Rapa Nui,
also known as Easter Island.
This tiny little island in the South Pacific
is world-famous for one thing.
The moai.
Moais are incredible.
The moai is the first part that people see.
These enigmatic stone giants stand like sentinels
all around the island,
but what was their purpose, and why have so many fallen?
It is easy to imagine that this is the scene of some catastrophe
where things fell apart.
For centuries, Western researchers have studied the moai,
trying to answer these questions,
and they've come up with their own theories.
But now, new research that looks beyond the moai
is challenging those views.
In all the evidence that we saw,
we were seeing signs of sustainability.
There was really no evidence of collapse.
For you, this can be an ancient abandoned village.
For me, it's the place where my family used to live.
Genetics is revealing surprising clues about the origins
of the island's earliest settlers.
When we first saw this, we thought maybe we did something wrong.
From their incredible engineering
to their beautiful and unique writing...
Some people say that they contain legends.
..the real story of Rapa Nui is finally coming to light.
Most visitors come all the way to Easter Island
because of these stone statues,
the moai.
Moai, they're amazing and they're outstanding.
And they are unique.
Constructed between 1300 and some time after the 1700s,
there are more than 1,000 of these giant carved figures
scattered across the landscape.
Cut from volcanic rock...
..some are more than 30ft high.
Over time, all of the moai have fallen down.
The 50 or so that are upright today were put back up in recent decades.
With their backs to the sea,
they stare impassively into the island,
arms held rigidly by their sides.
Some stand on ceremonial platforms known as ahu.
Others are sunk into the earth.
Moais are incredible,
but Rapa Nui is so much more than that,
and its archaeology is so much richer than just moais.
The moai is the first part that people see,
but behind the moais there is a big history.
One archaeologist who believes the story of Rapa Nui encompasses
more than just the moai is Sonia Haoa Cardinali.
Born on Rapa Nui 70 years ago,
she has dedicated her entire life to the history and anthropology
of the island.
I feel sorry when they're just talking about the moai.
70% of the island is surveyed.
More than 25,000 archaeological sites.
So that means not only the sites,
it means also how people live, what they do,
their family and everything.
Sonia wants to understand more about the moai,
but she and other Rapa Nui islanders see them as only part of the puzzle.
There are bigger questions to ask.
Who are the ancestors of the Rapa Nui people?
Where did they come from,
and how did they survive and thrive
in this remote and hostile land?
The island of Rapa Nui stands alone.
The easternmost inhabited rock of the Polynesian island chains,
it lies approximately 2,000 miles from the Tuamotu Archipelago
of French Polynesia in the west and Chile in the east,
4,500 miles from Hawaii.
Only 14 miles long by seven miles wide,
today, most of the roughly 8,000 inhabitants live beneath
an extinct volcano on the western corner of the island.
First encountered by the Dutch in 1722,
it was claimed by the Spanish nearly 50 years later,
then annexed by Chile in 1888.
But when the original Rapa Nui people first came to this land,
and where from, remains hotly debated.
The general consensus
is that the first people to settle here were sailors
from other Polynesian islands,
migrating east some time around 1200 CE.
We are Polynesians.
Our life was the canoe and our territory was the ocean.
Polynesians, we were populating
and colonising islands across the Pacific.
That belief forms the heart of Rapa Nui identity,
cherished by elders like Carlos Edmunds.
It is the bedrock of Rapa Nui oral tradition.
There's knowledge in the old people and in the oral history.
Behind every legend,
there's knowledge there.
Legends handed down from generation to generation
tell how and why their ancestors came to this land.
They are retold even today by Rapa Nui performers
dedicated to keeping the old traditions alive.
That is the base of all our history.
Fortunately, today, science and scientists
are helping us to show how oral tradition
was the first, the most and the real history.
For settlers migrating from the warm tropical islands
of western Polynesia,
this windswept lump of inactive volcanoes
in the Southeastern Pacific
was a bad land where their crops could not grow.
Rapa Nui is a subtropical island, so there's a big difference
in climate to the tropical islands,
for example, of French Polynesia.
The problem was that some of those tropical species
just didn't grow and didn't take.
Because it's colder here,
the first settlers of Rapa Nui,
travelling from the Polynesian tropics,
would have struggled to grow any plants
they'd brought with them.
One man who is fascinated by how those settlers survived
on this bad land is Hetereki Huke.
You know what? There's not that much material about any...
An architect by trade,
Hete started an office in 2014
to record Rapa Nui's heritage
through the archaeological record.
At that moment, there were not many young researchers in Rapa Nui.
They're releasing the water...
So, Hete turned to Terry Hunt and Carl Lipo from the USA.
We have been collaborating with Carl and Terry for a long time,
and we have done so many things together.
They were a great support during this fieldwork.
And that was amazing because with Carl and Terry,
we could map the rocks and at the same time
we could have the legend behind them.
And that is just beautiful.
One of the sites they studied was Ahu Tepeu,
which lies on the northwestern coast of the island
and was a typical ancient Rapa Nui settlement.
Central to its layout is the ahu,
a raised stone platform.
At Ahu Tepeu,
there are five of these.
Some of them with moais and some others without.
Fanning out from the ahu are the houses, chicken coops
and walled gardens known as manavai,
and behind the houses lie the fields that fed the community.
For you, this can be an ancient abandoned village.
For me, it's the place where my family used to live.
And they still are here.
This place, it's quite alive for us.
So, the approach of a Rapa Nui researcher,
or any Pacific researcher,
would be dramatically different from a Western researcher.
Rapa Nui and Western researchers agree
that the ancient settlers were Polynesian.
But where did those Pacific Islanders come from?
Some previous research suggested that they came from the islands
of East Asia.
But in 1947, a Norwegian explorer named Thor Heyerdahl
launched an expedition called Kon-Tiki,
intended to prove a drastically different view
of where the Polynesians originated.
His theory on South American origins
flew in the face of known linguistic evidence,
so Heyerdahl followed this up with a series
of archaeological expeditions to Rapa Nui.
Despite years of investigating the island,
he could never prove a definite link to South America.
One Rapa Nui archaeologist who worked with him was Sonia Haoa Cardinali.
I worked with Thor Heyerdahl for almost ten years, and for me,
it's an honour to work with him.
No matter how we think about his theory,
never forget that he is one of the person
who puts Rapa Nui in the map.
In Heyerdahl's day, experimental archaeology seemed the only way
to explore possible links between Polynesia and South America.
But today, we can use DNA,
which is a powerful tool for tracing human ancestry.
So, did the original settlers of Rapa Nui have links
with South America?
One geneticist who set out to answer that question
was Andres Moreno-Estrada.
Genetics can be a powerful tool to answer this big question
about whether the Rapa Nui people made contact or not
with Native Americans in prehistory, which has been a debate
that has been on for decades.
Andres put together an international team,
including researchers from Hawaii and Rapa Nui,
to study the DNA of the people of Polynesia.
..gracias.
And they reached out to the community to gain the support
of Rapa Nui's elders.
Community engagement is really the essence of all these approaches.
When you study human genetic diversity,
it's all about humans, really.
It's a voluntary participation,
so it's really key to talk with the community beforehand,
and as we carry out the research as well,
keep them informed about the results of the study.
Collaborating with Andres is genetic data analyst Alex Ioannidis.
What I really love about genetics is it's essentially
about participation with the people whose story you're telling.
It's their sample that's telling the story.
Stories like Bianca's, the daughter of a Chilean father who moved back
from mainland Chile and wanted to know if what her mother
had told her was true.
An individual's DNA is contained within 23 pairs of chromosomes
known as a genome.
And that's your genetic fingerprint.
When they began the research,
Andres and his colleagues were expecting
the Rapa Nui fingerprint to contain markers showing mostly
Polynesian, Spanish and Chilean ancestry,
since these were the main colonists of the island
in the last 250 years.
To extract the DNA,
they take swabs from their volunteers in the field,
then take it back to the lab in cold storage for analysis.
DNA samples are loaded into a sequencer
so that we can get the pieces of DNA
that make up the whole genome of that individual.
This allows the researchers to identify specific chains of DNA
that can be attributed to certain groups.
Red denotes Spanish ancestry,
blue, Polynesian,
green, Chilean,
and yellow, other European.
The process is very rewarding,
because participants are very interested in knowing
about their own genetic origins,
and when they see that actually they have retained a lot
of the Polynesian roots in their DNA,
it's something that helps them to basically value
and identify their own lineages.
Most of the results helped confirm the islanders' beliefs
about their Polynesian origins,
mixed with more recent colonists.
I just found out the results.
I'm so mixed.
My mum is from Chile and from England and Scotland,
and my father is an islander,
but he's also mixed with French
and other people,
so it's very interesting to know
where you come from.
They did, however, find some pieces of DNA that they didn't expect.
When we first saw this, we were really surprised
and so we thought maybe we did something wrong.
We thought, "Well, let's double-check this."
These pieces of DNA seem to have their origins
in South America,
but when they tried to pinpoint the source,
they got a surprise.
They were quite different from the more modern Chilean ancestry
found in some volunteers.
We compared it to a panel of indigenous groups
from across the entire Pacific coast of South America,
and the closest match was the Zenu group.
The Zenu are a Native American people who occupied the coast
of Colombia long before Chile
annexed Rapa Nui in 1888.
How could their genetic markers wind up in the DNA
of modern Polynesians?
And how many generations back did they go?
Because each parent only hands down half of its DNA to the next,
Alex was able to figure out when that piece of pre-Colombian DNA
had been incorporated into Polynesian chromosomes,
by measuring its length.
We can actually look at the length of those individual pieces
and figure out how many generations ago
this combination of Native Americans
and Polynesians took place.
The date they came up with was much earlier than they expected.
We saw very small pieces, indicating that this ancestry from the coast
of Colombia entered Rapa Nui a long time ago,
actually in a period around what we would call
the European Middle Ages, around 1200 AD.
What's more, the same identical DNA segments were often seen
in volunteers from different islands.
Which means that these segments came from the same ancestors,
and since they came from the same ancestor,
we think that this means there was a single contact event
between Indigenous Americans from the coast of Colombia
and Polynesians.
This means that a group of Polynesians met somewhere
with Native Americans, had descendants, and more likely,
this never happened again.
By looking at the DNA of people on other Polynesian islands,
the team traced the telltale genetic markers
back to the Marquesas and Tuamotu Isles,
and were also able to plot a timeline of migration
across eastern Polynesia to Rapa Nui from around 1100.
Polynesian migrations spread east into Tuamotu Archipelago,
up to the Marquesas and all the way down to Mangareva,
and from there,
all the way out to Rapa Nui around 1200.
Looking closely at these particular islands,
there's something else they all have in common,
something much bigger than DNA.
Most of these islands, the Marquesas, Rapa Nui,
and Raivavae have these very large
stone statues on them.
Where the idea of creating large stone statues comes from,
we can't say, and we can't say for sure if these islands develop
the idea independently, but the fact that they're all existing together
in the same genetic cluster suggested to us that this culture
was developed once and spread to all these islands.
Sonia believes that even if this culture developed
within the Polynesian islands,
there was also some influence from South America.
And behind the spectacular ahu of Tongariki,
she believes she has the evidence to back up her hunch.
We see the very good evidence of influence of South America.
This single broken moai has its hands across its body,
in a style that can be found in...
..ancient Colombia.
If you compare with the South America, it's the same.
The hands and the description of the arm.
The body is completely the same.
There is no doubt the influence of South America.
And here we have the structural evidence.
I cannot lie to you that that looks like a moai normal.
No, no.
Maybe if I am blind, yes, but it's here.
But this is the only moai on the island with arms
across its body.
All others have their arms by their sides.
So it cannot prove that the template for carving statues in stone
came from ancient Colombia,
though the DNA suggests some ancient,
albeit isolated, link.
What is provable is where the moai were created.
Almost all of the statues scattered around the island were carved
from the volcanic rock of Rano Raraku.
And on the slopes of its massive crater,
about 400 statues can still be found
in various states of completion.
High up on these slopes, Terry Hunt and Carl Lipo can see evidence
of the skill and ingenuity of the Rapa Nui stonemasons.
It's amazing, being up this high in the quarry,
and all the work and quarrying out of the bedrock
and statues this big that, way up here, had to be
taken down the slope.
You can see several moai being carved.
The large moai here,
and there, you can see the beginnings of moai
up on the side, as well,
high up here in the quarry.
You know, being this high up on the cliff,
really, they can take advantage of the gravity, right? Yeah.
So you've got them up high, and now you can use that to slide them down
and get them in the upright position. That's right, yeah.
While it's a huge amount of investment and labour,
they actually take advantage of the positions
in order to get them out, down to the base.
The moai were slid down the slope
and into purpose-built trenches.
Over time,
weathering has filled the trenches,
burying the bodies of those moai.
You can see several moai being carved.
The large moai here, and there, you can see the beginnings
of moai up on the side, as well.
They stopped. They abandoned this.
And it's a reminder that this isn't like Pompeii,
where something happened and everybody dropped their tools
and ran on one day.
There's a lot of history in the quarry.
There are many older statues that were abandoned,
more recent statues that were also abandoned,
and so you have to look at the chronology here.
Yeah, what we're seeing is the aggregate of events
that occurred over 500 years of activity here at the quarry,
not a final product.
This is all the things that happened here.
It's interesting because the quarry,
it's kind of a common area that's shared.
And so there's an understanding that everyone on the island,
every community on the island, has access to the resource here.
But rock isn't just confined to the quarry.
All over Rapa Nui, rock is spread across the land.
To Western explorers like Captain James Cook,
who visited the island in 1774,
this looked like a wilderness.
"The ground had but a barren appearance, being a dry, hard clay,
"and everywhere covered with stones."
The early European visitors saw crops being grown in stones,
and they thought this was somehow pathetic
because they're expecting to see ploughed fields
and the agriculture of Europe.
How could the Rapa Nui survive
on what appeared to be such a barren wilderness?
But this wasn't what it seemed.
The soils on Rapa Nui are nutrient-poor.
There is an ingenious solution to that,
and it's using rock mulch.
Volcanic rock is packed full of nutrients
that bring new life into the world.
Somehow, the ancient Rapa Nui
had learned how to make the best of this austere landscape
by fertilising their fields with stones.
And using rocks in cultivation will release nutrients into the soil
and make them available to the plants.
Sonia also sees lots of evidence that the rock-strewn wilderness
described by Captain Cook was actually fertile fields.
Here, you see a very nice complex,
and that means you have everything here.
In the centre part, you can see they take all the rocks.
And what you see in the landscape around here is like a garden, yeah?
This was not the first or last time
that Western misconceptions would colour the history of Rapa Nui.
Right from their very first encounter, on April 5th, 1722,
the world-view of its European visitors
would have a profound effect on the island.
The name Easter Island comes from the first Europeans
arriving here on Easter Sunday.
The modern traditional name is Rapa Nui,
and the older traditional name is Te Pito o Te Henua,
which really means "the navel of the world",
which probably reflects the island's isolation
and-or its centrality as to the whole world.
The first encounter between the Dutch explorers
and the local residents was marked by curiosity
and a tragic misunderstanding.
What we know from the historic accounts,
from the logs of Captain Roggeveen himself
and of other crew members,
is that there was big interest in the Netherlands ships arriving,
in the construction of the ships,
and so there was no hostility towards those newcomers.
Also, bearing in mind that Rapa Nui had been isolated
for many generations at that point.
People swam out to the ships, they went aboard,
they measured every aspect of the ships,
and the landing party was quite substantial.
MAN SINGS The Dutch landing party
found themselves confronted by a vibrantly painted man.
He performs what they perceive as a very strange dance,
and this strange dance was probably really an important ritual
that the Rapa Nui would have perceived as proper
in these people coming ashore to their land.
He saw the possessions that the Dutch had,
the clothes, the hats and the guns, and he reached for the gun.
MAN SPEAKS
And several crewmen opened fire.
GUNFIRE
So the very first encounter on the shores of Rapa Nui
was overshadowed by 12 islanders dead and many more injured.
The clash of cultures that led to this massacre
would profoundly affect the way that Rapa Nui was perceived
in the centuries to come.
Western preconceptions have coloured the view of Rapa Nui in many ways.
Seeing the moai, seeing the monuments here,
they can't imagine how people would move them
with no wooden carts or wheels,
and because they don't understand how it could have been done,
it leads to notions of the mystery of Easter Island -
and the mystery is really just what visitors didn't understand.
Just as with Captain Cook, Western visitors saw a barren land,
covered in rocks
and devoid of the trees needed to make wooden sleds or wheels.
But it wasn't always like this.
Researchers found pollen evidence in the fossil record
suggesting that 1,000 years ago,
much of this land was covered in dense forest.
For many Western researchers,
the answer lay strewn across the island at sites like Ahu Tepeu.
Yeah, it's interesting. It has the triangle stones.
These are pieces of moai,
the large statues that once stood on top of the ahu.
I don't know how many of the statues there were here. Maybe four or five.
It is easy to look at these landscapes,
when you see the ahu when they're broken down,
and statues that have fallen and broken -
like this one here, which has no head, it's just the body,
the head, that's over here - to imagine that this is the scene
of some catastrophe where things fell apart.
To Western eyes, this was evidence of a collapse of society,
so successive generations of Western scholars constructed a narrative.
It explained the barren, rock-strewn land,
the collapse of the moai
and the disappearance of the trees.
The collapse story basically goes that people got to an island
that was filled with trees, palm trees,
other kinds of trees as well, sort of an earthly Paradise,
filled with food and opportunities for the people that were here.
The moai-building has often been portrayed as some kind of frenzy,
as some kind of competition between different clan groups,
where lots of trees were cut down
in order to construct and to transport the moai.
Archaeologists had long investigated stone monument-building
in places like ancient Egypt.
Westerners thought the moai were probably moved on wooden sleds
or rollers pulled by hundreds of men,
which required people and trees -
lots of people and trees.
And these Westerners assumed that moai-building
had spiralled out of control.
People here kind of got into a moai mania.
They started to make bigger and bigger statues,
and at some point,
that overexuberance of statue construction
ultimately depleted the island of the resources needed
to make up ahu in the first place.
According to this view, moai-building deforested the island.
The soil was starved of nutrients, leaving a barren, rock-strewn land.
Then, this theory goes, things got worse.
The scarcity of resources resulted in a societal collapse.
The island erupted into inter-tribal warfare
and led to a very impoverished population
living on a barren island.
This so-called collapse theory posited that the island
once had more than 10,000 inhabitants,
whose own folly triggered a collapse of the forest ecosystem
and reduced them to a mere 3,000, living on the scraps.
For many Western scholars, it was a compelling narrative,
a morality tale for our times.
But for some researchers, this idea had one big problem.
When we looked at the evidence on the ground,
we simply didn't see evidence of warfare.
In 1722, at the very first contact, the descriptions of the island
are very positive still,
to the point that the island is described as an earthen Paradise
that the inhabitants, the Rapa Nui people,
are described as very healthy, of very good stature.
There's no indications of warfare, no weapons carried.
Well, it looks like this one is being dismantled,
because we find some of these construction elements
in other features over there.
For Hete, what were once considered ruins at Ahu Tepeu
turn out to be evidence of continuous use.
This is the head of a moai that was part of the second ahu
in this ceremonial complex.
In this second ahu,
all of the moais are laid down in the back of the platform.
That is because that second ahu was being dismantled
to enlarge the first one.
Pieces of earlier moai were being reused
to create an even more spectacular ahu.
From this particular ahu, we couldn't say that
there's evidence of collapse.
There's evidence of transformation and human societies changing,
and that's beautiful. Destruction is recycling
and creation. It's part of a larger process,
and, in a certain way, this moai reflects that.
Across the island, what some Western researchers
had seen as evidence of collapse didn't stand up to scrutiny.
Even the island's caves, long seen as refuges against an enemy tribe,
appear to be something very different.
This is a great example of a cave that has that construction,
where they've taken a cave and added these features to it.
Yeah, and it's not a refuge cave.
It's not a hiding place. It's a habitation.
So they made this nice entrance, with paving stones and everything.
And they've used lots of different materials, like this paenga stone.
Paenga are a kind of foundation stone found in elite houses.
The holes bored into them acted as bases for the wooden struts.
The use of these paenga in cave walls
was argued to be evidence of some last-ditch defence against attack.
Some people think that this is evidence of tearing down elaborate
or elite houses and reusing the stone out of desperation,
but these stones are reused everywhere.
We see the re-use of these paenga stones not only in things like ahu,
but also in the chicken houses, the hare moa,
as well as earth ovens. So they're really used in all kinds of contexts
because people used the stone that was available to them,
and some of that stone were paenga.
Reusing and recycling stone materials here is really the norm.
At another set of caves nearby,
Hete, Carl and Terry find yet more evidence of a thriving community.
Here, the Rapa Nui even used the collapsed lava tubes as hothouses,
fed by something rare on an island of permeable volcanic rock -
an abundant supply of water in caverns deep within the caves.
In those caves, we can find fresh water.
It was one of the largest water reservoirs,
so it's a very rich part of the island.
So Rapa Nui's caves weren't just simple refuges.
They were complex, sun-dappled ecosystems
that had been used for centuries,
long before the collapse that was supposed
to have driven people into them.
Nothing here in Te Pahu, or in the area that we worked,
shows that people were struggling.
On the contrary, they were thriving.
We were seeing signs of sustainability.
There was really no evidence of collapse.
Even though Carl and Terry found no direct evidence for collapse,
they would not dismiss the idea without more research...
..especially when it came to the population of the island over time.
They started by mapping all the moai on one side of the island...
..then moved on to the settlement and resource sites.
Our goal is really to sort of characterise the settlement systems
and how people are distributed across the landscape
and use resources there.
We've got a good sample of the communities,
but we're continuing to do that as an ongoing basis.
They match these with carbon dates from the sites
to build up a pattern showing when each settlement was in use.
Then they ran them through a computer model
which converted the carbon data into population numbers
by calculating the highs and lows of human activity on the island.
The results confirmed their hunch.
It showed the population rise from a small number of first settlers,
continuing to grow steadily, with no sign of collapse at any point.
The population could fluctuate slightly,
but its average maximum is probably around 3,000,
probably what Europeans encountered
when they first arrived on the island.
A maximum population of 3,000 was much smaller
than the numbers cited in the Western collapse story.
The collapse theory proposed all kinds of numbers -
7,000, 10,000, 15,000,
even up to 30,000 population for this small island.
But Carl, Terry and their colleagues found no evidence
that there were ever that many people living on Rapa Nui.
The lack of huge populations being on the island
sort of takes the wind out of the collapse theory,
because, in fact, there's nothing from which to collapse.
There isn't a large population.
But if you don't have tens of thousands of people
living on the island,
how could the Rapa Nui build and transport the moai?
For some Western researchers,
Rapa Nui oral history suggested an answer.
This actually referred to small wooden statues,
but some Westerners thought it also described the stone moai.
Thor Heyerdahl and his colleagues
attempted to move the statues upright,
to effectively make them walk.
But the experiment hadn't worked,
so most experts still believed that they were dragged on their backs.
But when Carl and Terry analysed the moai
lying by the roads that led from the quarry,
they noticed something significant.
These are impressive things, aren't they? Yeah.
We're looking, right here,
at the reason why they were not transported on logs on their backs.
That's true. How would they be in this position,
face down, and the neck broken?
Right. It makes no sense.
That just simply doesn't happen if they're on their backs on rollers.
They also noticed a structural difference
between moai lying on the road and those standing on the ahu.
A moai on the ahu has a flat base, so the statue stands straight up.
But most of the moai lying on the road have angled bases,
and Carl and Terry believe that angle had a very specific purpose.
A road moai has to be shaped in a way that can be transported.
They did it by shaping their base
so they leaned forward to enable them to walk.
This is a great example of the forward lean
of these transport moai.
So, if you took the statue and we could put it back up,
it would be leaning really far forward.
It means that as you rock it side to side,
it falls forward across that front edge and takes a step. Yeah.
Without that, it would just rock back and forth
and not really go anywhere.
And walking really describes what these moai did.
To test their theory,
in 2012, Carl and Terry built a model of a moai out of concrete,
carefully mixed to match the fragile density
of the ancient statues' volcanic rock,
and made it walk.
In our experiments, we found it took remarkably few people
to move the statue - and we were terrible at it.
You know, we were the least expert of any people
who've ever moved a moai in the world -
but we were able to do a five-tonne statue with 18 people.
Whether they walked or not,
most experts now agree that building moai
could not have caused the loss of the forest.
I like to use a...basically, just a math example.
There's about a thousand moai on the island.
About 400 of them are still at the quarry site,
so only 600 have been transported,
and the amount of trees that you need to fell to move 600 statues
cannot even closely account for that degree
of deforestation that happened.
There are vegetation reconstructions for Rapa Nui,
talking of 18 million, 19 million palm trees on the island,
so the amount that were cut down for transporting or building moai
would only have been a very, very small percentage.
So, if trees across the island weren't felled to transport moai,
what happened to them?
An area of forest is cleared.
It is used for gardening, for horticulture.
This process is known as slash and burn,
and is a millennia-old practice used all over the world.
In slash-and-burn cultivation,
you can clear an area, burn the wood that you've cleared.
This releases nutrients into the soil.
Plant the crops.
As that soil becomes exhausted from cultivation,
you repeat the sequence.
As the vegetation grows back, especially trees,
this can be a rotating system
where you're continually adding nutrients to the soil.
But on Rapa Nui, the burned woodland didn't grow back
as it did elsewhere in Polynesia.
Why not?
The fossilised DNA of ancient animals may hold some answers.
Analysis suggests that the early settlers
of Rapa Nui had a passenger.
And they reach an environment with unlimited food.
The nuts of the palm trees,
the nuts and seeds of other native plants on the island.
You get a vicious cycle here
where people are practising slash and burn,
as they have throughout the Pacific,
and the rats are busy eating the next generation of plants
as they eat the seeds.
We don't know if this is what happened,
because there are no historical records
to chart the island's early history.
But it is clear that trees were not needed to move the moai,
as the Rapa Nui continued to erect moai
long after the trees had died out.
So why did the Rapa Nui go to such lengths
to build them in the first place?
What were the moai for?
One tradition that might one day tell us the answer
is being lovingly preserved by Luis Huki,
a park ranger on Rapa Nui.
Rongorongo is the traditional writing system of the Rapa Nui.
It is inscribed onto wooden tablets.
Luis is one of just a handful of people still carving rongorongo.
No-one knows how old rongorongo is, or what it actually says,
but in a secluded monastery in Rome,
Silvia Ferrara is studying a remarkable wooden artefact
which might help answer those questions.
This is the Echancree tablet.
It's made of wood,
and it's one of the 27 tablets written in this script,
which is still undeciphered.
The Echancree tablet was gifted to the Bishop of Tahiti in 1869
by Catholic converts from Rapa Nui.
It is one of only 27 scattered across museums around the world,
and the way its figures are oriented
suggests a very unusual reading method.
What you need to do is turn the tablet from one line to the next
in order to read it, and this is a unique feature
of this writing system.
No other script works in the same way, all over the world,
so it's really quite special.
Despite this unique system, it has been said that rongorongo
was inspired by European writing.
That's kind of a degrading view of Rapa Nui ingenuity.
It's not only simplistic, but it's patronising.
It's one of the most unique and beautiful
forms of knowledge, of art, in the world.
Nevertheless, we have to face critics,
or thoughts that we were copying.
The glyphs in rongorongo are clearly connected to the art on the island.
You see the glyph forms in petroglyphs.
They don't imitate European writing in any sense.
To put the debate to bed once and for all,
Silvia gained permission to radiocarbon date this tablet.
The radiocarbon date points in the direction of a 15th century date,
which antecedes the arrival of the Europeans
by more than 200 years.
Silvia believes this might make rongorongo one of the few instances
of independently invented writing in the world.
But what was rongorongo for?
Many believe that it contains the secrets of Rapa Nui culture.
Some people say that they contain legends, or rhythms,
or encrypted instructions of how to move moais,
or develop some technologies.
There are many, many different theories about it,
but what we do know is that they contain knowledge.
Until rongorongo surrenders its secrets,
researchers are using tried and tested scientific methods
to understand why the moai and the ahu platforms
are located where they are.
When we look at the question of where ahu are located,
why are they located there?
Why are some of them very large and some of them smaller?
Why are there some ahu in the interior
while most of them are on the shoreline?
It's easy to describe them as being religious.
Certainly, that's part of the story.
But the question is, why would you invest so much energy
in doing these over and over again?
They started with a map.
They marked out the locations of all the ahu
on the east side of the island.
Then they began to compare them with the locations
of vital resources.
They chose three as the key sources of sustenance -
rock mulch, seafood, and fresh water.
But when they tried to map the ahu over the rock mulches,
a simple mismatch became glaringly obvious.
There's rock mulch everywhere across the island,
but we don't see ahu and moai everywhere.
What we find is, in fact, that ahu and moai are in particular locations
independent of the mulch itself.
Next, they looked at resources from the sea.
When you drive around the island, you see, one after the other,
an ahu with moai all the way along the coast.
And, of course, the coast
has a lot of resources -
fish, shellfish, other kinds of things
that would support populations.
But while the ahu on the coast matched sea resources very well,
this cannot explain the ahu erected in the interior of the island.
That left one final resource - fresh water.
Most of the moai are along the coastline
with their backs to the sea.
At first glance, that doesn't seem like a good place
to find fresh water -
but look a little closer.
The water is fresh.
You'd think this water is salty, that it's sea water,
but, in fact, this is a freshwater sea,
a source of water that comes from the interior of the island,
moves through the underground and then comes out at the coast.
It's a place where Rapa Nui people access water for their daily lives.
On a young volcanic island like Rapa Nui,
the rocks are very porous.
The rainwater will enter the island
and flow through the porous island
and into lava tubes, etc,
and will come down to the level and float on top of salt water
and then enter the ocean at low tide.
When Captain Cook arrived on the island,
what he saw was people drinking straight from the ocean,
and he thought, "This is crazy. Why would people do that?"
What he was actually seeing is people drinking water
that comes from these freshwater seeps
that emerge right at the coast of the island.
And when Carl and Terry compared their map of ahu moai
with a map of fresh water sources, they got a roughly 90% match.
In fact, the locations of fresh water are the best predictor
of the locations of ahu throughout the island.
For many, this near-perfect match is not surprising,
because ahu are usually linked with settlements.
Those hamlets or villages are located, in many cases,
close to water sources, which makes perfect sense, that the essentials
for survival, like your crops and your drinking water,
is close to where the people actually settle.
Yet for Carl and Terry, it's the precise location of the moai
that is the key to this theory.
One of the interesting aspects about Rapa Nui people
is they lived in a dispersed settlement pattern,
in which people used the landscape around the ahu
in sort of a wide area,
but they're brought together at the ahu and the moai.
Again and again,
the ahu, not the settlements, are closest to the water.
So we find, in fact, the ahu and the moai
right next to the critical resource,
because in fact, that is the heart of the community.
It seems the moai acted as a statement,
erected close to a community's most vital resource.
But Rapa Nui tradition would see this differently.
They represent the soul of a dead king.
So, moais' location and eventual collapse
is also related with an evolution of a political and social structure.
The statement is, "We're honouring our ancestors",
and they might even say to us, if we could time travel,
"Don't you honour your ancestors in this way?"
Looking at all the archaeological evidence,
it seems more likely that, rather than a self-inflicted ecocide,
the true collapse of Rapa Nui society
was caused by outside influences.
As time went on and the evidence accumulated,
we realised that a lot of what people thought was collapse
was something that actually happened after Europeans arrived,
and it had an entirely different cause,
and that was the introduction of Old World disease.
There was the smallpox, there was the Spanish flu,
leprosy, slave trading.
It was difficult to live here,
and it was more difficult to keep the social structures
and the life as the way that we knew it.
Over time, we see people sort of abandoning ahu and moai.
It's a loss of population.
There are just fewer people because of the effects of diseases.
So people are not attending to the ahu
and rebuilding them in the way that they did in the past.
Things got even worse in the 1860s.
Peruvian slave traders
captured about a third of the population on the island
and forced them onto their ships to work in Peru.
By the time it was over,
there were less than 200 Rapa Nui left alive.
The true story of Rapa Nui is one of survival against the odds
by an ingenious and resilient people
who came to a bad land and made it good.
But that story has been overshadowed
by a Western fascination with the moai,
and for Sonia and Hete,
that is the true tragedy and triumph of Rapa Nui.
If we look only at the moai, we are not making this place bigger.
We are making it small.
That means you don't believe in my capacity as a human being.
If there's one thing that I would like people to take from Rapa Nui,
it's that the history has been narrated
by a very selective group of people.
There are different realities.
The world is full of beautiful, amazing stories
that deserve to be told, and people deserve to hear.
Our history is not unique.
We share with many islands, and we share a beautiful past,
a complex present,
and many, many tragedies in the midway.