Food produced by fermentation was surprisingly early on the menu of miners at the ancient Hallstatt salt mine in Austria, researchers report: They found traces of certain types of mushrooms in around 2,700-year-old “shops” that apparently came from blue cheese and beer. The team also reports interesting insights into the composition of the intestinal flora of a miner from the Baroque period.
Salt has been extracted here for thousands of years: the prehistoric salt mine of Hallstatt is the oldest salt mine still in operation in the world. The high salt concentration in the tunnels and the constant temperature of eight degrees Celsius have made them a treasure trove for archeology: in the shafts, exceptionally well-preserved objects such as textiles or tools from different times were discovered.
The researchers led by Frank Maixner from the Bolzano research center Eurac Research were now aiming for traces of the former workers, which at first glance do not look like archaeological treasures – but they are: almost perfectly preserved human excrement. As part of their study, they examined specimens from different epochs using microscopic as well as genetic and biochemical analysis methods. “They still contain human genome, as well as DNA from intestinal bacteria, as well as proteins and parts of the food that was once consumed,” explains Maixner.
Blue cheese and beer
As the scientists report, a fossil fecal sample, which was dated to an age of around 2700 years, provided the most exciting result: In it they found clear traces of two types of fungus: Penicillium roqueforti and Saccharomyces cerevisiae. As the researchers explain, they apparently came from foods fermented by them. Specifically, Penicillium roqueforti is a type of mushroom that is still used today to make blue cheese. Saccharomyces cerevisiae, in turn, is known as brewer’s yeast. In their analyzes, the scientists also found clear indications that these specific mushroom variants were not only used by chance, but were specifically bred and used for production.
Older references to fermented milk products and beverages were discovered in the Middle East and Ancient Egypt. Little is known about the history of the spread of cheese and beer in Europe. The scientists are now providing direct molecular evidence that complex foods already played a greater role in the Iron Age than previously assumed. “It is becoming increasingly clear that prehistoric culinary practices were not only highly developed, but that complex processed foods and fermentation technology also played a prominent role in our early nutritional history,” summarizes senior author Kerstin Kowarik.
Legacies rich in rejects
In addition, the microscopic and molecular examinations of the samples showed that the miners’ diet for around 3,000 years was heavily influenced by a diet rich in fiber and carbohydrates – supplemented by proteins from beans and occasionally by fruits, nuts or animal substances. As far as the characteristics of the intestinal flora are concerned, the researchers report significant differences from today’s patterns. Interestingly, this also applied to the most recent of the analyzed samples: although the investigation showed that the miner from the Baroque period was already consuming grain in a more processed form – more finely ground – than was usual in the Bronze or Iron Ages The researchers report that the microbiome is more of the old form than that of a human being in today’s industrial society.
“If 300 years ago people still had a microbiome like their ancestors thousands of years ago, that would mean that major changes would take place in a relatively short time,” says Maixner. The impoverishment of the microbiome through the lifestyle of western industrial societies is classified as an important factor in connection with numerous diseases – but many aspects are still not understood.
“This is one of the reasons why the studies in Hallstatt are of very topical interest,” says co-author Albert Zink from Eurac Research. The researchers now want to continue their search for clues in the old little business: In ongoing and future studies, they hope to find out more about the early production of fermented foods and the interaction between nutrition and the intestinal microbiome in different periods of time.
Source: Cell Press, Eurac Reaserch, technical article: Current Biology, doi: 10.1016 / j.cub.2021.09.031