In a first, scientists have found clear evidence suggesting that cheese was made more than 7,000 years ago in Northern Europe.

A team of international researchers led by University of Bristol, U.K., carried out a chemical analysis on fatty acids extracted from pottery vessels that were excavated in Poland. The vessels date back to more than 7,000 years ago.

The pottery sieves were found pierced with small holes similar to modern cheese-strainers, showing evidence that the specialized vessels were used by prehistoric humans to make cheese.

The research team examined the fatty acids in the pottery sieves using lipid biomarker and stable isotope analysis, which showed that the sieves were indeed used for making dairy products like cheese. They also noticed milk residues in non-perforated bowls that might have been used along with the sieves.

"The presence of milk residues in sieves (which look like modern cheese-strainers) constitutes the earliest direct evidence for cheese-making.  So far, early evidence for cheese-making were mostly iconographic, that is to say murals showing milk processing, which dates to several millennia later than the cheese strainers," study author Mélanie Salque, a PhD student from the University of Bristol, said in a statement.

Apart from the sieves, experts also analyzed non-perforated pottery such as cooking pots and bottles, which clearly showed that these vessels were not used for processing cheese or any other dairy products.

They found ruminant carcass fat in cooking pots, suggesting that the vessels were used to cook meat. The bottles had beeswax, showing that ancient humans used waterproofed bottles for storing water.

This is the first evidence which shows how different types of pottery vessels available from the same area were used for specific purposes.

It was important for prehistoric farmers to process milk and make cheese, as most of the adults were not tolerant to lactose. It was difficult for them to digest lactose, a sugar found in milk. In order to make milk a more digestible commodity, ancient humans preserved milk and processed them into cheese, as the product is comparatively low in lactose, researchers said.

The findings of the study, "Earliest evidence for cheese making in the sixth millennium BC in northern Europe", are published in the scientific journal Nature.