(birds tweeting)
On this hill nearly four million years ago,
Little Foot, one of our early ancestors, wandered.
Today the excavations at Sterkfontein Caves
near Johannesburg in South Africa
have provided us with one of the richest sources
of knowledge about our origins.
So much so that the area has become known
as the cradle of mankind.
(dramatic music)
Over 800 early human fossils have been found
here to date, including the most complete skeleton
of its kind in the world, Little Foot.
Today the Sterkfontein Cave system is surrounded
by grassland and scrub,
and was just another koppie or small hill
until the first fossils were found here in the 1930s.
But 3,670,000 years ago, in the time of Little Foot,
the Sterkfontein region of South Africa
was more like the Central African forests of today.
There were massive trees with lianas or vines
clinging to their towering trunks,
and of course, there were many apes.
Apes all sharing the forest and its food
and shelter from the formidable array
of predators on the ground.
Amongst them were our ancestors.
We know more about the environment that
Little Foot lived in then because
fossilized material from her days
has been found in the caves, along with her own fossils.
With a lot of Australopithecus fossils,
we find fossil wood, and that fossil wood
has been identified by Professor Marion Bamford
of this Evolutionary Studies Institute,
and she's identified most of those fragments
as belonging to a species of liana,
Dichapetalum mombuttense, which now only grows
in tropical West and Central Africa.
It's a very interesting piece of wood
because it's a liana.
Now, lianas have a very special structure,
so we know it's a vine, and vines don't grow
upright by themselves.
They have to have something to grow over.
In other words, large trees.
So although we don't get the large trees preserved,
we get the vines, which means that there were
large trees at that time, and that fits in
nicely with the animals that we've found there,
because they were hoard of monkeys
that are arborial, and so the hominids at the time,
and even earlier than that, were growing in
a much more wooded environment than we have today,
and the hominids would have been living in there
or associated with there, and they fell into
the little cavities that are opened
down to the caves, along with the woods,
along with the fauna and all sorts of bits and pieces.
The Sterkfontein cave system is still
pockmarked with dangerous holes,
so now walkways protect visitors and scientists.
In the time of Little Foot, 3.6 million years ago,
covered with lush vegetation, the holes surrounding
the vast cave system were often a death trap.
Sterkfontein is almost daily yielding
important new discoveries related to our origins.
The considerable excavations over decades
have yielded famous discoveries,
including the Australopithecus africanus
and prometheus species, not least of which
is that of Little Foot.
At once tragic and ironic, the fact
that Little Foot fell into one of these holes
leading to the caves below meant that
her skeleton was preserved mostly intact,
safe from the ravages of predators and scavengers
for millions of years.
The skeleton was sealed mostly within breccia,
a type of natural concrete which had covered
and hardened over the bones for nearly four million years.
To reveal her fossil remains within this
was little short of a miracle, a miracle
that took over 25 years of exploring
and extraordinary patience, working through the rock
in fractions of millimeters.
Even more astonishing was that evidence
of Little Foot had been discovered but overlooked
for some 15 years before this at Sterkfontein.
The story of Little Foot nearly goes back to
before my time, in 1978 to 1990.
Lime miners' rubble that had been
blasted out as early as the 1920s.
Crushed limestone was used then as a building material,
was removed from a very deep cave at Sterkfontein
known as the Silverberg Grotto.
Teams were sent in to remove the blasted material.
The reason they wanted to take this material out
was that it was full of fossil bone,
and Phillip Tobias thought that they might find
something older than the hominids
or Australopithecus that they'd been finding
at higher levels at Sterkfontein.
He thought they might find something as old
as the famous Lucy from Ethiopia.
This sculpture of the late
Professor Phillip Tobias stands at Sterkfontein
in memoriam as the team leader of the excavations here
for 50 years, establishing the caves
as a World Heritage Site in 1999.
Tobias' hunch about discovering a much older
hominid deep in the caves was correct,
but would only be realized years later
through the detective of Professor Ron Clark,
for the secret lay not in a cave, but in a story.
So they removed all this rubble
and they processed it over the years.
It remained like that for a long time
until 1994, when Phillip Tobias asked me
if I could do an in situ excavation
in that deep underground cave.
We got many fossils of monkeys and of carnivores,
but very few bovids.
Bovids are hoofed animals,
including ancient buffalo and many antelope species.
And I thought this is very strange,
because up in Member 4, we find a lot of bovids
and also a lot of Australopithecus,
but down here we hadn't found a single
tooth of Australopithecus, the ape man.
The various Australopithecus
species found at Sterkfontein, Australopithecus
meaning a southern ape, were all
before the various Homo species,
which are believed to be more directly linked
to early humans.
So I went to the boxes of fossils
that were in our shed at Sterkfontein,
in our big store room there.
In the store room, Ron Clark
was hoping to find some fossils of bovids
or cloven-hoofed animals.
Instead, he found something that would
change his life and the history of our origins forever.
I took one of the boxes, put it on the desk,
hoping I would find some bovids in there.
I took out a bag and tipped it on the desk,
and to my surprise, I found this
among the animal fossils.
Ron Clark had found the very first
bone of Little Foot.
This is a hominid talus, an ankle bone.
How was it that this was missed?
And then, to my delight, in the same bag
I found the bone that went in front of it,
the navicular, and then the bone that went
in front of that, the medial cuneiform,
and then part of the first metatarsal,
leading down to the big toe.
It was unusual to find four articulating
foot bones like that in Sterkfontein.
Normally you find just one foot bone
if you're lucky, but to find four together was unheard of.
That was exciting, but then, some years later
in May 1997, I chanced upon more of the same foot,
and the way that happened was interesting.
Ron Clark found the next link
in the Little Foot discovery in the hominid vault
here at the University of the Witwatersrand
in Johannesburg, South Africa.
And to my surprise, I saw a box there
that was labeled as containing monkey fossils
from a lime miners' dump number 18.
And the first bag I took out, through it
I could see a little white bone
that I recognized as a foot bone of a hominid,
and then another one, and then another one.
I also found part of a tibia, and I found
part of a fibula.
So I had parts of the foot and lower legs
from left and right, and that convinced me
that the rest of the skeleton must be in the cave,
and that these bones had been blasted off by lime miners,
leaving the rest of it still there
in the cave infill.
So I thought, wouldn't it be wonderful
if we could find the rest of it?
And I gave this cast to Stephen Motsumi
and Nkwane Molefe and said, "Go with torches
"down into the cave and see if you can find
"anywhere that will fit it."
Well, this was a seemingly impossible task,
because the cave was vast, it was dark,
it was deep, the surface of the ground
was irregular, rock-strewn and dusty.
Anyway, they took me at my word,
and miraculously, after one and a half days
of searching in that cavern, they found the spot,
and when I next went down there,
Stephen told me that they'd found it,
took me down, showed me, and next to it
I was able to fit this one on as well.
After five years, Ron and his team
now had the complete Little Foot.
Stephen Motsumi and Nkwane Molefe
had pulled off another miracle
on the long journey to Little Foot.
The few bones he now had told Ron a lot.
The first was that Little Foot walked upright like us.
Now, Ron and the team wanted to find the rest.
We began chiseling away the enormous rocks
that were above this.
There were some huge rocks of dolomite and chert,
and we were chiseling that away to get down
to that level.
We uncovered much of the lower legs
after several weeks, months of work,
just carefully, carefully cleaning away the rock,
and when we got close to the bones
we used what we call an air scribe
which is a pneumatically-driven needle.
The air scribes allowed the team
to uncover the bones from tons of rock
over years without damaging them.
Experienced researchers learn to tell rock from bone
by color, texture and shape.
So we uncovered the lower legs.
When we got to the middle of the thighs,
there was no more.
And I asked them, "This is impossible.
"How can there be just the lower legs
"and not the rest of the skeleton?"
So we went on chiseling away these big rocks
and breccia cave infill, right up to the roof,
month after month, and found nothing,
until I realized that there was a cavity
underneath these legs at a lower level,
and I concluded that what must have happened
is that millions of years previously there'd been
an ancient collapse, and the upper part
of the body had collapsed down to a lower level
and then been sealed in by a
very thick flowstone, stalagmite.
Ron thought that possibly
part of the body, with the upper legs and skull,
had dropped away over the millions of years
to a lower part of the cave.
His instinct was right.
And it had been sealed in by that,
which went over the upper part of the body
and beneath the lower legs.
So I said to Stephen, "Let's chisel through this."
And we chiseled and chiseled, and...
One day, miraculously, again, his chisel struck bone.
There.
And it uncovered that.
And I thought, what on earth is it?
Is this a cast?
It's like a...
Ron and his team had uncovered a skull
that would change everything.
Ron's instinct had led them to an unprecedented find,
the complete skull of Little Foot,
its left side partly compressed by the weight of rock.
Not only was it the most complete skull
of its kind ever found, it was even more astounding
in that it still had a complete set of teeth
or dead tissue.
This was the first time ever that a complete
adult skull of an Australopithecus had been found.
Years of dedicated
millimeter by millimeter progress through the rock
were revealing their rewards, and there
was more to come.
That was the beginning of the excitement that was to come.
We went on cleaning away very carefully
with this little air scribe, month after month.
The air scribes would remove
the hard rock from around the soft fossils
with scalpel-like precision.
And then we worked further up slow,
and we got the arm, and we got ribs,
and we got vertebrae, and then at the lower level
we got the pelvis and so on.
(slow, atmospheric music)
It had been a miraculous journey
with the discovery of the first foot bones alone
from 1980 to 1997, and from then on until
the final skeleton in 2017.
Now the world had a comprehensive intact skeleton
from one individual, and the learning would begin.
And the learning started from the very beginning
with the first bones.
Starting with the big toe, Ron discovered
the first notable difference about Little Foot.
When I found the first four bones, I had already
determined that it had a very interesting development
here, this joint, in that it had some mobility.
So it had a slightly mobile big toe,
not as much as the apes, but slight mobility
which would have assisted it in climbing in trees.
Little Foot's intact arm and hand
revealed even more secrets.
So a beautiful arm.
What this told us, it's the first time ever
that a complete hand had been found like that,
and still attached to the arm.
The hand was exactly like ours, with long thumb
and short fingers.
It was not like that of the apes,
which have a shorter thumb and long fingers
because they suspend themselves from branches.
They also have long arms to assist them
in swinging in trees.
When they come down to the ground,
they use those long arms and long hands
as supports for walking.
This one didn't have that.
It had arms that were like ours, relatively short.
It had a hand that was like ours,
and when I was eventually able to reconstruct the legs,
I could see that the legs were actually
longer than the arms, just like us.
This, a human ancestor, had proportions similar to us,
and it walked fully upright as we do.
And it would have to climb in trees for two reasons.
Firstly, to get at fruits, which were up there.
And secondly, to get away from the carnivores
that were on the ground.
We know that at the time when Little Foot lived,
there were many, many very big carnivores.
There were several types of saber-tooth cat.
There were also the leopard and the lion
that we get today, although some of them
were larger than those that we get today.
And there were several different types of hyena,
so it was a very, very (laughs) unhappy environment
on the ground for a small hominid or Australopithecus.
Now that we have Little Foot's
full skeleton, we now have an accurate measure
of her height compared to modern humans.
And I'm sure that at night, Little Foot
would have wanted to nest up in the trees.
(birds singing)
Learning from Little Foot continues.
Her pelvis, with its greater sciatic notch,
indicates that she was probably female.
Her teeth have let us know her age of about 35 years.
Her brain, with its complete endocast and skull,
will hopefully answer questions about how
she might have thought or felt,
and about her cognitive processes.
The scientist beginning their journey
into Little Foot's brain is Dr. Amelie Beaudet
of the University of the Witwatersrand.
Yeah.
Little Foot can be used as a reference
for understanding evolutionary patterns,
because we have this individual which is
very well-preserved at a specific time,
so 3.67 million years old, and the specific
geographical context, so we can really use it
as a reference for understanding later evolutionary changes.
We extracted two very important structures from the skull.
One was the brain endocast that we can see in red here,
and here's the inner ear, and that,
because we know that those two structures
could be very informative to know about how
Little Foot lived at that time in South Africa.
Today Little Foot lies in place of honor
in the hominid vault in the Evolutionary Studies Institute
at the University of the Witwatersrand,
freed from the rock that held her fast four million year.
Hopefully, she will teach us even more about ourselves
in the time to come.
(ethereal, atmospheric music)