https://phys.org/news/2018-10-sweet-discovery-chocolate.html

Archaeological evidence of cacao's use, dating back to 3,900 years ago, previously planted the idea that the cacao tree was first domesticated in Central America. But genetic evidence showing that the highest diversity of the cacao tree and related species is actually found in equatorial South America-where cacao is important to contemporary Indigenous groups-led the UBC team and their colleagues to search for evidence of the plant at an archaeological site in the region.

"This new study shows us that people in the upper reaches of the Amazon basin, extending up into the foothills of the Andes in southeastern Ecuador, were harvesting and consuming cacao that appears to be a close relative of the type of cacao later used in Mexico—and they were doing this 1,500 years earlier," said Michael Blake, study co-author and professor in the UBC department of anthropology. "They were also doing so using elaborate pottery that pre-dates the pottery found in Central America and Mexico. This suggests that the use of cacao, probably as a drink, was something that caught on and very likely spread northwards by farmers growing cacao in what is now Colombia and eventually Panama and other parts of Central America and southern Mexico."