(gentle music)
(birds chirping)
This is the cradle of mankind.
More early man fossils have been found here
in South Africa than any other place on Earth.
Here at Rising Star Cave, two enthusiastic cavers,
Rick Hunter and Stephen Tucker,
were about to make the discovery of a lifetime.
I'd probably been in and out of this cave about 20 times
and I thought I knew every inch of it.
And on one Friday night, Rick Hunter and I came to
see if there was anything interesting.
And we climbed up this very bad climb,
the Dragon's Back, it's like 20 meters high
with sheer drops on either side.
And Rick was taking some GoPro footage.
I was basically getting in his way.
He asked me to move into a little crack so that
he could step over me and as I climbed into
this little crack, straight below me,
I noticed that on the one hand, on the one side,
the crack was going down further.
So, I climbed down it and it just continued
and continued going down for 12 meters
in this very narrow, jagged shaft.
I got to the bottom and suddenly, a big chamber opened up
in front of me with pristine white stalactites
hanging off the floor and I immediately called Rick down
'cause I was getting excited.
We had discovered something new in the cave.
But that wasn't all we discovered.
We walked into the chamber a couple of meters
and saw that on the floor, we started to notice fossils.
(gentle music)
So, on that very night, Lee Berger told me that
my life was gonna change forever.
Lee Berger, Research Professor at the
Evolutionary Studies Institute of the University
of the Witwatersrand in South Africa,
headed up the project,
calling for institute scientists around the globe
who were both qualified and small enough
to climb into the Dinaledi fossil chamber.
That looked great down there.
Yeah, brought up a couple little fragments.
Dr. Marina Elliott was the first scientist
to enter the Dinaledi chamber here.
(laughing) The odd one or two.
Don't be coy.
So, the first time I sort of slid through that hallway
and into the open area where the chamber is and sort of
started looking around, you're only wearing your
head lamp, so you just see flashes,
but every flash of my headlamp showed bone.
So, I think right at that point, I realized that
we had a lot more than the original photographs
actually had portrayed.
So, that was pretty exciting.
When we actually got into the chamber and could
start removing it, we realized that not only was there
one individual lying there on the surface,
but the floor was literally comprised of Homo Naledi.
There are thousands and thousands and thousands
of remains down in those chambers and all you have to do
is sweep the surface off and there they are.
To date, over 18,000 fossils
of Homo Naledi have been discovered in the
Rising Star Cave system.
Homo Naledi isn't really similar to any known
hominin species in its entirety of its package,
but it's almost like a, you've got little bits
and pieces of almost everything we've ever found.
Parts of the skull, if you just look at it quickly,
look a little bit like Homo erectus.
Of course, got a very small brain.
Other parts of the skull look very modern,
like Homo sapiens.
The fossils showed that Homo Naledi
had a small skull and that many of its features
were archaic.
It gets stranger and stranger as you move down the body.
You get the ape-like shoulders.
You get these more and more humanlike arms,
which end with the hand that's human proportioned.
This is a much smaller hand than mine.
When I put the wrist bones in place and then place it
in my palm, you'll see that the thumb is almost
the length of my thumb, yet my hand is
clearly, obviously a lot bigger.
So, that was the first thing, big thumb.
The final strange thing about this hand
is how curved it is.
I don't really need to do anything to demonstrate that
except hold this cast up and show you the extreme curvature.
That curvature is as great as the most primitive
members of our lineage.
When we first discovered Homo Naledi,
the idea was, based on its morphology,
that it was gonna be millions of years old.
That meant we couldn't even guess what
the age of Homo Naledi was.
That led us on a search for laboratories and specialists
around the world that would either invent technology,
improve technology to date these fossils.
One of the scientists tasked with the
complexity of determining an accurate age for the
newest member of the human family was
Dr. Renaud Joannes-Boyau
of Southern Cross University in Australia.
He's a specialist in electron spin resonance,
or ESR dating, which can determine the age
of Homo Naledi teeth by measuring the natural radiation
they have absorbed over time.
ESR dating is the only one
that can go back in time sufficiently to actually cover
human evolution and date directly the fossil.
Most of the other technique will date the sediments
around the fossil and then you have to assume
that the age of the fossil is the same
as the dating of the sediments around.
ESR analyzes the behavior of electrons
within the crystalline structures of the tooth
and can determine from this, very accurately,
how many years the tooth has absorbed the Earth's
natural radiation and so, provide a date to the fossil.
By dating the actual teeth, an accurate age for
Homo Naledi could be determined.
Initially, its age was estimated to be between
one and two million years old,
in the same range as this nearby find
of Australopithecus sediba.
But the new dating technology was about
to astound the world.
I was actually at the London Natural History Museum
and Homo Naledi was on the wall and then,
there was the estimated age between
1.2 and 1.8 million years.
But then, when we actually did the scientific dating
of those teeth, this is when things got very interesting
because then we got an age of 200 to 300,000 years old,
so much, much younger in human evolution,
actually overlapping with Homo sapiens.
When we got a date that was much younger than that,
a quarter of a million years, give or take,
we realized that we were dealing with a primitive creature,
almost like a time traveler that had come down
from deep time, the species clearly originates there,
that's where its morphology originates,
and had come down through time invisible to us
in the fossil record to a point where it is
very possible that Homo Naledi was in direct contact
with the emergence of modern humans.
We never thought that was possible in Africa.
Until this moment, we thought that there was effectively,
during that entire time period of the Middle Pleistocene,
late Middle Pleistocene, one form, a big-brained
form of Homo sapiens.
Now, there are two and that adds incredible
complexity to our record.
Homo Naledi comes out equidistant from,
for example, Homo erectus, as it does from Homo sapiens.
Homo Naledi would be an equally-likely ancestor
to modern humans, as Homo erectus.
The anatomy isn't lying to us,
it's telling us something real.
Naledi comes from a very ancient time.
Naledi was the size of a very small human.
It stood about 1.3, 1.4 meters at the most.
And yet, its legs were relatively long in that.
That tells us that it was probably a very effective
long-distance walker, possibly a runner.
It was moving around the landscape in an entirely
humanlike way and that's really fascinating
because it may not have been the only humanlike
creature on this landscape.
Archaic humans, or even early modern humans,
might have been here at the same time.
Homo Naledi may also have buried their dead.
The fossils were often intact,
held together by soft tissue.
There was none of the typical damage.
We could see that it wasn't a mass death.
See that water hadn't washed them in there.
And what was I guess most remarkable is they were alone.
They were the only species in it.
And we came to the conclusion, obviously, that this was
perhaps a deliberate body disposal site.
We're still, remarkably, this long down the line,
still hypothesizing that Homo Neladi did something
that we thought previously unique only to modern humans,
deliberately disposed of its dead in a ritualized fashion.
Then of course, we found a second chamber
that's practically like the first one.
The Lacetti chamber, also inside the same
cave system, is yielding as rich a trove of
Homo Neladi fossils as the original Dinaledi chamber.
Here, Lee and John man the command center
for the new excavation.
The Lacetti chamber is amazing.
Scientists are unearthing new discoveries
about our ancestors daily.
Some of them are very complete, like the Neo skeleton,
they are identical.
We hypothesize now they're probably
from the same time period.
It is a remarkable situation.
It's as rich in many ways as the Dinaledi chamber.
I can't wait til we find the next one.
In the past four years,
new discoveries in the cradle of mankind
have changed the landscape of evolution forever.
Has the cradle offered us all its secrets?
Not only do I not think that there are
more sites out there, I know there are more sites out there.
(gentle instrumental music)