NARRATOR: Deep inside the labyrinth
of a flooded cave system.
ALBERTO: All of a sudden, the floor just drops.
NARRATOR: Divers come across human remains.
ALBERTO: You can see these dark eye sockets kinda looking back at us.
NARRATOR: And the bones of giant prehistoric creatures.
DOMINIQUE: Saber-tooth cats, bears, giant ground sloths.
NARRATOR: Discoveries that could revolutionize our
understanding of how the first humans came to the Americas.
LOREN: They must have come here another way.
(theme music plays)
ALBERTO (off-screen): We have 800 miles of underwater tunnels
that have been mapped.
We think there's another half still to be discovered.
NARRATOR: A team of divers is exploring the world's largest
underground flooded cave system.
ALBERTO (off-screen): It's like a labyrinth of tunnels everywhere,
almost like a Swiss cheese in the ground, full with, with water.
NARRATOR: Their aim, to survey this lost world,
sealed off from humanity since the Ice Age.
ALBERTO (off-screen): The Yucatán is special,
because all the cave here were once dry.
We know this because of the stalagmites and the
stalactites which only form in a dry cave.
About 12,000 years ago, at the end of the Ice Age,
the ice sheet melted and the cave began to flood.
NARRATOR: Now, these flooded caves pose grave risks
to the divers.
ALBERTO: Caves can be very dangerous.
ALBERTO (off-screen): You have, you know, going in an environment where,
if you have a problem, you cannot ascend.
The tunnel that you're traveling is, is totally dark.
Your lights now not have a way to see.
If you go in a small area, you could get trapped
inside the cave, so there's a lot of risk.
NARRATOR: The team's goal is to map this complex network.
ALBERTO (off-screen): When we go into these tunnels,
we do a very simple map of the cave.
Then we bring the camera, and then what we do
is we take a lot of images.
NARRATOR: It's taken 150 hours to map as far as this point,
and now the divers stop.
ALBERTO: All of a sudden the floor just drops.
ALBERTO (off-screen): We have these really powerful underwater lights,
and all you can see was darkness.
So, like, the biggest, darkest hole we've seen on the cave.
NARRATOR: Using the divers' own data and imagery,
the scale of the abyss becomes clear.
ALBERTO (off-screen): If we were to drain the water,
we would see these bell-shaped structure,
maybe, like a football field stadium kinda size.
NARRATOR: They name the vast cave "Hoyo Negro";
"Black Hole."
ALBERTO (off-screen): As we descended into the pit,
we were moving our lights,
trying to figure out what was down there.
NARRATOR: Anything Alberto and his team find here will come
from pre-history, when the abyss was a dry cave.
ALBERTO (off-screen): And then, then we saw a bone.
It was a really long, tall bone.
We moved around it, and then we saw another bone.
We started noticing that there were, there were remains
all over the place on the floor.
Whatever they were, it has to have been a really big animal.
ALBERTO (off-screen): We knew we had found something really important here,
so we mapped everything in the cave,
recorded the exact locations of the bones and took photos,
and then we sent all our data to our
colleagues in California.
DOMINIQUE: Our goal is to capture these places,
these wild places, using our visualization systems.
VID: Okay, I'm just gonna go through the different views.
So, we're now just kinda reliving the dive paths.
NARRATOR: In 2014, Dominique Rissolo and his team
begin to process the divers' mapping data and images.
Their aim is to create a 3D digital replica of Hoyo Negro,
which they can explore from dry land.
DOMINIQUE (off-screen): The divers have tremendous experience in doing
different kinds of documentation underwater,
and we're able to take all of those images, and,
through computer vision algorithms,
translate them into a 3D model.
And it's really, essentially, a, a point cloud,
a cloud of points.
VID (off-screen): So far we have around 15 billion reconstructed points.
The exciting thing is it grows every year,
so every time they go diving, take pictures,
we run new reconstructions.
We just add to the set.
DOMINIQUE (off-screen): The way that we can create maybe a more
photo-realistic 3D model is by then texturing those points
with the original photographs.
DOMINIQUE (off-screen): So, these are high-resolution images that can be essentially
draped on to this 3D point cloud.
Wow! So, here we are at the bottom of Hoyo Negro.
JOEL (off-screen): This is one of the most powerful virtual reality
systems in the world.
Being inside the SunCAVE is similar to being on the dive itself,
with the exception that you're able to be well lit.
You're able to see everything that you can't see.
DOMINIQUE (off-screen): This is essentially an interactive digital twin
that enables us to come here and do virtual dives,
and sometimes even find new animals.
DOMINIQUE (off-screen): Finding new animals in a virtual cave, right?
So, exploring a real cave by using a virtual one.
The first big animal that the divers came upon was right
here at this gomphothere.
DOMINIQUE (off-screen): It wasn't as if it was just this proboscidean,
this relative of the elephant.
It's such an incredible diversity of Ice Age fauna.
Bears, saber-tooth cats,
giant ground sloths.
DOMINIQUE (off-screen): Just amazing!
So, Joel, if you take us sort of on to the wall of the cave here,
we can see this saber-tooth cat emerge,
smilodon fatalis.
Clinging to the wall we see, you know, another scapula,
of course, the scapula over here of the giant ground sloth,
it's ribs.
NARRATOR: By examining the bones,
Dominique's colleagues identify at least 16 Ice Age species.
DOMINIQUE (off-screen): Whether they were looking for water,
or to build a den, or even to hunt,
these are massive animals that were walking through these passageways,
coming to the edge of this, this precipice and
making their way to the bottom of this pit.
It's a really wonderful view into what the planet was like
at a time thousands of years ago.
DOMINIQUE (off-screen): As incredible as those discoveries were,
that wasn't the only thing they found that day.
♪ ♪
ALBERTO (off-screen): We were swimming at the bottom of the site,
looking at the animal remains,
and then all of a sudden my friend,
Alex, just moved his light and he pointed in
a particular direction.
NARRATOR: Within touching distance,
at the bottom of the vast, flooded cave system,
dive, Alberto Nava and his team are about to make
the discovery of a lifetime.
ALBERTO (off-screen): We see these just beautiful cranium,
its just sitting, sitting upside down.
You can see these dark eye sockets kinda, kinda looking
back at us.
DOMINIQUE (off-screen): My, my, my blood ran cold.
I mean, my, the hairs stood on end.
ALBERTO (off-screen): I don't think I'll find anything like that in my
exploration life.
This is probably the best it's ever gonna get.
DOMINIQUE (off-screen): All these things come to mind.
Who was this person?
You know, how did they come to be here?
When did they arrive at the bottom of this pit?
HELENA: Let's remember,
we are a prestigious project
and a great team.
NARRATOR: To help find the answers,
the team consults experts from around the world,
led by Mexico's National Institute of Anthropology and History.
DOMINIQUE: We have now over 30 scientists
and engineers involved.
DOMINIQUE (off-screen): The paleontologists,
the archaeologists and anthropologists,
who are all helping to put together this puzzle.
JAMES (over computer): We have a fairly consistent 3,000-year
offset between.
DOMINIQUE (off-screen): As a project, we made the decision to reach out
to Jim Chatters, who had the experience and expertise we
really needed to understand the significance of the site
of Hoyo Negro and everything it contained.
JAMES: Well, you just don't see this,
this kind of preservation, so it's just unbelievable quality.
NARRATOR: The first question on the team's mind,
"Who is this person at the bottom of the cave?"
DOMINIQUE (off-screen): I shared photographs of the discoveries,
and his eyes lit up.
I could see his hands trembling a little bit.
JAMES: And here's our human.
The skeleton, is, it's a diary of someone's life, okay,
and it's especially a diary of their early years.
This is a really good picture here.
JAMES (off-screen): Here's the telling piece.
I can see, first of all, that a feature in the base of the
skull called the "basilar suture" was still open,
and that tends to close somewhere around the 20s.
And it was not only a full-size skull,
but the, the third molars had already erupted.
JAMES (off-screen): So, it's a fully formed tooth, or nearly fully formed,
which puts this more than 15 years old.
JAMES (off-screen): In looking at this right away I'm thinking,
16 to 19 years is the most likely age of this individual.
JAMES (off-screen): To determine the sex of a skull,
you're looking at how rugged it is, mainly.
In this case, what I did was I look at the mastoid processes,
and that's the position on the skull here where the large
neck muscles attach, and they tend to be large in males
and small in females.
And in this case, they were very small.
JAMES (off-screen): I asked Dominique if anyone had told him what he had there,
and he said, "No, they hadn't."
And I said,
"Well, what you've got here is, is the bones of a teenage girl,
and a bunch of really large megafauna."
This is the first time we have a human skull in direct association
with the skeleton of an extinct animal in the Americas, period.
That's really exciting.
NARRATOR: Over successive dives,
the team finds and scans more bones belonging
to the teenage girl.
By 2013, they've documented her near complete skeleton,
and she has become more than simply an archaeological find.
DOMINIQUE: Here we are in Hoyo Negro.
JAMES: Yeah.
Wow!
I've always wanted to dive this.
JAMES (off-screen): This is about the closest I'm ever gonna come, I think.
She's spread over about a 16 feet span here.
What I stressed with the divers was that basically they
needed to remember the personhood of these bones.
ALBERTO (off-screen): If you give it a name,
you, you become more caring about this skeleton,
and it goes from a skeleton to becoming a person.
ALBERTO (off-screen): We had a lot of candidates for names.
We decided to call it "Naia."
JAMES: Naiads were water
spirits in Greek mythology.
They were the, the female spirits that watched over small bodies
of water, so it seemed a very fitting name for her.
NARRATOR: Naia's remains are found close to Ice Age mammals,
but that isn't enough to prove that Naia herself
is prehistoric.
JAMES: Our goal with Naia was to collect a specimen from the
skeleton to use for radiocarbon dating.
JAMES (off-screen): We chose to do one third molar,
because third molars are often very simply rooted and
therefore easy to take out of a skeleton.
DOMINIQUE: There are a number of problems inherent in, in carbon dating,
and those can include contamination.
DOMINIQUE (off-screen): It was not a foregone conclusion that we were going
to get a viable date from Naia.
JAMES (off-screen): We ran dates independently in two laboratories,
fully expecting the dates to be completely
different from each other, and it came back within 15 years.
And between those, those translate to
close to 12,900 years ago.
JAMES (off-screen): It was pretty exciting to find out,
because only one other skeleton at that time had
dated that old, and all that there was of that individual
was one bone.
Not even a complete bone.
JAMES (off-screen) :The fact that Naia's skeleton was so complete makes her an
incredibly rare find.
NARRATOR: And, as the oldest near complete skeleton ever
found in the Americas, Naia could provide answers
about early humans living here, but to protect her remains,
the team must first remove her from the cave.
ALBERTO: So, it's been, you know, six, seven years of adventure,
and although we didn't really
wanna take any human remains, we have to do it to protect it,
and that's kind of what the day is all about,
protecting Naia and her remains.
NARRATOR: The operation to recover Naia's fragile
skeleton begins with her skull.
It is fraught with risk.
JAMES: Well, we're doing a pre-dive practice,
or the, the procedures drill.
NARRATOR: Jim rehearses the recovery with a replica skull.
JAMES: My endeavor was designing how Naia's bones
were gonna be safely removed.
JAMES (off-screen): Your strongest part is here.
SUSAN (off-screen): Mm-hmm.
JAMES: Your weakest points are here and here,
so we must protect them.
JAMES (off-screen): This was a big deal.
I mean, imagine, I'm the one responsible for making sure
that thing doesn't get destroyed in the collection process,
so I was just a little on the nervous side.
And just gently, chin first.
SUSAN (off-screen): Okay.
JAMES (off-screen): And release.
The reason Susan was the one to handle the bones had in
part to do with the fact that she had very steady hands,
but she also felt a linkage to the young woman who was in the cave.
SUSAN: And I just feel very connected with her spirit.
I feel like she's been there a long time and is ready
to go home.
ALBERTO: There was one chance and we had to get it right.
ALBERTO (off-screen): The moment Susan picked up the skull,
everybody's breathing stopped.
JAMES (off-screen): That was a really tense three hours of waiting,
waiting to see if what would be in the box when it came up?
Was it a complete skull or a whole pile of bone fragments?
Here they come!
My, oh, my.
JAMES (off-screen): Okay, Susan's on the left, Beto's on the right.
DOMINIQUE (off-screen): She comes to the surface, and you know that,
as an archaeologist, you're never gonna have another
experience like this.
I mean, this is it.
Okay, go ahead. Okay, she's fine in there.
Nice!
JAMES (off-screen): I remember getting down and peeking in the end and seeing
a whole skull there, and tremendous elation
that came from that.
Welcome, Naia!
We got her out and we got her out whole.
ALBERTO: Jim Chatters, it's good to meet you.
JAMES: Gracias! Gracias! Good job, man.
JAMES (off-screen): I've been at this for 60-plus years,
and that was the top moment in all that time.
SUSAN: Hey!
JAMES (off-screen): We cried.
NARRATOR: Naia's remains give the team an unprecedented
opportunity to learn about America's early humans.
A key question is whether Naia is a direct ancestor to
modern Native Americans?
In a replica of her skeleton, Jim looks for clues.
JAMES (off-screen): The characteristics that jumped out at me was the
very distinct angularity to the back of her skull,
and the tendency for her face to project forward.
NARRATOR: These are not common features of modern
Native Americans.
JAMES: The contrast with more recent Native American skulls
represented by these casts here.
Here's a female.
You can see a much more rounded skull.
The face, in a similar position,
is much more straight up and down.
NARRATOR: When the team turns to facial reconstruction technology,
the mystery deepens.
JAMES: What we got, we went from the printed skull here,
and then this is how she turned out.
DOMINIQUE: Wow!
JAMES (off-screen): I didn't expect her to look like she did.
She almost looks like a South African busman from the Kalahari Desert,
or someone outta South East Asia.
Her eyes are wider set, her nose is broader,
so those are all things that were different from what I'm used to.
DOMINIQUE (off-screen): There's a mystery then,
if she appears to be so different from the ancestors
of modern Native Americans, where did she come from?
NARRATOR: To find out, the team tests Naia's DNA.
JAMES: When I got the result back,
I was very happy that we got a result,
but as happy as I was to get the result,
it was not the result I expected.
JAMES (off-screen): What it showed was that although Naia's skull seemed
different from modern Native Americans,
they still shared a genetic background.
They shared the same heritage.
NARRATOR: So, Naia is an ancestor of modern
Native Americans.
Now, the age of her skeleton, dated to the very end of the Ice Age,
propels her into the center of one of the hottest
controversies in science.
How did she and her people get to the American continent?
JAMES: So, part of the question about Naia was can
she help contribute to an answer to that question?
(waves crashing)
NARRATOR: For decades, experts agreed on how the first humans
migrated to the Americas.
DELGADO: In school, studying archaeology,
I heard a great deal about the Bering Land Bridge.
DELGADO (off-screen): During the last Ice Age, huge ice sheets blocked
the land route from Siberia to Alaska,
but when the ice thaws around 13,000 years ago,
which is when Naia is living in the Yucatán,
it becomes possible for humans to walk into America,
and a group previously known as the
"Clovis people" do just that.
LOREN (off-screen): The Clovis First model is that people came into the
Americas by way of migrating through an ice-free corridor,
exiting south of the ice, hunting megafauna like
mammoths and bison, using a very specific kind
of technology known as a "Clovis spear point."
DELGADO (off-screen): That view that this Clovis group were the people
that had come across the Bering Straits,
and were the ancestors of modern
Native Americans became so fixed in archaeological orthodoxy,
that to suggest an earlier date and other
migrations was scientific heresy.
NARRATOR: The question is, do Naia's people travel
to the Yucatán through the opening ice-free corridor,
or some other way?
LOREN (off-screen): The problem with explaining everything as an
interior migration, that's just not an explanation that
accounts for the facts, and the facts are that people are south
of the ice before this ice-free corridor opens.
The earliest sites, for example,
are actually in South America.
So, there's one in Peru called "Huaca Prieta,"
and there's another one in Chile known as "Monte Verde."
Stone tools, bones and charcoal from these sites show
that humans were in the Americas at least
14 and a half thousand years ago,
more than 1,000 years before the ice melts.
NARRATOR: So, if ice is blocking the land route,
how do these earliest Americans arrive?
LOREN (off-screen): They must have come here another way,
so that's why we're interested in looking on the coast,
cause that is the easiest explanation to explain how we
can get people south of the ice before this ice-free
corridor opens up.
NARRATOR: In 1997, scientists begin to uncover evidence of
very early human habitation in this remote valley in Idaho.
LOREN (off-screen): As people were migrating south along the coast,
they would have had ice to their left and the ocean to their right,
and they would have encountered the Columbia River eventually.
They may have decided to just simply take a left-hand turn
south of the ice, and penetrate into North America
at that point, and if they kept going upriver,
they would have made their way here, to Cooper's Ferry.
NARRATOR: Loren and his students search for stone
tools that migrating humans may have left behind.
LOREN (off-screen): Well, if this site was old enough,
we might actually find evidence of Clovis peoples,
but, sorta to my surprise, we didn't see that at all.
LOREN (off-screen): Do you see this thing?
What we did find instead were these other kind of spear points,
and these are known as "stemmed points."
Stemmed points look very different than Clovis points.
LOREN (off-screen): They have a little, small rectangular tab at the bottom.
That just made it very clear that we have some other kind
of cultural pattern that's present at the site,
at the same time people were making Clovis artifacts
somewhere else.
When we first found these, I really didn't have any idea
how old they were, so that was a big question.
Radiocarbon dating showed us that points like these are
13,000 years old.
LOREN (off-screen): Some of them were older, 14,000, 14,500.
And it just blew our minds that this technology could
actually be as old as Clovis, and then even earlier.
NARRATOR: Some challenged this,
but if those dates are correct,
that's 1,000 years before the ice-free corridor,
and at least 2,000 before Naia's time.
How might these people arrive?
Are the stemmed points a clue?
LOREN: The only other place that we find artifacts that
look like this during the end of the last Ice Age are in the
northern part of Japan, on the island of Hokkaido.
NARRATOR: Loren believes this shows how early people
traveled into the Americas from the Far East,
via the Ice Age coastline and rivers.
LOREN (off-screen): If we imagine that people might have been able to
come along the coastline, along the Northern Pacific,
into the Americas, we don't really need to look much farther
than Japan, the Russian Far East,
and they show us that there's a population already in place.
They are on the doorstep, waiting to migrate their way
into the Americas.
DELGADO (off-screen): It didn't mean that you'd have
to sail all the way
across the Pacific or across the Atlantic.
You just island-hopped from bay to bay, making your way,
sometimes over a generation.
LOREN (off-screen): As new sites are being discovered that show us that
people are south of the ice before an ice-free corridor opens,
that requires us to really rethink things.
NARRATOR: To truly understand human migration,
Loren needs to explore the Ice Age coastline.
The problem is, it's now more than 400 feet underwater.
LOREN: How can we find the evidence out there where it
likely exists?
And that takes us offshore,
and we need to look beneath the waves.
LOREN: It's important to understand the coast from an archaeological perspective,
because it could be the place
that holds evidence for the earliest peoples to
come into the Americas.
NARRATOR: Loren Davis is searching for evidence that
early settlers use a coastal route into the Americas,
but he's not looking at today's coastline
for a very good reason.
LOREN (off-screen): During the Ice Age, the coast of the continent
looked very different to how it does now.
When the ice melted, all that trapped water raised sea levels
by over 400 feet, so any evidence of early peoples
living on the coast are now deep underwater.
NARRATOR: And that means searching below the waves,
30 miles out to sea.
LOREN (off-screen): Getting on this ship was a real breakthrough for us,
cause it allowed us to then go out and then ground
truth our theoretical ideas.
WOMAN (over radio): We are off the north east of Heceta Bank,
which is off the central coast of Oregon.
LOREN: We went out to the very edge of the ancient coastline,
so these are areas that are about 130 meters
below modern sea level.
LOREN (over radio): Oh, man!
We went off a cliff!
NARRATOR: Loren one day hopes to find evidence of
prehistoric human settlements on this ancient coastline.
The first step is to build an accurate picture of the hidden
Ice Age landscape below the waves.
LOREN (off-screen): As sea level comes up, it brings a lotta sediment with it,
and it will bury the ancient landscape that was once there,
so this obscures our view.
We really need a technique that allows us to see into the sea floor,
and one of the tools that we use is called a "sub-bottom profiler,"
and what this does is it sends a
sound pulse into the sea floor, and it will reflect back an
acoustic signal that it then turns into sort
of a depth map.
MAN (off-screen): Could we track a line bearing 317 at Point Four?
NARRATOR: Merging the deep sea scans with data from computer
models reveals a world not seen for millennia,
the shoreline of Ice Age America.
LOREN: Is we were to lower the ocean down to about 13,000 years ago,
the position where it was then,
we would see a really different coastline.
LOREN (off-screen): We would be able to see river valleys,
we would see embayment's,
we would see a low mountain range.
It would be a broad coastal plain that looks really
different than the rugged, mountainous coastline of
today's central coast.
DELGADO (off-screen): That's a landscape with estuaries full of marine life,
as well as sea birds and animals.
And with that, we would see this lost world,
the Americas as they were at the time of
initial human settlement.
LOREN: This story of ancient coastlines under lower sea
level associated with the last Ice Age is not just an Oregon story.
This is a story that happens everywhere.
NARRATOR: Similar investigations are being conducted
all along the Pacific coast.
LOREN (off-screen): As you go farther south,
San Francisco would have been an area that isn't on the
coast in the past, that it's lowered sea level would have
taken it much farther away from its modern position,
so San Francisco would have been really sort of
an inland valley.
NARRATOR: Having accurate mapping of North America's Ice Age coastline
now allows Loren to narrow his search for signs
of early human habitation.
LOREN (off-screen): So, if I'm a traditional hunter-gatherer or
fisher person, you know, I'm living on an ancient coastline,
where are the hot spots?
Where are the places that are gonna take care of
me the best?
And the estuaries are really, really important
places for people.
I mean, there's more calories per square meter in an estuary
than almost any other place on the coast.
NARRATOR: What really happened remains unclear,
but Loren and others continue to explore,
debate and seek new clues.
LOREN (off-screen): Archaeology works by making discoveries.
In time, my bet is on that these discoveries are going to
be made up and down the Pacific coast of the Americas.
JAMES: This is more anatomical position here.
NARRATOR: When Naia dies, 13,000 years ago,
early humans are arriving in North America via the ice-free corridor,
and the place she is found in the Yucatán is only a
few miles from the Ice Age coastline.
So, which route to Naia's people take?
Jim hopes to find clues in Naia's remains.
JAMES: Here we're looking at a micro-CT scan.
You see one little stress line right there.
See that little line right along,
right near the junction with the dentine?
NARRATOR: He's looking for telltale signs of stress from
her lifestyle and environment.
JAMES: The other place we look is in the long bones
and how they grow.
Here we're looking at Naia's thigh bone,
which is the longest bone and therefore the one that's gonna
give us the most detail.
JAMES (off-screen): See these lines?
These are the places where growth has been interrupted,
and then begun again.
One, two, three, four, five, six.
Two, three, four, five, six years we can see,
and the spacing of those lines in Naia suggest that she had a
protein deficiency during one season of every year.
DOMINIQUE: And so she lived a kind of feast and famine life.
JAMES (off-screen): Seeing that Naia had protein deficiency during some
times of the year raises the question of why was she
protein deficient if she lived so close to the sea?
DOMINIQUE (off-screen): There's fish, there are crustaceans.
The sea is a plentiful place.
JAMES (off-screen): Nothing we're seeing in the evidence for her diet is
consistent with being marine-adapted.
It is quite consistent with being strictly terrestrial.
Her people were not adapted to the coast.
DOMINIQUE: Really what it suggests is that she was among
these highly mobile hunter-gatherers who were
heavily reliant on a successful hunt,
their ability to hunt and to kill and to consume megafauna.
DOMINIQUE (off-screen): And the fact that she appears unable to fish or make use of
marine proteins, that really doesn't make sense if her
people had traveled to the Americas
via a coastal highway.
DELGADO: The most dangerous thing in science is to be
disappointed when the evidence doesn't support your theory,
so when Naia was found, given her age, it was, like,
"Wow! She had to be a coastal person."
Well, that doesn't show up in her bones.
JAMES (off-screen): While she doesn't disprove the coastal migration theory,
she certainly does not support it.
NARRATOR: But that doesn't rule out others coming via the
coastal route at least 2,000 years before her time.
DELGADO (off-screen): It's just the most fascinating puzzle.
I think it's likely that there were multiple migrations,
following different routes, over thousands of years.
NARRATOR: As for Naia, we are still finding out
more about her life and death.
JAMES (off-screen): The hardest ones to work with are the young people.
You think about a life not lived,
but you also think about the impact of the loss of that individual
on their parents, their siblings,
their, their young spouses.
NARRATOR: Now they want to piece together the clues to
understand what may have happened to Naia in the
Yucatán cave system, 13,000 years ago.
JAMES (off-screen): When we're working with ancient human skeletons,
we're dealing with the ultimate cold cases.
NARRATOR: Jim Chatters' forensic examinations reveal
an injury from which Naia would not have recovered.
JAMES (off-screen): We know from her pelvis,
she struck the front of her pelvis here,
and it broke away the pubic bones on both sides.
JAMES (off-screen): These jagged, jagged breaks that you see here
are green bone fractures.
They're the kinda breaks that fresh bone gets, not old,
dead bone gets.
This was a serious accident.
It is not easy to break your pelvis,
not to shatter it like that.
NARRATOR: To determine would could have caused Naia's fatal injury,
Dominique Rissolo and Jim attempt to retrace her
footsteps in the 3D replica of the cave.
DOMINIQUE: It's impossible not to wonder why Naia
was in the cave.
JAMES (off-screen): Hoyo Negro had a pool of water in the bottom.
Was she there for water?
DOMINIQUE: This would have been the route that she would have walked.
JAMES: This is the most likely way she came in.
The closest entrance is about 2,000 feet behind us.
(Naia breathing heavily)
Imagine she is deep in the cave and she's lost her way,
which would have been easy in these caverns.
These tunnels, they join and they separate,
and join and separate, and getting lost would be
a very easy thing to do.
You can turn to the left,
and work your way over some boulders.
DOMINIQUE: Was she being pursued by another animal
inside the cave?
JAMES (off-screen): She knows there are large, dangerous animals there.
DOMINIQUE: So, kinda climbing over these rocks and close to the edge.
JAMES: Yeah.
DOMINIQUE: You know, maybe trying to find a way around
the pit?
JAMES (off-screen): Otherwise we can't get her over to where she fell.
Eventually her light's gonna go out
and she's wandering in the dark.
(Naia breathing heavily)
JAMES (off-screen): And suddenly she takes one final step,
and the bottom falls away.
Whoa!
From the floor of that tunnel to the surface of the water
below was right about 100 feet, 30 meters.
JAMES (off-screen): And if you look straight down the rim here.
DOMINIQUE (off-screen): Yeah, that's the rim, yeah.
Yeah, yeah, yeah.
JAMES (off-screen): She's right down there.
DOMINIQUE (off-screen): Oh my goodness!
JAMES: So you fall. Okay, now, Joel, just swing straight down.
From where her body was, it looks like she probably went through the water
and smacked the rocks down below it.
JAMES (off-screen): I imagine she was knocked unconscious and didn't know a
thing after that.
NARRATOR: What happens next sets in motion an
extraordinary series of events,
which preserved Naia's remains for the next 13,000 years.
DOMINIQUE (off-screen): And what we see, of course,
is global sea level rise, and those rising sea levels
are pushing the fresh water that lies under the Peninsula up.
And this chamber is flooding,
and it's flooding surprisingly fast.
Over a few thousand years we see a, a dry cave,
to a completely flooded one.
It's a really rapid and incredible transformation.
JAMES (off-screen): That sealed the cave off,
and it became absolutely isolated from the
rest of the world.
JAMES (off-screen): It wasn't until cave divers, just exploring for the sheer
joy of it, happened upon this huge black hole.
NARRATOR: For Dominique and the team of scientists studying her,
Naia's story is not yet complete.
JAMES (off-screen): She comes to us forward in time as a messenger,
and tells us of the life of people lost so long ago.
DOMINIQUE (off-screen): We know very little about her culture.
We certainly don't know what language she spoke.
We don't have stone tools, we don't have artifacts.
DOMINIQUE (off-screen): Those have yet to be discovered.
LOREN (off-screen): One of these days I hope that we actually find
artifacts that are a very clear human origin.
I hope that we find information about the foods
that they're eating.
We may even get as lucky as to find something that reflects
the personal life of somebody.
LOREN (off-screen): To me, it's only a matter of time.
Captioned by Cotter Media Group.