DUBLIN, IRELAND—According to a BBC News report, a team of Irish, British, and American researchers identified ten genetic clusters in the modern Irish population that accord roughly with ancient boundaries. The 194 Irish individuals in the sample each had ties to specific regions dating back four generations. And although the differences between the groups were “really subtle,” the clusters seemed to reflect either the borders of Ulster, Leinster, Munster, and Connacht—the four Irish provinces—or the land's historical kingdoms. Geographical divisions created by mountains may also have played a role. “The likelihood is that it’s a combination of these things—a little bit of geography combined with wars or rivalry generates kinship in each distinct area,” said Gianpiero Cavalleri of the Royal College of Surgeons in Ireland. The tests also detected Norwegian-like ancestry in some of the samples, which could reflect the presence of Vikings on the island. Cavalleri noted, however, that if the Vikings carried a large number of Irish individuals back to Norway, it could have reduced the genetic differences between the two groups. For more, go to “The Vikings in Ireland.”