By Steven McKenzie
Highlands and Islands reporter, BBC Scotland news website
Dr Edwards had hoped to compare ancient and modern polar bear DNA
A sample taken from what are believed to be the only polar bear remains to have been found in Britain has defied DNA analysis, it has emerged.
Ireland-based genetics expert Ceiridwen Edwards had hoped to compare the DNA of the animal found in a cave in Scotland with that of modern polar bears.
However, she said there was not enough DNA left in the sample for an analysis to be done.
The sample was taken from a skull found in the Bone Caves at Inchnadamph.
It was thought the bear was washed into the caves in Sutherland 18,000 years ago.
The skull was found in 1927 and is held in the collections of the National Museum of Scotland in Edinburgh.
Dr Edwards told the BBC Scotland news website: "The original rationale behind targeting the Inchnadamph polar bear for ancient DNA analysis was to try and generate an ancient sequence from a morphological polar bear.
"The only sequences of polar bear are from modern samples, and I was wondering if there would be any significant difference between modern and ancient sequences.
"I can usually tell by the colour and texture of a bone sample if it will yield DNA or not, and the Inchnadamph polar bear seemed to me to have a chance of giving data."
However, in an effort to protect the skull, a smaller sample of bone than Dr Edwards would normally work with was extracted.
Dr Edwards said: "This would not have made much difference to the overall results as, if there is any DNA present in a sample, having a small starting amount does not usually jeopardise success.
"Therefore, I rather think the problem was that there was little or no DNA left in the skull - possibly due to water leaching the DNA out of the bone while it was in the cave."
She added: "This was such a shame as I would very much have liked to get some ancient polar bear data with which to compare to both modern polar bear and from a number of other archaeological bears."
Protected by environmental designations and Scottish Natural Heritage (SNH), the caves at Inchnadamph have provided scientists with a treasure trove of wild animal remains.
POLAR BEAR FACT FILE
Largest land carnivore
Can live for up to 25 years
Polar bears evolved from brown bears about 3m years ago
It was also discovered to have been a burial site and the bones of four people found there have been radiocarbon dated to between 4,515 and 4,720 years ago.
Last July it was revealed that an almost complete skeleton of another bear - which could be a brown or polar and may have died 11,000 years ago - had also been recovered from a cave at Inchnadamph.
The first pieces of bone from the skeleton were found in 1995 by cavers, but it was only later that Edinburgh-based caving club, Grampian Speleological Group, reached some of the final fragments.
The National Museum of Scotland said at the time it would try to establish if the incomplete skeleton was that of a brown or polar bear.
The remains found include the skull, the second lower mandible, fragments of upper mandible, vertebrae, ribs, most of the long bones, the main elements making up the pelvis, and several elements from the feet.