Everything Everywhere Daily: History, Science, Geography & More - Giving the Finger to the Denisovans

Episode Date: November 3, 2021

In 2008, researchers searching for fossils in the Denisova cave in Siberia came across something interesting. It appeared to be the bone from an ancient hominid species. Subsequent DNA analysis on this bone has revolutionized everything we know about the origin of humanity. Had this bone been discovered a few decades beforehand, we might never have known about it. Learn more about the Denisovans and how they affect humanity today, on this episode of Everything Everywhere Daily. Learn more about your ad choices. Visit megaphone.fm/adchoices

In 2008, researchers searching for fossils in the Denozova cave in Siberia came across something interesting. It appeared to be the bone from an ancient hominid species. Subsequent DNA analysis on the bone has revolutionized everything we know about the origin of humanity. Had this bone been discovered a few decades beforehand, we might never have known about it. Learn more about the Denozovans, how we discovered them, and how they affect humanity today on this episode of Everything Everywhere Daily. Do you ever climb into bed ready to sleep only to have your mind start racing the moment your head hits the pillow? Thoughts bouncing around, replaying the day or jumping ahead to tomorrow?

That is exactly why Catherine Nikolai created Nothing Much Happens. Each episode is a gentle, cozy bedtime story where, well, nothing much happens. No drama, no tension, nothing you need to follow closely. Just soft narration, calming repetition, and soothing sensory details designed to help your mind slow down and your body relax. It's not about entertainment, it's about rest. And millions of listeners around the world use it every night to quiet their thoughts and finally fall asleep. If you've ever struggled to shut your brain off at night, this might be exactly what you've been

missing. You can listen to Nothing Much Happens wherever you get your podcasts. Episodes are every Monday and Thursday. Today, human beings, aka Homo sapiens, are the only hominid species on Earth. Tens of thousands to hundreds of thousands of years ago, however, that was not the case. We shared the planet with other hominid species which were closely related to humans. Probably the best-known hominid species is Homo Neanderthal. The first Neanderthal skeleton was found in 1856, and since then we found countless fossils and other evidence of their existence.

The only other species of hominids that we found were far older, going back many hundreds of thousands or millions of years. There was a big gap in the fossil record between the last Homo erectus, which appeared about 300,000 years ago, and Neanderthals. We didn't know of any other hominid species which existed in the last 100,000 years other than humans and Neanderthals. In Siberia, there's a remote cave in the Al-Tai Mountains. Caves are usually good places to search for fossils because they're protected from the elements. Some of the most significant paleontology finds have been found in caves around the world. The Siberian cave is known as the Denisova Cave. It is named after an 18th century hermit known as St. Dionisi, which is the Russian word for Dennis.

The cave is unique in that the average temperature inside the cave is 0 degrees Celsius or 32 degrees Fahrenheit. The cave had been explored in the early 1970s, and they found evidence of some early humans who had lived in the cave as well as some Neanderthal artifacts. In 2008, a team led by Michael Shuranov of the Russian Academy of Sciences returned to the cave. It was during this expedition that they found something which seemed rather small and insignificant, but turned out to be earth-shattering. They found a single bone from the little finger of the right hand of a juvenile female hominid. The bone was said to have come from Woman X. They really didn't know anything more. The bone was so small that they really couldn't figure out what hominid species it came from or anything else. If this had been discovered several decades earlier, this might have been the end of the story.

The bone might have been put in a museum somewhere, cataloged, and forgotten. However, given the conditions in the cave, they were able to extract DNA, from the bone. What they discovered was remarkable and unexpected. It wasn't from a human, and it wasn't from a Neanderthal. It was from something totally different. They named this new species, Denisovans, after the cave in Siberia in which it was found. Radiometric dating on the sample put it between 30,000 to 50,000 years old, but a more recent analysis has pushed the date back from 50,000 to 76,000 years ago. That means that Denisovans were around at the same time as both humans and Neanderthals. Since the 2008 discovery of the finger bone, there have been several

other fossils found, and some bones which have been found earlier have been identified as Denisovan. However, the total number of fossils that have been identified is still very small. In total, there are fragments from five distinct individuals which have been found, and those don't amount to very much. In addition to the finger bone, there have been found three teeth, a bone fragment from an arm or a leg, and some other bone fragment from an unknown body part. There has only been one other piece of denisovin bone that has been found outside of the cave. That was part of a mandible that was discovered back in 2000 in a cave in the Tibetan plateau of China. For most very ancient fossils, there's no possibility of DNA analysis.

You're limited to doing skeletal analysis in a study of comparative anatomy of fossils. Because the fragments which have been found are so recent, geologically speaking, and given the conditions under which they were preserved, we did have DNA, and from that, we have been able to learn more than you would from just the bone itself. First, we know from DNA that the Denisovans mixed with both Neanderthals and Homo sapiens. We found DNA fragments from each group in the genetic makeup of the others. Second, via the genetic profiles of current humans, we can estimate where the Denisovans lived. They're believed to have lived across mostly Siberia and East Asia.

However, the modern human population with the highest percentage of Denisovan DNA are in Papua New Guinea and the Aboriginal people in Australia. They may have migrated into this region when it was connected to Asia by land and when sea levels were lower. If so, they were probably the first hominic group to cross the Wallace line, which is a line that extends through Indonesia, where most forms of life on one side are from Asia and on the other side are from Australia. And I'll be doing a future episode on this topic. However, they also probably weren't only in Asia. Another group with a large amount of denisovin DNA are people from Iceland. That means there may have been a population of them in Europe as well. Also, you probably have some denisovin DNA in you, as well as some Neanderthal DNA as well.

Another theory is that all three of the recent hominid species, Neanderthal, Denisovans, and humans, descended from an earlier species, homohydelbergensis, about 600,000 years ago in Africa. Some groups left Africa and spread into different groups becoming the various hominid species. There is still an awful lot we don't know, and many of these theories are just that. It's a best guess based on the scant evidence we have that conforms to the fact so far as we know them. We can't know, based on the bone fragments that we have, how big they were, or what their skeletal structure was like. We know that Neanderthals were rather stocky with pronounced brows, but we have no idea if the Denisovans were the same. It's entirely possible that there are Denisovan bones sitting in a museum somewhere that were found decades ago, but no one knew what they were.

Or, now that we know what to look for, there might be more attempts at trying to find Denisovan remains in other places around the world. There's still a lot we have to learn and discover about the Denisovans, and I'm sure that there are more discoveries to be had in the future. At least we can be thankful that from 50,000 years in the past, the Denisovans were able to give us the finger. The associate producers of Everything Everywhere Daily are Peter Bennett and Thor Thompson. If you'd like to support the show, please join the list of patrons over at patreon.com. And also remember, if you leave a review or send me a question, you two can have it read on the show.