Researchers on Wednesday said they found the earliest known chemical evidence of cheese-making, based on the analysis of milk-fat residues in pottery dating back about 7,200 years. The discovery suggests Europe's early farmers added a cheese course to their diet almost as soon as they learned to domesticate cattle and started regularly milking cows.

Scientists led by geochemist Richard Evershed at the U.K.'s University of Bristol tested ancient, perforated clay pots excavated at sites along the Vistula River in Poland, and found they had likely been used by prehistoric cheese mongers as strainers to separate curds and whey—a critical step in making cheese.

The pots have long puzzled archeologists, but their new analysis, reported in Nature, revealed unique carbon isotopes of milk in the traces of fatty acids that had soaked into the ceramic sieves....