The remains of the last known wild polar bear to live in Britain are to be investigated by scientists hoping to find out what it ate and how it is related to its modern-day Arctic cousins.
A polar bear skull excavated from a cave at Inchnadamph in the Scottish Highlands is the only known remains of the species in Britain. It probably dates to about 18,000 years ago when massive ice sheets covered much of the country at the height of the last ice age.
The creature's bones were first unearthed in 1927 but it was only when the remains were recently re-evaluated that scientists realised that they once belonged to a polar bear that lived at a time when the climate in Britain was in the grip of a deep freeze.
Now Ceiridwen Edwards, an ancient-bear specialist at Trinity College Dublin, is hoping to get permission to take small samples of bone from the skull to analyse the animal's DNA sequence, as well as taking further measurements to investigate its diet.
"I would be hoping to do some stable-isotope analysis to gather evidence which we would hope to show whether it was eating a mainly marine or terrestrial diet," Dr Edwards said. The tests could, for instance, determine whether the bear was hunting reindeer or seals – which would indicate what sort of habitat it lived in at the time.
In addition, the DNA analysis would reveal the relationship of the animal with modern bears, both polar bears and brown bears, and possibly whether polar bears at this time were interbreeding with brown bears, Dr Edwards said.
"There is a theory that brown bears and polar bears were hybridising and this could show up in the DNA sequence. I'm quite interested to see where this polar bear fits in to the overall genetic diversity of bears," she said.
The study will involve drilling a small hole into the skull to extract about a gram of bone, which will be reduced to powder before its DNA is extracted. The scientists will concentrate on the DNA of the mitochondria – the power packs of the cell – which are transmitted down the maternal line.
It is not known how the remains of the polar bear got into the cave at Inchnadamph. The animal could have crawled into it for protection, or its remains may have been dragged by another animal or washed into the cave when the ice sheet melted.
There is no evidence that people ever lived in the caves but there are abundant indications that they were inhabited or explored by other prehistoric animals, such as lynx, hyenas and hippos – from a time when the climate was much warmer than it is today.
However, evidence does exist of a nearby human burial site which dates to about 4,600 years ago. Cave systems in the Highlands are important in understanding prehistoric Scotland because they survived being scrapped clean by the heavy ice sheets which covered much of the land and some of the artefacts that have survived in them date back more than 45,000 years.
Alex Scott, an area officer for Scottish Natural Heritage said: "The only window in to the past was what went into the caves – so it's a unique record."