Earlier long-necked pots would have been used for beer making. Chemical evidence in a pot such as this is seen as proof that beer brewing involved fermenting cacao (Illustration: PNAS/National Academy of Sciences) Pots with shorter, wider necks were used for making the frothed chocolate drink after 900 BC (Image: PNAS/National Academy of Sciences)

Chocolate was first produced by the ancients as a by-product of beer, suggests a new archaeological study. And evidence from drinking vessels left by the Mesoamericans who developed chocolate suggests that the source of chocolate, cacao, was first used 500 years earlier than thought.

Mesoamericans – who flourished in central America before it was colonised by the Spanish – developed chocolate as a by-product of fermenting cacao fruit to make a beer-like drink called chicha still brewed by South American tribal people.


The Mesoamericans before Columbus’s time, developed a taste for the chocolate, but their cousins down in South America stuck with the beer, says Cornell University archaeologist John Henderson, who led the new study.

Unsweetened chocolate drinks became a central element of Mesoamerican cultures including the Aztecs, from whom Europeans learned of chocolate in the 16th century.

Archaeologists have found pottery made to serve the frothed chocolate drink preferred by the pre-Columbians in earlier sites, and have found traces of chocolate in pots dating back to 600 BC. But the origins of the drink had been unclear.

Chemical clues

Chocolate’s unique flavour develops only when the watery pulp of raw cacao fruit and seeds are fermented together, colouring the seeds purple. Grinding the seeds yields the chocolate.

“It struck us that it wasn’t obvious how to do this,” says study co-author Rosemary Joyce at the University of California at Berkeley. The involvement of fermentation led her and Henderson to speculate that cacao beer might have been the originating process

Only now has hard evidence come to light in the form of pot sherds dating from 200 BC to before 1100 BC that they found in the ruins of an ancient village called Puerto Escondido in the Ulúa Valley in Honduras.

Harnessing a technique developed by Patrick McGovern at the University of Pennsylvania, they were able to extract chocolate residues from the pores in the pottery. Tests found theobromine – a chemical signature of cacao – in 11 of 13 fragments, including one that Joyce estimates dates from 1100 to 1200 BC.

‘Smoking gun’

That pushed evidence for cacao drinking back 500 years. That pot, and others older than about 900 BC, also lacked any traces of the chilli pepper Mesoamericans used to spice up their chocolate. Pots designed for making a frothed chocolate first appeared after this date, the researchers report.

The oldest fragment was the long neck of a bottle that could have held beer, but could not have been used to make the frothed chocolate beverage that became popular later. Joyce called that “the smoking gun” showing that beer had come first.

She suggests that the key step in switching to chocolate came when ancient brewers ground up the cacao seeds remaining after fermentation and added them to thicken the beer – giving it a chocolate taste.

Journal reference: Proceedings of the National Academy of Sciences (DOI: 10.1073/pnas.0708815104)