Credited to Ecuador. This is the oldest evidence of cacao use, but whether these people domesticated the plant is debated, and the culture extended into what is now Peru.
How it began
The evidence comes from Santa Ana-La Florida in southeastern Ecuador, the oldest known site of the Mayo-Chinchipe culture, which occupied the western Amazon from about 5,500 years ago. Archaeologist Michael Blake of the University of British Columbia noticed that elaborate vessels excavated there by a team including Francisco Valdez resembled the ones the Maya later used for cacao drinks, and asked whether anyone had tested them. Nobody had.
The resulting study, led by Sonia Zarrillo and published in Nature Ecology & Evolution in October 2018, found cacao residues on pottery from radiocarbon-dated layers. It concluded that people at the site used cacao routinely between about 5,300 and 2,100 years ago.
Before it existed
Before this find, the oldest use of cacao was placed in Mesoamerica. Olmec and Maya societies processed cacao seeds into drinks for rituals and feasts as far back as about 1900 BCE, and some of the oldest physical evidence came from pottery about 3,100 years old in Honduras. Many researchers therefore treated cacao processing as a Mesoamerican invention, even though genetic studies had shown that the cacao tree is most diverse in the upper Amazon, which pointed to a South American homeland for the plant.
How it works
The claim rests on three independent lines of evidence taken from ceramic vessels, including plain bowls and decorated spouted bottles. Researchers scraped charred residue from the inside of sherds and found starch grains with a shape specific to Theobroma. They detected theobromine, a compound found in mature cacao seeds. They also recovered fragments of ancient DNA with sequences that match the modern cacao tree.
Residue turned up on 19 different artifacts. The study shows that cacao was prepared and consumed in these vessels. It does not show the recipe, and whether the result resembled later Mesoamerican chocolate drinks is not known.
Who pushed back
The dating and the identification of cacao were widely accepted, but the claim of domestication was questioned. Rosemary Joyce of the University of California, Berkeley, who called the demonstration very strong, noted that the people of Santa Ana-La Florida could simply have gathered pods from wild trees. Juan Carlos Motamayor Arias pointed to a genomic analysis that traced the signature of cacao domestication to about 3,600 years ago in Central America and found no such signal in upper Amazon samples.
The study's authors replied that use across thousands of years suggests cultivation, and that domesticating a long-lived tree might leave no clear genetic signal while wild relatives grew nearby.
What lasted
The find moved the earliest known use of cacao about 1,500 years back in time and from Central America to the upper Amazon. It also raised a question that remains open: how cacao traveled thousands of kilometers north. Cacao seeds lose viability quickly in storage, so they do not transport easily. Artifacts at the site point to contact with the Pacific coast, and Blake has suggested that seedlings may have been moved by boat. The vessel styles at Santa Ana-La Florida also resemble later Central American ones, which has prompted new interest in South American influence on Mesoamerica.
