New analysis of the skull of a brown bear discovered in Aillwee Cave in Co Clare over four decades ago has found that it is more than 10,400 years old.
The study by researchers at IT Sligo also made the surprising finding that a collection of other bones found with the bear skull include those of a second bear dated to the late Neolithic period, 4,600 years ago.
The discovery was made using radiocarbon dating during the re-analysis of more than 450 bones originally collected from the cave system in Co Clare.
The Early Mesolithic or Stone Age bones were first found when the cave was being developed as a tourist attraction in 1976.
The research was led by Dr Marion Dowd, Lecturer in Prehistoric Archaeology at the Centre of Environmental Research Innovation and Sustainability (CERIS), at IT Sligo.
"To discover that this small assemblage of bear bones represented two bears instead of one is an unexpected bonus," she said.
The radiocarbon dating work was carried out by the Chrono Centre at Queen's University, Belfast.
The researchers say the population on the island at the time the older bear was living was likely a very small group of hunter gatherers, numbering less than 1,000 people.
They would have travelled the land, collecting food including salmon, pig, eel and hazelnuts.
The bear bones have been on display at Aillwee Cave for some time and have been viewed by more than 5 million visitors.
"It is wonderful to finally know how old our brown bear bones are," said Nuala Mulqueeney, a Director of Aillwee Cave.
"Over the years there have been many differing schools of thought about the age. But to discover now that we have remains of two bears, one of which is over 10,000 years old, is really significant."
The remains of the second bear showed signs of a chop-mark, leading researchers to surmise that the bear carcass was butchered by humans after being hunted or dying of natural causes.
Brown bears became extinct in Ireland around 1,000BC.