A study published on Thursday in the journal Nature reveals that a majority of present-day Europeans can trace their ancestry back to at least three highly differentiated population groups, following an analysis and comparison of ancient European genomes to modern genetics.

According to a recent statement, an international team of researchers contributed to the study, led by scientists from the University of Tübingen in Germany, the Harvard Medical School in the United States, and the University of Adelaide in Australia. Researchers sequenced the ancient human genomes of one 7,000-year-old German farmer, one 8,000-year-old hunter-gatherer from Luxembourg, and seven 8,000-year-old hunter-gatherers from Sweden.

“Recent genetic studies we did at the University of Adelaide on ancient hunter-gatherers and early farmer remains suggested a massive expansion of people into Europe coinciding with the spread of farming,” said Dr. Wolfgang Haak, Research Fellow with the Australian Centre for Ancient DNA (ACAD).

The team then compared these genomes, along with additional ancient genomes, to the genetics of 2,345 individuals from nearly 200 modern worldwide populations. “The surprising finding was that present-day Europeans trace their ancestry back to three and not just two ancestral groups as previously thought,” said Professor Alan Cooper, Director of ACAD and co-author on the study.

According to the study, these three ancestral groups include west European hunter-gatherers, early Middle Eastern farmers who migrated to Europe 7,500 years ago, and ancient north Eurasians who genetically connect the Europeans and Native Americans. Researchers suggest that the west European hunter-gathers contributed ancestry to all Europeans except Near Easterners, the European farmers harbored hunter-gatherer ancestry from west Europeans, and the north Eurasians contributed to both Europeans and Near Easterners.

“It seems clear now that the third group linking Europeans and Native Americans arrived in Central Europe after the early farmers,” said Professor Johannes Krause, a lead investigator in the study from the University of Tübingen. “We are however not sure yet when the Northern Eurasian component entered central Europe.”

According to the statement, a majority of Europeans today have ancestry from all three ancestral populations, and any differences between them are due to relative proportions of ancestry. “This study has added significantly to our knowledge of the genetic make-up of our European ancestors,” said Haak.

“Ancient human genomes suggest three ancestral populations for present-day Europeans” was published in Nature on Wednesday, Sep. 17, 2014.