Blue cheese and pale ale have been on the menu for longer than researchers thought

(Austrian music plays)

Delaney Dryfoos: In a valley deep in the Eastern Alps of Austria, a salt deposit lying at sea level offered early humans access to one of the world’s most precious commodities: salt. Today, scientists can analyze a different invaluable material left behind in the salt mines: paleofeces, otherwise known as… very old human poop. This prized, well preserved excrement gives today’s archeologists and microbiologists a glimpse into the diets and lives of European salt miners as far back as the 14th century B.C. 

Kerstin Kowarik: UNESCO World Heritage Region of Hallstatt is a very special place because we have in the salt mines salt preservation.

Delaney Dryfoos: That’s Kerstin Kowarik, an archeologist in the prehistoric department of the Vienna Museum of Natural History. Salt is a natural preservative, something cheesemongers know all about.

Kerstin Kowarik: This means that all organic materials that were left behind in the mines are preserved there. This is something very, very special for archeology. 

Delaney Dryfoos: Kowarik’s research team analyzed four preserved poop samples from within the Hallstatt salt mine that date back to the approximate years of 1300 B.C., 650 B.C. and 1750 A.D.  Previously, microscopes were only powerful enough to broadly identify what our ancestors had been eating. 

Kerstin Kowarik: Looking through the microscope, those excrements were very, very standardized. People were eating the same stew every day, which was based on millet, beans and barley. And now we see that they are eating special cheeses. We also see that they are eating foreign foods. 

Delaney Dryfoos: New techniques allowed them to retrieve DNA and proteins from the samples to perform molecular analyses.  The salt in the mines preserved the poop so well that Kowarik’s team was able to sequence its DNA and proteins and compare it to the known genomes of modern foods. 

Kerstin Kowarik: This is really something very new where we can go really deep and we can start looking for spices and herbs. This is something you wouldn’t find through microscopic investigations of excrements.

Delaney Dryfoos: The results of the study were a surprise to her team. Over 3,000 years ago, our ancestors were eating products similar to those we enjoy today: cheese and beer. The Institute for Mummy Studies in Bolzano, Italy extracted well-preserved DNA from the excrements that allowed the scientists to identify a yeast commonly used to brew pale ales.

Kerstin Kowarik: Because they analyzed the genome and compared it to all known genomes and it’s clearly the beer and baking yeast. There seems to be already in the genome something  that prevents the beer basically turning bad and poisonous. 

Delaney Dryfoos: The new study confirms what researchers have long suspected: that our human ancestors had been drinking beer for a long time. What scholars weren’t expecting to find in this ancient excrement is evidence of blue cheese. 

Kerstin Kowarik: We find this Penicillium roqueforti that indicates that people were not only eating cheese but that they were creating special products. Also, if you put the Penicillium roqueforti to a cheese it’s not only for preservation purposes, but you’re trying to achieve a special type of taste. 

Delaney Dryfoos: As it turns out, humans during the Iron Age were able to apply fungi to food to create unique, recognizable tastes that extended beyond the need for preservation. 

Ashutosh Mangalam: So the first requirement is to get food. Once we have that, then we can develop a taste for cheese and wine and beer. 

Delaney Dryfoos: That’s Ashutosh Mangalam, a pathology professor at the University of Iowa’s Carver College of Medicine who studies the gut microbiome and was not involved in this research. What Ashutosh was most excited to see was evidence of how the prehistoric gut microbiome has changed over time. 

Ashutosh Mangalam: We have outsourced lots of our jobs to bacteria. So it means they are integrated with human physiology. And it is like a small city. You can think about it like there is a doctor, there is a cobbler, restaurant guy, a flower guy. So all of them are depending on each other. So if you disturb one, the others can be disturbed. 

Delaney Dryfoos: Kowarik and her team looked at paleofeces from different time periods spanning over 3,000 years. Their results hinted at how recently our gut microbiomes have changed.  

Kerstin Kowarik: We also had an excrement from the Baroque time, so that’s the 18th century [A.D.], and here we saw again that the gut microbiome was much closer to the prehistoric microbiomes than to our modern microbiome. Which shows us, at least in this instance, that this turn to the modern microbiome occurs very, very late. 

Delaney Dryfoos: Researchers don’t exactly know when our gut microbiomes became more “modern” but they think it was around the industrial age. Kowarik hopes that this discovery can lead to further research using the analysis of biomolecules to investigate medications that may have been used by our ancestors. A better understanding of how our gut microbiota evolved alongside us may also offer intriguing details into how to better treat modern ailments. 

For Scienceline, I’m Delaney Dryfoos.