<i> - Who were the first people
to reach the Americas?</i> - This sits squarely in the
middle of that debate. <i> [dramatic musical sting]</i> <i> stunning new evidence
has come to light...</i> - It rewrites history. <i> - ...that suggests we may have
been wrong about everything...</i> - It's probably not true. <i> - ...and that a mysterious
cave-dwelling culture</i> <i> may have stretched all across
the Americas...</i> <i> ♪ ♪</i> <i> ...long before
we ever thought.</i> - The evidence is so strong. <i> ♪ ♪</i> <i> - So I'm traveling deep
into the underworld...</i> <i> - You can get lost here
very easily.</i> <i> ♪ ♪</i> <i> - ...and getting
my hands real dirty...</i> - It's dried... poop. You can wash your hands later. <i> ♪ ♪</i> <i> - ...to try and find out who
these ancient peoples</i> <i> may have been...</i> <i> ♪ ♪</i> <i> ...and how long ago
they arrived.</i> - 12,000.
- 16,000. - 20,000.
- 130,000 years ago. <i> - That blows the theory
out of the water.</i> <i> [dramatic percussion]</i> [boat horn sounds] <i> ♪ ♪</i> <i> - Right beneath our feet,</i> <i> there are cities...</i> <i> ♪ ♪</i> <i> Hidden by time.</i> <i> They hold the clues
that could rewrite history.</i> <i> ♪ ♪</i> <i> Into the abyss, huh?</i> [exhales] [cheering] <i> I'm Don Wildman,</i> <i> and my mission is to explore</i> <i> the farthest and deepest
reaches of our planet</i> <i> using cutting-edge
technology...</i> <i> How cool is that?</i> <i> ...to dig into the greatest
mysteries of our past...</i> [metal clangs] <i> ...going deep...</i> <i> [music heightens]</i> <i> ...into the cities
of the underworld.</i> <i> [mysterious ambient music]</i> <i> ♪ ♪</i> <i> Our understanding
of the world we live in</i> <i> is constantly changing.</i> <i> Take for example, the question
of who were the first people</i> <i> to arrive in North America.</i> <i> ♪ ♪</i> For almost a century, accepted truth of how man
came to the new world, the Americas, <i> is that prehistoric man,</i> <i> in search of richer
hunting grounds,</i> <i> crossed the frozen
Bering Strait.</i> <i> This is about
13,000 years ago.</i> <i> Way back in high school,</i> <i> we learned that these
early humans</i> <i> were hunter-gatherers,</i> <i> small groups of nomads</i> <i> who followed herds
of animals for food.</i> <i> And when the animals
migrated to a new area,</i> <i> the people went with them.</i> <i> ♪ ♪</i> <i> In this case,
to an entirely new continent.</i> <i> And that early migration</i> creates
the Native American tribes, both in North
and South America. And evidence of this migration
is found from Washington State <i> all the way down to Florida.</i> <i> [exciting music]</i> <i> In North America at least,</i> <i> the group credited
with being the first to arrive</i> <i> is called the Clovis,</i> <i> named after
a specific arrowhead</i> <i> found in Clovis, New Mexico.</i> <i> They're the ones who
supposedly crossed</i> <i> the Bering Strait
13,000 years ago.</i> <i> ♪ ♪</i> <i> But what if people
came earlier--much earlier?</i> <i> And the clues lay
in the underworld.</i> <i> ♪ ♪</i> <i> I'm on my way
to meet Chris Roxburgh,</i> <i> the local diver who saw
something very strange</i> <i> at the bottom
of Lake Michigan,</i> <i> a very strange place
for an archeological find.</i> <i> And as always...</i> [grunts] <i> I wanna see it for myself.</i> <i> ♪ ♪</i> <i> So tell me about this site.</i> - Originally I thought
it would have been some of the first Native
American nomadic tribes that would have created this... - Yeah.
- But it seems that it predates that-- it goes back
farther than that. It kind of rewrites history
if this is man-made. <i> - All right, let's suit up.
- Excellent.</i> <i> ♪ ♪</i> Follow me and stay close,
'cause visibility is low and we don't want to get lost
or turned around down here. - Okay, following you. <i> [eerie music]</i> <i> Chris is very protective
over the location.</i> <i> He wants to ensure
it can be studied</i> <i> before someone
tampers with it.</i> <i> ♪ ♪</i> When did you find it?
- I found it five years ago when I went out
to locate a shipwreck. I free-dove down <i> and I could see the stone
circle directly under my boat.</i> This was
a one-of-kind finding-- six symmetrically placed
boulders. <i> ♪ ♪</i> <i> - So you've measured this out
and you can see the symmetry?</i> <i> - Yes.</i> <i> ♪ ♪</i> Stands out, to me,
to be man-made. - I see. - I don't exactly know
what it is, but there's another rock with a carving
of a mastodon on it... <i> ♪ ♪</i> <i> ...directly in the middle
of this symmetrical circle.</i> <i> - That's amazing.</i> - Look, Don.
This is the mastodon rock. - That's the rock there. <i> ♪ ♪</i> Wait, wait a minute,
right there? <i> ♪ ♪</i> I don't see it. Just trace that for me,
would you? <i> ♪ ♪</i> - You can see the tusk
and the legs. - Oh, I see. That's it. <i> ♪ ♪</i> <i> Mastodon roamed North America</i> <i> from about
16 million years ago</i> <i> until they went extinct
just over 10,000 years ago.</i> <i> We know that our early
ancestors relied on them</i> <i> as a major food source,</i> <i> but what's interesting here
is the location of this rock.</i> <i> ♪ ♪</i> <i> This was dry land
until 16,000 years ago.</i> <i> That's when glacial melting
filled the Great Lakes.</i> <i> So anything man-made
that's down here</i> <i> was done long before humans</i> <i> were thought to have come
to the Americas.</i> <i> ♪ ♪</i> - I would like to have
more investigation done on it by a professional
archeologist... - Yeah. - But I didn't want to show
everybody where it was and have ten boats a day
going out there with tons of people diving
and disturbing the site. [water burbles] <i> - Now, I'm not
a professional archeologist,</i> <i> but I do have some
pretty cool technology</i> <i> that may be able to shine some
new light on this discovery.</i> Okay, here we go. <i> [exciting music]</i> <i> ♪ ♪</i> <i> We're doing something
called photogrammetry.</i> <i> You take thousands of images</i> <i> from all different points
around your subject,</i> <i> and then the computer software
stitches them together.</i> <i> So you get a very,
very detailed, 3-D image</i> <i> you can flip around
and look at on a computer.</i> <i> ♪ ♪</i> <i> Thanks to this tech,</i> <i> we'll have a high-resolution
3-D model of the rock.</i> <i> Then we can see</i> <i> if the markings on it
are made by nature</i> <i> or if this really is</i> <i> a man-made carving
of a mastodon.</i> <i> If it is, it could suggest
an unidentified civilization</i> <i> was here thousands of years
before we thought.</i> <i> ♪ ♪</i> <i> I shared the results
with Chris.</i> <i> ♪ ♪</i> <i> All right. Look at that.</i> - This is the
photogrammetry here. <i> ♪ ♪</i> <i> This is the rock.</i> - Right.
- And that's the carving-- the mastodon carving
that's in there. - Interesting.
- You can clearly see it. - Get in real close, can you? <i> ♪ ♪</i> <i> - This would be the back.</i> <i> The trunk comes down here
and the tusk,</i> <i> and this is the eye.</i> <i> ♪ ♪</i> <i> - Cool.</i> <i> ♪ ♪</i> - It clearly looks
chiseled to me. You can actually
see the chisel marks... <i> - Mm-hmm.
- So it's not natural.</i> <i> ♪ ♪</i> <i> - This is
a subjective process,</i> <i> So I can't say for sure</i> <i> it's evidence that someone
carved a mastodon here.</i> <i> But to me, this trip
to the underworld</i> <i> seems to reveal something</i> <i> that's more than just a
naturally formed coincidence.</i> <i> And considering the stone
is at the center</i> <i> of a perfectly symmetrical
formation of rocks</i> <i> that are equally spaced
apart...</i> <i> ♪ ♪</i> <i> That carving seems
to be evidence</i> that mankind came here
earlier than everyone thinks. <i> ♪ ♪</i> That is fricking cool, man. <i> ♪ ♪</i> <i> Could the rocks we just saw</i> <i> really be evidence
of a different culture</i> <i> that lived in America
thousands of years</i> <i> before anyone thought
humans were here?</i> <i> I can't be the judge of that.</i> <i> ♪ ♪</i> <i> So I'm meeting
with someone who can.</i> <i> ♪ ♪</i> - Clovis first would basically
have nobody here before about 12,000 years ago. <i> ♪ ♪</i> And there's a strong group
of archeologists that believe that,
but it's probably not true. <i> ♪ ♪</i> <i> - Dr. John O'Shea
is an archeologist</i> <i> at
the University of Michigan...</i> <i> ♪ ♪</i> <i> ...who believes
he's found evidence</i> <i> showing that a mysterious
and unknown culture</i> <i> hunted game in the Great Lakes
before they filled with water.</i> <i> ♪ ♪</i> - The Great Lakes basins were
basically carved by ice. - Uh-huh.
-And then as the ice withdraws, you start getting water
filling them. That's how they fill. And so this is
the depth of Lake Huron, but it's also telling us about where the land
was at different times. And the Great Lakes would have
been dry land 16,000 years ago. <i> ♪ ♪</i> <i> - The last ice age started
around 31,000 years ago</i> <i> and ended about
16,000 years ago.</i> <i> ♪ ♪</i> <i> During that time,
glaciers locked away water,</i> <i> lowering the sea levels
and exposing dry land</i> <i> that had been
previously underwater.</i> <i> ♪ ♪</i> <i> So everything on this map
of Lake Huron</i> <i> that's in red or yellow
was dry land</i> <i> before the glaciers melted,</i> <i> just like the area where Chris
found the mastodon rock</i> <i> in nearby Lake Michigan.</i> <i> ♪ ♪</i> - What's really kind of curious
about this is, this is
the Alpena-Amberley Ridge. This provides
a very predictable route for migratory caribou. - Okay.
- And we have found hunting structures at natural
choke points along this ridge. We've mapped more than 70
that we're pretty satisfied are human construction. But what's cool is
it goes underwater just like your lava
at Pompeii... - Yeah. - And it's never,
never been seen again, literally until we got there. - That's amazing. - Let me show you
what this looks like. It's actually pretty cool. Put on the headset. The joystick will let you move and you'll get the sound
over the headphones. <i> ♪ ♪</i> <i> - Using 3-D scans
of the bottom of the lake,</i> <i> Dr. O'Shea dials back
the water levels...</i> <i> [digital blips]</i> <i> ...to provide
a 3-D experience</i> <i> of what it would've been like</i> <i> to be in the Great Lakes
16,000 years ago.</i> <i> ♪ ♪</i> I love this. It brings this whole,
you know, lost world to life. - Yep. <i> ♪ ♪</i> <i> - This program,
known as "Virtual Worlds,"</i> <i> provides a never-before-seen
way to experience</i> <i> what life would have been like</i> <i> for America's
earliest inhabitants.</i> <i> So this is the land
of early man.</i> <i> ♪ ♪</i> Cool. - This is what it would've
looked like in real life. <i> And you see how these rocks go
out in this long line?</i> <i> - Yep.</i> <i> - There are no other
rocks out here.</i> They basically
just found rocks and put them
in the right place. - It's cool. <i> - So all of these little spots</i> <i> would have provided places
for the hunters</i> <i> to hunker down in their blind,</i> <i> and then they pop up</i> and they kill
whatever's in reach. - Interesting. <i> A blind is a place
where hunters can hide</i> <i> which appears natural
to any animals nearby,</i> <i> allowing the hunters
to launch a surprise attack.</i> <i> ♪ ♪</i> <i> So here is where
I would hide, right?</i> <i> - Yep.</i> There you got a caribou.
Look at that. <i> - [chuckles]</i> <i> It's a beautiful landscape.</i> - And yet, a place
that's very different from what we see today. - Of course; I'd be under
100 feet of water right here. - [chuckles] <i> ♪ ♪</i> - Is there a society
to these people? - Oh, of course
there's a society. - Yeah.
- What we think we see is, we see very small
kind of family bands. - Mm-hmm.
- And then in the spring, you know,
when people are really hungry, these small little groups
aggregating and they're building these
more complex hunting structures that would've
taken multiple people to hunt the animals. - Okay. <i> ♪ ♪</i> - I don't know when
the earliest people were here, whether it was 18,000
or 16,000 years ago, but it's clearly
very complicated. <i> ♪ ♪</i> - Interesting. <i> ♪ ♪</i> <i> So it sounds like humans
crossed the land bridge</i> <i> from Siberia to Alaska</i> <i> long before commonly thought.</i> <i> But who were these
mysterious people?</i> <i> To find out more, we're going
deeper into the underworld.</i> <i> ♪ ♪</i> <i> seem to reveal
a lost society</i> <i> of early inhabitants
in North America,</i> <i> 3,000 years before
we thought humans arrived.</i> - We see small groups building these complex hunting
structures along this ridge. <i> - Besides the fact
that they were hunters,</i> <i> we don't know
much else about them.</i> <i> How did they live?
What did they look like?</i> <i> ♪ ♪</i> <i> To find out more,</i> <i> we're heading
just over 2,000 miles</i> <i> due west of the Great Lakes...</i> <i> ♪ ♪</i> <i> ...all the way
to the Great Basin.</i> <i> ♪ ♪</i> <i> This is central Oregon,</i> where there are numerous caves which were once occupied
by prehistoric man. <i> ♪ ♪</i> <i> Archeologist Dennis Jenkins
says</i> <i> that caves in
the Oregon High Desert</i> <i> hold the secret</i> <i> to a completely unknown
society of ancient people.</i> <i> And he has the evidence
to back it up.</i> [bird calls] - This is Fort Rock Cave, one of the largest
in the region. It's about 60 feet deep,
30 feet wide, absolutely dry inside. <i> ♪ ♪</i> Home, sweet home.
[both chuckle] <i> ♪ ♪</i> <i> - I asked how many people
would have lived here.</i> <i> ♪ ♪</i> - Probably five to ten people.
- Okay. <i> - Basically an
extended family:</i> <i> mom and dad
and two or three children...</i> <i> - Yep.
- And maybe grandma.</i> Sometimes bands would get
as big as 25 or so. - That's fascinating. <i> Looking at the land of
America's earliest inhabitants</i> <i> through a VR headset was cool,</i> <i> but it's nothing like actually
standing on the ground</i> <i> where ancient people lived.</i> <i> ♪ ♪</i> You can picture the fires,
the skins on the ground, the whole group of people
doing their work, dinner being cooked over here. - Yes.
These people are foragers. In other words, they're eating a lot of
different kinds of foods. They have their carbohydrates,
their proteins from animals, plants. - What interests me
is how you know this. How does the archeologist know
what these people were eating? - Well, the most intimate item
that we find regularly as archeologists
in dry caves like this is actually called a coprolite. - Coprolite. - And what that means is that
it's a dried poop. - I did not expect that
to be the discovery that we're talking about. - You can wash
your hands later. They're not fossilized,
they're not stone. And inside there is exactly
what that person ate. - Hmm. - So you can see
the fibers of plants. - Yep.
- You can see the bone. You can find seeds.
- Huh. <i> ♪ ♪</i> - So they understood all
their different food groups? - Yes, they did. - But this person did not
follow the maxim, do not [bleep]
where you live, right? Okay. So what is the date
of this poop? - Those got a radio carbon date of almost 16,000
calendar years ago. - Wow. So that's a lot earlier. - Absolutely.
3,000 to 4,000 years earlier. <i> ♪ ♪</i> So this would prove people had
been successfully living here when archeologists didn't
believe that that was possible. <i> ♪ ♪</i> <i> - This links up</i> <i> with what we saw in our dive
to the underworld:</i> <i> clear signs of much earlier
human life in the Americas.</i> <i> Could this be the same group
that was hunting</i> <i> in the Great Lakes
around the same time?</i> <i> It's hard to say.</i> <i> But another clue these
cave dwellers left behind</i> <i> provides new insight</i> <i> into the technology
they were using.</i> <i> ♪ ♪</i> - This is a complete
Haskett point. Very sharp.
- Yeah. - Very stout.
- Okay. - We got carbon dates on it that indicate it is at least
16,000 calendar years old. - Wow. <i> - That technology is
actually found through Mexico,</i> Central America, all the way
down into South America. - And these are pre-Clovis?
- Mm-hmm, yeah. <i> These are really early.</i> <i> ♪ ♪</i> <i> - Interesting.</i> <i> ♪ ♪</i> <i> So these ancient people
had their own tools</i> <i> not known to have been used</i> <i> by other groups
who came after.</i> <i> And Dr. Jenkins says
this same culture</i> <i> stretches as far south
as Central America.</i> <i> So who are they?</i> <i> How did they get here?</i> <i> And how is it possible
that such radical evidence</i> <i> has evaded archeologists
for hundreds of years?</i> <i> ♪ ♪</i> <i> Because it's extremely,
extremely hard</i> <i> to get to,</i> <i> buried deep
in the underworld.</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> - Where did we come from?</i> <i> And I'm not referring
to the talk I had</i> <i> with my parents
when I was nine.</i> <i> I'm talking about
the first humans</i> <i> to come to the Americas.</i> <i> Discoveries made
within the last 20 years</i> <i> show that a group
of organized hunters</i> <i> who may have lived in caves</i> <i> were here 3,000 years
before we previously thought.</i> <i> ♪ ♪</i> <i> Who is this mystery group?</i> <i> ♪ ♪</i> <i> A thrilling find on
the southeastern tip of Mexico</i> <i> could give us
a much clearer idea.</i> <i> ♪ ♪</i> <i> I'm meeting the man
who made it.</i> There you go.
How are you doing? - Hey, Don.
- Octavio, how are you doing? - How are you doing?
Welcome to the planetarium. - Nice to meet you.
- Nice meeting you. - Thank you.
- Great to see you. - You too. <i> Octavio del Río</i> <i> from the National Institute of
Anthropology in Tulum</i> <i> personally made the discovery.</i> <i> And to do so, he traveled
very deep into the underworld.</i> <i> ♪ ♪</i> <i> Running beneath
this entire region,</i> <i> there's a maze of underwater
caverns, called</i> "cenotes," <i> that extends
for over 100 miles.</i> <i> Just like the Great Lakes,</i> <i> this cave system was bone dry
during the Ice Age.</i> <i> After the glacial melt,</i> <i> trillions of gallons of fresh
water filled these caverns,</i> <i> covering up evidence that
could give us new insights</i> <i> into the true first
inhabitants of the Americas.</i> <i> Octavio told me
the astonishing story</i> <i> of how he made this discovery.</i> <i> - Listos.</i> <i> ♪ ♪</i> <i> - Octavio and his team started
diving the cenotes</i> <i> underneath Tulum in 1998.</i> <i> For almost three years,</i> <i> they journeyed deeper and
deeper into the underworld,</i> <i> creating a map</i> <i> of this previously
uncharted cave system.</i> <i> Finally, in the year 2000,</i> <i> Octavio discovered the holy
grail of underwater archeology</i> <i> hiding a thousand feet
from the cave entrance:</i> <i> an extremely well-preserved
human skeleton.</i> <i> ♪ ♪</i> - No kidding. <i> ♪ ♪</i> <i> - The isolated
and remote conditions</i> <i> of these underwater caves
provide a perfect environment</i> <i> for the preservation
of fossils.</i> <i> That's why the four oldest
human skeletons</i> <i> in the Americas</i> <i> were all found in cenotes
in the Yucatán.</i> <i> A teenage girl named Naia</i> <i> was found in the nearby
Hoyo Negro Cenote.</i> <i> A 50-year-old woman
was discovered in Las Palmas</i> <i> and a 30-year-old woman
in Chan Hol</i> <i> near the Caribbean coast.</i> <i> But no fossil on this
continent is older than Eve.</i> <i> 13,700 years old.</i> <i> ♪ ♪</i> That's amazing.
- Sí. - So how do you think she's
related to the Clovis people? - Because you found no points
or no Clovis-- - So these were not
nomadic tribes. This is actually
a civilization here on the Yucatán that is planted. - No kidding. - That's amazing. <i> - Similar to what we saw
in Oregon,</i> <i> Octavio is describing
cave-dwelling people</i> <i> who used different tools.</i> <i> So if his theory is right</i> <i> and the oldest human fossil
ever found in the Americas</i> <i> is more
than just a standalone,</i> <i> these caves could tell us more
about how the society lived</i> <i> and maybe get us
one step closer</i> <i> to identifying
these ancient peoples.</i> So how dangerous is this
to go down and find? <i> ♪ ♪</i> <i> [drum roll]</i> <i> ♪ ♪</i> <i> Who would miss the chance
to dive</i> <i> into the underworld
and experience</i> <i> Eve's world firsthand?</i> That's why
I'm going down there, to see the kind of
habitation she lived in. <i> ♪ ♪</i> <i> This is the home of people
who lived here</i> <i> 16,000 years ago...</i> <i> ♪ ♪</i> <i> ...the most ancient peoples
in the Americas.</i> <i> How crazy is that?</i> <i> ♪ ♪</i> <i> - I'm on the southeastern
tip of Mexico</i> <i> in the Yucatán Peninsula.</i> <i> Right here, the four oldest
human skeletons</i> <i> ever discovered
in North America were found,</i> <i> but I'm interested in one:
Eve.</i> <i> She's the oldest of the old.</i> <i> And an underwater
anthropologist thinks</i> <i> that the cave system
she lived in could hold clues</i> <i> that reveal
the mysterious identity</i> <i> of the first inhabitants
who came to the Americas.</i> <i> [mysterious music]</i> <i> ♪ ♪</i> The thing about archeology: it's one thing
to talk about it. It's another thing to see it. So that's why
I'm going down there to see the kind of habitation
she lived in. If there is evidence
of a more complex settlement inside this cave
where she was living, that challenges the timeline
in all sorts of ways. <i> ♪ ♪</i> <i> Eve's skeleton could have
ended up in a cave</i> <i> for all sorts of reasons.</i> <i> She could have wandered
in searching for shelter.</i> <i> She could have been buried
there,</i> <i> or, as Octavio believes,</i> <i> she could have lived there
as part of a group.</i> <i> I can't wait to experience
this for myself.</i> <i> ♪ ♪</i> <i> There's just one problem.</i> <i> Getting to the spot
where Eve was found</i> <i> will require me to do
something</i> <i> that's gonna make my wife
furious when she sees this.</i> <i> ♪ ♪</i> If anything goes wrong,
if you see bubbles coming out where they shouldn't
be coming out, if you tangle up anything, we are going up
and that's the signal, okay? <i> ♪ ♪</i> Immediately. <i> ♪ ♪</i> There's one way in,
one way out. <i> ♪ ♪</i> The key is keeping your cool. This is a really,
really dangerous chamber we're going into, and a lot of things
can go wrong. <i> ♪ ♪</i> Any questions?
- No. - Cool.
- Let's do it. <i> ♪ ♪</i> You know how to dive, right? - [chuckles] <i> ♪ ♪</i> <i> Every cenote is unique</i> <i> and no matter
how breathtaking the scenery,</i> <i> they all have their own risks
and danger zones.</i> <i> So I try to go into every dive
as prepared as I can be.</i> <i> And Octavio gave me
some very specific directions,</i> <i> which I believe
I have memorized.</i> <i> But the fact is,</i> <i> nothing can really prepare
you for this place.</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> - Despite the darkness,
the water is so clear.</i> <i> It's almost like
I'm taking the same route</i> <i> that the cave dwellers
would have taken on foot</i> <i> before this place flooded.</i> <i> ♪ ♪</i> <i> Every moment, getting closer
and closer to the past</i> <i> and deeper and deeper
into the underworld.</i> <i> ♪ ♪</i> <i> - And eventually coming
to a point of no return.</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> - Disorientation is always
a danger when diving,</i> <i> but here, a quarter mile deep</i> <i> in a pitch-black maze
of flooded tunnels,</i> <i> it's terrifying.</i> <i> ♪ ♪</i> <i> You can get lost here
very easily.</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> - I'm moving through
the confusing darkness</i> <i> of a flooded
100-mile-long cavern system.</i> <i> ♪ ♪</i> <i> A quarter mile from
the entrance is a chamber</i> <i> where anthropologists found
the oldest human fossil</i> <i> ever discovered
in the Americas.</i> <i> ♪ ♪</i> <i> The man who found it said</i> <i> there's evidence
of an entire civilization</i> <i> who lived here
before this place flooded.</i> <i> I'm hoping the evidence
in this cave</i> <i> can give us a better look</i> <i> at the mysterious
cave-dwelling society</i> <i> who may have been the first
humans in the Americas.</i> <i> As always,
I wanna see it for myself.</i> <i> ♪ ♪</i> <i> The cave is intense,
spooky, surreal.</i> <i> Once inside the chamber,</i> <i> Octavio told me to look
for stones used as tools...</i> <i> ♪ ♪</i> <i> And then for firepits--
14 of them.</i> <i> ♪ ♪</i> <i> ♪ ♪</i> <i> - Seeing this cave
with not only human tools,</i> <i> but carbon-dated firepits and
human remains is breathtaking.</i> <i> It seems clear to me
that our oldest ancestors</i> <i> are far older than
long thought.</i> <i> This massive cavern system
hasn't been fully mapped.</i> <i> And until that work
has been completed,</i> <i> many of the bones
and artifacts</i> <i> will remain right here
in this chamber.</i> <i> But Octavio and his team
got special permission</i> <i> to remove Eve's skeleton</i> <i> so they could do testing
and map her face.</i> <i> Having seen where Eve lived,
I can't wait to meet her.</i> <i> [mystical music]</i> <i> ♪ ♪</i> It's an incredible thing
to see. - Wow. <i> ♪ ♪</i> - No, she's just quite lovely. - Sí, no? <i> ♪ ♪</i> - What an amazing moment
that must have been for you. <i> ♪ ♪</i> - That's amazing. You can just so easily picture
the life of this person, you know, and civilization
that she's with. <i> ♪ ♪</i> <i> According
to Octavio's research,</i> <i> the testing revealed
that Eve stood roughly</i> <i> 140 centimeters tall--
about 4 feet, 7 inches.</i> <i> She was most likely
between 60 and 80 pounds</i> <i> and she died in her early-
to mid-20s.</i> <i> ♪ ♪</i> Completely humanizes this
whole experience, doesn't it? - Sí.
- Yeah. - There you go. <i> Sitting face-to-face
with a portrait</i> <i> of the oldest person
in the Americas is incredible.</i> <i> ♪ ♪</i> <i> And who knows?</i> <i> Maybe these people
could be the ones</i> <i> who inhabited
the caves in Oregon</i> <i> and built hunting blinds
in the Great Lakes.</i> Are you still finding these?
- Absolutely. <i> - The more we dig
into the question</i> <i> of who really came first,</i> <i> the more we realized
that what we know now</i> <i> is probably just
the tip of the iceberg.</i> <i> And it makes me wonder</i> <i> how much more we'll know
100 years from now.</i> <i> Could a new discovery blow
all this out of the water?</i> <i> Well, a recent piece
of evidence that was uncovered</i> <i> during a freeway
construction project</i> <i> could be the beginning
of just that.</i> <i> But brace yourselves--</i> <i> this one is really weird.</i> <i> [mysterious music]</i> <i> ♪ ♪</i> <i> - From 16,000-year-old
arrowheads in Oregon</i> <i> to hunting blinds in Michigan</i> <i> to human fossils
in the Yucatán Peninsula,</i> <i> we've seen evidence</i> <i> that ancient peoples
probably lived in the Americas</i> <i> for thousands of years
before the first humans</i> <i> were thought to have crossed
the Bering Sea Land Bridge.</i> <i> ♪ ♪</i> <i> But here's
an interesting question:</i> <i> How many thousands of years?</i> <i> A relatively new
piece of evidence</i> <i> was discovered
by Dr. Tom Deméré,</i> <i> the curator of paleontology</i> <i> at the San Diego
Natural History Museum.</i> <i> And he says humans have been
here for over 100,000 years.</i> <i> I asked him to explain.</i> <i> ♪ ♪</i> <i> - We were monitoring
a construction site</i> <i> and Richard Cerutti,
paleontologist,</i> saw an area where there
were pieces of ivory, fossil ivory of a mastodon. "Whoa, hold on." <i> ♪ ♪</i> We probed it out for a day
or two and realized it was a very unusual site. <i> ♪ ♪</i> <i> What was unusual is that one
tusk was laying horizontal</i> and the other was vertical. <i> - Hmm.</i> <i> - The heads of the femurs</i> were found together,
side by side, separated from the shafts. - Okay. <i> - And that was something
that was really puzzling.</i> - Yeah. <i> - So we went through
these various scenarios</i> <i> trying to figure it out what
would explain this crime scene</i> and just kept coming back
to human activity. <i> ♪ ♪</i> We also found spiral fractures, which indicate that the bones
are broken while they're fresh. - Okay. <i> So here's why spiral
fractures are a big deal.</i> - Welcome to Pete's Meat.
- Hey, how are you doing? I got a crazy request. Do you have any cow
femur bones? That smells bad. Okay. <i> Say an early human</i> <i> comes across
a mastodon carcass,</i> <i> represented by a cow femur,</i> <i> which closely matches the
bone density of a mastodon.</i> <i> And in order to make a spear,
walking stick, baton--</i> <i> who knows--</i> <i> they gave it a good whack
with a stone tool.</i> <i> And because the bone is still
fresh and spongy inside,</i> <i> it breaks along these
long curved fracture lines.</i> <i> They're called
spiral fractures.</i> <i> And it only happens this way
if the bone is fresh.</i> - Look at the sharp edge
on this. Take a look. <i> - But we already know that
America's early inhabitants</i> <i> overlapped with the mastodon.</i> <i> So what makes this one</i> <i> the proverbial elephant
in the room?</i> <i> - We sent some samples out</i> <i> and came up with a date</i> of 130,000 years ago. - Wow! Then you're suggesting
that there was human activity at this site 130,000 years ago. <i> That's a pretty big deal.</i> <i> - [chuckles] I mean,</i> I realize that it is... it sounds crazy. <i> 130,000 years ago
in North America,</i> <i> humans were here.</i> But the evidence
is so strong to me. <i> - Modern humans,
known as Homo sapiens,</i> <i> are thought to have
first evolved in Africa</i> <i> 200,000 or 300,000 years ago.</i> <i> Opinions differ as to when</i> <i> they migrated
to different places,</i> <i> but none have them
leaving Africa</i> <i> before 100,000 years ago.</i> <i> So if Dr. Deméré is right,</i> <i> it would suggest
that we may need to rethink</i> <i> our understanding
of human migration.</i> <i> And that is massive.</i> I'm going to say there must be
tremendous resistance to this, I would imagine. - Well, the archeologists
in our group didn't take too kindly to this. - I'm sure. <i> One such archeologist
is Dr. David Meltzer.</i> - We've always got to guard
against our natural tendency to say,
oh, this was done by people. <i> And the problem is, is that</i> <i> lots of things
can scratch bone</i> <i> when it's in the ground.</i> <i> And so there's a question:</i> Are there distinctively
human ways in which bones are broken that
we can definitely attribute it <i> to humans and humans only?</i> <i> That's the issue.</i> But go for your five minutes
of rebuttal. Everybody's entitled. <i> - Radical new theories
always lead to intense debate.</i> - Now, I think
that the more people-- - You've got half a dozen
different processes that could have caused
that process. <i> - And this one feels
especially fierce.</i> <i> ♪ ♪</i> - The heads of both femurs were
found together, side by side. <i> How do you explain that?</i> - It only shows you that humans
could have done that. It does not show you
that nature did not do that. - What's that tusk
doing vertical? <i> That doesn't
happen geologically.</i> <i> - It's not definitive.</i> I don't buy it. - I was surprised
at the emotional reaction, rather than
the objective reaction. <i> What's interesting that, at
this time, 130,000 years ago,</i> <i> that's when bison dispersed
into North America.</i> <i> ♪ ♪</i> <i> That's when wooly mammoths</i> <i> dispersed from Eurasia
into North America.</i> <i> - All right.</i> - Why not those bipedal
hominids at the same time? - That's interesting. <i> It's an amazing theory</i> <i> from an incredibly
accomplished scientist,</i> <i> but it's just so far different
than the accepted theory.</i> <i> So it's bound to be debated.</i> - But it's not definitive. <i> ♪ ♪</i> <i> - But we have seen compelling
signs of early humans</i> <i> near the Great Lakes
with mastodons.</i> - You can see the tusk
and the legs. - Oh, I see. That's it. <i> - Could it be that
these people were here</i> <i> not only a few thousand years
before some experts think,</i> <i> but a hundred thousand years?</i> That's pretty cool. <i> Our understanding of
the world we live in</i> <i> is constantly changing.</i> <i> And that includes our theories</i> <i> of America's first
inhabitants,</i> <i> who were perhaps
not roaming bands of nomads</i> <i> but instead groups of cave
dwellers who hunkered down</i> <i> and spent generations
hunting cooperatively</i> <i> and taking shelter
within the earth.</i> <i> But the evidence we've seen
doesn't give us</i> <i> a crystal-clear picture
of America's past.</i> - You know, you've got to keep
an open mind about these kinds of things. <i> - It's at least enough to know
that the story told about</i> <i> America's earliest inhabitants
is perhaps incomplete.</i> That's cool. <i> And as long as experts
like Octavio and Dr. O'Shea</i> <i> are shining new light into the
darkest secrets of the past,</i> <i> we'll continue to move
ever closer</i> <i> to the mysteries hidden deep
in the underworld.</i> <i> ♪ ♪</i>
