Ten years ago a pub owner in Northern Ireland uncovered an unusually large flat stone beneath which were the remains of three humans - an ancient burial that, after a recent DNA analysis, challenges the centuries-old account of Irish origins.
     "The DNA evidence based on those bones completely upends the traditional view," said Barry Cunliffe, an emeritus professor of archaeology at Oxford University.
     Since the 16th century CE, historians have taught that the Irish descend from Celts, an Iron Age people originating in the middle of Europe, invading Ireland sometime between 1000 BCE and 500 BCE, however the three skeletons are ancestors of the modern Irish, and predate the Celts and their purported arrival by 1,000 years or more. The most striking feature of the bones is how much their DNA resembles that of contemporary Irish, Welsh and Scots. Older bones found in Ireland were more like Mediterranean people.
     Radiocarbon dating shows that the bones go back to about 2000 BCE - hundreds of years older than the oldest artefacts from continental Europe generally considered to be Celtic.
     The Irish, Welsh, and Scottish Gaelic languages share words and grammar, are indisputably related, and part of a group that linguists have labeled Celtic. They seem to have emerged after a similar evolution from Indo-European. What is unclear is whether the term "Celtic" is appropriate for them. Over the last decade, a growing number of scholars have argued that the first Celtic languages were spoken not by Celts in the middle of Europe, but by ancient people on Europe's westernmost extremities - the British Isles or the Iberian Peninsula. Inscriptions on artefacts from southern Portugal strongly resemble the languages known as Celtic, yet date as far back as 700 BCE.
     Celts sacked Rome around 390 BCE, and attacked Delphi in 279 BCE. It seemed plausible that they had invaded Ireland as well, however for decades scholars have noted just how flimsy the evidence is for that standard account, and that the flow of Celtic culture was actually from the western edge of Europe into the rest of the continent.

Edited from Washington Post (17 March 2016)