You immediately descend into the mouth of a cave...We suit up, we put harnesses on
and we clip into some safety ropes and then we're climbing this knife edge of
rock. It goes about 20 meters up and so if you were to fall off the Dragons Back
that would be very bad. If any of us was injured on the sort of the far side of
the cave, the paramedics would be sent down to us and you had to live
underground until you could get yourself back out. You go through that little
tunnel and then you come out and there was a more open chamber. But, we only had
our headlamps on at that point and so everywhere we looked you could just see
flashes of bone.
Hey smart people, Joe here. There may be nearly 8 billion humans on earth, but homo sapiens is a lonely species. And not just because we
stared our phones all day, or never go outside, or just watch YouTube videos all the time.
Because our species is a relict. The only surviving member of the group
of upright Apes known as homo. But it wasn't always like that. Walk backwards
through time and you'll see that at various points, many other human and
hominid species walked the earth. Some like us and some very different.
Everything we know about those ancient species stories we know from fossil bones.
And in many cases that means we don't know very much at all.
Which is frustrating because we all want to know where we fit in this story.
How did this one species of intelligent ape come to dominate the planet and where do we fit
in with all the others. Well that story just got a whole lot
more complicated thanks to a ridiculously awesome bunch of fossils
discovered in South Africa. Over the past several years, which added a new species
to the ancient human family. For the first time ever, these fossils travelled
outside South Africa to Dallas, Texas. So I stopped by the Perot Museum of Nature
and Science to check them out and meet the scientists who discovered them...
and to take a selfie with my ancient cousin. We'll get to that. How many people have
found new human species like ever? Probably a dozen maybe, maybe 15. And you
found two! Yes! Paleoanthropologist Lee Berger
lives and works in South Africa searching for ancient human fossils.
Scientists have been digging up human fossils in this area for decades but
thanks to new technology and satellite imagery, in 2013,
Lee had identified a few spots he thought others might have missed. Expert
cavers on Lee's team had discovered an unexplored section and what's known as
the Rising Star cave system. They named it the Dinaledi Chamber, meaning
chamber of stars in one of the local South African languages. When they
descended to the bottom of that chamber they did find something bright shining
back at them; fossil bones, piles of them. When Lee saw pictures of the fossils in
the chamber, he immediately knew they were fossils of an ancient human
relative. Problem was that he was too big to fit inside the cave to study them so
he did what any of us would do. He put out a Facebook post asking for help:
"Volunteers needed. Excellent archaeological paleontological and
excavation skills, they must be skinny and preferably small and they must not
be claustrophobic." I mean, who wouldn't respond to that. They were looking for
archaeologists with caving and climbing experience and before I started studying
archaeology, I was doing outdoor leadership. So it sort of sounded like me, but I
didn't really expect to hear anything. But pretty soon I was underground! My
supervisor sent me the ad and said, "Hey you have climbing experience. Don't you"
have caving experience, too?" I said well yes and so it sounded bizarre and
bizarre enough that I would want to do it. Becca Peixotto and Marina Elliott are
two members of the six scientists team who descended into the cave to unearth
these fossils and bring them to the surface to study. Excavating these
fossils required what was essentially a military-level operation. Kilometers
worth of cables were strung so Lee and others in a command tent on the surface
could watch every moment of the excavation and communicate with the team
underground. We got dubbed the underground astronauts.
And the people who were on the surface who couldn't come underground with us
we're watching us on these sort of grainy CCTV cameras and it reminded them
of watching astronauts, you know working on spacewalks in the space station.
To say that it wasn't easy for them to get to work every day would be
a bit of an understatement. We have to travel through this cave where the
narrowest point that we have to get through is 18 centimeters wide. You have
to get down on your belly and sort of do a belly crawl to get through it. It's
called the Superman crawl because folks with broader shoulders have to put one
hand over their head, and sort of push themselves along with their
feet sort of flying like Superman. You come out from under the Superman crawl and
you can stand up and you're in a pretty big chamber and that's where the base of
the Dragons Back is. Yeah, and then we end up in an area called the top of the
chute and the chute is actually a long crack or fissure in the dolostone, or in the rock. meters high. At its widest, it's
And it's about 45 centimeters. At its narrowest it's that 18 centimeters. 18
centimeters is like the size of my head - it's just not possible. I have a big head. See if I've got what it takes to
join the underground astronaut squad.
As they brought the fossils to the surface, and began to look at their features, they began to realize they had found
something very strange. For one thing it was a totally new species. They named it
Homo naledi. And this wasn't just one individual. This cave held many
individuals, like plural. In that first 2013 expedition we brought up..whatever
it was 1350 fossil fragments which in itself is is crazy. But they all came
from a single excavation unit 80 centimeters by 80 centimeters by 20
centimeters deep. And we found bones representing, I think we're up to 22
individuals now. All of the body parts are represented, so there's foot bones
and hand bones and rib bones and vertebra and teeth and all of it.
The Rising Star site, the Dinaledi Chamber, the Lesedi Chamber, and other areas
around there, we've discovered more individual hominid remains than the
entire record of hominin evolution from the continent of Africa.
I think our field had convinced itself there was nothing left to find, and
people stopped looking. This is a message that there's more out there, and there's
not just a little bit more there's a lot more.
Okay now I don't know how you think fossil hunting works especially the
search for ancient human, but that is not how this usually goes. When people find
hominid fossils, you're finding part of a jaw, you're finding some teeth, maybe
you're finding just one little digit from a hand and that's how species are
described. So there are whole species that are known from just really small
parts of the body. Whereas, with Homo naledi, we have the whole body from a
bunch of different individuals several times over. Homo naledi's bones
don't look like the bones of other ancient humans or hominids. At least they
don't look like anything we've ever seen together in one single species. So we're
behind the scenes in the Perot museum and we're just going to go in and have a
peek at an at a reconstruction of Neo. So what those bones might have looked
like in life. And this is our buddy Neo here. So Homo Naledi has a sort of mosaic
of features. Some aspects of Homo naledi look a lot like our bodies and some
aspects look a lot like our more ancient relatives. So they have a really tiny
brain. If you can look at the cranium here. So they have a brain that's roughly
the size of an orange. But when we take endocasts, molds, of the inside of
the skull, we can see that the brain has a lot of similar features (in terms of
the sort of waves and folds on the outside of the brain) as ours do. So that
indicates that you know while they have a tiny brain they maybe had a brain that
had a lot of functions. So jaws are always cool. In part because everybody
knows what their own teeth look like. And so you can see that Neo's teeth actually
don't look that dissimilar from our own. And we've of course found complete hands
of Naledi . It becomes more and more human-like.
And so the wrist and hand proportions are almost completely human-like except
for two things; One the thumb. The thumb is utterly unique. It's extremely long.
And the fingers are curved. It's curved as the most ancient hominids that we
have. So that would make sense if this was alive two million years ago.
Absolutely! 3 million years ago. But it wasn't. When we first started looking at
the anatomy, I think a lot of people thought "Oh this thing has to be at least
a million, maybe two million years old." Some of the teeth were tested using a
technique called electron spin resonance. So that was one way we were able to
figure out that Naledi was in this three hundred thousand years ago range. It really
was surprising to find out that Naledi was as young as it was in the timeframe
that Homo naledi is. Anatomically modern humans were also on the African
landscape. Modern, primitive, and different at all once. As of today, the team has recovered
fossils from at least 20 individuals from Dinaledi and a nearby chamber.
That brings up a huge question - "How did all these bones get in this cave?"
Our hypothesis is that Homo naledi were deliberately disposing of their dead. So
we think that Homo naledis were dying on the surface and their fellows
were bringing the dead ones down into this cave system. We don't know why
because we don't have any evidence for that and we unfortunately can't ask Neo.
He's not too talkative. Deliberate body disposal was one of those behaviors,
those rituals, one of the few things that only our species did that made us unique.
And this shatters that idea. It's another in a long list of things that we used to
think of as uniquely part of our species that aren't. Up until Jane Goodall saw
chimpanzees actually termite fishing, boy that was our gig. You could look at us
and you said, "Wow we do tools no one does." Okay, cross tools off the list.
Art; We now know that other animals do complex ornamentation and
decoration. Birds do a great job of that, right? We know other animals mourn now. We
know that they grieve over their dead. They interact with death in a different
way and many different species do that. So, we've lost that. And then there's this
last thing though that we had. You know, this idea of recognition of self
mortality, deliberate body disposal. The idea that we deal with our dead. And the
reason that we thought we did that is because we saw ourselves as separate
from nature. We saw ourselves as a creature that was different from
other animals and therefore we wouldn't allow any of our individuals to undergo
those processes. If that hypothesis holds here for these
specimens in these many different places that we find them now. Then you're
looking at a creature that shared that. For me, I often talk about humans and
other animals. because we are animals. And I think when we think about ourselves as
being part of the animal kingdom, I think that, to me, that helps us bring
ourselves back into being you know co-inhabitants of this planet. This whole
story leads up to some big questions. Where does Homo naledi fit into our
story? Is it our ancestor? Is it something else? Well, the answer isn't simple. We're
all familiar with this version of human evolution. A primitive looking thing
giving rise to a slightly less primitive thing giving rise to another and another
and finally something like us - something advanced . A march of progress. Well, that
isn't how evolution works. And Homo naledi is proof of that. I think this
model of the braided stream helps us get over that hurdle of thinking that you
know one species and then the next generation is born and it's another
species, but that evolution happens gradually and through multiple
mechanisms through time. The idea that that we were this inevitable walk to be
this in humans or this successful dominant thing - we've hardly been tested yet.
Yeah, you take it air conditioning and delivery food away and we're in trouble. Absolutely!
Thanks to fossils like Homo naledi, we know that the human story played out
like a tangled braided stream.We're at the end of one branch near the end. But
we're not the only branch, and along the way, back through time, branches have
split off to fade out or perhaps even join back with others and combine again.
It isn't a tree that grows up and some march towards some ideal best species. It
trickles out simply forward in time following the landscape carved out by
natural selection. We're just along for the ride, looking
back and trying to figure out where we've come from
and who our fellow travelers were along the way. Stay curious.
I want to give a special thanks to the Perot Museum of Nature and Science in Dallas Texas for
inviting me up to see these fossils in person and meet the scientists. This is
the first and probably the only time these fossils will be outside of South
Africa and I'm just really honored that I got to be next to them and experience
this. They even gave them South African passports. Are you kidding me!
They'll be on display through early 2020 as part of an exhibit at the museum
called Origins. So if you're watching this before then and you find yourself
in Dallas, go check them out. They aren't paying me to say that...just an awesome
thing and you should know about it. There's links down in the description
and I'll probably have some more to show you from my visit in a few weeks, so stay
tuned. And thanks to everyone who supports the show on Patreon. You are
awesome! And thanks to you, I get to go see cool stuff like this and share it
with everyone. If you want to join our family go check out the Patreon page.
We've got a lot of cool perks at different levels and you can even join
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