Farmers first grew cacao tree 3,600 years ago

The ancient residents of Central America knew how to prioritize. Geneticists have found that they first domesticated the cacao tree about 3,600 years ago.

The discovery doesn’t just show that ancient farmers knew what was important. It can also help geneticists and anthropologists trace human migrations throughout the two continents that make up the Americas.

“This evidence increases our understanding of how humans moved and established in America,” lead author Dr. Omar Cornejo of Washington State University said in a press release. “It is important in itself because it gives us a timeframe for asking questions that are perhaps trickier: How long did it take to make a good cacao? How strong was the process of domestication? How many plants were necessary to domesticate a tree?”

Cornejo led a team of 18 scientists from 11 different institutions, including Stanford University, Indiana University, Mars, Inc. and the U.S. Department of Agriculture.

The researchers sequenced 200 plants, to spot variations in the genome that could indicate where and when the cacao tree was first domesticated.

They found that the “prince of cocoas,” a variety of Theobroma cacao known as Criollo, originated in the Amazon, near the border of Colombia and Ecuador. However, it was domesticated in Central America, where seeds were probably brought by traders.

The farmers who domesticated the cacao tree selected for flavor, disease resistance, and theobromine, a stimulant, but this meant that the plant kept genes linked to smaller crops.

These insights may be able to help researchers increase cacao tree production without sacrificing flavor, the researchers said.

“What we would like to have is a way to combine plants from populations with high productivity – like Iquitos – with plants of Criollo origin, while retaining all these desirable traits that make Criollo cacao be the best in the world,” Cornejo said.

The study has been published in the open source journal Communications Biology. Funding for the study came from chocolate company Mars, Inc., which is backing efforts to study the cacao tree genome.

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By Kyla Cathey, Earth.com Contributing Writer