Nova (1974–…): Season 49, Episode 9 - Ice Age Footprints - full transcript
A look at what thousands of prehistoric footprints in New Mexico's White Sands National Park might reveal about the peopling of the Americas.
[♪ ♪]
KIRK JOHNSON: White Sands National Park,
New Mexico...
A vast, open desert that
holds clues to a lost past.
DAVID BUSTOS:
At White Sands,
all good stories sort of
begin with a Bigfoot.
JOHNSON: Footprints dating all the way
back to the last Ice Age.
All these circular things
are fossil footprints.
JOHNSON:
That's amazing.
[♪ ♪]
JOHNSON:
Mammoths over 13 feet tall.
(mammoth grunting)
Dire wolves, camels,
and enormous ground sloths
that roamed North America
thousands of years ago.
White Sands has so many
hidden treasures.
There's all these
trackways here,
it's just such
an incredible discovery.
[♪ ♪]
JOHNSON:
Alongside them,
something even more astounding.
- That is a human footprint.
- Yeah, so there's
a human footprint right there.
(laughing):
Wow.
JOHNSON:
Ancient human journeys
printed on the landscape.
When you make tracks in sand,
they just blow away.
When you make tracks in
a place like this,
where the chemistry
is just right,
the tracks can last forever.
(voice over): Now a team of experts
is investigating
how these remarkable tracks
could shed new light
on life in the Ice Age.
MATTHEW BENNETT:
There's a double trail.
Somebody going this way,
and somebody going that way.
JOHNSON:
Wow, that is really incredible.
(voice over):
How long ago were they made?
KATHLEEN SPRINGER:
That's amazing.
MAN:
Yeah.
SPRINGER: The Ice Age megafauna
went extinct
about 11,500 years ago.
So they're at least that old.
How much older than that
is really anyone's guess
at this point.
JOHNSON: Could they provide
new information about
early peoples of the Americas?
It really does
put our feet prints
firmly into the past here
in North America.
KIM CHARLIE:
Here's our proof.
Footprints,
footprints of our ancestors.
[♪ ♪]
JOHNSON: Can the secrets
of these ancient footprints
help answer the questions
when and how did humans first
arrive in North America?
[♪ ♪]
"Ice Age Footprints"...
Right now on "NOVA."
[♪ ♪]
JOHNSON:
The dazzling dunes of
White Sands National Park.
Sand as bright as fresh snow.
[♪ ♪]
But hidden within this landscape
are traces of an ancient story
dating all the way back
to the last Ice Age.
When we search
for evidence of life
in the ice ages
in North America,
we find things like
the bones of mammoths
or maybe even hearth stones
or spear points
from the people
that used to live here,
and very rarely we find
the remains of those humans.
But the story
is still so incomplete,
there's so much more
information we need to find.
[♪ ♪]
JOHNSON: That's why
the discovery of footprints
here at White Sands is
so significant.
Could they help answer
some of the greatest mysteries
of the Ice Age?
[♪ ♪]
The precise location
of this site
is a secret.
These dunes cover
nearly 300 square miles...
with some rising over 50 feet.
I'm driving through
these snow-white dunes.
It's kind of
a surreal landscape.
Once we get through the dunes,
we'll be out in
the great ancient lake bed,
and it's absolutely
covered with tracks.
(voice over):
I'm Kirk Johnson.
As a paleontologist,
I've spent most of my career
studying the remains
of ancient life.
But footprints can tell
really detailed stories
about the past.
[♪ ♪]
30 minutes later,
we've reached our destination:
A huge dried-up lake bed.
As the wind scours
this remote area,
new prints are being revealed,
and old ones disappear.
It seems like such an
improbable place
to even look for tracks.
(voice over):
Joining me is David Bustos.
He's leading
the team of scientists
investigating the footprints.
BUSTOS: You look out
and it's just bleak desert,
and who would think that there's
all these trackways here?
JOHNSON (voice over): As
my eyes adjust to the brightness,
round patterns start to appear.
So there's one there...
Yes.
And there and there,
and there and there, there...
BUSTOS:
Yeah.
Oh, yeah. Those are amazing.
Uh-huh.
[♪ ♪]
(voice over): The mysterious shapes
are over five feet apart,
and nearly two feet across.
These are the fossilized tracks
of an Ice Age giant...
a Columbian mammoth.
It died more
than 10,000 years ago,
but its footprints remain.
[♪ ♪]
(mammoth trumpeting)
The tracks are
preserved in various ways.
Sometimes the wind fills them
with different textured sand,
leaving ghostly impressions,
while others dry into hard casts
which are exposed
when the softer ground
around them erodes away.
One of the things that
really stand out at White Sands
is just thousands and thousands
of footprints preserved.
In this area,
we'll see trackways
that go for ten miles
in one direction
and two or three miles
in another direction.
You know, there might be
over 100,000 prints
throughout this large area.
Do...
it's okay to walk on them?
We can walk
near them and around them,
as long as we don't
disturb the surface below
or add more sediment in.
JOHNSON (voice over):
We need to be careful not to
step on the fragile prints...
and the team tries to only
visit the trackway areas
when the ground is dry,
and hard enough
to support their weight.
The surface is always changing.
We are seeing more erosion.
Every year, more and more prints
are becoming visible.
JOHNSON (voice over): And along
with the many mammoth prints here,
we soon spot traces of another
large creature.
BUSTOS:
They're very common,
they'll sort of
look like an S shape...
Yep.
You'll see them connecting to each other.
There's one here, right?
Yep. There's another one
coming through...
I think as well, right there.
JOHNSON (voice over):
Twice the size of a human foot,
and with giant, curved claws,
these are the prints of
a massive ground sloth,
a beast more than double
the weight of a grizzly bear,
that walked this land
thousands of years ago.
(sloth panting)
So that's sort of how the story
of White Sands began.
People, they've seen these
incredible footprints,
and they thought
that it was Bigfoot.
(chuckling):
Bigfoot with three weird claws.
Yes.
JOHNSON (voice over): Then we
discover something even more special.
That is a human footprint.
Yeah, so there's... there's a
human footprint right there.
(laughing):
Wow.
Yeah, so if you look...
That is amazing.
Here's the heel.
Okay.
Right here.
JOHNSON (voice over):
Scattered across the landscape
are human footprints
from thousands of years ago.
Each track is the
trace of an ancient person,
the shape of their bare feet
locked in the sediment.
Look at this,
this is amazing here.
This actually looks like
a human print right in there.
[♪ ♪]
JOHNSON (voice over): Could
these extraordinary human footprints
help answer two big questions:
When did people first set foot
in North America?
And did their arrival
contribute to
the disappearance of
giant Ice Age animals?
20,000 years ago,
Earth was
in the grip of an ice age.
The climate was colder,
vast ice sheets covered
much of North America...
and White Sands
was not a desert,
but a huge lake... Lake Otero.
[♪ ♪]
The lake shore surrounding it
teemed with life.
Giant ground sloths
wielding big claws
shared this wetland with
mammoths
weighing up to ten tons.
Alongside them,
packs of dire wolves
hunting for a kill,
and hardy North American camels.
These Ice Age giants disappeared
from the fossil record
over 10,000 years ago.
So the human footprints here
are probably at least that old.
[♪ ♪]
But they could be much older.
What can they reveal
about the deep history
of humans on this continent,
and how they met the challenges
of life in the Ice Age?
[♪ ♪]
To find out,
David has assembled
a team of scientists
to uncover the tracks'
hidden secrets.
BENNETT:
I'm confident in it now,
that that's mammoth, and
it links to your one in the,
um, that you've got
in cross section there.
- Cross section over there? Okay.
- Yeah.
JOHNSON:
One of them is Matthew Bennett,
a forensic footprint expert
from England.
[♪ ♪]
On the eastern side of
the ancient lake,
close to the restricted area of
the White Sands Missile Range,
Matthew is excavating
a remarkable set
of human footprints.
JOHNSON:
Hey, Matthew,
how's it going?
It's going well.
These are amazing.
They are.
Are these... so, are these
just the ones you've exposed
this afternoon, then?
Yep, there's a double trail.
Um, somebody going this way,
and somebody going that way.
How far do they go off
in that direction?
So, in that direction,
about three-quarters of a mile,
something like that,
and then they go to
the boundary fence
on the missile range
and an unknown distance
into the missile range.
[♪ ♪]
JOHNSON: How common is it to have
a track this long?
BENNETT:
Okay, so I've looked at tracks
all around the world,
and this, to my knowledge,
is the longest human trackway
anywhere in the world.
JOHNSON:
Oh, that's amazing.
Could it be the same person
going away and coming back?
Absolutely.
They're the same size.
It's actually
quite a small individual.
It could be a woman,
but could be
a male adolescent equally.
The size is...
- Looks like a size five or something.
- Yeah.
But the tracks are very big.
There's sort of
30% of the track,
maybe more is pure slippage.
It's very wet and
slippery conditions
as the individual
has been moving.
JOHNSON (voice over): Some
are clearly defined imprints,
but many are
stretched out and distorted,
an indication that
the walker was moving fast,
and slipping
on wet, muddy ground.
Some prints are bent
out of shape,
from a foot sliding sideways,
which could mean
the person was carrying
something on their journey.
BENNETT:
They were also carrying a child.
Oh, they're
carrying a child as well?
They're carrying a child.
How do you know that
they're carrying a child?
BENNETT: Along the trackway,
there are very small,
tiny little children's prints.
They sort of face
the direction of travel.
So if you imagine you were
carrying a child on your hip
and you wanted
to readjust, you...
you put it down...
Right.
...and then you readjust,
and there's
a few small child prints,
pick the child up again
and carry on.
Just over to here...
JOHNSON (voice over): A little
farther along the same trackway,
Matthew discovers
a twist in the story.
The travelers were not alone.
What's this
unusual set of tracks?
So there are a series
of sloth tracks here
entering from, from...
to the left there...
So this is the first one.
And then it comes out over here.
That's really the amazing one,
you can see the claws
of the sloth so clearly.
BENNETT:
You can, yeah.
It's a beautiful,
a beautiful track.
They're not large tracks.
Yeah.
So it's a relatively
small sloth.
Bear-size,
I would have suggested.
JOHNSON (voice over):
Was this sloth here
at the same time as the humans?
The sloth's footprints
are right on top of
the outbound human track.
Which means this animal
must have arrived
after the travelers
first passed by.
Where do they actually
step on the human track?
So...
Is it this one?
It's actually just over there.
There's an example where they,
they cut across the human track.
But the sloth did
something quite cool.
It seems to have gone from
all fours up onto its hind legs.
It's done
a little dance around...
And then it goes off that way.
So it crawls in kind of
like sloth-like,
and then as it gets here,
it kind of pivots around and up
and looks, looks...
Looks, scents the air, and off.
...and pivots
and then heads off that way.
That's correct.
A little sloth dance.
Yeah, that's exactly what it is.
JOHNSON (voice over):
Matthew thinks the sloth
noticed the human tracks
and reacted.
Either the sloth's either
visually responding to the track
or it smells something.
My instinct is smell.
It basically reared up to scent
the air a little bit more
and then decided to,
to disappear off.
They're not here
at the same time,
but within a few minutes,
hours of each other,
they're here.
(chuckling):
That's a phenomenal thing.
Some small person
having a stroll
on a landscape full of
giant ground sloths.
(voice over):
The tracks at White Sands show
just how close humans here
came to Ice Age animals.
Imagine what
it must have been like
to meet one of these
enormous beasts in the flesh.
(sloth groaning)
[♪ ♪]
You can get a sense of
these Ice Age encounters
at La Brea Tar Pits
in Los Angeles.
Here, animals that wandered
into tar deposits were trapped,
and their bones were preserved.
In the last century,
experts have unearthed
more than a million fossils
here.
EMILY LINDSEY:
Hey.
Hey Emily, how are you doing?
Good, how are you?
Nice to see you again.
Good to see you.
Welcome to the Tar Pits.
Thanks.
Oh, here's our sloth, huh?
Yeah.
This thing is amazing,
so massive.
It's majestic.
JOHNSON (voice over): Curator Emily Lindsey
works with fossils of the giant beasts
that lived in North America
during the last Ice Age.
So how much do you think
this guy weighed?
Probably more than a ton.
And when people
talk about sloths,
they talk about
how they move so slowly,
would this guy have
moved slowly?
You know,
it wouldn't have been like,
a runner...
Yeah.
...but it wouldn't have been
so slow as the modern sloths
that are really only adapted
for living in trees.
What would
an animal like this eat?
So they were mostly herbivores,
and it looks like they
were eating a lot of
kind of desert shrubs
that would have
been prevalent in the area.
Sloths are part of this
very strange group of animals
called Xenarthrans,
and it includes the sloths,
the armadillos,
and the anteaters.
And like armadillos,
some species
produced bony armor,
only in this case,
it's in the form of these
small sort of pebble-like bones
that were embedded
inside its skin.
Oh, that's why
I love sloths so much.
(laughing):
They're so cool,
they're such amazing animals.
Yeah, they're one of the
weirdest animals,
and it's a piece of ecology
that has just
completely gone from earth.
(indistinct chatter)
JOHNSON (voice over):
Nearby, I've spotted another
lost species whose tracks
we see at White Sands.
This is an amazing beast,
isn't it?
Yeah, the Columbian mammoth.
JOHNSON (voice over):
From fossil evidence,
we know that mammoths
arrived in North America
around 1.8 million years ago.
When you stand beneath the
skeletons of these huge animals,
you can't help but wonder,
why did they go extinct
less than 13,000 years ago?
Was it because of
a change in climate?
Or human influence?
Or a combination of the two?
LINDSEY: It seems to have
been a really rapid event.
As we we're
coming out of the Ice Age,
we're going through all
these big climate upheavals,
so we need to know
how much overlap
there actually was
between when humans arrived
and when the
last animals disappeared
in order to know what role
humans might have played
in that extinction.
[♪ ♪]
JOHNSON (voice over):
The footprints at White Sands
might be the oldest human prints
ever found in North America.
They could shed new light on
the lives of Indigenous peoples
and their long history
on this continent.
It's, it's just so amazing
to see these tracks...
There's another one
crossing there.
Yeah.
JOHNSON (voice over):
Today, I'm visiting
the U.S. Army's
White Sands missile range,
just across the boundary
from the national park.
Here there are
more animal prints,
including those of a mammoth,
and this magnificent trackway
of a ground sloth,
crossed by the footprints
of an ancient camel.
Can you imagine this whole area
with all these animals here?
Would have been
amazing, huh? (Sighing): Oh.
Mammoths, sloths, cats, dogs.
Yeah.
Right?
Yes.
I always say we need
to build a time machine.
(laughter)
JOHNSON (voice over):
Joining me are Joe Watkins,
an archaeologist and member of
the Choctaw Nation of Oklahoma,
and Kim Charlie from the
Pueblo of A coma in New Mexico.
They want to
see the prints for themselves,
and learn more about
the people who once walked
across this landscape.
We have this tie
where us Native Americans
have been here
for a very long time.
And I believe that, you know,
I really believe that.
And that ties back into,
you know,
our migration stories where
we evolved somewhere,
but we don't
specifically know where.
These are stories that
we believe in our hearts
as tribes,
pueblos, you know, that we take,
that we hold sacred to us.
So when we come back to
these areas
and we find
evidence of footprints
of our thousands of
great ancestors,
you know, we just kind of, like,
it's amazing.
So we did exist here.
The tribes talk about
going way back.
We all talk about
having been here forever.
We've never been anywhere else.
We have the evidence,
it really does
put our feet prints
firmly into the past here
in North America.
These are our relatives.
We've been here since
time immemorial
and hopefully we'll continue on.
JOHNSON (voice over):
When Europeans arrived
on this continent,
they began a pattern of
ignoring the rights and stories
of Indigenous peoples.
With the colonization
in the 14, 1500s,
a lot of tribal histories
have either been lost
or have been pushed back
or have been tossed aside.
This was once
our land, you know.
Mother Earth was our mother... Mm-hmm.
...and we're
the descendants of her.
And we're the people
that try to take care of it,
but you've got the
Western people
have come in and just
taken over areas where,
you know, they have no respect.
Please understand that
we Native Americans
were here first.
It's kind of an awful thing
where we've been put on
little reservations.
You know, where we once had
the freedom to roam.
[♪ ♪]
JOHNSON (voice over):
European-Americans not only
took control of
Indigenous territories,
but some also spread
misleading narratives
about Indigenous people.
(indistinct chatter)
[♪ ♪]
WATKINS: There's pretty
much always been a conflict
between archaeologists
and American Indians.
In many ways,
archaeologists have taken over.
They've sort of colonized
American Indian history,
and they felt that they,
they're the ones
who tell
the true story of the past.
So there's been
that conflict between
whose story is the true history.
Archaeologists also
came out to
archaeological sites,
started excavating,
took the materials,
took them back to museums,
and tribal people
never saw them again.
[♪ ♪]
JOHNSON:
Over the centuries,
some white scholars
used archaeology
as a way to dismiss
Indigenous people's accounts
and ancestral connections
to the land.
It really wasn't
until 40 years ago
that Indians had a say in
who was excavating
and what happened with the
results of those excavations.
[♪ ♪]
JOHNSON:
Here at White Sands,
the scientists are consulting
with local tribes
and pueblos to study and record
these important prints.
They hope to solve one of
the biggest mysteries of all:
When did humans first arrive
in North America?
Fossil records show that by
at least 100,000 years ago,
modern humans... Homo sapiens...
Began spreading
from Africa across the planet.
The Americas
were surrounded by ocean
and out of reach.
But during the last Ice Age,
massive ice sheets formed
and sea levels
dropped by over 400 feet,
exposing land
between Siberia and Alaska.
Many scientists agree
that this is how humans
got to North America.
But when exactly
did they first arrive?
Throughout the 20th century,
many archaeologists
thought the answer lay in
these stone projectile points
found all across North America.
They were made by people from
what became known as
the Clovis culture.
WATKINS:
I have a replica
Clovis point with me.
They look about like this.
Some are larger,
some are smaller.
There's a very characteristic
flake
that's taken out of the base
up to the middle of the point.
JOHNSON:
The oldest known Clovis points
are about 13,000 years old.
And for a long time,
many archaeologists
thought that humans
arrived in North America
no earlier than that.
So these Clovis points
have been found
all across North America,
from the Atlantic coast
on the east,
all the way out into the,
the west coast.
So with this, such a broad
geographical span of material,
it's why most
archaeologists thought
that Clovis was the
first archaeological culture
in North America.
JOHNSON (voice over):
More recently,
this view has been challenged
by the excavation of
older sites,
with stone artifacts
that suggest humans lived
in North America
at least 2,000 years
before the Clovis culture.
[♪ ♪]
There are some
archaeological sites...
one in Florida, one in Texas...
that date about 15,000,
15,200 years ago.
So those are currently
the oldest dates we have
for the early peopling
of the New World.
[♪ ♪]
JOHNSON: But now the
discoveries at White Sands
may support even earlier dates,
and could shed new light on
how people
came to North America.
About 20,000 years ago was
the peak of the last Ice Age,
the Last Glacial Maximum.
Gigantic ice sheets blocked
the route into North America.
But there's geological evidence
that as the climate warmed,
an ice-free corridor opened up.
Was this how humans reached
the rest of the continent?
So one thing about the
ice-free corridor,
it didn't really open up
until 13, 14,000 years ago.
So if it wasn't open,
it wasn't likely that anyone
could have come that way
and come in to North America.
JOHNSON: If the tracks at White
Sands pre-date the ice-free corridor,
they will add more weight
to the idea that humans
arrived here earlier
than many archaeologists
previously thought.
[♪ ♪]
Searching for clues,
David Bustos is studying some
other remarkable human prints.
I don't know if you can
see right here,
this might be more of a child.
It's about, maybe, four,
four inches or so across.
And it's right next to
an adult print.
You don't normally think of,
you know,
taking your child all the way
across the country or so,
unless you're, um,
if you're hunting,
you might leave the child
back at home,
but we see the children
everywhere,
so they're part of the scene
or part of the landscape.
[♪ ♪]
JOHNSON: The footprints
tell stories of Ice Age life.
But how long ago were
these people here?
[♪ ♪]
In order to date the prints,
the team has dug a trench.
(rocks rumbling)
It reveals layers of sediment,
deposited over many years,
along the shore of this
ancient lake.
Stamped on these buried
surfaces are human prints,
and the further down they are,
the older they are.
But just how old are they?
I can put them both on.
Okay, sure.
JOHNSON: To help find the
answer, David has been joined
by geologists Kathleen Springer
and Jeff Pigati,
who is also an expert in
radiocarbon dating.
[♪ ♪]
You've cut a cross section...
What are you trying to see
with the cross section? SPRINGER:
So the footprints themselves
are just an impression
on a surface,
there's nothing to date.
It's an inorganic thing, you
have to find something organic
that you can date above
and below the footprints,
and get good dates on them,
so that you can actually say,
"That footprint is between
these two ages."
JOHNSON (voice over): In this trench,
Kathleen and Jeff have made a crucial find.
[♪ ♪]
Sandwiched in the layers
above and below the footprints
are scatterings
of ancient seeds,
precious organic material
which the team can date.
That way they can establish
a window of time,
for when the prints were made.
There were actually
plants growing on this,
on the surface when, you know,
these critters
were walking around.
So the same layers that have
the tracks will have the seeds.
Absolutely, above and below them. Yeah.
Yes, so above and below them,
that way we can constrain
in time.
So your seeds are effectively
little timepieces, right?
They're like little clocks
or something buried in the...
They're little capsules, yeah.
And basically the, the...
these things are really
resistant to, to decay.
And so they look like
they were put down on the,
on the landscape just yesterday,
but, in fact,
they might be tens and,
you know,
tens of thousands of years old.
JOHNSON (voice over): Jeff will
take the seeds back to his lab in Denver,
and use radiocarbon dating
to find out how old they are.
[♪ ♪]
JOHNSON: When I talk
to you in six months' time,
either you have what you expect,
PIGATI: Mm-hm. Which
is around 12,000 years,
or you have humans
here earlier than you expect,
or mammoths are here later
than you expect.
PIGATI: Something's going to
be pretty cool either way, right?
So it seems like you're going
to get
a really interesting result no
matter what the result is here.
PIGATI: It is a win-win,
no question about it. Yeah.
That's a rare thing
in paleontology.
PIGATI: It's kind of nice. Yeah.
JOHNSON: Dying to hear what you find out.
Yeah.
Yeah, us too, us too.
JOHNSON (voice over): The trackways
at White Sands are constantly changing...
as the wind erodes away the
surface to reveal new prints,
it's also turning existing ones
to dust.
BUSTOS: It's great because
we can see the prints,
but then they are
rapidly blowing away.
So we want to capture the data
before it's gone.
Some of these really soft ones
like this,
once they're exposed, in
a few months they'll be gone.
Some type of, you know,
priceless data is, is being...
is right here, is being lost.
It's the surface,
we're losing the surface,
and these are
where all the prints are.
[♪ ♪]
JOHNSON: To record this precious
evidence before the wind blows it away,
the team is mapping the site
using aerial imagery.
BUSTOS: One of the main
reasons is to fly over the area
and then get an elevation model
so we can see where
these prints are.
And then we're gonna
re-fly it again,
and so with that we'll be able
to look at
from this year to next year
we'll see how much erosion's
happening,
so we can see how fast
the prints are moving
and going away.
JOHNSON: One question they
hope to answer using digital imaging
is whether the people here were
hunting the giant animals.
David shows me an intriguing set
of tracks that may hold clues.
Dave, what kind of
image is this?
BUSTOS:
It's a photogrammetry.
You know, so basically
overlapping photos.
I think in this image,
there might have been
400 or 500 different images
and they're all stitched
together.
You can, you know,
tip the images upside down,
see it in different directions.
So this image right here
is actually
a giant ground sloth.
It's walking along.
These are hind and fore feet,
so when they weave in and out,
what you see is a hind foot,
and then the forefoot comes
in front
with the very long claw.
And then right here, it changes.
So it stands up, actually.
JOHNSON (voice over): What
caused this sudden change in behavior?
David has a theory.
BUSTOS: If you look close,
you'll see a set of human tracks,
And what's really exciting,
we took measurements.
You can see they're running
toward the sloth.
If you're in the field,
you'd actually see where they're
almost toe to toe, you know,
almost chest to chest,
it looks like.
I don't know if they're
throwing a spear
or what they're doing, but they
come right up to each other.
The sloth's spinning around
and making, like,
it looks like a sweeping motion.
Actually, there's claw marks
on the ground.
There's another set
of human prints
sort of running up along
this direction.
JOHNSON (voice over):
David believes these trackways
are evidence that humans
were actually hunting sloths.
(sloth grunts)
But what was it like to take
on such big animals?
(sloth growls)
La Brea Museum curator
Emily Lindsey
has investigated
how humans hunted them.
So these are our collections
where we keep all of the fossils
that have been excavated
over the last hundred years.
There's millions
of fossils here.
Yeah, there are literally
millions of fossils here.
And here are some
of our sloth claws.
JOHNSON:
Oh man, look at those things,
these are serious claws.
What did they use the claws for?
Some paleontologists
think they might have used them
to dig roots out of the ground.
They've found burrows
that they think these guys
dug there,
where there's actually
scratch marks on the wall
that line up with the the hands
of giant sloths.
But, of course,
they would have been really
useful for defense, as well.
JOHNSON (voice over): But
despite their fearsome appearance,
archaeological evidence shows
that ground sloths
might have been on the menu
for hungry humans.
LINDSEY: You know,
we have a couple of sites
that have been found where it
looks pretty clear
that humans were,
if not hunting,
at least butchering
giant ground sloths.
We've got stone tools
and we've
got cut marks on the bones.
Although we have many more sites
that show humans hunting
and eating things like mammoths
and horses and camels
than we do of giant sloths.
So, they may have been a food
source of last resort.
Maybe bison tastes better, or...
Yeah, given the types of plants
that we find in the sloth dung.
You know, desert plants
that tend to have a lot of
chemicals in them.
They might not have tasted
very good.
Huh, interesting.
So what kind of techniques
were humans using
to hunt and kill these animals?
LINDSEY:
They had spears, but, of course,
the most important tool
that humans had
were their big brains
and their social groups
and ability to communicate.
Hm.
[♪ ♪]
JOHNSON (voice over):
Teamwork and planning,
these were the keys to bringing
down huge Ice Age beasts.
[♪ ♪]
But once the animal was dead,
what did people do
with all that meat?
[♪ ♪]
One of the challenges
you have, if you're,
if you're living
in this environment,
or hunting in this environment,
is how do you get your meat
from where you kill the animal
to where you camp?
[♪ ♪]
JOHNSON:
Dan Odess is an expert
in prehistoric archaeology.
He searches for evidence to show
how humans might have dealt
with the animals they killed.
And alongside the footprints,
he shows me
a very different kind of track.
DAN ODESS: We have
these, these really interesting
linear structures.
There are four of them.
You can see here
one, two, three, four.
JOHNSON: What could have caused
these strange marks in the sand?
ODESS:
We were kind of wondering
initially, could this be
a product of animal behavior
rather than human behavior?
But, interestingly,
one of the things we see
and you can see it very clearly
in this one,
we've got people walking along
behind it.
JOHNSON: Dan believes this is
important archaeological evidence
of human engineering.
They're, they're drag lines.
So impressions left in the mud
as somebody probably pulled
a pole or poles.
Okay.
With presumably meat
or something else on them.
JOHNSON: And that's a typical
way to move meat around?
I think this is the first time
it's been described for
the Ice Age.
JOHNSON (voice over):
The team thinks these tracks
could be the earliest known
evidence of an ancient device
used to carry heavy loads,
such as large amounts of meat.
ODESS: Instead of dragging
the carcass back to the camp,
they would strap it onto
a couple of poles,
and not one, or two poles.
At this point,
we're not sure whether
they're dragging a single pole
or whether they're using
two poles hitched together.
JOHNSON (off-camera): Huh, so like a
primitive wheelbarrow, basically, right?
ODESS: So far we, we
don't have any reason to think
they had a wheel.
Right.
Well, wheelbarrow with
no wheel, how about that?
Yeah, right, right.
(chuckles)
A barrow!
Right, there you go.
Let's just call it a barrow. A barrow.
[♪ ♪]
JOHNSON (voice over): But what
could the device have looked like?
(birds flapping wings,
squawking)
60 miles from the trackways
is Elephant Butte Lake.
Experts think White Sands
had a similar environment
during parts of the Ice Age.
Archaeologist Joe Watkins
has come here to conduct
an experiment.
Joining him are fellow
archaeologists Carol Ellick,
CAROL ELLICK: I'll start
with the lashing on this corner,
all right?
Yup.
JOHNSON: And Edward Jolie,
of Lakota and Muscogee descent,
and a citizen of the
Muscogee Nation of Oklahoma.
EDWARD JOLIE: Is this
going to be sufficiently stout,
or should we cut a thicker one?
ELLICK: I think that's pretty tiny, Ed.
JOLIE:
It is.
JOHNSON: The team
wants to carry out experiments
to try to reproduce the tracks
at White Sands.
[♪ ♪]
They're building two simple
structures
to see if one of them
might leave
similar drag marks to those
found in the desert.
Ed, if you want to
lash the end pieces
together. JOLIE: Okay.
I'll grab the important piece.
JOHNSON: The first design
is an A-frame structure,
based on a traditional device
used by Indigenous peoples
called a travois.
They're attaching
40-pound weights
to represent a hunk of meat.
I think that's the 40 pounds.
This feels, like, more than
40 pounds, is this...?
Honestly, that's 40 pounds.
Two 15-pound weights,
plus two 5-pound weights.
(chuckling)
That's...
We might have some
structural issues.
(laughter)
I don't remember my daughter
ever weighing this much!
(laughs)
JOHNSON: Carol is
going to pull each design.
Walking barefoot,
like the people
who created the prints
at White Sands.
It feels pretty stable.
ELLICK: It looks pretty stable. It feels,
from my end,
it feels pretty good too.
ELLICK: I was going to
follow the edge of the water,
is that what you were thinking?
WATKINS:
I think that's a good way.
Okay.
Okay.
(grunts)
Whoa, getting started.
JOHNSON: Carol leaves
behind clear footprints
and drag marks in the mud.
[♪ ♪]
WATKINS: Look at that.
JOLIE: Yeah, that's great.
WATKINS: The footprints
are both on one side.
I would have thought
there would have been footprints
on either side
and that the drag line,
would have been between
the two. JOLIE: Mm-hm.
And it appears to me, as well,
that what we're seeing
is that the footprints
are the side opposite
the weight imbalance
on the travois.
WATKINS: Either that or the
fact that there are two sticks
is having an impact
on the way it's moving.
JOLIE:
Looks great.
JOHNSON: They record
the marks for further study.
WATKINS: Let's get
one up by that footprint
where the mud has
pushed over to, okay?
That's a good start.
[♪ ♪]
JOHNSON: Next, they
try the second design...
a single pole with the same
weight attached.
WATKINS: Do you want
me to come up a little bit?
ELLICK:
Pull it forward a little bit.
So...
Put that end down.
JOLIE: Come up parallel to this one.
ELLICK:
All right, all right.
(stick dragging)
[♪ ♪]
JOHNSON: This creates a single
drag line with a regular wobble pattern.
That feels quite
different pulling it
on the single pole
rather than the double travois.
WATKINS: So it definitely
is wobbling back and forth
much more than the one with
the two-pole travois.
Standing and staring at them
both in parallel,
it's really drawn into
stark relief
Yeah.
How different they are.
It's a bit of a surprise,
actually. (Shutter clicks)
[♪ ♪]
JOHNSON: But which
design makes a pattern closest
to the tracks found
at White Sands?
WATKINS: My impressions
are that the straighter lines
at White Sands
pretty much equate with
the straighter lines
we're getting with the travois.
That's definitely not saying
that's the only way
they could
have had those straight lines.
But just based on
this initial experiment,
I would be more inclined
to go with the double pole.
JOHNSON: This experiment
suggests how Ice Age humans
might have transported meat
or other heavy objects.
But how long ago
were they walking along
the ancient lakeside at
White Sands?
[♪ ♪]
It was time to visit Denver
to catch up
with Jeff Pigati
and Kathleen Springer.
PIGATI: Yeah, right at the
top of the sequence there.
So that one has a stem attached.
Still has a stem attached?
Yeah.
That's awesome.
We'll go through there.
Yeah.
JOHNSON: At the U.S.
Geological Survey Lab,
Jeff has been analyzing
the seeds they found
in the sediment layers
at White Sands.
[♪ ♪]
He's been using
radiocarbon dating
to calculate the age of
the seeds, and from that,
the age of the footprints.
PIGATI:
This is the carbon extraction
and graphitization system.
And, basically, what we do here
is take a seed.
We com bust it in oxygen.
We turn the carbon
that's in the seed
into carbon dioxide.
We get rid of everything
else that's in the seed...
water and other other
contaminant gases
that we don't want...
and we end up with pure CO2.
[♪ ♪]
And we basically take that
carbon dioxide,
convert it to graphite,
and that's what we actually
send out to the AMS lab.
So you turn the seed into a gas
and then back into a solid.
That's exactly right,
we start with a solid,
we turn it into a gas,
clean it up,
and then end up with a
pure graphite pellet at the end.
In these little targets,
right here.
That's a tiny little thing. Exactly.
It's about the size of a pencil
lead, they're very small.
And they're sealed
into this thing?
That's right, exactly.
I see this little closed chamber. Yeah.
JOHNSON (voice over):
The precious graphite pellets
are then sent to a mass
spectrometry lab to be analyzed.
So what happens at the
mass spectrometry lab?
Yeah, so that's where they
measure the ratios
of the various carbon isotopes. Uh-huh.
And those are the data
that we get back,
and we use those
to calculate the age.
[♪ ♪]
JOHNSON (voice over):
It's the moment of truth.
After more than
a year and a half,
have Kathleen and Jeff
managed to find out
the age of the footprints?
So tell me, what were the
dates of those footprints?
We were able to document
that humans
were in White Sands
National Park
between 23,000 years ago,
and about 21,000 years ago,
JOHNSON:
23,000 years ago?
That's way older than there's
been good evidence
for humans in North America.
It's about 10,000 years older
than sort of the established,
sort of,
thought of when humans arrived
in the Americas.
JOHNSON: And you got
tracks at more than one layer,
which means that
wasn't just one group of people
at one moment in time.
No.
That it was many groups
of people over a lot of time.
SPRINGER:
2,000 years.
I mean, 2,000 years itself
is a long duration.
It is.
But the fact that they were here
23,000 thousand years ago...
Yeah, crazy, huh?
JOHNSON: Blows my mind, I mean...
SPRINGER: It blew our mind! (Laughs)
That's like 10,000 years
before Clovis.
SPRINGER:
Yes.
That's like the entire length
of human civilization
before Clovis.
SPRINGER:
Yeah, go figure.
This is not a subtle result.
[♪ ♪]
(voice over):
If these dates are correct,
that would make the White Sands
footprints
the earliest direct evidence
of humans
ever found in North America.
PIGATI: This is the Last Glacial Maximum.
This is when the ice sheets
were at their maximum,
and it's been thought that those
ice sheets
blocked people from coming down
into North America.
And what we found was
that the people
were already here at that time.
JOHNSON: So you couldn't
be blocked from getting here
if you're already here.
SPRINGER: That's right.
If you're already here.
JOHNSON: And if you've been
here for a couple thousand years?
SPRINGER: Right. Yeah.
JOHNSON: What did you
think when you saw the results?
Holy...
(laughter)
It was pretty much like that.
I mean...
There was words that were spoken
that were emphatic words.
Wow. Just wow, yeah.
[♪ ♪]
JOHNSON (voice over): But
some experts question these results.
They're troubled by the lack
of additional
archaeological evidence
of this ancient population.
Others say the dating method
could be flawed
arguing that the sediment layers
may have been disturbed.
Or the seeds may have absorbed
older carbon
from surrounding groundwater,
which could skew
the carbon dating.
This is an extraordinary
discovery.
How confident are you
in the quality of the dates
that you've achieved?
We're very confident...
These, these ages,
we were able to reproduce them
extremely well.
They maintain what we call
stratigraphic order.
Basically, the oldest at the
bottom, youngest on the top.
And even though some
of these samples
were only separated by a
centimeter or two of sediment,
they still maintain that order,
and that's one of the,
one of the, one of the key
things that we wanted to see.
And so it's not just what
we see in the lab,
but it's also what we see
in the field taken together
is really what
makes this powerful.
JOHNSON: This is a huge
discovery, how do you feel?
(laughs)
Exhausted!
(laughing)
[♪ ♪]
JOHNSON (voice over):
If the results are correct,
then these prints could have
been left behind
by some of the earliest
known Americans.
Back at White Sands,
I was curious to find out
what Kim Charlie and Joe Watkins
make of the discovery.
So now that there are
dates of 23,000 years ago
with Native American footprints,
how does that make you feel?
WATKINS:
It's just amazing.
We talk about having
always been here,
it's just remarkable to put
that much of a movement
further back in time.
So now we've added another
6,000 to 8,000 years
to what archaeologists have
told us was
the time depth of our history.
And so this keeps putting
that history back in the news,
keeps telling people,
"Well, yeah,
you've been here 500 years,
we've been here for 20,000."
Here's our proof, you know?
Footprints,
footprints of our ancestors.
You know, that goes to show,
we were here.
We were here on this earth
a very long time ago.
[♪ ♪]
JOHNSON: But if humans
were here 23,000 years ago,
how did they get here?
At that time,
the corridor between
the ice sheets did not exist.
So humans might have followed
the Pacific shoreline,
possibly by boat,
a route known as the
"kelp highway."
But how exactly
they would have made it here
during the Ice Age is still
unknown.
JOHNSON: These footprints
tell us that people were here
during the Last Glacial Maximum.
So how, how do you think
they got here?
WATKINS: I think probably the
coastal highway is the best bet.
Many old sites are going to be
submerged under water now.
So I, I think that's where
we need to look.
[♪ ♪]
JOHNSON (voice over):
Whatever the answer,
there's no doubt that these
astonishing discoveries
are another step forward
in scientists' understanding
of human history.
And perhaps they could also
shed new light on humans' role
in the extinction of
Ice Age animals.
So where does this leave us?
For many years, we thought that
the Ice Age animals went extinct
about the same time that people
got to North America.
Now this site is telling us
something very different.
Basically what we're seeing is
that humans were here
more than 10,000 years before
the extinction of the animals.
So the question of was the
extinction caused by climate,
or people, or both,
has just become a much more
complex problem to solve.
[♪ ♪]
One theory is that when humans
arrived on this continent,
their numbers were too small
to make a big impact
on the wildlife.
But at some point,
populations increased,
and they developed
better hunting techniques.
Was this what eventually spelled
the end for the animals?
People have always thought
it was either
climate or people that caused
the extinction of the Ice Age
megafauna.
What do you think?
You know, I...
we really don't know yet.
But what we do see, you know,
without a reasonable doubt,
is that, you know,
around 12,000 years,
the area starts to dry out,
the lake dries up
and then the dunes form.
So climate change might have
been influencing that as well.
Maybe someday we'll,
we'll find out.
We might not ever learn.
But, but you know, the
exciting thing about White Sands
is there's thousands
of prints to study.
So, you know, the secret
might be locked there
somewhere in the sand.
[♪ ♪]
JOHNSON:
The unique preservation
of these ancient footprints
could yield more clues
about the lives of
Ice Age Americans.
SPRINGER: We're very
excited because it's, it's kind of
the tip of the iceberg,
you know?
White Sands is still there.
Those tracks are still there.
They're eroding out every day,
every minute.
And we get the opportunity to go
back and, and to learn more.
JOHNSON:
So the research goes on, then.
Yeah, it goes on, sure.
PIGATI: Yeah, this is just the
beginning, that's exactly right.
It's a tremendous opportunity.
It... it's opening up
the world of archaeology
way beyond where it's been.
It's going to give a new
generation of archaeologists
something more to shoot for,
to see whether we can go back
any farther than 23,000 years,
or whether this, in and of
itself, is the threshold.
[♪ ♪]
[♪ ♪]
ANNOUNCER: To order this
program on DVD, visit ShopPBS.
Or call 1-800-PLAY-PBS.
Episodes of "NOVA"
are available with Passport.
"NOVA" is also available
on Amazon Prime Video.
[♪ ♪]
[♪ ♪]
KIRK JOHNSON: White Sands National Park,
New Mexico...
A vast, open desert that
holds clues to a lost past.
DAVID BUSTOS:
At White Sands,
all good stories sort of
begin with a Bigfoot.
JOHNSON: Footprints dating all the way
back to the last Ice Age.
All these circular things
are fossil footprints.
JOHNSON:
That's amazing.
[♪ ♪]
JOHNSON:
Mammoths over 13 feet tall.
(mammoth grunting)
Dire wolves, camels,
and enormous ground sloths
that roamed North America
thousands of years ago.
White Sands has so many
hidden treasures.
There's all these
trackways here,
it's just such
an incredible discovery.
[♪ ♪]
JOHNSON:
Alongside them,
something even more astounding.
- That is a human footprint.
- Yeah, so there's
a human footprint right there.
(laughing):
Wow.
JOHNSON:
Ancient human journeys
printed on the landscape.
When you make tracks in sand,
they just blow away.
When you make tracks in
a place like this,
where the chemistry
is just right,
the tracks can last forever.
(voice over): Now a team of experts
is investigating
how these remarkable tracks
could shed new light
on life in the Ice Age.
MATTHEW BENNETT:
There's a double trail.
Somebody going this way,
and somebody going that way.
JOHNSON:
Wow, that is really incredible.
(voice over):
How long ago were they made?
KATHLEEN SPRINGER:
That's amazing.
MAN:
Yeah.
SPRINGER: The Ice Age megafauna
went extinct
about 11,500 years ago.
So they're at least that old.
How much older than that
is really anyone's guess
at this point.
JOHNSON: Could they provide
new information about
early peoples of the Americas?
It really does
put our feet prints
firmly into the past here
in North America.
KIM CHARLIE:
Here's our proof.
Footprints,
footprints of our ancestors.
[♪ ♪]
JOHNSON: Can the secrets
of these ancient footprints
help answer the questions
when and how did humans first
arrive in North America?
[♪ ♪]
"Ice Age Footprints"...
Right now on "NOVA."
[♪ ♪]
JOHNSON:
The dazzling dunes of
White Sands National Park.
Sand as bright as fresh snow.
[♪ ♪]
But hidden within this landscape
are traces of an ancient story
dating all the way back
to the last Ice Age.
When we search
for evidence of life
in the ice ages
in North America,
we find things like
the bones of mammoths
or maybe even hearth stones
or spear points
from the people
that used to live here,
and very rarely we find
the remains of those humans.
But the story
is still so incomplete,
there's so much more
information we need to find.
[♪ ♪]
JOHNSON: That's why
the discovery of footprints
here at White Sands is
so significant.
Could they help answer
some of the greatest mysteries
of the Ice Age?
[♪ ♪]
The precise location
of this site
is a secret.
These dunes cover
nearly 300 square miles...
with some rising over 50 feet.
I'm driving through
these snow-white dunes.
It's kind of
a surreal landscape.
Once we get through the dunes,
we'll be out in
the great ancient lake bed,
and it's absolutely
covered with tracks.
(voice over):
I'm Kirk Johnson.
As a paleontologist,
I've spent most of my career
studying the remains
of ancient life.
But footprints can tell
really detailed stories
about the past.
[♪ ♪]
30 minutes later,
we've reached our destination:
A huge dried-up lake bed.
As the wind scours
this remote area,
new prints are being revealed,
and old ones disappear.
It seems like such an
improbable place
to even look for tracks.
(voice over):
Joining me is David Bustos.
He's leading
the team of scientists
investigating the footprints.
BUSTOS: You look out
and it's just bleak desert,
and who would think that there's
all these trackways here?
JOHNSON (voice over): As
my eyes adjust to the brightness,
round patterns start to appear.
So there's one there...
Yes.
And there and there,
and there and there, there...
BUSTOS:
Yeah.
Oh, yeah. Those are amazing.
Uh-huh.
[♪ ♪]
(voice over): The mysterious shapes
are over five feet apart,
and nearly two feet across.
These are the fossilized tracks
of an Ice Age giant...
a Columbian mammoth.
It died more
than 10,000 years ago,
but its footprints remain.
[♪ ♪]
(mammoth trumpeting)
The tracks are
preserved in various ways.
Sometimes the wind fills them
with different textured sand,
leaving ghostly impressions,
while others dry into hard casts
which are exposed
when the softer ground
around them erodes away.
One of the things that
really stand out at White Sands
is just thousands and thousands
of footprints preserved.
In this area,
we'll see trackways
that go for ten miles
in one direction
and two or three miles
in another direction.
You know, there might be
over 100,000 prints
throughout this large area.
Do...
it's okay to walk on them?
We can walk
near them and around them,
as long as we don't
disturb the surface below
or add more sediment in.
JOHNSON (voice over):
We need to be careful not to
step on the fragile prints...
and the team tries to only
visit the trackway areas
when the ground is dry,
and hard enough
to support their weight.
The surface is always changing.
We are seeing more erosion.
Every year, more and more prints
are becoming visible.
JOHNSON (voice over): And along
with the many mammoth prints here,
we soon spot traces of another
large creature.
BUSTOS:
They're very common,
they'll sort of
look like an S shape...
Yep.
You'll see them connecting to each other.
There's one here, right?
Yep. There's another one
coming through...
I think as well, right there.
JOHNSON (voice over):
Twice the size of a human foot,
and with giant, curved claws,
these are the prints of
a massive ground sloth,
a beast more than double
the weight of a grizzly bear,
that walked this land
thousands of years ago.
(sloth panting)
So that's sort of how the story
of White Sands began.
People, they've seen these
incredible footprints,
and they thought
that it was Bigfoot.
(chuckling):
Bigfoot with three weird claws.
Yes.
JOHNSON (voice over): Then we
discover something even more special.
That is a human footprint.
Yeah, so there's... there's a
human footprint right there.
(laughing):
Wow.
Yeah, so if you look...
That is amazing.
Here's the heel.
Okay.
Right here.
JOHNSON (voice over):
Scattered across the landscape
are human footprints
from thousands of years ago.
Each track is the
trace of an ancient person,
the shape of their bare feet
locked in the sediment.
Look at this,
this is amazing here.
This actually looks like
a human print right in there.
[♪ ♪]
JOHNSON (voice over): Could
these extraordinary human footprints
help answer two big questions:
When did people first set foot
in North America?
And did their arrival
contribute to
the disappearance of
giant Ice Age animals?
20,000 years ago,
Earth was
in the grip of an ice age.
The climate was colder,
vast ice sheets covered
much of North America...
and White Sands
was not a desert,
but a huge lake... Lake Otero.
[♪ ♪]
The lake shore surrounding it
teemed with life.
Giant ground sloths
wielding big claws
shared this wetland with
mammoths
weighing up to ten tons.
Alongside them,
packs of dire wolves
hunting for a kill,
and hardy North American camels.
These Ice Age giants disappeared
from the fossil record
over 10,000 years ago.
So the human footprints here
are probably at least that old.
[♪ ♪]
But they could be much older.
What can they reveal
about the deep history
of humans on this continent,
and how they met the challenges
of life in the Ice Age?
[♪ ♪]
To find out,
David has assembled
a team of scientists
to uncover the tracks'
hidden secrets.
BENNETT:
I'm confident in it now,
that that's mammoth, and
it links to your one in the,
um, that you've got
in cross section there.
- Cross section over there? Okay.
- Yeah.
JOHNSON:
One of them is Matthew Bennett,
a forensic footprint expert
from England.
[♪ ♪]
On the eastern side of
the ancient lake,
close to the restricted area of
the White Sands Missile Range,
Matthew is excavating
a remarkable set
of human footprints.
JOHNSON:
Hey, Matthew,
how's it going?
It's going well.
These are amazing.
They are.
Are these... so, are these
just the ones you've exposed
this afternoon, then?
Yep, there's a double trail.
Um, somebody going this way,
and somebody going that way.
How far do they go off
in that direction?
So, in that direction,
about three-quarters of a mile,
something like that,
and then they go to
the boundary fence
on the missile range
and an unknown distance
into the missile range.
[♪ ♪]
JOHNSON: How common is it to have
a track this long?
BENNETT:
Okay, so I've looked at tracks
all around the world,
and this, to my knowledge,
is the longest human trackway
anywhere in the world.
JOHNSON:
Oh, that's amazing.
Could it be the same person
going away and coming back?
Absolutely.
They're the same size.
It's actually
quite a small individual.
It could be a woman,
but could be
a male adolescent equally.
The size is...
- Looks like a size five or something.
- Yeah.
But the tracks are very big.
There's sort of
30% of the track,
maybe more is pure slippage.
It's very wet and
slippery conditions
as the individual
has been moving.
JOHNSON (voice over): Some
are clearly defined imprints,
but many are
stretched out and distorted,
an indication that
the walker was moving fast,
and slipping
on wet, muddy ground.
Some prints are bent
out of shape,
from a foot sliding sideways,
which could mean
the person was carrying
something on their journey.
BENNETT:
They were also carrying a child.
Oh, they're
carrying a child as well?
They're carrying a child.
How do you know that
they're carrying a child?
BENNETT: Along the trackway,
there are very small,
tiny little children's prints.
They sort of face
the direction of travel.
So if you imagine you were
carrying a child on your hip
and you wanted
to readjust, you...
you put it down...
Right.
...and then you readjust,
and there's
a few small child prints,
pick the child up again
and carry on.
Just over to here...
JOHNSON (voice over): A little
farther along the same trackway,
Matthew discovers
a twist in the story.
The travelers were not alone.
What's this
unusual set of tracks?
So there are a series
of sloth tracks here
entering from, from...
to the left there...
So this is the first one.
And then it comes out over here.
That's really the amazing one,
you can see the claws
of the sloth so clearly.
BENNETT:
You can, yeah.
It's a beautiful,
a beautiful track.
They're not large tracks.
Yeah.
So it's a relatively
small sloth.
Bear-size,
I would have suggested.
JOHNSON (voice over):
Was this sloth here
at the same time as the humans?
The sloth's footprints
are right on top of
the outbound human track.
Which means this animal
must have arrived
after the travelers
first passed by.
Where do they actually
step on the human track?
So...
Is it this one?
It's actually just over there.
There's an example where they,
they cut across the human track.
But the sloth did
something quite cool.
It seems to have gone from
all fours up onto its hind legs.
It's done
a little dance around...
And then it goes off that way.
So it crawls in kind of
like sloth-like,
and then as it gets here,
it kind of pivots around and up
and looks, looks...
Looks, scents the air, and off.
...and pivots
and then heads off that way.
That's correct.
A little sloth dance.
Yeah, that's exactly what it is.
JOHNSON (voice over):
Matthew thinks the sloth
noticed the human tracks
and reacted.
Either the sloth's either
visually responding to the track
or it smells something.
My instinct is smell.
It basically reared up to scent
the air a little bit more
and then decided to,
to disappear off.
They're not here
at the same time,
but within a few minutes,
hours of each other,
they're here.
(chuckling):
That's a phenomenal thing.
Some small person
having a stroll
on a landscape full of
giant ground sloths.
(voice over):
The tracks at White Sands show
just how close humans here
came to Ice Age animals.
Imagine what
it must have been like
to meet one of these
enormous beasts in the flesh.
(sloth groaning)
[♪ ♪]
You can get a sense of
these Ice Age encounters
at La Brea Tar Pits
in Los Angeles.
Here, animals that wandered
into tar deposits were trapped,
and their bones were preserved.
In the last century,
experts have unearthed
more than a million fossils
here.
EMILY LINDSEY:
Hey.
Hey Emily, how are you doing?
Good, how are you?
Nice to see you again.
Good to see you.
Welcome to the Tar Pits.
Thanks.
Oh, here's our sloth, huh?
Yeah.
This thing is amazing,
so massive.
It's majestic.
JOHNSON (voice over): Curator Emily Lindsey
works with fossils of the giant beasts
that lived in North America
during the last Ice Age.
So how much do you think
this guy weighed?
Probably more than a ton.
And when people
talk about sloths,
they talk about
how they move so slowly,
would this guy have
moved slowly?
You know,
it wouldn't have been like,
a runner...
Yeah.
...but it wouldn't have been
so slow as the modern sloths
that are really only adapted
for living in trees.
What would
an animal like this eat?
So they were mostly herbivores,
and it looks like they
were eating a lot of
kind of desert shrubs
that would have
been prevalent in the area.
Sloths are part of this
very strange group of animals
called Xenarthrans,
and it includes the sloths,
the armadillos,
and the anteaters.
And like armadillos,
some species
produced bony armor,
only in this case,
it's in the form of these
small sort of pebble-like bones
that were embedded
inside its skin.
Oh, that's why
I love sloths so much.
(laughing):
They're so cool,
they're such amazing animals.
Yeah, they're one of the
weirdest animals,
and it's a piece of ecology
that has just
completely gone from earth.
(indistinct chatter)
JOHNSON (voice over):
Nearby, I've spotted another
lost species whose tracks
we see at White Sands.
This is an amazing beast,
isn't it?
Yeah, the Columbian mammoth.
JOHNSON (voice over):
From fossil evidence,
we know that mammoths
arrived in North America
around 1.8 million years ago.
When you stand beneath the
skeletons of these huge animals,
you can't help but wonder,
why did they go extinct
less than 13,000 years ago?
Was it because of
a change in climate?
Or human influence?
Or a combination of the two?
LINDSEY: It seems to have
been a really rapid event.
As we we're
coming out of the Ice Age,
we're going through all
these big climate upheavals,
so we need to know
how much overlap
there actually was
between when humans arrived
and when the
last animals disappeared
in order to know what role
humans might have played
in that extinction.
[♪ ♪]
JOHNSON (voice over):
The footprints at White Sands
might be the oldest human prints
ever found in North America.
They could shed new light on
the lives of Indigenous peoples
and their long history
on this continent.
It's, it's just so amazing
to see these tracks...
There's another one
crossing there.
Yeah.
JOHNSON (voice over):
Today, I'm visiting
the U.S. Army's
White Sands missile range,
just across the boundary
from the national park.
Here there are
more animal prints,
including those of a mammoth,
and this magnificent trackway
of a ground sloth,
crossed by the footprints
of an ancient camel.
Can you imagine this whole area
with all these animals here?
Would have been
amazing, huh? (Sighing): Oh.
Mammoths, sloths, cats, dogs.
Yeah.
Right?
Yes.
I always say we need
to build a time machine.
(laughter)
JOHNSON (voice over):
Joining me are Joe Watkins,
an archaeologist and member of
the Choctaw Nation of Oklahoma,
and Kim Charlie from the
Pueblo of A coma in New Mexico.
They want to
see the prints for themselves,
and learn more about
the people who once walked
across this landscape.
We have this tie
where us Native Americans
have been here
for a very long time.
And I believe that, you know,
I really believe that.
And that ties back into,
you know,
our migration stories where
we evolved somewhere,
but we don't
specifically know where.
These are stories that
we believe in our hearts
as tribes,
pueblos, you know, that we take,
that we hold sacred to us.
So when we come back to
these areas
and we find
evidence of footprints
of our thousands of
great ancestors,
you know, we just kind of, like,
it's amazing.
So we did exist here.
The tribes talk about
going way back.
We all talk about
having been here forever.
We've never been anywhere else.
We have the evidence,
it really does
put our feet prints
firmly into the past here
in North America.
These are our relatives.
We've been here since
time immemorial
and hopefully we'll continue on.
JOHNSON (voice over):
When Europeans arrived
on this continent,
they began a pattern of
ignoring the rights and stories
of Indigenous peoples.
With the colonization
in the 14, 1500s,
a lot of tribal histories
have either been lost
or have been pushed back
or have been tossed aside.
This was once
our land, you know.
Mother Earth was our mother... Mm-hmm.
...and we're
the descendants of her.
And we're the people
that try to take care of it,
but you've got the
Western people
have come in and just
taken over areas where,
you know, they have no respect.
Please understand that
we Native Americans
were here first.
It's kind of an awful thing
where we've been put on
little reservations.
You know, where we once had
the freedom to roam.
[♪ ♪]
JOHNSON (voice over):
European-Americans not only
took control of
Indigenous territories,
but some also spread
misleading narratives
about Indigenous people.
(indistinct chatter)
[♪ ♪]
WATKINS: There's pretty
much always been a conflict
between archaeologists
and American Indians.
In many ways,
archaeologists have taken over.
They've sort of colonized
American Indian history,
and they felt that they,
they're the ones
who tell
the true story of the past.
So there's been
that conflict between
whose story is the true history.
Archaeologists also
came out to
archaeological sites,
started excavating,
took the materials,
took them back to museums,
and tribal people
never saw them again.
[♪ ♪]
JOHNSON:
Over the centuries,
some white scholars
used archaeology
as a way to dismiss
Indigenous people's accounts
and ancestral connections
to the land.
It really wasn't
until 40 years ago
that Indians had a say in
who was excavating
and what happened with the
results of those excavations.
[♪ ♪]
JOHNSON:
Here at White Sands,
the scientists are consulting
with local tribes
and pueblos to study and record
these important prints.
They hope to solve one of
the biggest mysteries of all:
When did humans first arrive
in North America?
Fossil records show that by
at least 100,000 years ago,
modern humans... Homo sapiens...
Began spreading
from Africa across the planet.
The Americas
were surrounded by ocean
and out of reach.
But during the last Ice Age,
massive ice sheets formed
and sea levels
dropped by over 400 feet,
exposing land
between Siberia and Alaska.
Many scientists agree
that this is how humans
got to North America.
But when exactly
did they first arrive?
Throughout the 20th century,
many archaeologists
thought the answer lay in
these stone projectile points
found all across North America.
They were made by people from
what became known as
the Clovis culture.
WATKINS:
I have a replica
Clovis point with me.
They look about like this.
Some are larger,
some are smaller.
There's a very characteristic
flake
that's taken out of the base
up to the middle of the point.
JOHNSON:
The oldest known Clovis points
are about 13,000 years old.
And for a long time,
many archaeologists
thought that humans
arrived in North America
no earlier than that.
So these Clovis points
have been found
all across North America,
from the Atlantic coast
on the east,
all the way out into the,
the west coast.
So with this, such a broad
geographical span of material,
it's why most
archaeologists thought
that Clovis was the
first archaeological culture
in North America.
JOHNSON (voice over):
More recently,
this view has been challenged
by the excavation of
older sites,
with stone artifacts
that suggest humans lived
in North America
at least 2,000 years
before the Clovis culture.
[♪ ♪]
There are some
archaeological sites...
one in Florida, one in Texas...
that date about 15,000,
15,200 years ago.
So those are currently
the oldest dates we have
for the early peopling
of the New World.
[♪ ♪]
JOHNSON: But now the
discoveries at White Sands
may support even earlier dates,
and could shed new light on
how people
came to North America.
About 20,000 years ago was
the peak of the last Ice Age,
the Last Glacial Maximum.
Gigantic ice sheets blocked
the route into North America.
But there's geological evidence
that as the climate warmed,
an ice-free corridor opened up.
Was this how humans reached
the rest of the continent?
So one thing about the
ice-free corridor,
it didn't really open up
until 13, 14,000 years ago.
So if it wasn't open,
it wasn't likely that anyone
could have come that way
and come in to North America.
JOHNSON: If the tracks at White
Sands pre-date the ice-free corridor,
they will add more weight
to the idea that humans
arrived here earlier
than many archaeologists
previously thought.
[♪ ♪]
Searching for clues,
David Bustos is studying some
other remarkable human prints.
I don't know if you can
see right here,
this might be more of a child.
It's about, maybe, four,
four inches or so across.
And it's right next to
an adult print.
You don't normally think of,
you know,
taking your child all the way
across the country or so,
unless you're, um,
if you're hunting,
you might leave the child
back at home,
but we see the children
everywhere,
so they're part of the scene
or part of the landscape.
[♪ ♪]
JOHNSON: The footprints
tell stories of Ice Age life.
But how long ago were
these people here?
[♪ ♪]
In order to date the prints,
the team has dug a trench.
(rocks rumbling)
It reveals layers of sediment,
deposited over many years,
along the shore of this
ancient lake.
Stamped on these buried
surfaces are human prints,
and the further down they are,
the older they are.
But just how old are they?
I can put them both on.
Okay, sure.
JOHNSON: To help find the
answer, David has been joined
by geologists Kathleen Springer
and Jeff Pigati,
who is also an expert in
radiocarbon dating.
[♪ ♪]
You've cut a cross section...
What are you trying to see
with the cross section? SPRINGER:
So the footprints themselves
are just an impression
on a surface,
there's nothing to date.
It's an inorganic thing, you
have to find something organic
that you can date above
and below the footprints,
and get good dates on them,
so that you can actually say,
"That footprint is between
these two ages."
JOHNSON (voice over): In this trench,
Kathleen and Jeff have made a crucial find.
[♪ ♪]
Sandwiched in the layers
above and below the footprints
are scatterings
of ancient seeds,
precious organic material
which the team can date.
That way they can establish
a window of time,
for when the prints were made.
There were actually
plants growing on this,
on the surface when, you know,
these critters
were walking around.
So the same layers that have
the tracks will have the seeds.
Absolutely, above and below them. Yeah.
Yes, so above and below them,
that way we can constrain
in time.
So your seeds are effectively
little timepieces, right?
They're like little clocks
or something buried in the...
They're little capsules, yeah.
And basically the, the...
these things are really
resistant to, to decay.
And so they look like
they were put down on the,
on the landscape just yesterday,
but, in fact,
they might be tens and,
you know,
tens of thousands of years old.
JOHNSON (voice over): Jeff will
take the seeds back to his lab in Denver,
and use radiocarbon dating
to find out how old they are.
[♪ ♪]
JOHNSON: When I talk
to you in six months' time,
either you have what you expect,
PIGATI: Mm-hm. Which
is around 12,000 years,
or you have humans
here earlier than you expect,
or mammoths are here later
than you expect.
PIGATI: Something's going to
be pretty cool either way, right?
So it seems like you're going
to get
a really interesting result no
matter what the result is here.
PIGATI: It is a win-win,
no question about it. Yeah.
That's a rare thing
in paleontology.
PIGATI: It's kind of nice. Yeah.
JOHNSON: Dying to hear what you find out.
Yeah.
Yeah, us too, us too.
JOHNSON (voice over): The trackways
at White Sands are constantly changing...
as the wind erodes away the
surface to reveal new prints,
it's also turning existing ones
to dust.
BUSTOS: It's great because
we can see the prints,
but then they are
rapidly blowing away.
So we want to capture the data
before it's gone.
Some of these really soft ones
like this,
once they're exposed, in
a few months they'll be gone.
Some type of, you know,
priceless data is, is being...
is right here, is being lost.
It's the surface,
we're losing the surface,
and these are
where all the prints are.
[♪ ♪]
JOHNSON: To record this precious
evidence before the wind blows it away,
the team is mapping the site
using aerial imagery.
BUSTOS: One of the main
reasons is to fly over the area
and then get an elevation model
so we can see where
these prints are.
And then we're gonna
re-fly it again,
and so with that we'll be able
to look at
from this year to next year
we'll see how much erosion's
happening,
so we can see how fast
the prints are moving
and going away.
JOHNSON: One question they
hope to answer using digital imaging
is whether the people here were
hunting the giant animals.
David shows me an intriguing set
of tracks that may hold clues.
Dave, what kind of
image is this?
BUSTOS:
It's a photogrammetry.
You know, so basically
overlapping photos.
I think in this image,
there might have been
400 or 500 different images
and they're all stitched
together.
You can, you know,
tip the images upside down,
see it in different directions.
So this image right here
is actually
a giant ground sloth.
It's walking along.
These are hind and fore feet,
so when they weave in and out,
what you see is a hind foot,
and then the forefoot comes
in front
with the very long claw.
And then right here, it changes.
So it stands up, actually.
JOHNSON (voice over): What
caused this sudden change in behavior?
David has a theory.
BUSTOS: If you look close,
you'll see a set of human tracks,
And what's really exciting,
we took measurements.
You can see they're running
toward the sloth.
If you're in the field,
you'd actually see where they're
almost toe to toe, you know,
almost chest to chest,
it looks like.
I don't know if they're
throwing a spear
or what they're doing, but they
come right up to each other.
The sloth's spinning around
and making, like,
it looks like a sweeping motion.
Actually, there's claw marks
on the ground.
There's another set
of human prints
sort of running up along
this direction.
JOHNSON (voice over):
David believes these trackways
are evidence that humans
were actually hunting sloths.
(sloth grunts)
But what was it like to take
on such big animals?
(sloth growls)
La Brea Museum curator
Emily Lindsey
has investigated
how humans hunted them.
So these are our collections
where we keep all of the fossils
that have been excavated
over the last hundred years.
There's millions
of fossils here.
Yeah, there are literally
millions of fossils here.
And here are some
of our sloth claws.
JOHNSON:
Oh man, look at those things,
these are serious claws.
What did they use the claws for?
Some paleontologists
think they might have used them
to dig roots out of the ground.
They've found burrows
that they think these guys
dug there,
where there's actually
scratch marks on the wall
that line up with the the hands
of giant sloths.
But, of course,
they would have been really
useful for defense, as well.
JOHNSON (voice over): But
despite their fearsome appearance,
archaeological evidence shows
that ground sloths
might have been on the menu
for hungry humans.
LINDSEY: You know,
we have a couple of sites
that have been found where it
looks pretty clear
that humans were,
if not hunting,
at least butchering
giant ground sloths.
We've got stone tools
and we've
got cut marks on the bones.
Although we have many more sites
that show humans hunting
and eating things like mammoths
and horses and camels
than we do of giant sloths.
So, they may have been a food
source of last resort.
Maybe bison tastes better, or...
Yeah, given the types of plants
that we find in the sloth dung.
You know, desert plants
that tend to have a lot of
chemicals in them.
They might not have tasted
very good.
Huh, interesting.
So what kind of techniques
were humans using
to hunt and kill these animals?
LINDSEY:
They had spears, but, of course,
the most important tool
that humans had
were their big brains
and their social groups
and ability to communicate.
Hm.
[♪ ♪]
JOHNSON (voice over):
Teamwork and planning,
these were the keys to bringing
down huge Ice Age beasts.
[♪ ♪]
But once the animal was dead,
what did people do
with all that meat?
[♪ ♪]
One of the challenges
you have, if you're,
if you're living
in this environment,
or hunting in this environment,
is how do you get your meat
from where you kill the animal
to where you camp?
[♪ ♪]
JOHNSON:
Dan Odess is an expert
in prehistoric archaeology.
He searches for evidence to show
how humans might have dealt
with the animals they killed.
And alongside the footprints,
he shows me
a very different kind of track.
DAN ODESS: We have
these, these really interesting
linear structures.
There are four of them.
You can see here
one, two, three, four.
JOHNSON: What could have caused
these strange marks in the sand?
ODESS:
We were kind of wondering
initially, could this be
a product of animal behavior
rather than human behavior?
But, interestingly,
one of the things we see
and you can see it very clearly
in this one,
we've got people walking along
behind it.
JOHNSON: Dan believes this is
important archaeological evidence
of human engineering.
They're, they're drag lines.
So impressions left in the mud
as somebody probably pulled
a pole or poles.
Okay.
With presumably meat
or something else on them.
JOHNSON: And that's a typical
way to move meat around?
I think this is the first time
it's been described for
the Ice Age.
JOHNSON (voice over):
The team thinks these tracks
could be the earliest known
evidence of an ancient device
used to carry heavy loads,
such as large amounts of meat.
ODESS: Instead of dragging
the carcass back to the camp,
they would strap it onto
a couple of poles,
and not one, or two poles.
At this point,
we're not sure whether
they're dragging a single pole
or whether they're using
two poles hitched together.
JOHNSON (off-camera): Huh, so like a
primitive wheelbarrow, basically, right?
ODESS: So far we, we
don't have any reason to think
they had a wheel.
Right.
Well, wheelbarrow with
no wheel, how about that?
Yeah, right, right.
(chuckles)
A barrow!
Right, there you go.
Let's just call it a barrow. A barrow.
[♪ ♪]
JOHNSON (voice over): But what
could the device have looked like?
(birds flapping wings,
squawking)
60 miles from the trackways
is Elephant Butte Lake.
Experts think White Sands
had a similar environment
during parts of the Ice Age.
Archaeologist Joe Watkins
has come here to conduct
an experiment.
Joining him are fellow
archaeologists Carol Ellick,
CAROL ELLICK: I'll start
with the lashing on this corner,
all right?
Yup.
JOHNSON: And Edward Jolie,
of Lakota and Muscogee descent,
and a citizen of the
Muscogee Nation of Oklahoma.
EDWARD JOLIE: Is this
going to be sufficiently stout,
or should we cut a thicker one?
ELLICK: I think that's pretty tiny, Ed.
JOLIE:
It is.
JOHNSON: The team
wants to carry out experiments
to try to reproduce the tracks
at White Sands.
[♪ ♪]
They're building two simple
structures
to see if one of them
might leave
similar drag marks to those
found in the desert.
Ed, if you want to
lash the end pieces
together. JOLIE: Okay.
I'll grab the important piece.
JOHNSON: The first design
is an A-frame structure,
based on a traditional device
used by Indigenous peoples
called a travois.
They're attaching
40-pound weights
to represent a hunk of meat.
I think that's the 40 pounds.
This feels, like, more than
40 pounds, is this...?
Honestly, that's 40 pounds.
Two 15-pound weights,
plus two 5-pound weights.
(chuckling)
That's...
We might have some
structural issues.
(laughter)
I don't remember my daughter
ever weighing this much!
(laughs)
JOHNSON: Carol is
going to pull each design.
Walking barefoot,
like the people
who created the prints
at White Sands.
It feels pretty stable.
ELLICK: It looks pretty stable. It feels,
from my end,
it feels pretty good too.
ELLICK: I was going to
follow the edge of the water,
is that what you were thinking?
WATKINS:
I think that's a good way.
Okay.
Okay.
(grunts)
Whoa, getting started.
JOHNSON: Carol leaves
behind clear footprints
and drag marks in the mud.
[♪ ♪]
WATKINS: Look at that.
JOLIE: Yeah, that's great.
WATKINS: The footprints
are both on one side.
I would have thought
there would have been footprints
on either side
and that the drag line,
would have been between
the two. JOLIE: Mm-hm.
And it appears to me, as well,
that what we're seeing
is that the footprints
are the side opposite
the weight imbalance
on the travois.
WATKINS: Either that or the
fact that there are two sticks
is having an impact
on the way it's moving.
JOLIE:
Looks great.
JOHNSON: They record
the marks for further study.
WATKINS: Let's get
one up by that footprint
where the mud has
pushed over to, okay?
That's a good start.
[♪ ♪]
JOHNSON: Next, they
try the second design...
a single pole with the same
weight attached.
WATKINS: Do you want
me to come up a little bit?
ELLICK:
Pull it forward a little bit.
So...
Put that end down.
JOLIE: Come up parallel to this one.
ELLICK:
All right, all right.
(stick dragging)
[♪ ♪]
JOHNSON: This creates a single
drag line with a regular wobble pattern.
That feels quite
different pulling it
on the single pole
rather than the double travois.
WATKINS: So it definitely
is wobbling back and forth
much more than the one with
the two-pole travois.
Standing and staring at them
both in parallel,
it's really drawn into
stark relief
Yeah.
How different they are.
It's a bit of a surprise,
actually. (Shutter clicks)
[♪ ♪]
JOHNSON: But which
design makes a pattern closest
to the tracks found
at White Sands?
WATKINS: My impressions
are that the straighter lines
at White Sands
pretty much equate with
the straighter lines
we're getting with the travois.
That's definitely not saying
that's the only way
they could
have had those straight lines.
But just based on
this initial experiment,
I would be more inclined
to go with the double pole.
JOHNSON: This experiment
suggests how Ice Age humans
might have transported meat
or other heavy objects.
But how long ago
were they walking along
the ancient lakeside at
White Sands?
[♪ ♪]
It was time to visit Denver
to catch up
with Jeff Pigati
and Kathleen Springer.
PIGATI: Yeah, right at the
top of the sequence there.
So that one has a stem attached.
Still has a stem attached?
Yeah.
That's awesome.
We'll go through there.
Yeah.
JOHNSON: At the U.S.
Geological Survey Lab,
Jeff has been analyzing
the seeds they found
in the sediment layers
at White Sands.
[♪ ♪]
He's been using
radiocarbon dating
to calculate the age of
the seeds, and from that,
the age of the footprints.
PIGATI:
This is the carbon extraction
and graphitization system.
And, basically, what we do here
is take a seed.
We com bust it in oxygen.
We turn the carbon
that's in the seed
into carbon dioxide.
We get rid of everything
else that's in the seed...
water and other other
contaminant gases
that we don't want...
and we end up with pure CO2.
[♪ ♪]
And we basically take that
carbon dioxide,
convert it to graphite,
and that's what we actually
send out to the AMS lab.
So you turn the seed into a gas
and then back into a solid.
That's exactly right,
we start with a solid,
we turn it into a gas,
clean it up,
and then end up with a
pure graphite pellet at the end.
In these little targets,
right here.
That's a tiny little thing. Exactly.
It's about the size of a pencil
lead, they're very small.
And they're sealed
into this thing?
That's right, exactly.
I see this little closed chamber. Yeah.
JOHNSON (voice over):
The precious graphite pellets
are then sent to a mass
spectrometry lab to be analyzed.
So what happens at the
mass spectrometry lab?
Yeah, so that's where they
measure the ratios
of the various carbon isotopes. Uh-huh.
And those are the data
that we get back,
and we use those
to calculate the age.
[♪ ♪]
JOHNSON (voice over):
It's the moment of truth.
After more than
a year and a half,
have Kathleen and Jeff
managed to find out
the age of the footprints?
So tell me, what were the
dates of those footprints?
We were able to document
that humans
were in White Sands
National Park
between 23,000 years ago,
and about 21,000 years ago,
JOHNSON:
23,000 years ago?
That's way older than there's
been good evidence
for humans in North America.
It's about 10,000 years older
than sort of the established,
sort of,
thought of when humans arrived
in the Americas.
JOHNSON: And you got
tracks at more than one layer,
which means that
wasn't just one group of people
at one moment in time.
No.
That it was many groups
of people over a lot of time.
SPRINGER:
2,000 years.
I mean, 2,000 years itself
is a long duration.
It is.
But the fact that they were here
23,000 thousand years ago...
Yeah, crazy, huh?
JOHNSON: Blows my mind, I mean...
SPRINGER: It blew our mind! (Laughs)
That's like 10,000 years
before Clovis.
SPRINGER:
Yes.
That's like the entire length
of human civilization
before Clovis.
SPRINGER:
Yeah, go figure.
This is not a subtle result.
[♪ ♪]
(voice over):
If these dates are correct,
that would make the White Sands
footprints
the earliest direct evidence
of humans
ever found in North America.
PIGATI: This is the Last Glacial Maximum.
This is when the ice sheets
were at their maximum,
and it's been thought that those
ice sheets
blocked people from coming down
into North America.
And what we found was
that the people
were already here at that time.
JOHNSON: So you couldn't
be blocked from getting here
if you're already here.
SPRINGER: That's right.
If you're already here.
JOHNSON: And if you've been
here for a couple thousand years?
SPRINGER: Right. Yeah.
JOHNSON: What did you
think when you saw the results?
Holy...
(laughter)
It was pretty much like that.
I mean...
There was words that were spoken
that were emphatic words.
Wow. Just wow, yeah.
[♪ ♪]
JOHNSON (voice over): But
some experts question these results.
They're troubled by the lack
of additional
archaeological evidence
of this ancient population.
Others say the dating method
could be flawed
arguing that the sediment layers
may have been disturbed.
Or the seeds may have absorbed
older carbon
from surrounding groundwater,
which could skew
the carbon dating.
This is an extraordinary
discovery.
How confident are you
in the quality of the dates
that you've achieved?
We're very confident...
These, these ages,
we were able to reproduce them
extremely well.
They maintain what we call
stratigraphic order.
Basically, the oldest at the
bottom, youngest on the top.
And even though some
of these samples
were only separated by a
centimeter or two of sediment,
they still maintain that order,
and that's one of the,
one of the, one of the key
things that we wanted to see.
And so it's not just what
we see in the lab,
but it's also what we see
in the field taken together
is really what
makes this powerful.
JOHNSON: This is a huge
discovery, how do you feel?
(laughs)
Exhausted!
(laughing)
[♪ ♪]
JOHNSON (voice over):
If the results are correct,
then these prints could have
been left behind
by some of the earliest
known Americans.
Back at White Sands,
I was curious to find out
what Kim Charlie and Joe Watkins
make of the discovery.
So now that there are
dates of 23,000 years ago
with Native American footprints,
how does that make you feel?
WATKINS:
It's just amazing.
We talk about having
always been here,
it's just remarkable to put
that much of a movement
further back in time.
So now we've added another
6,000 to 8,000 years
to what archaeologists have
told us was
the time depth of our history.
And so this keeps putting
that history back in the news,
keeps telling people,
"Well, yeah,
you've been here 500 years,
we've been here for 20,000."
Here's our proof, you know?
Footprints,
footprints of our ancestors.
You know, that goes to show,
we were here.
We were here on this earth
a very long time ago.
[♪ ♪]
JOHNSON: But if humans
were here 23,000 years ago,
how did they get here?
At that time,
the corridor between
the ice sheets did not exist.
So humans might have followed
the Pacific shoreline,
possibly by boat,
a route known as the
"kelp highway."
But how exactly
they would have made it here
during the Ice Age is still
unknown.
JOHNSON: These footprints
tell us that people were here
during the Last Glacial Maximum.
So how, how do you think
they got here?
WATKINS: I think probably the
coastal highway is the best bet.
Many old sites are going to be
submerged under water now.
So I, I think that's where
we need to look.
[♪ ♪]
JOHNSON (voice over):
Whatever the answer,
there's no doubt that these
astonishing discoveries
are another step forward
in scientists' understanding
of human history.
And perhaps they could also
shed new light on humans' role
in the extinction of
Ice Age animals.
So where does this leave us?
For many years, we thought that
the Ice Age animals went extinct
about the same time that people
got to North America.
Now this site is telling us
something very different.
Basically what we're seeing is
that humans were here
more than 10,000 years before
the extinction of the animals.
So the question of was the
extinction caused by climate,
or people, or both,
has just become a much more
complex problem to solve.
[♪ ♪]
One theory is that when humans
arrived on this continent,
their numbers were too small
to make a big impact
on the wildlife.
But at some point,
populations increased,
and they developed
better hunting techniques.
Was this what eventually spelled
the end for the animals?
People have always thought
it was either
climate or people that caused
the extinction of the Ice Age
megafauna.
What do you think?
You know, I...
we really don't know yet.
But what we do see, you know,
without a reasonable doubt,
is that, you know,
around 12,000 years,
the area starts to dry out,
the lake dries up
and then the dunes form.
So climate change might have
been influencing that as well.
Maybe someday we'll,
we'll find out.
We might not ever learn.
But, but you know, the
exciting thing about White Sands
is there's thousands
of prints to study.
So, you know, the secret
might be locked there
somewhere in the sand.
[♪ ♪]
JOHNSON:
The unique preservation
of these ancient footprints
could yield more clues
about the lives of
Ice Age Americans.
SPRINGER: We're very
excited because it's, it's kind of
the tip of the iceberg,
you know?
White Sands is still there.
Those tracks are still there.
They're eroding out every day,
every minute.
And we get the opportunity to go
back and, and to learn more.
JOHNSON:
So the research goes on, then.
Yeah, it goes on, sure.
PIGATI: Yeah, this is just the
beginning, that's exactly right.
It's a tremendous opportunity.
It... it's opening up
the world of archaeology
way beyond where it's been.
It's going to give a new
generation of archaeologists
something more to shoot for,
to see whether we can go back
any farther than 23,000 years,
or whether this, in and of
itself, is the threshold.
[♪ ♪]
[♪ ♪]
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[♪ ♪]
[♪ ♪]