[woman chanting]
[Narrator] In every corner of the world today are humans.
Seven billion of us.
How did we come to so dominate our planet?
It's one of science's greatest mysteries.
Amazing new evidence suggests
it began with a single tiny group of people
who left Africa on an incredible journey.
With the help of bones, stones and genes
we'll uncover the trials their descendants left
across the world,
and find out how their journeys transformed our species
into the people we are today.
This time the final frontier,
the Americas
cut off from the world by mountains of ice.
[Jim] Ooh. Certainly don't want to go down there.
[Narrator] This is a story of ingenuity.
And danger.
Just how did we reach the Americas?
The Americas today
are home to almost a billion people,
living in nearly 50 different countries
and speaking over 700 different languages.
But of course, it wasn't always like this.
Not so long ago
no human had ever set foot in North or South America.
[helicopter whirring]
[Narrator] By the height of the last Ice Age
our species had occupied
Africa, Australia, Europe and Asia
for at least 15,000 years.
But the Americas remained untouched.
[helicopter whirring]
[Narrator] There were three very good reasons for this.
To the east lay the Atlantic,
to the west over 10,000 kilometers of Pacific Ocean
and to the north lay ice.
Almost the whole of Canada and Alaska were covered by it,
up to several kilometers thick.
It was 5,000 kilometers from north to south
and stretched from coast to coast.
It's hard to think of anything more dangerous or forbidding.
So just how much of a barrier would it have been to anyone
attempting to cross it?
[tools clinking]
[Narrator] Jim O'Rather is a mountaineer
who has scaled some of the world's tallest peeks.
He knows first-hand just how dangerous ice can be.
[Jim] It's so easy to break your leg
or to, uh, puncture yourself.
It's quite rotten here, isn't it?
[Narrator] A fall would easily be fatal.
[Jim] I've been on rope and fallen into crevasses
in White Oaks.
And hung hundreds of feet
without even seeing the bottom of the crevasse,
and looked down between my legs and just quivered hanging there.
[Narrator] Even with modern equipment,
hyperthermia, frost bite and dehydration
are serious risks.
So imagine what it would have been like in the ice age,
without the gear carrying all your food for the journey.
[Jim] Stand on it, and then it disappears on you.
[Narrator]But would have simply been impossible.
But what's extraordinary and baffling
is that somehow Stone Age people did make it to the Americas.
To a land that was, to all intense and purposes,
totally unreachable.
[Jim] Whoa!
[grandiose music]
[Narrator] Our quest is to find out how they did it.
-[chanting indistinctly] -[drum banging]
[Narrator] In Calgary in modern day Canada
the native American Tsuu T'ina first nation
has gathered for one of the most important events in their year.
They're hosting their annual powwow.
[man] All right, give them a round of applause,
ladies and gentlemen.
[Narrator] The Tsuu T'ina are descendants
of some of the first people to reach to America.
They're our proof that human kind made it here.
But the question for us
is did they arrive before or after
the North American ice sheets disappeared?
Like most native Americans
the Tsuu T'ina believe
they have always lived in this land.
But maybe there's something
in their own story of their origins
which can give us hints about the world
their ancestors lived in.
The story begins in the north.
[Bigplume] Well, what was told to us by our ancestors,
[...], the old people,
was that thousands of years ago,
we were one huge tribe, the Dené.
We were mitigating south because the ice.
The legend goes on to say that,
um, there was a grandmother with one of her grandchildren
who spotted a horn in the ice
as we crossed over the Great Lakes up north.
The child was asking for that horn
so they proceeded to...
uh, chop away at the ice
to dig out the horn for the child.
It magically separated the ice.
[drum rumbling]
[Bigplume] Cracked and split in two.
So the clans that were on the south side
continued to mitigate south,
the ones who were left on the north
stayed in the north,
that's how the story is always told.
[Narrator]This tale of a great family journey across the ice
seems to give us a clue
to how long the Tsuu T'ina have been here.
Back when this was a land of ice.
[man] Okay, let's hold them into the gate.
Wow, Look at that.
[crowd cheering]
[Narrator] And perhaps just as intriguing
is something visible in their faces.
They have distinctive features,
high cheek bones,
a comparatively flat face and almond shaped eyes.
It's a look we've seen before on the human journey,
though a long way from here.
In Siberia, over 6,000 kilometers west of Calgary.
The Evenki people of northern Siberia
share the same facial characteristics.
And the similarities are not just facial.
The tepee of the Native Americans
bears a striking resemblance to the chume
the Evenki use when on hunting trips.
Could these similarities hold the key to the origins
of the native Americans?
Scientist Tracy Literre from Cambridge University
has a particular reason
to be interested in this question.
She herself is a member of the Colville Indian tribes
of Washington state,
and is studying the history of Native Americans.
One of the tools she uses to find out about her ancestry
is Mitochondrial DNA.
A genetic fingerprint stored within each of our cells
that's passed on through the female line
from mother to child.
It's a science that hasn't always been popular here.
There is some controversy
surrounding genetic research among native communities.
A lot of times in the past there's been research conducted
without the knowledge
of the tribes that are under study.
Many native communities believe that your biological resources
or their bodily tissues, hairs and fluids are sacred.
[Narrator] But by working with Native American communities,
scientists like Tracey
have been able to discover a surprising amount
from their DNA.
All living Native Americans
from North to South America belong to one of five lineages
and can be traced back to southern Siberia.
For many years scientists have been suggesting
that there is a link based on the physical attributes
and i think genetics now proves that.
[Narrator] The latest genetic research
suggests that we all originate from Africa.
Around 70,000 years ago,
a tiny group of us left the continent.
Their descendants went on to populate
Asia, Australia and Europe.
And genetics now helps us extend the story to America.
It suggests that the ancestors of all Native Americans
originally came from Siberia.
And what's more,
the evidence implies they entered America
sometime during the last Ice Age.
Around 15 to 18,000 years ago.
So it seems like people mitigated
from Siberia into America at a point when North America
was under the impenetrable sheet of ice.
Today Siberia and Alaska
are separated by 80 kilometers of water,
but 20,000 years ago,
what we know as the Bearing Straight
was part of a vast swathe of land,
a long-lost continent known as Beringia
which could have taken people as far as Alaska.
But this doesn't explain how people entered America,
because once they had crossed the land bridge
the way was still blocked by the massive wall of ice
stretching east to west.
So how and when
did the first people enter America,
south of the ice?
It's a question that has puzzled scientists
for decades.
In 1933,
archaeologists working in the western United States
unearthed a beautiful stone object.
It was an ancient tool
later dated to some 13,000 years ago.
The stone tool was one of the first of many
almost identical
to be uncovered across the United States.
They were given a name
after the place where several of them were found,
Clovis.
They were the earliest known evidence
of people living in America.
But no one knew how these people had got there.
[wind howling]
[Narrator] Today, modern climatologists
can look back in time
and stimulate the weather conditions
of the past.
Maybe this can help us find out
how people could have made it past the ice.
But 22,000 years ago,
we can see the vast sheet of ice.
But around 13 and half thousand years ago, it parts
and a corridor emerges,
from northern Canada
to the heart of the United States.
Perhaps people entered America through the ice sheets.
It would certainly fit with the appearance
of the early stone tools.
So what do we know about these Clovis pioneers?
One way to find out about them
is to look at what they left behind.
Archaeologist Andy Hemmings
is an expert on prehistoric stone tools
and today he's recreating one of the Clovis tools.
[Andy] I've got a modern replica of a clovis point
that I'm in the process of hafting up
on a seven-foot spear.
There's a little groove cut in the end of the dart
and...
the spear fits inside it
and then we'll take some sinew
and... and just start wrapping it
snugly and firmly in there.
[Narrator] When attached to a shaft
these stone tools become lethal spears.
In Southeast Arizona there were eight Clovis points
found with one mammoth,
five of them were behind the back of the skull
and the front of the shoulder blades,
any one of which would probably have been a lethal wound.
At Clovis, they were found in the body cavity of mammoths
in the lung and heart area.
This is state of the art technology 13,000 years ago.
[Narrator] With no prehistoric beasts available today
to test the weapons on,
Andy has a novel way of demonstrating their power.
[tense music]
[glass shattering]
[Narrator] So what would it do to a mammoth?
[Andy] Us sticking that much through into the hay bales
so incredibly lethal
and now the animal somewhere about this far into it
has a projectile wiggling around.
Even minimal movement is incredibly painful
and debilitating so even a non-lethal wound becomes...
debilitating enough that with the rest of our darts
we're going to be able to kill this animal.
[Narrator] So early Americans
were armed with powerful weapons,
and were clearly formidable hunters.
In fact, some think they were so formidable
that they changed the world forever.
[rumbling]
[Narrator] And unexpectedly
the evidence for this
lies right in the heart of Los Angeles.
In a prehistoric treasure trove called, the La Brea Tar Pits.
[tar boiling]
[Narrator] The result of oil
which formed over 5,000,000 years ago,
these pits are the sight of over 3,000,000
archaeological finds.
If anywhere can tell us about the world
of the early Americans, it's this site,
one of the strangest archaeological digs on earth.
Tar pits are difficult to work in.
They're smelly and dirty
and it's impossible not to get stuck in them.
But for Dr. John Harris it doesn't get better than this.
[John] This paleontologist's dream to work here at La Brea
because you've got so many specimens
and they're so well preserved,
it's like a library of the Ice Age,
um, you never know what you might find.
[Narrator] The reason they're so special
is that thousands of years before LA was built,
the stickiness wasn't just an annoyance
it was a death trap.
It will only take two inches of this tar
to immobilize a horse.
[John] The scenario goes like this,
that a bison or a camel or a horse
would inadvertently step into the tar and get stuck
and that would attract saber-tooth cats,
and dire wolves to feed on it
and they in turn would get stuck.
So very quickly you build up the food chain.
[Narrator]Many of the animals which met their death at La Brea
are now extinct.
Strange almost mystical creatures known as megafauna
which lived alongside the early Americans.
Giant ground sloths,
the American lion,
and one of the largest mammals ever to walk the earth,
-the Columbian mammoth. -[mammoth growling]
The mammoth stood between 12 and 13 feet tall
- and weighed about ten tons. -[mammoth roars]
[John] Its thick skin and its size
would have been a deterrent to predators
but it also had a pair of ten-feet long tusks
which helped it to defend itself.
[mammoth growls]
[Narrator]The mammoth wouldn't have been an easy target
for Stone Age hunters,
but we know that they did kill mammoths with stone tools.
[mammoth growls]
[Narrator] In fact, some people think
that they were so good at it,
they hunted both the mammoth
and many other giant animals to extinction.
[mammoth growling]
[Narrator] And the story told by the megafauna remains
suggests this may well be true.
Because the record of mammoths and many other large beasts
stops around 13,000 years ago,
just a little after the first Clovis tools appear in America.
It's as if the animal's disappearance
is linked to people's arrival.
If this is true,
perhaps the extinction of the megafauna is another clue
to when humans arrived.
So we know these early Americans were tough and ingenious people
with sophisticated weapons
they hunted some of the largest animals on the planet.
And for much of the last century
experts agree that they first entered America
around 13,000 years ago,
down through the gap in the ice sheets.
But now, new discoveries
are threatening to undermine this entire theory.
And just outside the small community of Golt
in Central Texas,
is our first hint that the story might need to be rewritten.
Here in an unassuming field,
Mike Collins is leading the excavation
of one of the largest records of prehistoric human life
in all of the Americas.
[Mike] We have over a million and half artifacts.
An absolutely amazing number,
that's probably more than half
of the excavated Clovis artifacts
from all of North America
and we've only excavated
about three percent of this site.
[Narrator] The site is what is known as a base camp,
a place that people made their home.
[Mike] It was kind of a central operation,
where the whole social group stayed,
men, women, children.
And carried on a whole lot of domestic activities.
We found cooking, food processing, tool making,
they were clearly working leather working wood,
working bone, all of these kind of things.
[Narrator] Most of the finds are from the period of history
known as Clovis.
Around 13,000 years ago.
This has been thought to be when people first arrived.
But Mike's excavations throw a spanner in the works.
You know what's really exciting?
We've got stuff below that.
We have a layer below Clovis.
[Narrator] And to an archaeologist,
below means older.
[Mike] Right through here we get Clovis artifacts,
but as we dug down we continued to get artifacts below that
for about 20, or 25 centimeters more.
And they're absolutely
the product of human workmanship,
a nice flake here for example with a platform
we have one date from down here of 14,400 years.
That's a thousand years before Clovis.
And yes, we have to rethink our period time,
we have to come up with a new accounting
of the peopling of the Americas.
[Narrator] Because if people were living here at Golt
over 14,000 years ago,
this challenges the theory of the corridor through the ice.
It hadn't even appeared by then.
It's only a single date and Mike needs more evidence
but his team aren't the only ones
coming up with challenging theories
about the early Americans.
In 2007, research was published
claiming it wasn't humans
that killed the megafauna after all.
It was something far more dramatic.
[explosion]
[Narrator] Some scientists believe
that not long after humans first arrived in the Americas
a broken comet exploded above North America,
showering the land with debris.
The heat from these blasts were so immense,
it could have set fire to vegetation
throughout the North American continent.
[fire crackling]
Even today, the scientists find evidence of fires
in a mysterious black layer
embedded in the rock in sites across America.
Inside the layers are tiny spheres
like beads made of carbon
which only form in extreme temperatures.
If it was the comet explosion that created them,
it would have had a catastrophic effect on life in the continent.
With the vegetation gone,
mammoths would have struggled to find food,
so even if they survived the blast
they would have been faced with starvation.
If this is true,
the disappearance of the megafauna
may have nothing to do
with the arrival of humans after all.
And what's more,
some scientists are starting to doubt
that a migration through the ice sheets
would even have been possible.
[dramatic music]
This Canadian landscape may look beautiful on a summer's day
but in winter it's a very different picture
as trucker, Burt van Durvetting knows all too well.
[Burt] It can get very crazy here.
We see a lot of snow.
The area we're going to get into here in a little bit
has all these shoots coming down,
so they're slides and the highway is closed
a lot of the time because of these avalanches.
[Narrator] Even in the comfort of a modern truck,
traveling through this landscape
is a phenomenal challenge.
You can get freezing rain,
you can get real cold temperatures
around minus 20 and minus 25.
[Narrator] And we now know
that when the corridor through the ice first opened
it would have been far worse,
full of icy lakes, marshes and bogs,
constantly blown by a bitterly cold wind.
And with so little food people couldn't have survived.
So the theory that the first people entered the Americas
through this corridor is looking decidedly shaky.
And to find a new explanation
we need to look for the earliest evidence
of our arrival.
The site with the greatest claim to this
is in South America
in a part of Chile known as Los Lagos,
or the lake district
famous for its stunning volcanic landscape.
Some years back a stream in the area
became the site of one of the most important
archaeological finds in all of the Americas.
Local laborers working in the stream
accidentally stumbled upon an object,
sticking out of the bank.
On closer inspection,
it turned out to be one of a number of bones.
And when experts began to examine
the place in more detail,
it soon became clear that what the workers had found
was something more than mere animals remains.
Mario Pino was the geologist on the team
which excavated the remains of an entire human settlement.
[Mario speaking Spanish]
[interpreter] Among others,
the remains of a huge awning from a tent of rare dimensions
where around 20 people could sleep.
[Mario speaking Spanish]
[interpreter] The tent was heated with braciers,
small holes in the sand filled with clay
where they put hot coal.
Very different to the bigger bonfires outside
that were probably made for cooking.
[speaking Spanish]
[interpreter] The construction of the tent
required a lot of energy, a lot of work,
so it probably wasn't made for a short stay.
[Narrator]And 30 meters away they found another smaller tent,
so small only a couple of people could fit inside.
[speaking in Spanish]
[interpreter] The foundation is made of gravel and sand
and was glued with animal fat.
[Narrator] Inside the tent
they found the remains of several medicinal plants.
[speaking Spanish]
[interpreter] Very useful for many things,
analgesic, antibiotic and anti-epliectic,
incidentally they are still used by the Mapuche Indians
to cure these types of illness today.
[Narrator] And the team also found
some more familiar plant remains.
-[Mario speaking Spanish] -[interpreter] The leftovers
of the white potato
which apparently is the oldest potato in America.
[Narrator] The 50,000 or so items retrieved from Monte Verde
are now stored at the University of Southern Chile.
Many of the objects show signs of human workmanship.
There's a piece of wood
with what looks like a hole drilled in it.
a wooden stake and a piece of the hide of a mastodon,
an extinct elephant-like creature,
perhaps used to cover the huts.
Wood and hide normally decay very quickly
so you'd be forgiven for thinking
the finds weren't that ancient.
But in fact, they are so ancient
they've caused major controversy.
When their age was first announced
other archaeologists refused to believe it.
And it was not until ten years after the excavation began
that the implications of these finds
started to be accepted.
People were living in Monte Verde
fourteen and a half thousand years ago.
More than a thousand years
before the Clovis people of North America.
This shatters our theory of how humans reached America.
There's no way these people could have entered the continent
through the ice sheets,
the corridor through them just didn't exist.
There must have been another way in.
But how?
Maybe the finds of Monte Verde
can lead us to a different solution.
The site was littered with seaweed,
pebbles and salt, that all point to one place.
The sea.
Up till now,
we've assumed the people entered America from the north,
but is it possible
that instead of coming over land from the north,
they came from the south over the water.
[upbeat music]
Extraordinary as a 12,000 kilometer
sea crossing might sound,
in a museum in Rio de Janeiro
of a skeletal remains of a lady
which could convince us this was possible.
[Walter] What I have here is the skull of Luzia,
one of the oldest if not the oldest
human skeleton ever found in the Americas.
She died like, 13,000 years ago
and she was aged between 20 and 25 years.
[Narrator] Luzia was found in central Brazil in the 1970's.
Whilst she may not look unusual
her skull actually poses a puzzle.
Whilst today's Native Americans
share the wide high cheek bone face shape
of people from Siberia and East Asia.
Walter's detailed measurements show Luzia's skull is different.
[Walter] When one of the greatest differences
happens in the cheek bones.
You see that here
you have a very high cheek bone and flatten cheek bone.
When you look at Luzia you have very low cheek bones
and they are not flat as you saw in this Asian's skull.
[Narrator] And when experts reconstructed Luzia's head
in clay, the results confirmed their suspicions.
She didn't look Asian at all.
So who does she look like?
I show you what we discover,
we discovered that amazingly...
she looks much more like Australasians
than with East Asians or Native Americans.
[Narrator] Comparing Luzia
with skulls from the Australian region
Walter was able to identify
a number of striking similarities.
Given these similarities could
Luzia's ancestors originally have come
not from Siberia over the land
but from Australia by sea?
[Walter] Well, lots of people think
that because Luzia looking like Australian Aborigines
that we are proposing a trans-pacific mitigation
from Australia to South America to explain this.
If you take into account
the technology available to about 13,000 years ago,
that would be impossible.
We know these people did not have enough sailing technology
to cross such a long...
a longer way from Australia to South America.
[Narrator] In which case the ocean crossing route is out!
And despite her appearance,
it seems even Luzia's people
must have somehow come here by land.
So once again we're faced with our conundrum.
Archaeology suggests people were living
in South and North America
at a time when the land route into the continent was blocked
by an impassable barrier of ice.
But so far,
these archaeological clues
have not told us how they got there.
This seemingly impossible riddle
has stimulated scientists in many different fields
using many different methods,
they're all looking for an answer to the question,
"How did these people get past the ice?"
One reason archaeology can't tell us everything
is that some of possibly the best clues
are very difficult to dig for.
During the Ice Age,
so much water was locked in the ice sheets
that sea levels were much lower
and some of what is sea today would then have been land.
So maybe the land the early Americans crossed
and any clues they left behind are now underwater.
But there is one science we can turn to
which could help us uncover this underwater evidence.
It's a science that's more usually associated with crime,
forensics.
[reporter] On Sunday.
the partially clothed body of a...
[Narrator] When a young girl's body was found in a lake
near Vancouver in Canada,
it was identification of tiny particles in her hair
that helped convict her killer.
The man that did that identification is Rolf Matthews
a forensic botanist.
And when he's not helping solve murders,
Rolf uses his knowledge of minuscule particles
to recreate landscapes of the past.
So maybe his forensics
can help us uncover the path taken by our American ancestors.
The evidence Rolf uses
is something we wouldn't normally think of
as being very useful.
Pollen.
[Rolf] Pollen, even though it's microscopic,
is produced in huge quantities
as any hay fever sufferer would know.
Um, It also preserves extremely well in wet environments,
in fact, it can preserve essentially forever.
In a place like a lake bottom
where mud accumulates year by year in small increments
the pollen is trapped in that mud
and...
is buried at the bottom of the lake
and over time it builds up.
[Narrator] Because the pollen preserves so well,
Rolf and his colleagues are able to study samples
from thousands of years ago.
[Rolf] Now to get our history of the vegetation area,
we can use coring devices of various kinds
that are pushed down into sediments
like lake bottoms or bogs,
and we can recover cores much like this one
and this material contains a record of plants
from the Ice Age right to the present day.
That gives you like a book
a story of how the climate has changed.
[Narrator] Rolf and his team
studied samples from under the water
off the west coast of Canada.
When they analyzed them
they found a particularly distinctive type of pollen.
[Rolf] These pollen types here are sedges
and here's a typical example of a sedge pollen grain
that this characteristic triangular shape,
and they also all have these light areas
with the dark spots on them.
These are magnified 600 times.
[Narrator] As well as sedge
they found grasses and other plants
typical of wet swampy environments.
But the major discovery
was when they found out how old their samples were.
The pollen they were looking at dated back to 17,000 years ago
the last Ice Age.
Well, the interpretation of all the pollen
and the radio carbon dates
makes it very clear that
the coast had a growing thriving vegetation cover on it
when the mainland was still locked in the huge ice cap.
[Narrator] It seems that even whilst the mainland
was buried under ice,
there were places along the coast
where it had begun to melt enough for plants to grow.
This means, it's theoretically possible
that humans could have edged their way around the ice.
But the landscape Rolf's pollen grains tell us about
wasn't always warm or inviting.
Would there have been enough food
to sustain whole families?
To find out
scientists are turning to some unlikely helpers.
Bears.
[bear growls]
Strange as it sounds
their history may hold crucial clues about our past.
Over the last few years anthropologist Quentin Mackie
has been delving into the history
of these iconic creatures.
[Quentin] We've been looking at cave sites
on the Northwest coast of North America
that date to the end of the last Ice Age,
and in them we've been finding an awful lot of bear bones,
we've found over 6,000 bear bones
and most of them are little chewed up bits and pieces
but some of them are fairly nice bear bones.
This is for example, the skull of a brown bear
that died about fourteen and a half thousand years ago.
There's no sign of injury,
we think that the bear fell down a little pit inside the cave
and was trapped and couldn't get out
and died a lonely death.
This is a more typical little piece,
this is part of the leg bone of a juvenile brown bear
and this is actually the oldest specimen that we have,
and this dates to over 17,000 years old.
[Narrator] This is a surprising find
because it tells Quentin
that bears were able to live on the coast of America
before the Ice Age ended.
And this piece of information is curiously significant
for the human story.
[Quentin] You know bears by their nature are large
terrestrial omnivores they eat both plants,
they eat terrestrial animals and they eat marine resources.
They're quite territorial, they're slow to reproduce
they need a large territory,
in other words they're quite similar to humans.
[Narrator] So maybe if bears could find food in the ice age,
humans could too.
[Quentin] Humans are omnivores
and they would have been able to eat pretty well anything
that a bear would eat
as well as a whole variety of foods especially marine foods
that wouldn't have been accessible to bears.
So i think if it was a good environment for bears
which it clearly was, then it was a great environment
for humans.
[dramatic music]
[Narrator] And new research suggests there something else,
lurking under the water
which may have helped people survive right down the length
of the American coast.
Forests of kelp a tough buoyant seaweed
which can grow at the phenomenal rate
of up to half a meter a day.
Kelp forests make up
some of the world's richest ecosystems
and are teaming with life.
They provide nutrients for fish, crustaceans,
sea mammals and birds.
In fact, with so much living in the sea
these forests may have made
excellent hunting and fishing grounds
for people battling to survive on the newly ice-free coast.
And as varieties of kelp are found in Siberia, Alaska
and along virtually the entire length
of both North and South America,
some have gone as far as to call it the kelp highway.
So the idea of people moving into America along the coast
is starting to sound more likely.
The first migrants could have found refuge
in the ice-free sections of the western coast
and it seems that there would have been plenty of food.
But are there any clues that they actually lived this way?
An intriguing piece of archaeological evidence
may tell us more.
[engine revving]
[Narrator] Off the coast of southern California
is a craggy island called Santa Rosa.
Even today there's no daily ferry
and visitor numbers are limited.
The best way to get there is by air taxi.
But it's here in this isolated spot
that we find the key to how people may have lived
and travelled along the coast.
[birds squawking]
[Narrator] For museum curator John Johnson,
this island has a special significance.
Some years ago his predecessor
of the Santa Barbara Museum of Natural History
was on the island looking for mammoth bones
when he made an accidental discovery.
Back in 1959, Phil Ore got his vehicle stuck in the mud
right here below where we are right now.
And when he was looking around
trying to figure out how he was going to get his vehicle unstuck
he found two bones sticking out of the side of Arlington Cannon.
And these are casts of the original bones
just like the ones that he found.
There was this one femur that was pretty much complete...
you can see right here.
Uh, and then there's a second one here you can see,
these two bones were all that were left
of Arlington man.
[Narrator] For 30 years,
Arlington man's bones were kept in the museum.
And little was done with them.
Then in 1994 something happened.
I had a visit from a colleague of mine,
a specialist doing radio carbon dating,
and he told me he says
You know, John, you have the oldest dated human skeleton
in North America.
And i about fell out of my chair.
I couldn't believe that it was as old as he said it was.
[Narrator] Arlington man was alive 13,000 years ago.
What's so surprising about this date
is not so much its age,
but what it tells us about the life
that people were leading on the island.
[Johnson] The significance of Arlington man
being here 13,000 years ago
is that this island was ten kilometers from the mainland,
so the only way he could get here is by boat,
and that means that people are using watercraft
along the Pacific coast of North America
13,000 years ago
and probably exploiting coastal resources,
hunting sea mammals, fishing in the kelp beds
and gathering shellfish.
[Narrator]And some people think that the coastal waterway
was crucial to the journey of our American ancestors.
If they could cross ten kilometers
to reach an offshore island,
they could no doubt make short journeys down the coast
fishing and hunting in the water on their doorstep.
Perhaps this was how the early Americans
made the journey into the continent.
It's frustrating that pretty much
the only archaeological evidence is two leg bones,
but John has some evidence of another kind
which might make the picture clearer.
For the last 15 years
he's been involved in a project looking at the prehistory
of some of today's Native Americans,
using a database of DNA.
What he and the rest of his team have discovered
is nothing less than an ancient genetic route map.
[Johnson] A few years ago, a colleague of mine called me
and told me that a very rare type
of DNA had been found
in an ancient jaw bone from Southern Alaska,
that was found in a cave in Southern Alaska.
The remarkable thing is that this rare type of DNA
matched a rare type
that I also found here among the Chumash Indians
who live in this part of California.
[Narrator]And more excitingly,
when checked against a wider database of DNA samples
from Native Americans,
there were several other matches too.
In Northwest Mexico,
in the Kauppa Indians in coastal Ecuador,
the Mapuche Indians in southern Chile,
the Yargon in southern Patagonia
and in prehistoric burials in Tierra del Fuego .
Plotted on a map,
this DNA signature forms a pattern
all the way down the Pacific coast.
[Johnson] What's interesting about this distribution
is it's all Pacific coastal,
or almost entirely Pacific coastal.
This is the best evidence to date
that there was a coastal migration,
leaving behind these pockets of people
all along the western margin of the two continents.
And their descendants still live in this area today.
[Narrator] At last,
it feels like we could have found the key to this,
our final great human journey.
In this series we've seen how a small group of our ancestors
emerged out of Africa around 70,000 years ago.
Over the next 50,000 odd years,
their descendants traveled to the ends of the earth.
Eventually some of our ancestors began
to explore the Americas.
These people were skilled craftsmen and fantastic hunters,
at home on land and sea.
And the descendants of America's
Stone Age pioneers still live here today.
They like all of us are members of a young species,
and the study of bones, stones and genes shows
wherever we've ended up
we're all part of one family.
[closing theme music]