The Rising Star cave,
which is underneath this hillside,
which is pretty nondescript.
Inside of it are
more than a kilometer of underground passageways
that make up the Rising Star cave system.
This is a small part of the system map
that shows you the area that we're actually working in,
from our entrance to the chamber
where we found the massive fossil deposit.
The ' Dinaledi Chamber' is on the far right side.
And there's this vertical little drop.
And Steve, one of the cavers who was responsible
for the initial discovery of the bones in the cave,
he had wedged himself down in this crack to rest.
And he noticed that he didn't touch the bottom.
And so he did exactly what you or I would have done in the same situation.
[laughter]
- He said, "I wonder what's down there!"
[swooshing sound]
And he went down 12 meters.
And Rick followed him.
So that was how the discovery was made.
This was not an obvious place to look.
It was very difficult to reach.
And basically, this is our view.
We're watching the excavation in progress.
What a lot of people are surprised about
with the Rising Star assemblage
is that unlike many fossil sites in southern Africa,
our fossils are not embedded in a hard rock.
Our bone is in a soft sediment
that's basically like a very fine-grained clay.
And to work in it we just have to brush it away.
The challenge is that our bones are incredibly fragile.
And those bones are laid like pick-up sticks,
one on top of the other, as far down as we could sense.
Every bone that we were finding there
was a bone of a fossil hominin .
They were in exceptional completeness, in many cases.
We were working, literally, probably centimeters a day.
We were very carefully exposing the bones,
and then safely bringing them out.
Everything that came out of the cave had to be marked,
catalogued on the site, photographed,
put into secure water-tight bags,
but into a waterproof, padded caving bag,
and had to come out that narrow passageway.
We worked for 21 days in this site,
excavating an area less than a foot deep,
across less than a square yard.
This is an amazing assemblage to come out of that space.
So we had, in all, more than 1,500 pieces of bone.
That by itself is the largest assemblage of fossil hominins
ever discovered in Africa.
We have young children.
We have older children, adolescents.
And we have young adults and one very old adult.
So this is a picture of the demography of a population.
We've never had that before.
Not from one site like this.
For more than five weeks,
we put more than 10,000 person hours
into the analysis of these fossils.
We measured them in every way possible.
We scanned them.
We made surface models of them.
We described them in relation to every fossil hominin
that we had to compare them to.
So we really put together a scientific document
that shows the anatomy of something
that would turn out to be,
after our analysis,
a species that had been totally unknown to us before.
A new species that we named Homo naledi .
Naledi in the Sesotho language,
which is one of the local languages spoken in this area,
means 'star.'
And we named it star because of the Rising Star cave
that we found them in.
You guys are going to want to know
how the bodies get in there.
But we can tell from the sediments in this chamber
that this chamber was never open to the surface.
These hominins didn't fall in.
They were not washed in.
And we've got parts of bodies that are fully articulated.
It's clear that the bodies entered this chamber whole.
On no bone do we have something
that is a mark made by a carnivore.
They were not living there.
We think the most likely scenario is
that Homo naledi deliberately deposited them there.
This species with a brain a third the size of ours
was collecting its dead and putting them in this place.
That tells us something really interesting,
really important, I think.
It tells us that these were cultural creatures.
I can tell you that there are other hominin remains
inside the Rising Star cave in different places.
So we will learn more about what happened here.
Our science is going to change a lot in the next several years,
and this is just the beginning.
So keep watching.