Neanderthals.
We always believed they were just knuckle-dragging ape-men -
that they were the inferior prototype to us, modern humans,
and that about 40,000 years ago, they shuffled off into extinction.
But now, the latest scientific research is showing
that not only were the Neanderthals
much more sophisticated than we thought,
they also didn't completely disappear.
In fact, a part of them still lives on inside us.
Scientists have discovered that most of us - me, him,
most people living today - carry Neanderthal DNA inside of us,
and the only way that could have happened is if somewhere, somehow,
Neanderthals and early modern humans were having children together.
I'm Ella Al-Shamahi.
I study Neanderthals and I want to show you
what these mysterious ancestors of ours were really like.
In the previous episode,
with the help of Hollywood motion-capture guru Andy Serkis,
we reconstructed the fossil evidence to produce what we think is the most
scientifically accurate representation
of a Neanderthal ever made.
We discovered that although Neanderthals
were brilliantly adapted to their ice age environments,
they were also so similar to us that they would fit into today's world
almost unnoticed.
In this programme, we will be asking -
what happened to the Neanderthals?
Why did our species survive while theirs became extinct?
I tend to say they were reasonable. They were not mad.
Modern humans are mad, if you like.
We'll discover the evidence
of the Neanderthals' epic struggle for survival.
For really the first time in the human fossil record,
you see people living through these massive injuries.
And we'll reveal how recent discoveries
have shown that Neanderthal DNA still has a profound impact on us.
It's affecting our skin, it's affecting our immune system,
it's affecting our risk of cancer.
It turns out that studying Neanderthals
isn't just about understanding our distant past.
They also have so much to tell us about our present -
and even our future.
This is the very southern tip of Europe -
the Rock of Gibraltar.
I've come here in search of clues to what might have happened
to the Neanderthals.
We think that this dramatic peak rising out of the Mediterranean
may have been one of the last places that they survived.
At its peak, Neanderthal territory
spread right across western Asia and Europe.
But 45,000 years ago, as the ice ages grew colder,
the European Neanderthals were squeezed
into the warmer southern parts of their range.
Here, there was a milder climate,
plenty of food, and the fossil evidence tells us
that they settled in these caves.
So, who are these people?
These are my friends, Nana and Flint,
the two Gibraltar Neanderthals. Aren't they wonderful?
And they're so lifelike.
Yeah, they're amazing. The little fellow,
he was formerly known as Gibraltar 2,
from the fragments of a skull found in 1926 in an excavation.
I mean, they're such sentient beings when you see them here.
Those expressions, I mean - what are they thinking?
There's that sort of cheeky grin about her.
She's almost looking at you
and seeing right through you and understanding what you're thinking.
And the little fellow's almost, like, holding on,
because he's not sure.
But you know, we talk about Neanderthals and modern humans -
and that already creates a division.
Sadly, from Gibraltar 1, 2 skulls, we have faces and names,
and sadly, you're much closer to them
and they're much closer to you.
Hello, gull.
Archaeologists Clive and Geraldine Finlayson have spent 28 years
excavating the caves
and have discovered that for these Neanderthals, life was pretty good.
In the last 120,000 years,
the average sea level was about 80 metres below our present sea level,
which means that there was a sandy plain out there
and on that sandy plain,
you had red deer, you had horses, you had the forerunners of cattle,
the ibex that were living on the rocks -
these are a kind of mountain goats.
That's what they could add to their diet.
And a little bit further away, there was also a seafood buffet.
The species that we find here in the intertidal
are the species the Neanderthals were collecting
for food, 40, 50, 60,000 years ago.
So here we have these large beds of mussels, goose barnacles,
crabs - just pop round the corner there.
You can see and get a sense of how rich
that intertidal fauna would have been like.
Life in these caves was about as good as it got for the Neanderthals.
On a clear day, they would have been able to see Africa -
just 14 miles across the water,
and you wonder if they had any clue what was coming their way.
And so how close were the modern humans to here?
If we accept the view that modern humans came through the Middle East
and then spread across Europe,
then this would have been one of the last places that they reached.
The evidence suggests that by the time they got here,
the Neanderthals had disappeared.
But of course, there were modern humans on the other side
in North Africa for a very long time,
and all I can say is that if I was sitting here,
and I was a Neanderthal
and I looked there and these people were living there,
I would see the smoke of their campfires rising
and they could see the smoke of my campfires rising,
and knowing what humans are like,
somebody must have tried to get across.
We don't know if this group of Neanderthals in Gibraltar
ever encountered modern humans.
But about 40,000 years ago,
the last of the Neanderthals living here disappeared,
and I want to know what happened to them.
In the last programme,
we did something no-one has ever done before.
In this movie studio, we gathered together
the world's leading Neanderthal experts,
along with Hollywood actor Andy Serkis
and his team of motion-capture artists.
Our mission was to create the most accurate representation
of Neanderthals ever seen.
We want to find out how they behave, how they move,
how they present, how they walk, how they fight.
By gathering together the scientific evidence,
we were able to build computer models of Neanderthals.
I mean, Neanderthals were almost about 20% as wide as they were tall,
somebody who could wrestle you to the ground easily.
Then, through the magic of motion capture,
we were able to animate the models,
converting them into lifelike representations of Neanderthals
in their natural environment.
The ultimate result was Ned.
Based on a real fossil,
we believe he is the most accurate CGI Neanderthal ever created.
Now we have a new challenge for the team.
We want them to help us find out what happened to the Neanderthals.
And once again, we are going to start with Ned.
The version of Ned we brought back to life
showed how he would have looked as a young man in his twenties.
But as I discovered when I met Libby Cowgill
at the Smithsonian in Washington DC,
the evidence from his fossil
can tell us a great deal about Ned's later life.
And it shows that individually, at least,
Neanderthals were great survivors.
This poor guy is sort of the quintessential representation
of a Neanderthal that's had a really hard time.
We know that Ned lived to a ripe old age.
He was probably 40 or 50 when he died,
but he was in terrible shape.
His skull caved in, his right arm withered
and his right hand missing, perhaps amputated.
But none of these were new injuries.
He survived for many years after they were inflicted.
And this tells us something fascinating
about Neanderthal society.
For really the first time in the human fossil record,
you see people living through these massive injuries.
Things like possible amputations, right?
An Australopithecine, an earlier human ancestor,
much more closely related to apes,
would have never have been able to survive
that level of profound injury.
Ned's face was reconstructed by forensic anthropologist Chris Rynn
at the University of Dundee. He's used to working
with the remains of the victims of violent crime.
Initially, he'd ignored the injuries on the skull
to show us Ned as a young man.
But now we've asked him to show us
how he would have looked later in life.
This individual was struck on the left side of the face at a young age
with a heavy blow
that broke his skull, damaged the brain, damaged the orbit.
And then he went on to live for another two decades at least.
So he might have spent his entire adult life
blind in his left eye, with brain damage to this side of his brain.
And you can see on the rest of the skeleton,
it caused probably some kind of paralysis on the contralateral side,
on the right side of his body,
because his right arm and right leg on the skeleton were quite withered.
So this is not someone who could have survived on their own
in that state for their entire adult life.
So this is really strong evidence
that Neanderthals cared for one another
and looked after one another in groups.
I think it's really interesting that Ned is both the stereotype
of the Neanderthal in the sense that this dude has taken a beating...
Right. ..but in another sense, he's completely the opposite
of the stereotype in the sense that he was cared for,
because he would never have made it on his own.
So it needs to be represented on the face, this trauma.
The first thing is, this eye is going to droop slightly.
There's going to be overhang on the eyelids.
If you look down on top,
this side of the body is much bigger than this side,
so I shrunk one shoulder and enlarged the other.
Based on Chris's analysis of the damage to the skull,
this is what we think Ned would have looked like
at the end of his life...
Scarred by the wounds of his youth.
OK, so let's say if you've received a hit to the side there
and that's shattered there...
Back in the studio, we asked Andy Serkis and his team
to help us visualise how Ned's other injuries
would have affected him as an old man.
You know, just relax it, just relax it.
Maybe it would slightly drop on this side, maybe,
ever so slightly.
There might be a slight kind of...
If you've been bashed around, you may be taking hits,
and if you've broken your right foot, say...
Just drop that a little bit there. Just relax that arm.
OK, and then just try a little walk forward a little bit,
with ever such a slight limp.
OK. And then... Yeah, that's it. Yeah, that's it.
Then turn around and come this way.
And then if you were to sit down, bearing those injuries...
As we discovered in the previous programme,
Neanderthals' lives were physical and tough,
reliant on strength and speed.
There is no way that Ned could have survived in this world without help.
Looking after vulnerable members of the community
has often been seen as a key trait of modern humans.
But Ned's survival for so long after his crippling injuries
suggests a high level of care, even compassion for him.
It shows that Neanderthal society was sophisticated and resilient.
Why, then, did they become extinct?
One thing we do know is that Neanderthals went into decline
shortly after modern humans migrated out of Africa
and entered Neanderthal lands.
But were modern humans responsible
for the extinction of the Neanderthals?
And is there any evidence that these two groups
actually came into conflict?
To answer that, we need to visit the Shanidar Cave in northern Iraq.
This is the site where Ned's skeleton was found.
And it's also the scene of one of the world's oldest murder mysteries.
Around 60,000 years ago,
another Neanderthal, known as Shanidar 3,
died a pretty horrible death.
His bones make up
one of the most complete Neanderthal skeletons we have.
They're now at the Smithsonian in Washington, DC...
..under the loving care of Dr Rick Potts.
Here it is. Pretty cool.
Every time's like the first time for me.
HE LAUGHS It's pretty exciting. Yeah.
So this is Shanidar 3.
Shanidar 3, that's right.
It's the only Neanderthal skeleton,
or most of a skeleton that's based here in the United States.
With regard to the death of Shanidar 3, we have this right here.
And here, we must put on...
The special gloves. ..our special gloves
to make sure no oils from our hands get on the specimens,
since these are all original fossils.
It feels like, you know, jewellers, when they don't touch...?
Yeah, well, this is kind of like the jewel of our collection,
the gem of our collection.
And so this part right here, you can see a cut.
That's the injury, that's the injury that led to the death of Shanidar 3.
He would have punctured a lung, or...
Punctured a lung, yeah, probably caused infection. Mm-hm. Mm-hm.
And we can tell from the bony growth
that the individual lived for some days,
and yet it did not heal completely. Completely, yeah.
Almost certainly led to the death of the individual. He didn't make it.
Leads to all sorts of questions as to...well, whodunnit?
So this is, like, a pretty old cold case?
Yeah. Yeah, that's for sure.
We, um...we really don't know how the individual died,
except by a sharp instrument to the chest,
to the lower part of the chest.
So we know someone with a pointed weapon killed Shanidar 3,
but who was it?
Back in the studio, our experts are trying to work out
if it was another Neanderthal, or a modern human
who delivered that fatal blow.
Amazingly, we do have archaeological evidence
of the weapons Neanderthals wielded.
But they're not exactly what you'd expect from the ape man stereotype.
Did they ever use any kind of club,
anything for battering, as opposed to stabbing?
Again, an archetypal image of a caveman, of a Neanderthal, is...
You know, someone with a club. I'm playing devil's advocate here,
I'm pretty certain this isn't going to be the answer.
Well, we don't have Neanderthal clubs in the fossil record.
I mean, the kind of fantasy clubs that we see in cartoons.
But we should not discard completely this possibility
because the archaeological record for wooden objects
is very, very, er...scarce.
Just because we don't have preserved clubs
doesn't mean clubs couldn't ever possibly exist,
it just means we don't have them.
All right, so we haven't found any Neanderthal clubs,
but we have found some spears.
And amazingly, we know that Neanderthals and modern humans
were using different sorts of spears.
Now, this, this is a modern human sphere.
It's a lightweight weapon made for throwing and killing at a distance.
But this, this is a Neanderthal spear.
It's thicker, it's heavier,
and it's pretty fearsome.
These Neanderthal spears, actually,
are like digging sticks, they're so thick,
way larger than any living human hunter-gatherer
would make for throwing.
THEY LAUGH
So we're really thinking they're not built...
They're not built for... ..for throwing.
..for long-range throwing, no.
Instead, we think Neanderthal spears
were used for killing at close range, for thrusting and stabbing.
The question now is,
was Shanidar 3 killed by one of these Neanderthal thrusting spears,
or a lighter, modern-human throwing one?
That's a spear thrower, is it? Yeah. Exactly.
The best way to find out is with a dead pig.
Police forensics labs often use pig carcasses
as a way to simulate the human body.
So, Steve,
you did an experiment similar to this, but more...
..accurate, maybe. Controlled. More controlled.
THEY LAUGH
We actually stabbed the spear under two conditions,
high kinetic energy and momentum, like a thrusting spear,
and low kinetic energy and momentum, like a dart.
So that's the entry wound that was made by the Neanderthal spear?
And what we found was that it did massive damage to the ribs.
So, for instance, here are three ribs.
The in-bending that was created in the ribcage from the force
cracked this adjacent rib
and resulted in a loss of bone here,
and even cracked this adjacent rib on the other side.
So three ribs were damaged from a single strike.
When we did it under circumstances like a long-range projectile weapon,
less kinetic energy, less velocity.
What we got were nice, clean little lesions
with no other involvement of other ribs,
like what we see in Shanidar 3.
We're not saying that a modern human killed him,
but we're saying whatever did had low kinetic energy
and low momentum, like a long-range projectile weapon.
But the other thing that's interesting about the wound
is that the wound track is at about 45 degrees
to the angle of the rib
in anatomical position.
And projectile weapons, long-range projectile weapons,
tend to take a ballistic trajectory
and drop in at about a 45-degree angle.
We don't know what position he was in.
Maybe he was laying on the ground. Who knows?
But it is kind of an interesting case.
Steve's being cautious.
But it is a definite possibility that Shanidar 3 was killed
by a spear thrown by a modern human.
And there is even more circumstantial evidence
that we played a role in the Neanderthals' demise.
Because it wasn't just the Neanderthals that disappeared
as modern humans spread north out of Africa.
So once upon a time, we weren't the only human
that was walking this earth?
I don't think it would be too much of a stretch to say
that if you go back 70 or 80 or 100,000 years,
it was much more like a Lord Of The Rings-type world.
We live in a very strange world today.
Only from the last, you know, maybe 30,000 years or less,
in which there's only one species of us around.
So now is the strange time.
There's the Denisovans that disappeared,
there's Floresiensis that disappeared,
possibly Homo erectus that disappeared.
So it's not just a Neanderthal issue,
those populations were displaced and replaced, eventually,
by that success, that growing success of modern humans.
So what happened? Why are we the only ones left?
The real question is not why the Neanderthals got extinct,
the real question is what happened with modern humans,
what created this irresistible expansion of one group
that led, basically, to the replacement
or swamping of everything else?
So it does seem likely that we at least played a part
in the Neanderthal extinction,
but we probably weren't solely responsible.
We don't know if the Neanderthals in Gibraltar
ever came into contact with modern humans,
yet they disappeared, so there may have been other factors at play.
One of those factors
may have been the Neanderthals' small population size.
At any given time,
there were probably no more than 100,000 Neanderthals.
And though they ranged across almost 5,000 miles,
their tiny communities were few and far between.
This would have made them vulnerable to sudden environmental change.
One thing about Neanderthals that we really have to understand
is that they were a small population.
And as soon as there was any major climatic fluctuation,
we had, probably, major demographic, er...crashes.
In Gibraltar, Clive Finlayson has found evidence that climate change
may have been a factor for these Neanderthals.
But although they were battling an ice age,
it may not have been the cold that was their problem.
When we look at the marine cores,
which give us a long climatic record,
there's a point where, for some reason,
the region is suffering from severe droughts.
It's...it may be coincidence,
but that moment is the moment where we lose the Neanderthals here.
And after that, we have modern humans.
It's perfectly possible
that these last populations were very stressed out.
They experienced droughts
like nobody had experienced for a quarter of a million years,
and it may have been what tipped them over the edge,
which is a new angle and a different way
of seeing how these things could have happened.
But it also tells us a very important story.
Neanderthals, we think, were extremely intelligent,
had fantastic technology,
they survived on the planet for longer than we have done,
and yet a successful hominid can go extinct.
There might be a message for us humans here.
When we were in Gibraltar,
it was hatching time for the seagull colonies living along the cliffs.
But it was also the time of year
when migrating black vultures fly past the rock.
We were riveted as the seagulls swarmed each vulture.
The huge, cumbersome black birds
became a metaphor for the Neanderthals -
a creature supremely adapted to a particular world, but going nowhere.
And it made me think how it might have been here,
thousands of years ago,
that the last Neanderthal disappeared from this earth.
It reminds me of sitting at the back of the cave and everybody had left,
and suddenly I thought, there must have been a last Neanderthal.
And the image of little Flint came to my mind and I thought,
maybe that last Neanderthal was a little boy like Flint,
and his parents went out hunting and never came back.
And that's the story of an extinction,
maybe at the personal level. And to me, that was very...
You know, maybe it was nothing like that,
but for me, that was so moving, that moment.
That little fellow, with that face,
sitting there waiting, and they never came back.
And the rest is prehistory.
Neanderthals disappeared.
And over the next 40,000 years or so,
we have taken over the whole world.
And here we all are today,
seven billion of us.
But the latest scientific evidence is now showing
that the Neanderthals weren't completely wiped out.
Instead, we absorbed them.
In some ways, the Neanderthals are still with us today.
This revelation was made possible by a remarkable genetic breakthrough
made here, at the Max Planck Institute in Leipzig.
When I started out studying human evolution,
I would never have believed that the Neanderthal genome
could ever be decoded.
But now we're standing in the place where it happened,
about to meet the man who made it possible.
Svante Paabo, the godfather of ancient DNA.
This is a Neanderthal.
Yes, it's a reconstructed Neanderthal skeleton.
It comes from several different, um...finds.
There is no such complete Neanderthal skeleton ever found.
So this is a Frankenstein, almost?
Yes. They have put this together.
Why's it in two pieces? What's happened?
That is because my 11-year-old son was in here once with a friend,
and this happened. THEY CHUCKLE
When I was studying evolution to start off with,
there was this ongoing debate as to the relationship
between the Neanderthals and ourselves.
And it was, you know, are we descendants of them?
Are they the same species as us? Are they this...?
And for 150 years, archaeologists and paleoanthropologists
have been arguing this, and then you came along
and you revolutionised the whole of this discipline.
Well, it's a group effort, of course.
I mean, sequencing, a lot of people worked on that,
a lot of people analysed it.
So here we are. Where are you taking me?
In the basement. Don't be scared. It's this way.
SHE LAUGHS
I'm not even slightly terrified!
To isolate Neanderthal DNA,
scientists in the basement of Svante's lab
took precious samples of Neanderthal bone, ground it up,
and from the resulting solution,
were able to isolate tiny fragments of ancient DNA.
Piecing those fragments together,
they were able to reconstruct the whole Neanderthal genome.
The complete genetic blueprint.
And the greater surprise from this extraordinary breakthrough
was that it showed that we modern humans
had inherited Neanderthal genes.
And there's only one way that could have happened.
Somewhere between 50,000 and 90,000 years ago,
modern humans come out of Africa and they meet the Neanderthals,
perhaps somewhere in the Middle East, and they have sex,
and the result of that is that
if you have, say, a Neanderthal father and a modern human mother,
the first generation, the offspring, is a hybrid
that has one chromosome from its father, the Neanderthal,
and one chromosome from its mother.
And over time, in each generation,
those pieces of Neanderthal DNA get smaller and smaller
until we have what we see today in people outside Africa,
these small pieces of Neanderthal DNA that persist in the genomes
of everyone that lives outside Africa.
To understand who has Neanderthal genes today and who doesn't,
we need to understand human migration.
So the story starts in Africa,
where the first hominin species all evolved.
It was here, about 600,000 years ago,
that we shared a common ancestor with the Neanderthals,
but then the lineage split,
and the group that eventually gave rise to the Neanderthals
left Africa, moved into Asia and Europe,
and they lived there for hundreds of thousands of years.
And then, about 100,000 years ago, modern humans also left Africa.
And before the Neanderthals went extinct, they interbred with them.
And that group, as a result, carries Neanderthal DNA.
That group of modern humans spread across Asia,
into the Americas and across the whole of the Pacific.
So today, everybody from this huge part of the world
still carries Neanderthal DNA.
In fact, on average, each of us can trace 2% of our DNA
back to our Neanderthal ancestors.
The only people today who don't have Neanderthal DNA
are the people of Sub-Saharan Africa.
And that's simply because their ancestors never left Africa,
and so never met the Neanderthals.
I've had my DNA tested,
and 2.5% of it is of Neanderthal origin.
That sounds like a lot.
But just how much Neanderthal DNA is there out there?
And what does it do?
I went to University College London
to see my friend, Professor Mark Thomas.
He's one of the world's top geneticists.
And this is his clean lab, where they isolate ancient DNA.
OK. So...let's just see.
Are you sizing me up? Yeah, I'm sizing you up.
That should be fine.
Mark's helped pioneer the protocols for making sure that ancient DNA
doesn't get contaminated during the extraction and analysis process.
This is just the first pair. Right.
And then we put on the second pair.
The biosecurity measures are so tight that not even our camera crew
are allowed into the lab where Mark and I went
to discuss just how Neanderthal we all are.
People talk about most non-Africans having something like
2% Neanderthal in them, OK? In their genome.
But here's the thing -
the bits of Neanderthal that you've got in YOUR genome,
some of them are different
from the bits of Neanderthal that I've got in my genome.
So although each of us might only have, say, 2%,
between us, we might have 2.5 or 3%.
And if we take lots and... You know, if we take lots and lots of people
from all over the world,
well, it turns out that theoretically,
we could have up to 70% of the Neanderthal genome
spread out all over people all over the world.
70% is a huge number.
Some other estimates have been lower,
but whichever is correct,
it still means there are scores of Neanderthal genes
floating around in the human population today.
But what do all these genes do?
The fact that so many have survived suggests that the Neanderthal genes
must have benefited us in some way.
It seems that all those thousands of years ago,
breeding with the Neanderthals
may have been a very smart survival strategy,
as modern humans migrated from the warmth of Africa.
So Neanderthals were living in Europe and in Western Asia
for 200,000 years before modern humans arrived.
And they were quite well adapted to that environment, right?
And then modern humans arrive and the things that they take away
from Neanderthals when they breed with them, and that they keep,
are the things that allow them to survive infections in that area,
to metabolise the foods that are available
and to live in the climate,
so to survive, whether it's high altitude or lower light conditions.
We see these things in regions where more people share Neanderthal DNA.
So it's a bit like a cheat, effectively.
You've got a species that is already adapted to that environment,
and then we come out of Africa and we're like,
"Actually, we could interbreed with you guys".
It's not so deliberate, but actually, it kind of makes sense.
It does make sense.
"You guys are adapted. You know how to deal with the landscape.
"I'm going to pick up tricks from you guys."
But while Neanderthal genes may have given us an advantage
in the distant past,
the question our scientists now have to answer is,
how do those Neanderthal genes affect us today?
Why is it so important to decode the genome, then?
Well, it has enormous potential to tell us about their evolution.
And, of course, their evolution is a part of our evolution.
And that informs us on things like our health vulnerabilities,
our vulnerabilities to disease.
Are there any Neanderthal genes that would be helpful to us now,
or, you know, take genes from Neanderthals
that helped them survive in some way that would affect human beings now?
Well, we have incredible variation in a class of genes
that have important function in immune systems.
And that's a good idea.
You want variation because it means we have the capacity
to respond to different diseases and disease threats.
In fact, it's so important
that it seems that we actually choose mates
who are more different from us than average
in order to maintain that variation.
So going and having sex with a Neanderthal,
from an immunity point of view, may actually be quite a good idea.
The idea that our Neanderthal genes may still affect our ability
to fight off disease is an intriguing one.
But is there any evidence that it actually happens?
At the Pasteur Institute in Paris,
Dr Lluis Quintana-Murci has been investigating
the origins of flu resistance.
Early modern humans come into Europe
and they found this new virus, for example,
to which they were not exposed in Africa.
But Neanderthal was adapted.
So by it mixing with Neanderthal,
it's a kind of quick way to acquire mutations
that allow early Europeans to resist flu infection.
So these are cells from modern humans, living humans, like us,
of both African ancestry and European ancestry.
So now I'm going to infect the cells with the Influenza A virus.
So we are putting the cells in the incubator at 37 degrees.
And in six hours, we are going to collect all the cells
and measure immune responses.
Once the cells have been infected,
the scientists can test to see how the different cell lines
respond to the infection.
And as you can see here,
the difference between the non-infected state
with the infected state.
So a major thing that we found is that Africans and Europeans
strongly differ in the intensity of their immune responses.
Europeans acquired from Neanderthals
mutations that are involved in the regulation of immune responses,
in particular, to viral challenges.
In other words, the European cells are much better at fighting off flu
because of the genes they inherited from our Neanderthal ancestors.
It's early days, but understanding how these genes work
may point the way to new approaches
to treating the flu virus in the future.
Let's try to understand and to dissect our past
to understand our present
and, eventually, predict and envisage future therapies.
Disease resistance is one definite advantage.
But not all our Neanderthal inheritance
is necessarily good for us.
We now believe that many of the traits we acquired
were those that would help us survive in an ice age.
But in the modern world, those same traits can be very harmful.
Neanderthals might, for example,
have developed ways of storing food in their bodies physiologically
to get them through those long winters in the north.
And we've picked that up.
Now, that's good news in a Palaeolithic world
with long winters,
but it's bad news when there's a McDonald's around the corner.
So, you know, it may be that Neanderthal DNA is also responsible
for some of our conditions linked with things like obesity.
Can we add type two diabetes to that list?
Yes. So there's evidence that diabetic conditions, you know,
the storage of fats and starches,
these may be correlated with the presence of Neanderthal DNA.
So in the future, I think this will be important for therapy.
It's been shown that if you carry the Neanderthal version
of the gene SLC16 A11,
you are 25% more likely to have type two diabetes.
It's the Neanderthals' revenge on us.
And diabetes is just one disease.
Scientists now believe that our Neanderthal genes
are having a much wider impact on our health.
At Vanderbilt University in Nashville,
Tony Capra is using all the power of modern technology
to discover what our Neanderthal past is doing to us today.
I never imagined when I started working on computational genomics
that I would be exploring
the effects of Neanderthal DNA in modern humans.
And I never dreamt
that we would be able to look back at these events in the past
and understand the legacy that they have on us today,
and potentially may continue to have in the future.
To explore that legacy,
Tony is analysing DNA from human blood samples.
So here we're coming into the home of the biobank,
the main room, where all the samples are processed and stored.
And so, when you say biobank, what do you mean?
So I mean that this freezer over here contains
more than 230,000 DNA samples
from patients who have been treated at Vanderbilt Hospital.
And what do people say when you tell them that you study the effects
of Neanderthal DNA on disease?
It's amazing. People get really, really excited.
The most often response
is that people want to donate their blood.
They're like, "Can I send you my blood"?
I get an e-mail like this several times a week.
"I've got hair on my toes, did that come from Neanderthals?"
I've gotten that one a couple of times.
So in here, we have the actual samples,
so 230,000 people's DNA.
So everything that it took to make that person
is in one of those little vials.
Actually, that blows my mind.
Everything that it would take to make that person is in here.
So effectively, there's 230,000 people...
Little person-instruction booklets, how you make life.
Person-instruction booklets! I love that!
We never get to go in there.
This robot is lucky enough to be the one who goes and pulls out samples.
It's freezing. Yeah, yeah. What temperature is this?
It's negative 20.
It is Nashville, Tennessee, so this is, like, really nice.
This feels nice. During the summer,
I'll just come here and open the door for a while.
The lab manager yells at me, but it's the only way to cool off.
We should probably close that door because... Yeah. It's cold.
Also there's, like, 230,000 people in there.
Keep them locked in. Keep them in there. Good people.
In the freezer, we have the DNA material,
but to analyse it, we actually need to know the sequence of the DNA,
the As, Ts, Cs and Gs.
Each one of these eight squares enables us to test
the DNA of an individual
at 2.5 million positions in their genome.
So this is eight different people on here?
So one, two, three, four, five, six, seven, eight. Right.
Then this information gets put into a computer,
and that's where, for me, the fun starts, because then we can look
at each one of these individuals' genomes
and see which of those 2.5 million pieces of DNA
came from Neanderthals.
So you're looking at the effect of interbreeding with Neanderthals?
Mm-hm. The DNA that you and I might have in us?
Right. And how that links up,
or is associated with various diseases?
Exactly. So does it?
Yes. And that's the amazing part.
The more we look, the more effects we find
of Neanderthal DNA on modern humans.
And it's affecting our skin, it's affecting our immune system,
it's affecting our risk of cancer,
it's even affecting certain neuropsychiatric disease,
like our risk for addiction.
And we also are finding suggestive evidence
that Neanderthal DNA influences some of our bone traits,
and that's really exciting.
So things like osteoporosis,
or risk for certain types of fractures.
Computational genomic research like Tony's is,
of course, only the first step on the way to developing
new approaches to treating many of these conditions,
conditions influenced by the downside of our Neanderthal DNA.
The decoding of the Neanderthal genome is helping us understand
how the genes we share affect us today.
But crucially, it's also helping us understand
the differences between us and our Neanderthal ancestors,
which is where this strange-looking thing comes in.
It's a bunch of nerve cells called an organoid,
and it was made by Benjamin Vernot
and his colleagues at the Max Planck Institute.
An organoid is kind of like a mini brain, right?
It has some of the characteristics of a brain.
It's not actually a brain,
it's not connected to anything, and it's very tiny,
but it does have neurons,
and the neurons behave in many of the ways that the neurons behave
in an actual human brain.
We think that some of the major differences between modern humans
and Neanderthals are found in the way our brains develop and operate.
So the Max Planck team are building human organoids
and slowly making them more and more Neanderthal.
As they do so, it will reveal the differences
between our brains and theirs.
So one of the cool things about Neanderthals
is that we only split with them about 600,000 years ago,
which, in evolutionary time, is pretty recent.
And so we can figure out what are the things that have happened to us
in the last 600,000 years.
It's early days in the research,
but it's already been suggested that modern human brains
went through a rapid period of evolution
after we split from Neanderthals.
And although that may have made us smarter,
there were also downsides
in that we may suffer from more mental and cognitive disorders.
There's certainly some thinking that neurological diseases
are involved in breaking very new things that humans have developed,
genes that are important for the functioning
or development of the brain.
Schizophrenia, right? And autism. Autism, yeah.
We see that a third of the genes that changed in our evolution
are linked to these diseases.
So these might be, it's just a theory at this point,
but these might be the cost we pay for these changes.
Is the major difference between Neanderthals and modern humans
in the way our brains have evolved?
Now, it's still a controversial idea,
but intriguingly, there's archaeological evidence
that points to a major difference between Neanderthals
and modern humans and a point of life
crucial to brain development.
Childhood.
For clues to how Neanderthal childhood
was different from our own,
I asked Libby Cowgill to show me around the collection
in the Smithsonian Institution.
So this guy is kind of... He's kind of near and dear to my heart.
This is probably one of the best-preserved baby skeletons
that we have of a Neanderthal.
Basically, if you make it to five in a hunter-gatherer population,
you're probably doing pretty well.
So theoretically, there should be lots of juvenile fossils,
but there's really, really not.
They're pretty fragile.
There may not be many bones around from Neanderthal children,
but the ones we have can tell us a surprising amount about their lives.
The guy who did this particular bronze, his name's John Gurche,
he's a pretty famous scientific artist.
He called me and he wanted to know
about what a baby Neanderthal would've looked like.
The thing that I really like about what's going on here is,
it looks she's teaching him.
She's holding this hide
and is about to show him how to work behind the hide
while holding it with her teeth.
They're using, essentially, their teeth... Mm-hm. Yeah.
..as a third hand. They are.
A large number of Neanderthals' front teeth are worn down
from a lifetime of doing this behaviour
of holding on to things with their front teeth.
Kids have a little bit of wear on their teeth, too.
So this behaviour actually started off fairly early
during growth, and then you just did it your whole life long.
To better understand what is going on in this sculpture,
we asked Andy and his team to bring the scene to life.
Now, I'm going to film it with a virtual camera,
so I'm going to give you that.
This probably would have influenced the children's bones
in just the same way that it does the adults',
where we start seeing signs of the kids developing strong bones
and asymmetrical bones at a fairly early age.
Once the animators have translated the motion-capture footage
into graphics, it becomes a familiar scene.
A parent teaching a child.
But the Neanderthal child is learning to do the same work
that the adults performed.
And the fossil evidence, this time from the teeth,
suggests that, for the Neanderthals, childhood was short.
So we have to set this container here.
Microscopic X-rays show that just like trees, teeth grow in rings.
These rings act like a journal
of people's lives and patterns of growth.
Reading the rings tells John Jacques that Neanderthal children
matured faster than modern human kids.
When we look at the speed of developments,
especially based on these structures in the teeth,
Neanderthals seem to be on the end of the modern variation
that is the fastest.
I mean, if you're saying accelerated juvenile periods, how accelerated?
Oh, we are talking about 20% faster.
Right. That's quite a bit. Yeah.
So it means maybe they would reach puberty and reproduction
two, three years younger than we do.
Because they live short lives,
they can't afford to spend all that time growing up into adulthood
because it's costly, it takes a lot of time,
it leaves very little time for reproduction.
So they have a longer period of time being reproductively active,
otherwise they are not going to survive.
This sheds interesting light on Neanderthal childhood.
There wouldn't have been much time to waste.
And there would have been little scope for play,
as the young Neanderthals learned the skills they needed to survive.
For modern humans, the story is different.
At the same age that a Neanderthal child is having to work and hunt,
we are still playing with childish toys.
And that's a good thing.
It gives us time for our brains to develop
and for us to harness the power of our imagination.
SQUEAK!
Neanderthals have been extinct for nearly 40,000 years,
but their legacy still lives on inside us today.
And in the 21st century, we can use our imagination
to envisage modern humans and Neanderthals meeting once again.
Now we know so much more about Neanderthals,
we can wonder who would win in a matchup between them and us.
We know that on a physical level,
the Neanderthals would have us beaten.
They may have been shorter than us,
but they were much faster and more powerful.
HE YELLS
But perhaps it's the ability to harness our imagination
that would give us an intellectual advantage,
a speed of thinking and a cutting edge
that would allow us to deliver the knockout blow.
Maybe that's what drove the Neanderthals
to their eventual demise.
But the only way we can know for sure
would be if we could actually meet a Neanderthal today.
Face-to-face, we could answer all our questions about them.
That may seem like the stuff of fantasy,
but thanks to modern genetics, it may now be a possibility.
I think one of the most interesting things
about when the Neanderthal genome was first sequenced
is that one of the headlines that came out, of course, was,
"We're going to bring back a Neanderthal".
Because if you've got the DNA code, the thinking is, we're done,
that's, like, the first step.
I mean, that's...
First of all, it's controversial, but how realistic is that?
Yeah. Is that possible?
You know, if you'd asked me ten years ago,
I'd have laughed and laughed and laughed and then laughed some more.
Now, I would just laugh a little bit.
THEY LAUGH
It might sound like an outrageous proposal,
but serious consideration has already been given
to bringing back other animals
that lived at the same time as the Neanderthals.
The long-extinct woolly mammoth
is very dear to the heart of Harvard's George Church.
He's a pioneer of gene editing
and a thought leader in the growing movement of de-extinction.
We went through all the different animals
that you could, um...make less extinct,
and the distance between the woolly mammoth
and the Asian elephant is tiny, genetically.
They're very closely related.
A very small number of edits needed to turn one into the other.
It could be just as easy to turn a modern human
into a Neanderthal through gene editing.
And theoretically, at least, it's a possibility.
We could make a start now.
I mean, it would take quite a long time,
but if you have that kind of embryo-level selection
or sperm-level selection,
then it could potentially be accelerated.
I don't know what you're telling me, Mark.
MARK LAUGHS I feel like Mark's trying to get me to...
You know, after a bit of time,
you'd learn to accept your little Neanderthal baby.
I would love the Neanderthal child.
It'd be like, look, it's a bit more strong and...and stuff.
The prerequisite before you can even talk about making a Neanderthal
by any method other than, um...dating,
is, er...
Can you manipulate the human germ line at all?
And so I've focused on the ethics of that
and flipped that on its head.
So, for example, the test-tube baby was a pejorative way
of dismissing a whole field that could help a lot of people.
But then when the first one was born, flipped 180 degrees,
so now it was unethical to prevent parents from having children.
But even if our notion of biomedical ethics
allows for bringing Neanderthals back,
is this something that's really desirable?
I'd love to meet a Neanderthal. It would be wonderful.
I don't know how I'd react. But on the other hand, you know...
..perhaps I wouldn't.
Because if it meant meeting a Neanderthal
because we had cloned one
or because we had discovered a relic population
that nobody had found before,
knowing the history of humanity, I'd rather it wouldn't happen.
Because we probably wouldn't deal with them very well.
You know, what would we do with a Neanderthal
if we found a population today?
Would we put them in cages?
Would we surround them by a fence?
Would we let them live like they were living?
What does history teach us of the way we have done it before?
What makes us think that it might be different
if we found a population of Neanderthals today?
Probably better that we don't.
Until recently, the popular image of Neanderthals
was of unsophisticated, brutish ape-men and women.
But we now know that was not the case.
We've discovered that physically,
the Neanderthals were much like modern humans.
And yet they were stronger and faster than us,
and brilliantly adapted to the Ice Age.
They developed technology and used tools
and lived in a society that looked after the elderly and infirm.
And although we may have had a hand in their extinction,
it's by no means certain that we were the superior species.
Neanderthals were around longer than modern humans have been around.
And as a population, they were much more stable than modern humans
in terms of being in harmony with their surroundings,
in terms of being sustainable.
In a quarter of the time,
we've managed to get the planet to a point where it's in danger.
Is that advanced?
I think the biggest question is, really,
what are the genetic foundations
for what sets modern humans apart?
Other forms of humans that existed for two million years
and never came to Madagascar, never to Australia,
never to the Americas.
There is extremely little evidence
that they ever spread across water
where you don't see land on the other side.
So I tend to say they were reasonable, they were not mad.
Then modern humans came around, and in, like, 70,000 years,
we spread not only to Madagascar, Australia and the Americas,
but to every little speck of land in the Pacific.
How many people must sail out on the Pacific
and just perish before you find Easter Island?
So modern humans are mad, if you like.
Maybe modern humans are mad, but for good or bad,
the planet is now ours and ours alone.
Honestly, I would have loved to have met a Neanderthal,
but Ned is probably the closest I'm going to get.
But the exciting thing is,
that Neanderthals still have so much to tell us.
See, until a few years ago,
Neanderthals were just this anthropological curiosity,
a few old bones from a long-ago extinct species.
But as we're understanding more about the genetics,
we can see that they're actually pretty integral to our own story
and how, by understanding them, we can learn so much about ourselves.