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Hank Green: Greetings, fellow hominins. Today, I wanted to be the first to bring you some late breaking news from the genus Homo. A team of more than two dozen scientists has sequenced the genome of the latest member to be added to the human family tree: the Denisova hominin. The Denisovans were just discovered in 2010 when a 41,000 year old finger bone and teeth were extracted from Denisova Cave in Siberia. Those remains had a unique signature in their mitochondrial DNA, that's the ancestral DNA, totally different from what you inherit from your parents, showing that it was neither a modern human nor a neanderthal. And I was just talking about these guys a few days ago, if you remember in last week's news, I mentioned that we found really old remains of like, modern humans in Southeast Asia, raising the odds that folks like us bumped into Denisovans, who lived as recently as 30,000 years ago. But today's revelation gives us our clearest picture yet of our very close but now sadly extinct relatives, so here are just three things we know about the Denisovans that we didn't know before.
 
Number one, all modern humans have some neanderthal DNA in them, suggesting that our ancient ancestors had some pretty open minded sex lives. But today, Denisovan DNA is found almost solely in people living on islands in Southeast Asia and Oceania. After comparing the new DNA with that of modern ethnic groups in Europe, Africa, South America, and Asia, the researchers found the highest concentration among the native peoples of Papua New Guinea, with 6% Denisovan genes. Melanesians and Australian Aborigines also show hefty genetic contributions from the Denisovans, but this does not mean the Denisovans made it with the human ancestors of modern Asians, instead, it turns out that Denisovans had a lot of Neanderthal DNA, too. So the gene flow probably came to us directly from Neanderthals, which makes sense, because I know that I, for one, can't resist a nice, thick monobrow.
 
Number two, the young Denisovan woman whose remains were studied had the alleles or variants of genes that today are associated with dark brown skin, brown hair, and brown eyes. That doesn't mean that all Denisovans looked that way, but the study did find that the species had very little genetic diversity, possibly because its population was very small and it shrank rapidly as modern human populations started to grow.
 
And number three, finally, it's not just about what's in the Denisovan DNA but also what's not there. The researchers looked at DNA sequences common among all primates, dating all the way back to before modern human ancestors diverged from Denisovan ancestors as much as 800,000 years ago. They found that most of the changes that have taken place in us since then are in the brain, especially in genes that regulate brain development and language skills.
 
So thanks to the researchers, but most of all, this ancient proto-Russian girl for leaving behind such lovely, well-preserved bones for us to study and learn from. You can read all about it in this week's issue of the journal Science. Thank you for watching this episode of SciShow Breaking News, if you want to keep getting smarter with us, you can go to youtube.com/scishow and subscribe, and if you want to ask us any questions or give us any suggestions, we're on Facebook or Twitter or, of course, in the comments below.
 
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