertility, Xochiquetzal.

But how did the cultivation of the cocoa tree, this small tree with shiny, bright green leaves, producing large green, yellow or red fruits, spread across South and Central America from its cradle in origin, the upper Amazon, where it was domesticated more than 5,000 years ago? A study coordinated by Claire Lanaud, geneticist at the Center for International Cooperation in Agricultural Research for Development, in Montpellier, and published on March 7 in the journal Scientific Reports, shows the speed of this diffusion, particularly on the Pacific coast.

We know that the cocoa tree originates from the upper Amazon because this region is home to the greatest diversity of this plant. In 2018, previous work carried out in particular with the Research Institute for Development (IRD) in Marseille had found, in the south-east of what is now Equator, the oldest traces of the use of cocoa beans, dating from 5,300 years ago.

The first traces on ceramics

In the new study, archaeologists, anthropologists, geneticists, biochemists and bioinformaticians joined forces to analyze food residue from 352 ceramic archaeological objects, belonging to 19 pre-Columbian cultures dating from 5,900 years ago to 400 years ago. Coming from South or Central America, these ceramics are held by museums such as those of Guayaquil and Quito, in Ecuador, or the National Museum of Colombia, in Bogota. Residues of other ceramics from excavations were sent by archaeologists.

The researchers first scraped these containers to recover these residues, the chemical content of which they analyzed. Result: of the 312 samples from South America, 116 contained theobromine, the main alkaloid in cocoa and chocolate. Of these, 73 contained traces of cocoa tree DNA. The reflection of a wide use of cocoa, hitherto little known, in successive cultures of South America. Above all, the dating of the ceramics where this DNA was found shows that already 5,300 years ago, the cocoa tree was used and domesticated outside its original cradle, the Amazon.

A ceramic pot containing cocoa from the Calima Ilama culture (1600 to 100 BC). This culture was located in western Colombia. C. LANAUD / CIRAD Reserve of the Guayaquil MAAC museum (Ecuador) from which some of the ceramics analyzed for this research work come. C. LANAUD/CIRAD

These traces were in fact found on the Pacific coast of what is now Ecuador and correspond to the culture of Valdivia, particularly known for its female statuettes, the “Venus of Valdivia”. The plant therefore seems to have been domesticated, on the Pacific coast of South America, around the same period as in one of its original homes, in southern Ecuador.

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