Locations of ancient sacred cacao-growing groves have been discovered over a thousand years after their peak, researchers say.
Cacao beans, from which we make chocolate, were so central to postclassic Maya culture that growing them appears to have been surrounded by religious rituals and tightly controlled to restrict supply. The ancient Maya didn’t just eat the product of cacao beans, they used them as currency and considered them a gift from the gods.
Cacao flourishes in the wet climate of the Guatemalan highlands that made up the Maya people's southern territory. The lowlands of the northern Yucatan Peninsula are generally too dry to support the precious plant, yet the great Maya cities of the area do not seem to have gone without.
Researchers set out to explain this paradox in collaboration with Mexican and US archaeologists. In the Journal of Archaeological Science Reports, the team announce the secret to the sacred groves lies in the peninsula’s geology.
Yucatan is formed from porous limestone leading to karst sinkholes, whose steep walls and sunken location offer shade and abundant water, producing microclimates well-suited to cacao.
The authors took samples from 11 sinkholes – three of which still contain cacao trees, and one whose trees were cut down 60 years ago.
They developed new hot water extraction techniques to identify cacao’s distinctive theobromine and caffeine molecules in the soil. Nine of the sinkholes tested positive, providing evidence cacao once grew in these sinkholes – although alone this would not prove their sacred status.
However, the team found evidence the holes had been modified not just to facilitate agriculture, but for the conduct of ceremonies. Some have remnants of ramps for processions leading down from the edges. Others contain altars or stone carvings and grinding stones, along with jade and ceramic objects thought to have been offerings to the gods.
"We were also amazed to see the ceremonial artifacts. My students rappelled into one of these sinkholes and said, 'Wow! There is a structure in here!' It was a staircase that filled one-third of the sinkhole with stone."
Possibly the most conclusive proof of the sinkholes’ purpose, and the reverence with which cacao was held, is the presence of ceramic cacao pods.
The groves' importance is emphasised by their locations close to the 115 kilometer (70 mile) highway that represented the most important Maya trade route. One city, Chichen Itzna, is suspected of having been located for its proximity to several sinkholes, which would have supplied the essentials of life: water, chocolate, avocados, and bananas.
How long the sinkholes were used in this way remains uncertain, but it seems they were sacred to the Maya by the 9th Century in our calendar if not before.
“The sinkholes were a place where the money could be grown and controlled,” Terry said. “This new understanding creates a rich historical narrative of a highly charged Maya landscape with economic, political and spiritual value."