(SciShow intro plays)

Hank: Good news everybody, we have a new addition to the family. You and me, humans, we got a new family member! Late last week, South African paleontologist Lee Berger announced the discover of a new species in the genus homo. That's the taxonomy for a small group of species that first appeared in African about three million years ago which includes homo erectus, homo neanderthalensis, and us, homo sapiens, along with a handful of others.

These hominins are our closest evolutionary relatives, and now I have to make room in the family photo album for homo naledi, the first humans species, we believe, to have buried their dead. This is a huge deal because ritualized behavior like burials requires a pretty high level of abstract thinking.

What makes it really weird is that homo naledi's brain was only about half the size of ours, but we can't really figure out how else their bodies could have ended up intact at the bottom of a cave in one of the most inaccessible places on Earth. Over the past two years, Berger's team recovered 15 intact skeletons from the bottom of a shaft in Dinaledi cave in South Africa. To reach the site, cavers had to travel seventy meters from the surface, most of it in complete darkness.

The bones were found in the bottom of a narrow chute in the rocks that's 12 meters deep and at one point narrows to only 18 centimeters across. Berger himself never actually set foot in the site because he couldn't fit. He had to recruit six research assistants, all women, to squeeze down the cave to recover the fossils for study.

Now the bones had no teeth marks on them and the bodies hadn't been pulled apart, so animals didn't drag the people down there. The remains also showed no signs of damage from tools or from falling, so they weren't killed and then dumped, and they didn't just slip down there. So the most likely explanation scientists can come up with is that these people died on the surface and then their bodies were carried into this cave, probably by the same dark, dangerous route used by Berger's research team except without headlamps.

Homo naledi stood about one and a half meters tall, had opposable thumbs, stiff feet for upright walking and probably used fire, since getting in and out of the cave without a torch would have been next to impossible and also super, super terrifying. There are some major things we don't know about them yet though, most important: when they existed.

Due to the geology of Dinaledi cave, the bones recovered by Berger's team were demineralized which makes it extremely difficult to date them. So we don't know if Homo naledi went extinct two million years before Homo sapiens existed, or if, at one point, we actually coexisted. I don't know about you, but I'm excited to find out.

In other news, a 30,000 year-old giant virus has been discovered in the melting Siberian permafrost, and I'm happy to report that it is not going to kill you! It's job is to infect like amoebas, so you are safe. And also by giant, I'm using relative terms here. The virus, mollivirus sibericum, is .6 microns across, that's big enough to be seen in an ordinary microscope, and it has over 500 genes which contain about 650,000 base pairs of information. That's about as much data as Namco shipped in the 1980's version of Pac-man.

Just to give you a sense of perspective, HIV has 7 genes and only about 9,000 base pares. Researchers found that while analyzing the permafrost, they found around an ancient Siberian squirrel's nest. And the virus itself isn't very troubling, scientists are making very, very sure that it can't infect any living animals or people, but it happens to be the 4th ancient virus that's been uncovered by melting ice since 2003, and they've all retained their infectivity. It now seems certain that many more prehistoric viruses will emerge from the ice as global temperatures continue to rise, and arctic oil drilling disrupts their environment.

But seriously, try not to freak out. Humans breathe in thousands of viruses a day and swallow billions whenever we go swimming in the ocean. We'd have to be supremely unlucky for some newly released ancient virus to be a serious direct health risk to us, but now that I have said that, I am terrified, and I'm sure that someone's gonna write a book about it. Just think of it as one more way climate change is making life very interesting for all of us.

Thanks for watching this episode of SciShow News especially to all of you who are supporters on Patreon, thank you so much for doing that. If you want to become one of those people so that I can be thanking you right now, though honestly I'm still thankful to you, you can go to patreon.com/scishow, and if you just want to keep getting smarter with us, go to youtube.com/scishow and subscribe.