Humankind has gulped down mouthfuls of milk and other dairy products from animals, such as sheep, goats and cows, for at least 9,000 years, a new study suggests.

Researchers made the discovery after analyzing and dating more than 500 prehistoric pottery vessels discovered in the northern Mediterranean region, which includes the modern-day countries of Spain France, Italy, Greece and Turkey. During each examination, they looked for remnants of milk, which indicated that people had used animal dairy products.

The scientists also examined the ceramic pots for residue from animal fat and other evidence, such as skeletal remains, that would suggest Neolithic people slaughtered domesticated animals for meat; they examined these bony remains from 82 sites around the Mediterranean dating from the seventh to fifth millennia B.C. [10 Mysteries of the First Humans]

Information about ancient dairy use and meat production can help scientists understand what factors drove the domestication of cud-chewing animals, the researchers said.

Dairy queen

Dairying was popular in some, but not all, northern Mediterranean areas, the researchers found.

The eastern and western parts of the northern Mediterranean, including parts of modern-day Spain, France and Turkey, commonly practiced dairying, but northern Greece did not, they said. Rather, "lipids from pots and the animal bones tell the same story: Meat production [in northern Greece] was the main activity, not dairying," they said.

The new analysis supports the team's earlier work showing "that milk use was highly regionalized in the Near East in the seventh millennium B.C.," study researchers Mélanie Roffet-Salque and Richard Evershed, chemists at the University of Bristol in the United Kingdom, said in a statement. "This new multidisciplinary study further emphasizes the existence of diverse use of animal products in the northern Mediterranean Neolithic."

The varying landscape in the northern Mediterranean likely influenced what sort of animals the Neolithic people domesticated, the researchers added.

"For example, rugged terrains are more suitable for sheep and goats, and open well-watered landscapes are better suited for cattle," said study researchers Rosalind Gillis and Jean-Denis Vigne, archaeozoologists at the Centre National de la Recherche Scientifique in the National Museum of Natural History in Paris.

Ancient milk

Dairying began with the onset of agriculture, and likely helped early farmers, said the study's lead researcher, Cynthianne Spiteri, a junior professor of archaeometry at the University of Tübingen in Germany, who conducted the residue analysis as part of her doctorate in archaeology at the University of York in the United Kingdom.

"[Milk] is likely to have played an important role in providing a nourishing and storable food product, which was able to sustain early farmers, and consequently, the spread of farming in the western Mediterranean," Spiteri said.

However, more research is needed to verify that Neolithic people consumed milk products. This could be accomplished by analyzing ancient human skeletons, said study researcher Oliver Craig, a professor of archaeology at the University of York. [8 Grisly Archaeological Discoveries]

"Despite this deficiency, our research shows that they certainly exploited milk because we have found organic remnants in the pots they were using," Craig said. "This implies they were transforming milk into dairy products, such as yogurt and cheese, to remove the lactose," which some people are unable to digest, he said.

"We know that much of the world's population today are still intolerant to lactose, so it is very important to know at what point people in the past were exposed to it and how long they have had to adapt to it," Craig said.

The study was published online Nov. 14 in the journal the Proceedings of the National Academy of Sciences.

Original article on Live Science.