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How a Fragment of Bone Told Us About a 90,000 Year Old Cross-Species Booty Call

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Transcript:
There’s so much bad news happening right now that I wanted to make a quick video about something pretty awesome. Even though it does involve a dead 13-year old girl. But hey, she died about 90,000 years ago so don’t feel too bad about it. Also, her remains have led to a really cool scientific discovery: that it was apparently pretty common for Neanderthals and Denisovans to mate.
She’s known only as Denisova 11, so from now on I will call her Eleven and picture her as the girl from Stranger Things. Eleven was discovered in Denisova Cave a few years ago. The cave is located in Siberia, and we call it Denisova because in the 18th century a hermit named Denis lived there. He may now be the most famous hermit in the world, considering the fact that his name has now been applied to many of the incredible things researchers found in his cave. The remains of many extinct plants and animals have been found there, including things like cave lions.
But the most famous discovery is the Denisova hominin — people who lived concurrently with Neanderthals (whose remains have also been found in Denisova cave). Denisovans and Neanderthals were two distinct species, so much more genetically diverse than any two humans on Earth today. Researchers didn’t think that they would have mated very often, but Eleven has been discovered to have had a Neanderthal mother and a Denisovan father. And since they’ve only been able to get DNA from about 20 ancient hominins (and only six from the Denisova cave), it stands to reason that either they got very, very lucky or else this was much more common than they thought.
What’s incredible is that they got all this information (and more) not from a big pile of bones but from a single fragment about 2 centimeters long. That’s about an inch for you Americans. And from this tiny scrap they learned so much. Protein extraction told them it came from a hominin. The thickness of the outer layer of bone told them that Eleven was about 13 years of age. Grinding the bone to dust and examining the DNA told them Eleven was a girl. A combination of radiocarbon dating and genetic data told them she lived 90,000 years ago. And comparing her DNA to that of previously identified Neanderthals, Denisovans, and present-day Africans told them she was a product of a Neanderthal and Denisovan.
Then they were able to look even more deeply into her genome to figure out that her family had a history of inter-species intermingling, with a Neanderthal ancestor on her Denisovan father’s side, possibly as far back as 600 generations prior. This means that the researchers weren’t just super lucky to find this interspecies child, but that the two species actually mated quite frequently.
But wait, there’s more! The DNA showed the researchers that Eleven’s Neanderthal mother was more closely related to Neanderthals from Western Europe than to the Neanderthals that were previously known to live in the Denisovan cave, meaning that they now have solid evidence that Neanderthals migrated across Europe and Asia for tens of thousands of years.
Researchers have wondered for years exactly what led to the extinction of the Neanderthals and Denisovans. This new information, combined with previous studies showing the frequent intermingling of Neanderthals and modern humans, strongly suggests that maybe all these ancient hominins just, well, fucked themselves to extinction. Maybe they just all ended up as what we know as modern humans.
All of that, researchers learned from one inch of a fragment of a bone. Science is fucking awesome.
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