Archaeological finds are the earliest evidence for cacao use in the world
Ancient South Americans domesticated and consumed cacao, the plant from which chocolate is made, long before other people did, a new study finds.
Artifacts with traces of cacao suggest that an Amazonian culture located in what’s now Ecuador developed a wide-ranging taste for cacao products between 5,450 and 5,300 years ago, researchers report online October 29 in Nature Ecology & Evolution. Societies in southern Mexico and Central America, such as the Olmec and Maya, didn’t start concocting their better known and more intensively studied chocolatey drinks for roughly another 1,500 years.
“This is not only the earliest archaeological evidence so far reported for cacao use in the Americas, but also the only archaeological evidence for cacao use in South America,” says study coauthor and anthropological archaeologist Michael Blake of the University of British Columbia in Vancouver.
For more than a decade, reports of heightened genetic diversity among present-day domesticated cacao plants in South America’s upper Amazon region — near where the artifacts were found — have suggested that domesticated cacao (Theobroma cacao) originated there. Differences in the genetic makeup of related populations of organisms accumulate gradually, so populations displaying the most DNA diversity are presumed to have evolved first. The new study confirms that genetic scenario for cacao for the first time at an archaeological site.
The ceramic objects that held the cacao clues were previously unearthed at Santa Ana-La Florida, a settlement occupied by members of an ancient South American culture known as Mayo-Chinchipe. Santa Ana-La Florida excavations began in 2002. Cacao-containing items came from in and around household structures and the tombs of presumably high-status individuals. The researchers suspect that cacao plants likely served as food, drink, medicine, stimulants and perhaps a ceremonial substance for Mayo-Chinchipe people.
Three lines of evidence point to cacao use at Santa Ana-La Florida, the team says. First, starch grains characteristic of domesticated cacao today were recovered from charred food stuck to six pottery shards. Second, traces of theobromine, a bitter chemical compound found in seeds of a domesticated cacao species but not in its wild relatives, were identified in 25 ceramic artifacts and 21 stone artifacts. Finally, three artifacts contained DNA fragments bearing gene variants typical of a domesticated cacao species. Genetic signs of domesticated and wild cacao came from another two artifacts.
It’s particularly interesting that ancient South Americans apparently consumed cacao seeds as well as pulp, says Cameron McNeil, an archaeobotanist at the City University of New York who was not involved in the study. Some researchers have speculated that ancient South Americans would have avoided the time-consuming process of preparing cacao seeds and focused mainly on cacao pulp as a readily available stimulant.
Domesticated cacao’s status as a prestigious, symbolic plant may have blossomed once it reached Central America and Mexico. Those societies further domesticated cacao, McNeil says, probably to enhance the flavor of seeds that were traded and used as currency (SN: 8/4/18, p. 16).
The new work could have implications for today’s chocolate lovers. A recent study found that harmful mutations that lower crop yields in a modern form of cacao accumulated as a result of domestication in Central America and Mexico around 3,600 years ago. Cacao growers can boost the plant’s productivity by incorporating the genetically diverse, South American varieties into current crops, Blake suggests.
S. Zarrillo et al. The use and domestication of Theobroma cacao during the mid-Holocene in the upper Amazon. Nature Ecology & Evolution. Published online October 29, 2018. doi:10.1038/s41559-018-0697-x.
O.E. Cornejo et al. Population genomic analyses of the chocolate tree, Theobroma cacao L., provide insights into its domestication process. Communications Biology. Published online October 16, 2018. doi:10.1038/s42003-018-0168-6.
B. Bower. Conflict reigns over the history and origins of money. Science News. Vol. 194, August 4, 2018, p. 16.
R. Eherenberg. Chocolate may have arrived early to U.S. Southwest. Science News. Vol. 175, February 28, 2009, p. 14.