Salt cultivation across Central and South America spans back thousands of years as evidenced by the still-active Salt Ponds of Maras in Peru Sunsinger/Shutterstock

Today, remnants of an ancient Central American salt mine rest below the brackish waters of a lagoon, but tools that have resurfaced at the hands of archaeologists are helping to illuminate what life looked like there more than 1,000 years ago and, among other things, how the ancient Mayans’ affinity for salt helped to expand their civilization through the production, storage, and trade of the mineral.

A new study published in PNAS reveals the Paynes Creek Salt Works in Belize was once the site of a salt kitchen used to produce and store the biologically and economically important commodity. At a time when society was shifting from hunters and gathers to agriculturalists, the need to preserve perishable food became crucial to the survival of stationary civilizations, leading to the birth of the salt-producing technique known as briquetage. Used across ancient Rome, Asia, and other civilizations, the technique calls for boiling brine in pots over fires to evaporate water, leaving salt behind. The salt in these pots would then be hardened into salt cakes, which could be used stored, transported to nearby trading hubs, or used to preserve fish and meat.

The 8-square-kilometer (3 square miles) site is surrounded by a mangrove forest that thrives on acidic soil, or peat, which disintegrates bone, shells, and other microfossils made from calcium carbonate but preserves woody materials. An international team of researchers mapped and excavated the site and found more than 4,000 wooden posts that indicate a series of buildings would have been used as salt kitchens.

“Our study suggests that salting fish was a significant activity at the salt works, which corresponds to Roman, Chinese, and other East Asian civilizations, where salt and salted fish were critical components of food storage, trade, and state finance,” wrote the authors.

But what tells a more interesting story is the presence of the tools found in the area. A microscopic analysis of 20 chert stone tools recovered from underwater show wear patterns that are consistent with fish preparations, despite there being no evidence of fish in the area.

"Since we found virtually no fish or other animal bones during our sea-floor survey or excavations, I was surprised that the microscopic markings on the stone tools, which we call 'use-wear,' showed that most of the tools were used to cut or scrape fish or meat," said Heather McKillop, the study's lead author, in a statement.

McKillop believes fish, meat, and animal hides could have been manufactured here and, along with the salt, would have been traded at other centers.

"These discoveries substantiate the model of regional production and distribution of salt to meet the biological needs of the Classic Maya," McKillop said.

The “surprising” find helps to explain how other marine resources – like conch shells, coral, and stingray spines – came to be found in inland caches and burials at Mayan sites around the region.