National Geographic states that the earliest people to use the cacao
plant were the Mayo Chinchipe in what is now Ecuador. Historians do not
know how they used the plant but traces of an active compound from it
have been found in archaeological digs. Cacao is where chocolate comes
from, and it is known that the Mesoamerican peoples in what are now
Mexico and Central America used it to make a warm brew. They were the
Olmec people.
To date, historians do not know how the Olmec peoples came to understand
that they could transform the cacao seeds into a drink.