A mysterious and unidentified ancestor of prehistoric polar bears may be behind the myth of the yeti, new research by scientists from Oxford University has suggested.
Genetic tests on two hair samples claimed to belong to the creature revealed a close match with bear DNA - but not any bear known to be living today, or in the Himalayas.
The DNA in both hairs was identical to that from a polar bear fossil dating back more than 40,000 years.
One golden-brown hair sample came from an animal shot by a hunter in Ladakh, India, 40 years ago.
The other, coloured reddish-brown, was recovered from a high altitude bamboo forest in Bhutan. The site was described as the nest of a "migyhur", or Bhutanese yeti.
Authors of the research, led by Bryan Sykes from Oxford University, wrote in the journal Proceedings Of The Royal Society B: "If these bears are widely distributed in the Himalayas, they may well contribute to the biological foundation of the yeti legend, especially, if as reported by the hunter who shot the Ladakh specimen, they behave more aggressively towards humans than known indigenous bear species."
In the first study of its kind, the scientists analysed 30 hair specimens reported to have come from "anomalous primates" - hairy human-like beasts - including the yeti, Bigfoot from the US, and Almasty from Russia.
In almost every case they had easily explainable origins, such as the modern brown bear - Ursus arctos - horses, dogs, cows, or, in one case, a person.
But the two yeti samples sprung a surprise, showing a 100% match with polar bear DNA from the Pleistocene period but not the present day.
There have been anecdotal reports of white bears in central Asia and the Himalayas, said the scientists.
They added: "It seems more likely that the two hairs reported here are from either a previously unrecognised bear species, colour variants of Ursus maritimus (polar bear), or U. arctos/U. maritimus hybrids."
If hybrids, the "yeti" specimens were likely to have been descended from ancient cross-breeding soon after brown and polar bears separated on the path of evolution.
A total of 57 hair samples ranging between two and four centimetres in length were originally obtained from museums and individual collections for the research.
Some were immediately excluded after being exposed as obvious "non-hairs" - one was from a plant and another made from glass fibre. Of the remaining 36 hair samples, DNA could only be recovered from 30.
The scientists concluded: "While it is important to bear in mind that absence of evidence is not evidence of absence and this survey cannot refute the existence of anomalous primates, neither has it found any evidence in support."