Ireland's first farmers settled the island later than some sites from Ulster have long suggested, but did so in a short period which may also have seen parallel migration into western England and Scotland. Radiocarbon dates indicate that sites from Co Kerry in the South West to Co Derry in Northern Ireland were all settled within the century after 3700 BCE.
     The immigrants built rectangular timber houses up to a hundred square metres in area, cultivated cereals such as wheat and barley, used flint tools and made plain pottery bowls, Cormac McSparron notes in Archaeology Ireland. They were not the first people in Ireland: Mesolithic fishers and gatherers lived in Kerry and Waterford, keeping cattle, and many years ago the site of Ballynagilly in Ulster yielded dates around 4000 BCE associated with what seems to have been a cattle-keeping settlement. Even earlier palaeolithic hunters may also have lived on the island.
     Many of the radiocarbon dates obtained using older technology are not of 'gold standard,' McSparron claims; only those run using accelerator mass spectrometry, from short-lived plant species such as nuts rather than long-lived timbers, and from securely understood archaeological contexts are reliable. Only 18 of 66 Irish early Neolithic dates meet these criteria, but their pattern suggests a 95 per cent likelihood that all the sites were settled and then abandoned within 90 years, between 3715 and 3625 BCE. This matches data from peat bogs which suggest that land clearance did not begin until after 3850 BCE.
     Sites of almost exactly the same age as the Irish ones are known from Llandegai in northwest Wales and from Lismore Fields in the West Midlands, and coeval structures are known from Claish and Balbridie in northern Scotland.
"It seems possible that settlers from the European mainland sailed up the Irish Sea and around the Atlantic coast, settling in a number of separate locations," McSparron says. A 'significant element of colonisation must have been involved' in the beginnings of settled agriculture in Ireland.
     Why these houses ceased to be built after around 3600 BCE is a mystery, but possibly population growth led to the rise of larger settlements, and even to defended ones as competition for the best land developed. A palisaded hamlet at Thornhill, Co Derry, may be an example of this, while in England Neolithic hilltop settlements such as Crickley Hill in the Cotswolds have been known for decades. Inter-community warfare may have followed the first peaceful settlement of farmers in Ireland much more rapidly than hitherto thought.

Source: The Times (9 January 2009)