Beer and blue cheese already on the menu 2,700 years ago

The prehistoric salt mine of Hallstatt is the world’s oldest and still active salt mine. What’s more, the mine’s combination of high salt concentration in its mine workings and a constant temperature of 8°C has preserved the millennia-old remains such as textiles, tools and even remnants of food discovered there, exceptionally well. And where there’s food, there’s usually human excrement too - "which makes the archaeological site a unique treasure trove for research," said Kerstin Kowarik, a prehistoric archaeologist at the Natural History Museum Vienna. "The specimens we studied are almost perfectly preserved - they still contain human DNA, specifically DNA from intestinal bacteria, as well as proteins and parts of the food eaten," explains microbiologist Frank Maixner of the Bolzano-based research center Eurac Research.

To their surprise, in a sample from the Iron Age, the research team discovered surprising quantities of two fungal species, Penicillium roqueforti and Saccharomyces cerevisiae, both of which are used for the refinement and fermentation of foods - in this case blue cheese and beer. "What's particularly exciting is that, based on our analyses, we have clear evidence that these specific yeast variants were not just used by chance, but were specifically bred and used for beer production," Maixner says. The consumption of a dish that consisted essentially of cattle blood, possibly a type of Iron Age blood sausage, could also be detected. The research group, led by Eurac Research and the Natural History Museum Vienna, have now provided the molecular evidence that complex processed foods played a greater role in the Iron Age than previously thought. "It is becoming increasingly clear that prehistoric culinary practices were not only highly developed, but that complexly processed foods as well as the technique of fermentation played a prominent role in our early nutritional history," Kerstin Kowarik emphasizes.

From the excrement, the team was not only able to reconstruct the diet of the miners over a period of 3,000 years through microscopic and molecular examinations - revealing highly fibrous diets rich in carbohydrates, supplemented by proteins from beans and occasionally by fruits, nuts or meat-based foods, but were also able to make astonishingly accurate statements about the bacterial community composition within the intestine.

The study was realized with the support of the Autonomous Province of Bolzano - Department of Innovation, Research and University.