In the fall of 2013, Charlotte Lindqvist got a call from a film company making an Animal Planet documentary about the yeti, the mythical apelike creature that roams the Himalayas. So, not the kind of thing scientists usually like to mess with. “Friends or colleagues were saying, ‘Oh, watch out. Don’t get into this whole area,’” she recalls with a laugh. But she said yes.
Lindqvist said yes because she is a geneticist who studies bears, and the rare Himalayan brown bear is one possible origin of the yeti legend. The team from Icon Films wanted to use science to investigate whether the yeti is real; Lindqvist wanted to investigate the enigmatic bears of the Himalayas.
Wild bear DNA is not easy to come by. Over the years, Lindqvist, a professor at the University at Buffalo, has built up a network of wildlife-biologist contacts in Alaska, who send her samples that have helped illuminate the evolution of polar bears. Scientists know much less about bears that live around the Himalayas. But if a film-production company was going to pay a crew to travel around the mountain range collecting possible samples of fur and bone, then she just might get a scientific project out of it, too.
The results of that unusual collaboration were published Tuesday in the Proceedings of the Royal Society B. Lindqvist and her colleagues used DNA to identify nine “yeti” samples provided by the documentary film crew.
These include: a thigh bone found by a spiritual healer in a cave that turned out to be from a Tibetan brown bear; hair from a mummified animal in a monastery that turned out to be from a Himalayan brown bear; a tooth from a stuffed animal collected by Nazis in the 1930s that turned out to be from a dog. The rest of the samples turned up five more Tibetan brown bears and another Himalayan brown bear. For comparison with verified bear samples, Lindqvist also reached out to her network of research contacts in museums, zoos, and Pakistan’s Khunjerab National Park, who provided her with bear hair, bone, and scat to sequence.
Altogether, this search for the yeti yielded a surprising portrait of bears living around the Himalayas. The Tibetan brown bear and Himalayan brown bear, long considered to be subspecies, are quite distinct genetically. The latter diverged from all other brown bears about 650,000 years ago, when the formation of glaciers may have isolated a population that became the first Himalayan brown bears. Today, this ancient lineage of bears is critically endangered.
Lindqvist focused her analysis on DNA in the mitochondria—structures in the cell that have their own small pieces of DNA separate from the DNA in chromosomes. Mitochondria DNA is only passed down the maternal line, but when it comes to sequencing, it has the advantage of being more abundant in cells. This is especially important when working with degraded and decades-old samples. Her team eventually sequenced, for the first time, the entire mitochondrial genome of the rare Himalayan brown bear.
Other scientists have sequenced supposed yeti samples before—notably Bryan Sykes, a geneticist at Oxford who actually appeared in a previous yeti film by the same documentary team that aired on the United Kingdom’s Channel 4 in 2013. (Interest in the yeti never dies, apparently.) In it, Sykes says the hair matched no modern bears but an ancient 40,000-year-old polar bear, suggesting the yeti is actually an unknown, perhaps hybrid bear. Sykes later published the results in a scientific journal, but other scientists criticized him for extrapolating too far from a fragment of a single mitochondrial gene.
Lindqvist thinks she has resequenced one of the same samples, and based on the whole mitochondrial genome, the purposed yeti hair indeed came from a Himalayan brown bear. Ross Barnett, a paleogeneticist at the University of Copenhagen, praised the methods in the new study. It’s the first time, he says, that he knows of a study using whole mitochondrial genomes to place bears in their evolutionary and geographic context.
The Animal Planet film eventually aired in May 2016 as Yeti or Not? Near the end, Lindqvist appears to reveal the last of the DNA-sequencing results. The show has been building up to this moment, hinting at possibilities like a new hybrid bear or maybe even an undiscovered hominid. “When I had to reveal to them that okay, these are bears, I was excited about that because it was my initial motive to get into this,” says Lindqvist. “They obviously were a little disappointed.”