Wednesday, November 29, 2017

Meet The Yeti

Granted, he doesn't look that much like a yeti on all fours. But imagine him standing up...

Back in 2013, I covered a paper that claimed to show that "yeti DNA" collected from the Himalayan mountains matched the DNA of an ancient species of polar bear. But as it turned out, that paper had a problem. While it did correctly identify the samples as bear DNA, the section that was highlighted turns out to be a mitochondrial DNA sequence that matches that of almost any bear. Bear evolution expert Charlotte Lindqvist and her team decided to take another look, and compare other regions of the "yeti DNA" with DNA from Himalayan brown bears (Ursus arctos isabellinus). As it turns out, the samples matched. This provides strong evidence that the Himalayan brown bear and the yeti are in fact the same animal.

That previous paper didn’t really prove what it claimed to prove. It looked at a sequence of mitochondrial DNA (yes, the powerhouse of the cell is used in genetic sequencing), but the particular region the scientists focused on is highly conserved in bear populations. That means that polar and brown and black bears all have extremely similar, if not identical, sequences there. It makes no sense to claim that a sample matched an ancient polar bear based on this stretch of DNA, because that sequence would match almost any bear.

To confirm a real match, you have to look at more variable parts of the mitochondrial DNA. So that’s exactly what Lindqvist did. And in the process, she and her international team in Pakistan and Singapore provided the first strong evidence that presumed yetis are actually bears. They published their results in the Proceedings of the Royal Society B on Tuesday. Icon Film secured nine samples that purported to be genuine yeti artifacts, and Lindqvist gathered 15 samples from known bear populations. By sequencing mitochondria from all these sources, she and her fellow researchers were able to determine that all but one of the yeti artifacts actually came from local bears. That last sample was from a dog.

They also figured out that Himalayan brown bears split off from the rest of the regional bear population several thousand years ago, which is why they’re so genetically distinct from most other brown bears. Living in geographic isolation for so long has separated them from other Asian brown bears, and even from their relatives on the nearby Tibetan plateau. They even look different. But prior to Lindqvist’s work, it wasn’t clear just how long Himalayan bears had been on their own. Researchers will need higher-quality samples to figure out the whole picture, but even this small step is major for a species that’s hardly been studied.

We don’t know a lot about Himalayan brown bear behavior, since they’re rare and tend to shy away from people, but bears make sense as a source of mythology. “We know that bears can be aggressive and get up on their hind legs, so they may have been attacking livestock or ravaging local villages,” says Lindqvist. “It’s not that surprising that a large animal like that could feel scary and lead to myths, especially in a culture that lives in very close connection to their environment.”

This means that just as Reinhold Messner told the world in 2000 in My Quest for the Yeti, the yeti is a real animal - a rare and reclusive species of bear rather than a rare and reclusive species of ape. Messner found that the whole "ape" identification was probably due to interviews conducted by westerners who spoke local languages poorly. When shown pictures of Himalayan brown bears, locals immediately identified them as yetis without any hesitation. So it's not really accurate to say that "yeti" is a sort of "nickname" for these bears, as the linked article suggests. "Yeti" has been a local term for them all along.

So when western mountaineers talked about seeing a large animal standing upright high in the Himalayas? The locals telling them that they had seen a "yeti" were telling them that they had seen a bear the whole time. The In Search Of team in the 1970s who were so disappointed that the "yeti artifacts" they were able to test came from bears? They actually had it right the whole time and could have broken the story back then. But they were still operating on the fundamental misunderstanding that the yeti had to be a completely unknown "ape-man" like the sasquatch was reputed to be.

What I love about this whole story is that it's exactly how science is supposed to work when confronted with the paranormal. You don't write off observations like capital-S Skeptics do all too often. You can't dismiss every weird observation as deliberate fraud, like the Randi folks tend to do. You investigate the data you have with the tools you have, and you see where it leads. A more "normal" explanation for weird phenomena usually emerges, but as I see it that doesn't make paranormal research useless or silly. Just as in engineering or application testing, "edge conditions" can teach us a lot more than we can learn from common situations that have already been extensively studied.

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