An illustrated scene of the Hallstatt salt mountain in the early Iron Age. Reschreiter_Groebner/NHM
Scientists analyzed the DNA in an ancient European salt miner's poop from some 2,600 years ago.
They found the feces contained microbes consistent with the production of beer and blue cheese.
Salt miners were previously thought to mostly eat gruel. The finding suggests they were more sophisticated.
A new study of 2,600-year-old feces from an Iron Age salt miner suggested that workers at the time ate blue cheese and drank beer, suggesting they had a much more sophisticated palate than previously thought.
The feces, which was taken from the Hallstatt-Dachstein salt mine in what's now western Austria, was part of a study published in the peer-reviewed journal Current Biology on Wednesday.
2,600-year-old human excrement from the Hallstatt salt mine. Anwora -NHMW
The study analyzed four feces samples: One from the Bronze Age, two from the Iron Age, and one from the 18th century.
In one of the Iron Age stools, which dates back 2,600 years, the scientists found DNA from Penicillium roqueforti and Saccharomyces cerevisiae, which are microbes used to this day for the manufacture of beer and blue cheese.
Milk fermentation and cheese predate the Iron Age. But the findings suggest that humans were doing much more sophisticated cheese ripening than was previously thought possible at the time, said Kerstin Kowarik, a prehistoric archaeologist at the Museum of Natural History Vienna and an author on the study.
"We're looking at complex and highly processed foodstuff that must have been produced for preservation but also to achieve a certain taste in mind and texture," she told Insider.
An archaeologist standing in the middle of layers of accumulated mining debris including paleofeces. D. Brander and H.Reschreiter - NHMW
"This is very fascinating," said Frank Maixner, a researcher at Italy's Eurac Research Institute for Mummy Studies and another author on the study. "This could indicate [there was] already a tradition" in food production at that time, he said.
The scientists said the team was also able to identify proteins in the stool that revealed traces of animal blood, suggesting the miners were eating foods like liver or blood pudding.
More sophisticated palates than previously thought
Until this discovery, evidence suggested that the salt miners mostly subsisted on gruel.
The Hallstatt salt mine would have been crawling with activity during the Iron Age, and the miners would have been extremely sophisticated and wealthy, partly because they traded salt with other tribes across Europe, said Kowarik.
The idea that they mostly ate gruel didn't seem to fit with that belief, Kowarik said: "It is very nourishing, but it also seems like a very boring food."
A graphic reconstruction of salt mines: Bronze Age in green, Iron Age in blue, and medieval to modern in grey. D. Brandner/NHM
So the evidence that the miners had access to this type of cheese is "something of a game-changer," she said.
Whether the cheese and beer were produced on site or imported isn't clear. Existing scientific studies already showed that the miners had access to luxurious foods like walnuts, which would have been imported from Slovenia, Kowarik said.
A lab at the Eurac Institute for Mummy Studies. Eurac Research - Ivo Corr
Analyzing 2,600-year-old poop
The Iron Age poop was incredibly well preserved, the study authors said, because the cold air and low humidity in the Hallstatt-Dachstein salt mine offer the perfect conditions to preserve human feces. The salt mine, which is now a UNESCO World Heritage site, had been used by humans since the 2nd millennium BC.
"Sometimes they even smell when they are excavated," Kowarik said.
Scientists have studied human excrement dating back thousands of years before, but it is only now that genomic testing technology is advanced enough to work on the DNA, said Maixner.
The cave is still being excavated, Kowarik said, adding: "The question is: what else are we going to find?"
