Humans have a long history of transporting and trading plants, contributing to the evolution of domesticated plants. The cacao tree (Theobroma cacao), whose beans are used to make products including chocolate, liquor and cocoa butter, originated in the Neotropics from South America. However, little is known about its domestication and use in these regions. In a new study, archaeologists analyzed ceramic residues from a large sample of pre-Columbian cultures from South and Central America. Their results reveal the widespread use of cacao in South America out of its native Amazonian area of origin, extending back 5,000 years.
Recent findings document the domestication of cacao tree (Theobroma cacao) in the Ecuadorian Amazon region, its region of origin, by at least 5,300 years ago. Lanaud et al. demonstrate the large landscape of domestication of cacao, out of its area of origin, along the Pacific coast of South America, occurring concurrently during this same early time period and in subsequent time periods. Image credit: Fernando Graniel.
The modern cacao tree — whose scientific name means ‘the food of the gods’ — is one of the world’s most important crops.
There are eleven known genetic groups including the widely used Criollo and Nacional strains.
Although it is well established that the cacao tree was originally domesticated in the upper Amazonian basin, it has not been clear how its use by other cultures spread throughout South and Central America.
In new research, AGAP Institut researcher Claire Lanaud and her colleagues analyzed residues from 352 ceramic items from 19 pre-Colombian cultures spanning from approximately 5,900 to 400 years ago across Ecuador, Colombia, Peru, Mexico, Belize, and Panama.
They tested for the presence of ancient cacao DNA and those of three methylxanthine (mild stimulant) components that are present in modern cacao tree strains — theobromine, theophylline, and caffeine — to identify ancient cacao residues.
The authors also used genetic information from 76 modern samples of cacao to establish the ancestry of ancient cacao present in the ceramic items, which could reveal how ancient strains diversified and spread.
The findings demonstrate that cacao was extensively cultivated along the Pacific Coast soon after its domestication in the Amazon at least 5,000 years ago, with high levels of diversity among the ancient strains indicating that genetically distinct populations were bred together.
The presence of cacao genotypes originating from the Peruvian Amazon in the coastal Valdivia Ecuadorian region suggests that these cultures had long-standing contact.
Peruvian strains were also detected in artifacts from the Colombian Caribbean coast.
“Together, this indicates that cacao strains underwent a wide diffusion across countries and were cross bred to adapt to new environments as different cultures adopted their use,” the researchers said.
“Greater understanding of cacao’s genetic history and diversity may help to counter threats, such as disease and climate change, facing modern cacao strains.”
A paper on the findings was published in the journal Scientific Reports.
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C. Lanaud et al. 2024. A revisited history of cacao domestication in pre-Columbian times revealed by archaeogenomic approaches. Sci Rep 14, 2972; doi: 10.1038/s41598-024-53010-6
