If you needed another reason not to lick the artifacts on your next trip to the museum, archaeologists have you covered; they’ve found chemical traces of 7,000-year-old cheese still stuck on ceramic containers from two Neolithic farming villages in Croatia.

This find is nothing like the 3,200-year-old chunk of cheese recently found in an Egyptian tomb; after 7,000 years, all that’s left is a microscopic residue on the inner surface of pottery fragments, once used by the farmers who settled just east of the Adriatic Sea to raise crops, cattle, goats, and sheep. But that faint residue of long-gone cheese is older than the Egyptian cheese by about 4,000 years, and archaeologists say it’s the earliest direct evidence of cheese production ever found.

“The cheese would likely have been a firm, softer cheese, something like what we today have as a farmer's cheese or Feta,” Pennsylvania State University archaeologist Sarah McClure told Ars Technica.

Very, very well-aged

McClure and her team gleaned important clues from what was left behind. Meat, fish, milk, and fermented dairy products like cheese and yogurt all contain specific fatty acids, giving each type of food residue its own chemical signature. (Have fun contemplating that next time your dishes don't come out entirely clean. You’re welcome.)

Stable carbon isotopes also help separate the cheese from the milk. The amount of carbon-13 in an animal’s tissues usually hints at what types of plants it ate; shrubs and trees, like those that grew around the Dalmatian coast 7,000 years ago, tend to pick up less carbon-13 than grasses and grains. Thanks to ancient environmental reconstructions, archaeologists have a pretty good idea of what Neolithic livestock around the ancient villages of Pokrovnik and Danilo Bitinj were eating, so they know how much carbon-13 to expect in fat from animal meat.

Fat stored in animal tissues generally contains more carbon-13 than that found in milk, but after fermentation, cheese and yogurt tend to be higher in carbon-13 than fats from meat. It’s a small difference—about 0.1 to 0.2 percent—but it’s enough, combined with other kinds of analysis, to identify what ancient farmers left on their dirty dishes.

Evidence of milk turns up earliest, in a globular storage jar dating to between 5715 and 5576 BCE, and later in finer-grained, often painted containers called figulina wares. The chemical analysis doesn’t reveal which species produced the milk, but archaeologists have found bones from sheep, goats, and cattle at both villages.

“It could have been one or all of the species,” McClure told Ars Technica, though she added that sheep and goat bones make up about 80 percent of those collections.

Cheese production first shows up in the archaeological record about 500 years later, with traces of lipids that match cheese recovered from three containers of a particular type, called rhyta. They were often shaped like animals, or sometimes people, supporting a cone with a wide opening. Most of the ones from Pokrovnik and Danilo Bitinj have feet and are decorated with geometric incisions, often highlighted in red or white. And those distinctive vessels, apparently, are how the ancient farmers of Dalmatia stored and served their cheese, because McClure and her colleagues found traces of lipids that best matched the chemical signature of cheese on fragments from three rhyta dating to around 5200 BCE.

And the broken pottery from Pokrovnik and Danilo Bitinj contains not just the oldest trace evidence of cheese, but the steps involved in making it. Ancient lipids still cling to the ceramic sieves once used to strain liquid whey from the more solid milk curds. They’re simpler vessels than the rhyta used to store the cheese: undecorated, with lots of holes punched into their clay walls to let the whey drain out and keep the curds inside. The lipids found on fragments of such sieves matched the chemical signature of milk in the process of fermentation.

A cheesy story about migration

The people who lived in Pokrovnik and Danilo Bitinj were part of a culture that settled on the Croatian coast by 8,000 years ago. Over the next 3,000 years or so, farming spread north and west across Europe. And according to McClure and her colleagues, cheese may have played an important role in that process.

Today, we think of cheese as a highly perishable food item, but for Neolithic farmers, it was much easier to store than milk, which would have made cheese a staple between harvests or during times when milk production was low. And it may have helped Neolithic farmers’ children live to adulthood.

We know from ancient DNA studies that early farmers in southeastern Europe were mostly lactose intolerant as adults. The process of fermenting milk into cheese also reduces its lactose content, because much of it drains away with the liquid whey. Children too old to safely drink milk could often still eat cheese—a calorie-rich, nutritious food supply that could have made the difference between life and death. And Neolithic mothers may have begun to wean their children earlier, shifting them straight from milk to cheese or other fermented dairy foods.

That, in turn, could have boosted the birthrate in communities like Pokrovnik and Danilo Bitinj. “Cheese probably helped these early farmers adapt a farming system to a much more seasonal climate, by providing a nutritious food that could be stored,” McClure told Ars Technica.

The resulting population boom (which has shown up in other studies) combined with a portable, easy-to-store source of fat, protein, and calories, may have helped early farmers spread north and west across central and western Europe over the next few thousand years, bringing agriculture—and cheese—with them. In fact, another study of potsherds from a site in Poland found lipid residues from cheese dating to around the same period as the Croatian samples.

“What is striking is that you have cheese production in the Mediterranean showing up at the same time as in central Europe, but that people had been farming in the Mediterranean for much longer already,” McClure told Ars. It’s likely that by the time agriculture reached central Europe, cheese had become part of the cultural package that came with it.

Behold, the power of cheese.

PLOS One, 2018. DOI: 10.1371/journal.pone.0202807 (About DOIs).