Laborers working in the salt mines of the Alps 2,700 years ago must have worked up quite an appetite. Now, research published in the journal Current Biology suggests these miners satisfied their hunger with cheese and beer—information gleaned thanks to the careful examination of ancient poop.
Lead author Frank Maixner, a microbiologist at the Eurac Research Institute in Bolzano, Italy, tells Agence-France Presse (AFP) that he was surprised the ancient humans appeared to have deliberately fermented food.
“This is very sophisticated in my opinion,” he says. “This is something I did not expect at that time.”
Human feces tend to break down quickly, so ancient poop—or paleofeces—can usually only be found in a small number of places that are very dry, frozen or waterlogged. In this case, the dry, cool conditions and high salt concentrations of the Hallstatt-Dachstein Unesco World Heritage Site helped preserve the material, reports Amy Woodyatt for CNN.
Researchers examined the paleofeces using molecular and DNA analysis. They found that bran and material from various cereal plants were common, along with proteins from broad beans, fruits, nuts and meats. Investigating the presence of fungi, the team discovered plentiful DNA from Penicillium roqueforti—used in the production of blue cheese today—and Saccharomyces cerevisiae—used in beer brewing and bread baking. The genomes of the fungi suggest they underwent a selection process that made them particularly valuable for food production.
“The Iron Age salt miners in the Hallstatt salt mountain seem to have intentionally applied food fermentation technologies with microorganisms which are still nowadays used in the food industry,” study co-author Kerstin Kowarik, an archaeologist at Vienna’s Natural History Museum, tells CNN.
“It is becoming increasingly clear that not only were prehistoric culinary practices sophisticated, but also that complex processed foodstuffs as well as the technique of fermentation have held a prominent role in our early food history,” adds Kowarik in a statement.
Records of humans imbibing long before the time studied in the new research exist. But the findings represent the first molecular evidence of beer-drinking in Iron Age Europe, the Times of Israel’s Lucie Aubourg reports. The results also constitute the earliest evidence of cheese ripening on the continent.
Per Unesco, people mined salt deposits at the Hallstatt-Dachstein site at various points between the late Bronze Age and the mid-20th century. As early as the eighth century B.C.E., trade routes of the Hallstatt Culture connected an organized operation at the mines with societies across Europe.
The researchers analyzed four fecal samples—the Bronze Age one containing the two food-fermenting fungi, two others from the Iron Age and one from the 18th century. The first three samples suggested that porridge made from whole grains was a major part of the miners’ diets. By the 18th century, however, grains were more often ground, showing that diets may have shifted to bread or biscuits.
All four samples contained microbes similar to those found in the guts of modern people with “non-Westernized” lifestyles—meaning that their owners ate mostly traditional, less-processed foods and made little use of modern pharmaceuticals. The fact that even the 18th-century sample fit this profile suggests the microbiomes of people in industrialized societies shifted only recently, “probably due to modern lifestyle, diet or medical advances,” according to the study.
Previous research has found that human gut microbes today are much less diverse than they were 2,000 years ago. As Michelle Starr reported for Science Alert in May, samples from paleofeces found across North America showed that almost 40 percent of their microbes were unknown in any modern humans.
“In ancient cultures, the foods you're eating are very diverse and can support a more eclectic collection of microbes,” said senior author Aleksandar Kostic of Harvard’s Joslin Diabetes Center in a statement. “But as you move toward industrialization and more of a grocery-store diet, you lose a lot of nutrients that help to support a more diverse microbiome.”