Was cacao domesticated in a single event in Central America about 3,600 years ago, or independently earlier in the upper Amazon, at the Santa Ana-La Florida site in present-day Ecuador, at least 5,300 years ago?
Two real, peer-reviewed lines of evidence disagree. Archaeological and residue evidence from the Santa Ana-La Florida site places cacao domestication in the upper Amazon (Mayo-Chinchipe culture, present-day Ecuador) at least 5,300 years ago, with cacao later introduced to Mesoamerica. A 2018 genomic study of cultivated cacao trees instead concluded that every domesticated cacao tree today descends from a single domestication event roughly 3,600 years ago somewhere in Central America, which would leave the older Amazonian material outside the domesticated lineage that survived. Neither study has been overturned by the other.
What would resolve this A direct ancient-DNA comparison between cacao remains recovered from Santa Ana-La Florida and the genomic reference set the 2018 study built its single-origin tree from, which would show whether the upper-Amazon material is ancestral to, or a side branch from, the lineage that was actually domesticated.
Archaeobotany / population genomicsCacao Tree (Wikipedia)