According to a new analysis published in the journal Current Biology, Iron Age miners in what is now Austria were very fond of beer and blue cheese. Researchers found evidence of two fungal species commonly used to produce blue cheese and beers, as well as evidence that the miners’ diet was particularly high in carbohydrates in the form of grains.
“Genome-wide analysis indicates that both fungi were involved in the fermentation of food and provide the first molecular evidence for the consumption of blue cheese and beer during the Iron Age in Europe,” said co-author Frank Maixner of the Eurac Research Institute for Mummy Studies in Bolzano, Italy. . “The miners appear to have intentionally applied food fermentation technologies with microorganisms that are still used in the food industry today.”
For archaeologists keen to learn more about the health and diets of past populations, as well as the evolution of certain parasites during the evolutionary history of the microbiome, preserved samples of ancient poo can be a real eye-catcher. mine of information. Samples are typically found in dry caves, desert areas, frozen areas, or waterlogged environments (like peatlands), according to Maixner and his co-authors, where desiccation, freezing, and similar processes preserve them. feces for posterity.
As we have previously reported, it can be difficult to determine whether the fecal samples are human or were produced by other animals, especially dogs. Usually, only samples found with human skeletons or mummies could be referred to as being of human origin with certainty. This is why scientists last year developed a tool (called coproID) capable of determining whether paleofeces and coprolites recovered from archaeological sites are of human or animal origin. Among other findings, researchers found that the archaeological record was unexpectedly “full of dog poop.”
The prehistoric underground salt mines of Hallstatt-Dachstein / Salzkammergut, a UNESCO World Heritage Site in Austria, are an excellent source of human paleofeces samples. Mines have high salt concentrations and a constant annual temperature of around 8 degrees Celsius, which is ideal for preserving organic material like faeces. Archaeologists have unearthed thousands of tools and tools from the Bronze and Iron Age wood and fur, as well as rawhide, fragments of woolen textile, ropes and yes, human excrement, usually recovered by sifting larger clumps of debris found in mines with water. These artefacts gave a glimpse into the daily life of the miners.
The present study focused on studying the eating habits of miners, as revealed by analysis of gut microbes present in preserved poop. Maixner et al. examined four paleofecal samples. Radiocarbon dating revealed that one was from the late Bronze Age, two from the Iron Age, and one from the 18th century AD, possibly because mines began to be reused around this time. The researchers were able to recover DNA and proteins from the four samples and determined that all four were from men. “DNA damage is exceptionally low,” note the authors in their article. “This high conservation is probably due to the rapid drying of the samples in the salt mine.”
Molecular and microscopic analysis showed that the miners lived mainly on grains like starch, spelled, barley and millet, a diet high in carbohydrates and supplemented by beans, fruits, seeds, nuts. (nuts) or meat (cattle and pigs). The Bronze Age sample showed almost exclusively leftover grain, as well as a few weeds like corn husk and poisoned parsley. The Iron Age samples were similar, except one sample contained remains of beans, crabapples, and cranberries.
The 18th century sample was particularly different. The leftover grain (wheat and barley bran) was much more finely textured – proof of crushing – with a few green beans and almost no fruit. “This suggests that protohistoric miners consumed cereals and legumes in some sort of porridge or porridge, while 18th century miners ate their cereals in a more processed form, for example in the form of bread or biscuit,” have wrote the authors. The team also found evidence that the men who produced Iron Age and 18th-century stool samples suffered from intestinal infections (whipworm and roundworm).
The microbiomes of the four samples were quite similar to the gut microbiomes of today’s non-Westernized populations, especially in terms of the abundance of Copra Prevotella, which is associated with the digestion of complex carbohydrates, according to the authors. This “adds weight to the hypothesis that the modern industrialized human gut microbiome has diverged from an ancestral state, possibly due to a modern lifestyle, diet or medical advancement,” they said. writing. Analysis of fecal samples from the past two to three centuries would help determine when this crucial change occurred.
All samples showed traces of fungal DNA, but the Iron Age sample also showed high abundance of two species of fungi: Penicillium roqueforti—Commonly used in the fermentation of cheese — and Saccharomyces cerevisiae, used for the fermentation of bread and alcoholic beverages like beer, mead and wine. The former would likely have produced a cheese similar to modern blue cheese, indicating “a major step in the transformation of ruminant milk from fresh cheese to ripened cheese,” the authors wrote, possibly because the ripened cheese is said to have a high content of lactose lower and could be stored longer. periods.
Regarding the S. cerevisiae, the researchers were able to reconstruct about 90 percent of the fungal genome from the paleo-poo sample and concluded that it was most likely used to ferment beer. With the many fermentable grains that made up the subject’s diet, the researchers were even able to speculate on the likely process. The miners could have simply added water to the wort and allowed fermentation to occur naturally via airborne wild yeasts. But they found no evidence of other yeast species common to this type of natural fermentation process.
On the contrary, they found evidence of the domestication of yeasts, either through the reuse of containers or through the practice of “back-slopping”, in which new batches are inoculated with portions of the previous batches. The team concluded that the miners were brewing the modern equivalent of lager beer, “produced primarily by top fermentation. S. cerevisiae strains, ”they wrote.
“These findings shed substantial new light on the life of prehistoric salt miners at Hallstatt and allow an understanding of ancient culinary practices in general to a whole new level,” said co-author Kerstin Kowarik of the Natural History Museum. Vienna. “It is becoming increasingly clear that not only were prehistoric culinary practices sophisticated, but also that complex processed foods as well as the fermentation technique played a prominent role in our early food history. “
DOI: Current Biology, 2021. 10.1016 / j.cub.2021.09.031 (About DOIs).