Is the Yeti really the polar bear's cousin?
DNA tests found no evidence of the Yeti, Bigfoot, Sasquatch or the Abominable Snowman. But, as Daniel Cossins reports, the bears may know more than they are letting on.
Grainy photographs, mysterious footprints, and breathless accounts of close encounters in the woods – for some people, that’s evidence enough for the existence of Bigfoot, Sasquatch or Yeti. Not so for scientists. Now, researchers have come out with the first scientifically rigorous, peer-reviewed genetic analysis of dozens of hair samples claimed to be from the elusive ape-men. They found that the hairs actually originate from known animals including dogs, horses, raccoons, and bears. None were from a primate.
No surprises there. But the new study, published in the Proceedings of the Royal Society B in June 2014, did turn up one strange result. The mitochondrial DNA (mtDNA) from two hair samples collected in the Himalayas closely matched polar bear mtDNA. If the preliminary results are confirmed, they raise the intriguing possibility that a population of polar bear/brown bear hybrids living in the Himalayas might be behind the Yeti legend.
Hybrid bears have been found before. “Recent studies have shown that bears on islands off the coast of Alaska carry small amounts of polar bear DNA as a result of hybridisation [in their evolutionary past], so it’s certainly possible that the same could be true of bears in the Himalayas,” says Frank Hailer, who studies the evolutionary history of bears at the Biodiversity and Climate Research Centre in Frankfurt, Germany, but who was not involved in the study. Hailer is quick to point out, however, that the authors would need to present more comprehensive genetic data to even begin to validate such speculation.
The Bigfoot study came about following years of criticism from cryptozoologists – people who search for animals known only from anecdote. They hold that mainstream science’s disregard for their claims is at odds with a core scientific principle: that we should neither reject nor accept anything without properly examining the evidence.
So Bryan Sykes, a geneticist at Oxford University, decided to do a proper scientific study of the best available evidence. In 2012 Sykes and Michael Sartori of the Museum of Zoology in Lausanne, Switzerland, asked cryptozoologists to send in hair samples thought to be from "anomalous primates". The plan was to extract DNA from the fur and compare it to that of known species held in the global database, GenBank.
Two hair samples, reportedly collected from India and Bhutan, matched DNA from fossils of a polar bear that lived ... in the late Pleistocene.
The researchers received 57 hair samples from across the world. Many were too contaminated for analysis and others turned out to be grass or fibreglass. But Sykes and his colleagues were able to extract genetic material from 30 hair samples and sequence a short section of the mtDNA known as S12 RNA – a segment often used for species identification although it cannot always distinguish closely related species.
Their analysis revealed that the samples came from a variety of well-known species including brown bear, black bear, cow, horse, deer, sheep, human, raccoon and porcupine. None came from an unknown species. “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,” the authors concluded.
Todd Disotell, an anthropologist at New York University who has performed unpublished analyses of claimed Bigfoot samples says that although the results are not surprising it’s important to have such a rigorous study. “Having someone of Sykes’ stature doing it is useful because it brings proper science to this question of cryptozoology,” he says.
The study did throw up one unexpected finding – the mysterious Himalayan bear. Sykes found that two hair samples, reportedly collected from India and Bhutan, matched DNA from fossils of a polar bear that lived on the Arctic island of Svalbard in the late Pleistocene, but not modern examples of the species. As polar bears have never been seen in the Himalayas, Sykes suggests the hair might have come from a previously unrecognised bear species, or from polar-bear/brown-bear hybrids.
Hailer was very surprised by the match Sykes claimed to have found: “Why would you find an mtDNA sequence from this Pleistocene polar bear in a sample from modern-day central Asia? That doesn’t fit with what we know.” When he compared the sequences generated from the two Himalayan samples Hailer could not confirm the results reported by Sykes and his colleagues. Instead, he found that the samples were an identical match to a polar bear sampled 10 years ago somewhere between Alaska and Siberia. “As far as I can tell, their sequences match with that of an extant polar bear,” he says.
So what could explain the presence of polar bear DNA in the genomes of present-day Himalayan bears? Disotell suggests it could be because there are no samples from Himalayan bears in the GenBank database, meaning the closest match was this polar bear. It’s also possible that the samples came from somewhere other than they are reported to have come from. Then again, given previous evidence of hybrid bears on Alaskan islands, “This paper might provide preliminary evidence for a similar finding in bears in the Himalayas,” says Hailer.
However, both Hailer and Disotell point out that the short fragments of mtDNA Sykes relied on for analysis are of limited use for identifying hybrids. “They provide a low-resolution picture,” says Hailer. “Maybe the authors didn’t have enough hair to analyse DNA from different parts of the genome, but that would be an important follow-up.”