Thousands of years ago, farming spread across Europe and replaced the hunter-gatherer lifestyle of early inhabitants. Now a study of ancient DNA says that trend was driven by farmers moving from place to place.

Scientists have long debated how farming expanded across Europe. Did farmers migrate? Did the idea of farming spread from culture to culture?

The new work, in Friday’s issue of the journal Science, joins some previous DNA research in arguing for migration. Farming originated in the Near East some 11,000 years ago, and extended over most of Europe by about 6,000 years ago.

For the new study, scientists analyzed genetic material from bones about 5,000 years old that had been found in Sweden. The bones came from three hunter-gatherers who’d been buried on the island of Gotland, which lies off the Swedish coast south of Stockholm, and a farmer buried less than 250 miles (400 kilometers) away on the mainland. Scientists knew their lifestyles because of artifacts. The two cultures apparently co-existed in the area for more than 1,000 years.

When the scientists compared the ancient DNA to that of modern-day Europeans, they found that the farmer’s DNA was most similar to Mediterranean populations like Cypriots and Greeks. In contrast, the hunter-gatherer DNA most closely resembled northerners like Finns.

The simplest explanation for this pattern is that an ancient migration of farmers started in southern Europe and moved northward over many generations, said the researchers, from Uppsala University in Sweden and other institutions in Sweden and Denmark.

Wolfgang Haak of the University of Adelaide in Australia, who has done similar research but didn’t participate in the new work, said in an email that the new results are “an important stepping stone... I’m looking forward to many more studies at this level of detail from different parts of Europe.”

■ Malcolm Ritter is an AP Science Writer