♪♪ [ Mid-tempo music plays ] -The Amazon -- more than 2 million square miles of dense forest, penetrable only by its rivers.

♪♪ Long considered a pristine forest, seemingly too hostile to have ever been inhabited by people prior to the arrival of Europeans.

And yet, in recent years, several discoveries have been made: evidence of human habitation, hidden in caves... under the canopy... buried in the ground.

What if, contrary to long-held belief, the tropical forest was not as untouched by human hands as we thought?

What if wide-ranging, complex cultures thrived throughout the jungle, long before European conquest?

♪♪ As scientists delve deeper into the exploration of this difficult terrain, they are convinced the Amazon was home to numerous, well-established communities.

Archaeologists, archaeobotanists, and anthropologists are studying the artifacts these people left behind, in an attempt to understand the ancient world of the Amazon.

Who were they?

How many of them were there?

How did they manage to live in the forest?

And what do these ceramic figures say about their beliefs and their vision of the world?

♪♪ Thanks to new investigative technologies, researchers are making great strides in understanding these highly developed communities and piecing together their existence in the years before the Conquest.

♪♪ From the depths of the jungle to the shores of the Amazon River, the full story of this isolated part of the world is only now being brought to light.

♪♪ [ Theme music plays ] [ Machete hacking vegetation ] -These images, recently shot by ethnologist David Green and his team in northern Brazil, not far from the border with Guyana, are of an exceptional discovery.

[ Brush rustling ] [ Birds chirping ] David was led to this cave, hidden in the hills of Amapá, by following indigenous guides who have special knowledge and accompanied him through their territory.

[ Bats chittering ] [ Wings flapping ] [ Indistinct conversation ] ♪♪ ♪♪ -I'm here at Bat Cave.

Some really beautiful works of art.

This is a mysterious site because it's still unknown.

And so this is really an important place to continue our archaeological work before it gets destroyed.

-[ Speaking native language ] ♪♪ -Acutely aware of the value of his discovery, David left everything untouched, only filming and photographing the artifacts until a proper archaeological assessment can be made.

♪♪ A few weeks later, he enlists the help of archaeologist Stéphen Rostain.

An expert in pre-Columbian cultures in the Amazon, he is one of the few people who can immediately identify what David found and place the items in historical context.

At his base in Guyana, Stéphen learns of the discovery.

-Did you see only one anthropomorphic urn, or some more?

-There are probably 9 or 10 urns.

-Yeah?

-But they have all been broken.

I've noticed there's a lot of different handles, and different zoomorphic forms.

Sometimes it's really hard to understand what animal they are.

They seem to be like a composite of different creatures.

But I believe there's a lot more.

This is just begi-- You know, really, we just looked at a small part.

-For the archaeologist, these remains are characteristic of the Aristé, one of the cultures present before the arrival of Europeans.

-[ Speaking native language ] -These are typical of the anthropomorphic funerary urns found all along the Amazon.

They are made from pottery with a sculpted human face, usually on the neck.

The ashes of the deceased were placed in them, or even their bones after decomposition.

The most important thing is that we have the main part of this pottery, which is familiar from other excavations at other sites.

So we can extrapolate and reconstruct the urn into something like its original form, as it initially was.

So we have a representation of a funerary urn from the so-called Aristé culture, located in the region straddling French Guyana and Brazil.

It is a huge territory, some 300 kilometers long.

The culture dates from around the year 1000 until the early centuries of colonization.

Anyway, it's a very interesting discovery, because these burial caves are extremely well hidden.

-More broadly, the discovery belongs to a vanished world, the traces of which remain buried in the largest tropical rainforest on the planet.

It's the forest itself that has made it so difficult to learn about the peoples living there in the pre-Columbian era.

The dense vegetation makes moving through it almost impossible, and has long stopped scientific exploration.

And there was little evidence to suggest that there was much to be studied.

The forest's vegetation consumes everything, breaking it down or growing over it.

And early accounts of exploration, like that of conquistador Francisco de Orellana, have been forgotten.

The year was 1542.

The Spaniards were engaged in the conquest of the Incas of Peru.

But Orellana wanted to push further into the forest, in search of mythical lands of gold and cinnamon.

He ventured inland, following the Amazon River from its source in the Andes.

Aboard two small ships carrying a total of 56 men, he was the first European to cross the entire Amazon forest, and to encounter the people who inhabited it.

[ Indistinct conversations ] -"All night long, we passed through a series of very large towns.

By daybreak, we had covered more than 20 leagues.

[ Water splashing ] But the further we advanced, the more densely populated the country became."

[ Indistinct conversations ] -[ Speaking native language ] -The problem is that a hundred years later, there was no one left on the banks of the Amazon.

The microbial impact of Western diseases had done its work.

So, disbelief prevailed, and persisted for five centuries, right up until the 1980s, when archaeologists began to take an interest in the Amazon.

-Stéphen has studied the Amazon for more than 30 years and is a pioneer of Amazonian archaeology.

His goal is to provide a better understanding of the cultures that existed before 1492.

-Obviously, we only have a very sketchy knowledge in certain regions, so we're trying to piece together a puzzle that still has many pieces missing.

-[ Speaking native language ] -Stéphen is eager to collect and connect scattered pieces of knowledge in order to paint a complete picture of the pre-Columbian Amazon.

♪♪ What do the today's tribes know about the mysterious designs their distant ancestors used to decorate the urns?

To address the question, Stéphen meets with Native Americans who still practice the art of pottery.

The Palikurs are an indigenous group whose territory is the same as the now-extinct Aristé culture, straddling Guyana and Brazil.

[ Indistinct conversations ] -[ Speaking native language ] -The Palikurs, as we know, have inhabited this region since at least the European conquest, and probably before.

So they were very possibly in contact with Aristés, and, indeed, may themselves have been Aristé.

So maybe they can help us understand the designs and see if they still have meaning today.

-[ Speaking native language ] -Doralice is part of a family that has been creating pottery for several generations.

-[ Speaking native language ] -The exchange takes place in the Palikur language, through an interpreter.

-[ Speaking native language ] -This is an urn that was found recently, and I wanted to know if, in the drawings, it means anything to her or nothing at all.

-[ Speaking native language ] -[ Speaking native language ] -[ Speaking native language ] -This one, I recognized.

And that one.

Definitely, I just noticed this one.

-Ah, good.

That's good.

So, this became the Palikur style, which has evolved until today.

I had another question.

For me, this pottery represents death, so we have a new body, and the soul will be at rest.

So, to find out the ethnicity... [ Conversation in native language ] -She says she can't confirm anything.

-[ Speaking native language ] -That one is unfamiliar.

-[ Speaking native language ] -We think there must have been a cultural upheaval throughout the Amerindian world at the time of the European conquest, resetting the ethnic map of the Amazon, and the meaning of certain designs disappeared with these populations.

So, you have to look at other vestiges, other sites, other signs left by the Amerindians in this great rainforest.

♪♪ -The next phase of exploration will be done by air.

Mickael Mestre is in charge of the operation.

This plane is equipped with a lidar system -- an airborne laser, able to penetrate the canopy and precisely map the contours at ground level.

To that end, the survey must be carried out from the sky.

♪♪ To cover the entire section under investigation, the small plane must make more than 50 tight turns.

♪♪ In an operation that lasts several hours, there's no room for weak stomachs.

In this way, dozens of square miles can be observed, as if the area had been deforested.

[ Birds chirping ] ♪♪ The data acquired during the flight is processed in Cayenne by the company that operates the lidar.

♪♪ Thousands of data points are assembled and transformed into a model that restores the contours in the terrain, from the undulations of the canopy to the tiniest variations in relief at ground level.

-[ Speaking native language ] -If we can zoom in here, on that zone, it could be -- could be a site with ditches.

A circular layout.

We have a trench dug at the top of the hill, marking out a central reservation.

These sites are typical of pre-Columbian occupation, particularly in French Guyana.

They are known as crowned mountains.

-"Crowned mountains."

Mickael has been studying this type of terrain for a long time.

And the use of lidar has made a series of archaeological discoveries possible.

-[ Speaking native language ] -Today, the figure is something close to a hundred.

It is a very widespread phenomenon.

Several cultures seem to have produced this kind of layout.

But for what purpose, we're not yet sure.

♪♪ -The sites could be almost anything: residential buildings, defensive structures, places of worship.

A few weeks later, Mickael has the opportunity to excavate one of the crowned-mountain sites spotted by lidar.

-I think there's another ceramic, right underneath the first one.

A second one, right there!

The shapes are common: large, undecorated basins.

We've seen them before.

Ordinary ceramics can be reused in a funerary context, too.

They may be objects that belonged to the deceased.

-These perfectly intact large vases were deliberately buried at the top of the crowned mountain: a form of offering that suggests a link to the beliefs of certain pre-Columbian peoples.

[ Rain falling ] [ Thunder rumbling ] Because they are so inaccessible, thorough excavations of hidden jungle sites like this are very rare.

Often, archaeologists can only access them when construction work happens, as was the case on the outskirts of Lake Tefé, more than 1,200 miles from the mouth of the Amazon, during building work on a school.

While digging, the residents discovered a ceramic funerary urn nestled at the bottom of a pit.

Aware of the importance of this type of find, they immediately informed archaeologists at the Mamirauá Institute.

-[ Speaking native language ] -First, we found one, then we unearthed two, three, four.

We thought that was already a lot.

Then, five, six, seven, eight, nine appeared.

The village accompanied us at all times.

It was a truly special moment for all of us.

[ Conversations in native language ] ♪♪ -Carefully collected, one by one, the urns then traveled more than 600 miles by boat through the forest, to the laboratory at the University of Santarém.

♪♪ There, archaeo-anthropologist Anne Rapp is charged with analyzing the urns and the material contained inside.

-[ Speaking native language ] -Here we now have a group of nine urns collected together.

We cannot say whether all the individuals died at the same time, but we may be sure that they were all buried during the same period.

That's to say, before the arrival of the first Europeans in the region.

-[ Speaking native language ] -For the scientists, it is a unique opportunity to examine the funeral rituals of pre-Columbian societies.

The first step is to X-ray the artifacts at a hospital.

Anne is the first to see the results.

-[ Speaking native language ] -Is that all bone?

-Bone, yes.

It's very interesting.

We really have a huge amount of material in this container.

-Yes.

How does it compare to the others?

-Yes, it's impressive.

-It's going to be an interesting dig, opening it up and getting it all out.

-[ Speaking native language ] -To access the contents of this small ceramic jar, the lid, which has not been moved for at least 500 years, must first be detached.

It's an extremely delicate operation, with the container itself weakened by its long stay underground.

♪♪ -[ Speaking native language ] -You lift, I'll put my hand here and pull.

This time, we'll try in the opposite direction.

♪♪ [ Crackle ] Ah!

There it is.

-[ Speaking native language ] -Examination of the urn can finally begin.

♪♪ Anne and her assistant are about to meet former inhabitants of Lake Tefé.

♪♪ -Here we may have the grandparents, or great-grandparents, of people who encountered Orellana in the 16th century.

♪♪ -To ensure she doesn't lose any material, Anne must proceed very slowly.

♪♪ It will take at least two days to clear away the sediment and reach the first significant remains.

♪♪ -[ Speaking native language ] -We have an exceptional amount of preserved material, especially in the context of the Amazon, where we generally see a very limited preservation of organic material.

-[ Speaking native language ] -Examination of the first bones immediately reveals what kind of ritual the bodies were subjected to.

-[ Speaking native language ] -You can actually see evidence of cremation.

-[ Speaking native language ] -The grayish areas are clearly marks of fire.

-But the scientist's first objective is to sort and organize the bones.

Do they come from the skeleton of a single individual, or of several?

-[ Speaking native language ] -That's probably one of the last bones in the chest.

Here we have an idea of the sections of the skeleton present.

There are no duplicate bones, so it appears there's only one individual inside.

-[ Speaking native language ] -A single individual, and a complete one at that.

The funeral ritual is becoming clearer.

-[ Speaking native language ] -We can see the two-stage process of the funeral: first, the cremation; followed by the bone material being placed inside the urn with extreme care.

-[ Speaking native language ] -Once the remains were inside the urn, it was decorated with a unique pattern meant to represent a new skin made of pottery.

♪♪ But, for the anthropologist, the investigation is not over.

The remains of the individual have more to share about their owner's identity.

-[ Speaking native language ] -Several parts are very marked.

These are joints and muscle insertions that have worn over time, so we may be sure that this is a fairly old adult.

We always tend to think that in the past, people died young, but that isn't the case with what we've seen in the Amazon.

There are several clues to indicate that people lived to advanced ages, maybe up to 50 or even 60 years.

-[ Speaking native language ] -The scientist notices other characteristics, too.

-[ Speaking native language ] -Here is the archaeological femur.

If we compare it with our model, which is from a 1.68-meter-tall individual, this is definitely from someone much smaller, measuring between 1.50 and 1.55 meters.

Based on the size, it may be a female individual.

[ Speaking native language ] ♪♪ -So, the occupant of this urn seems to have been an elderly woman.

♪♪ And the story continues.

The urn itself, particularly some of the patterns Anne is uncovering, shed more light on its significance.

♪♪ -[ Speaking native language ] -Here we begin to see the area around the eye, the mouth, and what appears to be a drawn cheek.

-[ Speaking native language ] -This is the eyebrow, the nose, a tiara, and here, the area around the ear.

♪♪ -A face, perhaps to evoke that of the old woman, or the spirit of the deceased.

-In reality, this pottery cannot be separated from the individual.

The study of the ceramics in the urns is based on a particular individual, so we try to tie it all together.

♪♪ -Cristiana Barreto is an expert on Amazonian iconography, working at the Emílio Goeldi Museum in Belém.

She has a particular interest in the drawings on the urns recently discovered at Tefé.

Her objective is to understand what the peoples who shaped and decorated these objects wanted to communicate with them.

-These ceramics were meant to have a great visual impact.

They are ritual ceramics, made to be used in funeral ceremonies.

There is always a white background to increase the contrast of red and black.

The high contrast is a way to attract the gaze of observers, drawing them into the labyrinths, into the iconography, where they see snakes, jaguars, and animals -- often somewhat disguised and hidden.

-[ Speaking native language ] -While mysterious in the eyes of the layman, to the initiated, these forms make perfect sense.

-It looks symmetrical and geometric, but it's actually the geometric representation of a jaguar.

We have the jaguar's eyes and the face.

They are in the background, but suddenly they come forward, then go back, giving the idea that the jaguar is moving, maybe coming towards us.

♪♪ -[ Speaking native language ] -Here we have a cobra -- the movement of a cobra -- but it isn't filled in.

It could be the background.

This also gives us a sense of movement, from the inside to the outside of the urn, as if it were coming out of the urn.

It isn't surprising.

It's a visual process of animation, where everything seems to be moving.

Everything in Amazon visual logic has to do with movement.

-[ Speaking native language ] -Patterns and symbols representing cultural beliefs and showing the role these urns played in funeral ceremonies.

-You have to imagine these urns as the focal point of a funeral ritual, with its dances, musical rhythms, alcoholic drinks, and other drugs.

It's all geared to attaining an altered state, etching these symbols in people's memories.

-[ Speaking native language ] -[ Singing in native language ] ♪♪ [ Animals chittering ] -Plants and animals from the natural world can be found on pre-Columbian objects throughout the Amazon.

Now scientists are interested in learning more about these traditions and these people.

♪♪ ♪♪ Stéphen meets with Cristiana in Belém in a bid to better understand the tribes of the Amazon and their conception of the world.

-[ Speaking native language ] -Belém is a large city at the mouth of the Amazon, and very interesting for its museum of Amazonian archaeology, the first of its kind in the world, set up in 1905 by Emílio Goeldi.

It has an absolutely fascinating collection of urns -- pieces of enormous beauty that you won't find anywhere else.

Some really innovative things for my investigation.

♪♪ -Today the institution's collection contains more than 2 million artifacts.

Taken together, they are like a huge clay book on the shared history between humanity and the world's greatest rainforest.

♪♪ Based on their similarities, some of the more recent additions to the collection seem to suggest that multiple Amazonian tribes shared a common belief system.

♪♪ -Here we have set aside some of the funeral urns from different cultures.

They are almost all from the Amazon estuary.

-They reflect the identity that each people wanted to give to its clan, to its ethnic group.

It is resounding proof of the human diversity that has existed in the Amazon.

♪♪ Ceramic styles and details have helped researchers identify hundreds of different cultures that existed in the Amazon basin.

♪♪ But it's the characteristics common to all of these artifacts that shed new light on the world view of those who created them.

-[ Speaking native language ] -There are also similarities.

For example, arms are represented as snakes, and here, animals are also used.

[ Animals chittering ] -[ Speaking native language ] -They use scorpions to represent the eyes.

We can also say that the use of animals to represent the human body is a pan-Amazonian tradition.

-There's a certain analogy to it all.

-An analogy between images and the natural world.

♪♪ It's this idea of not differentiating between nature and culture, of it all being part of a whole.

It's a complex concept for us Westerners to grasp.

-We have a very naturalistic society.

We need to separate culture and nature to know where civilization is, and where it isn't.

But with the Amerindian, there is a continuous thread, and ultimately, no frontier.

♪♪ -According to anthropologist Philippe Descola, animism was the predominant belief system for many Amazonian cultures.

-[ Speaking native language ] -Animism is something I discovered during my fieldwork, when I resided for a few years among the Achuar people in the deep Amazon.

It is also when I discovered that most of the plants and animals were conceived by them as having an interiority, a soul -- or in any case, a subjectivity, a capacity for reflection.

-[ Speaking native language ] ♪♪ [ Speaking native language ] -There is no nature in their world.

There are simply social partners with feathers, fur, leaves, bark, et cetera, with which the Achuar people exchange daily, through magical incantations, dreams in which they saw these non-human beings addressing them, in the form of a person, in order to start conversations, dialogues, et cetera.

-[ Speaking native language ] ♪♪ -I realized that this was something very common in the Amazon, and in other parts of the world.

There is no conquest of the wild by the domestic, which is the most characteristic way for us to conceive of our relationship to nature.

There are social relationships that are permanently established between humans and non-humans, that are not necessarily easy relationships.

-[ Speaking native language ] -After all, the woolly monkey that comes to see you during a dream, the next day, we will try to kill it and to eat it.

-[ Speaking native language ] -The relationships between humans and non-humans are relationships of mutual accommodation.

Very powerful relationships of attachment, competition, and solidarity.

-A spiritual union of people with the natural world was typical for Amazonian cultures.

But scientists want to find the cultures' creation myths -- stories that explain the origins of a people's world view -- in order to better understand the significance of the urns and their patterns.

♪♪ Handed down by oral tradition, these stories are difficult to piece together and understand today.

But Stéphen is keen to track them down among some of the peoples of the forest.

♪♪ This is the Maroni River, which separates Guyana from Suriname.

Here, the forest crowds the riverbanks, except in spots where it's been pushed back by the villages of the Wayana people.

Stéphen hopes they can tell him more about the ceramics and other artifacts.

[ Rooster crowing ] The Wayanas continue to represent their founding myths through symbolic figures, so this is an opportunity to find out more about the stories behind them.

-[ Speaking native language ] -The chief of the village where Stéphen stops has something to show him, and leads him to the large community shelter known as the tukusipan.

♪♪ This is what the archaeologist is looking for: a ciel de case -- or "maluwana" in their language -- a wooden disk decorated with strange beasts that represent the Wayanas' belief system.

-What is the name of the person who did this?

-Aimawale.

♪♪ -Aimawale is one of the few people still able to reproduce this type of design.

It is a very old art form that he learned from his grandfather -- one he keeps alive using ancestral painting techniques.

-I prepare my paintings -- how to put it -- it takes patience.

It takes a long time to paint a ciel de case.

-But he also knows the stories and the myths that inspire them.

♪♪ And that is what interests the archaeologist the most.

♪♪ -What is the ciel de case for?

-A ciel de case is an object that protects the community and the village.

There are six main patterns.

So, there's the jaguar, for example, here; the caterpillar; then there's the fish-animal; the tapir, which is often on the ciel de case, too; plus, the turtle; and the fish.

-Do you choose all the patterns?

-Yes, of course.

Here, I was inspired by my grandfather.

Each pattern represents a legend, a story.

-That's the giant anteater.

What does that do?

-Legend has it that the giant anteater killed its baby, then went to the aquatic monsters and killed a water spirit.

So the shamans know how to harness its power to take revenge -- for example, on evil spirits.

-What about the turtle?

-The turtle is the wife of God, the supreme god, called Kuyuli.

When there was the flood, the God transformed his wife into an underwater turtle, and his children are like eggs.

That's what the story says.

-And you tell these stories to children?

-Yes, of course.

Then there are other patterns, like the squirrel.

It's actually a squirrel monster.

It's small, but it has supernatural power.

-There are plenty of monsters in the stories.

And lots of legends.

-With us, yes, with the Wayana.

♪♪ -What the Native Americans describe today, when they tell us about their legends, is this close interaction between humans and nature.

We can better understand the relics they left behind.

-[ Speaking native language ] -Philippe Descola has collected and studied these myths, to try to understand if they connect to a broader story.

-[ Speaking native language ] -What we find absolutely everywhere are these little stories -- five-minute stories, which give a good indication of what the mythical times were like.

-[ Speaking native language ] -How, at such and such a time, such and such a species of hallucinogenic plant became what it is.

The sorts of small events that will cause so-called natural species to emerge, little by little.

And these are small stories.

These are small pieces of this great story of speciation.

-[ Speaking native language ] ♪♪ -The great story of speciation: how all living things -- plants and animals -- came to exist.

♪♪ -[ Speaking native language ] -There is an original unity, a great culture that unites humans and non-humans, who are not really distinguished from one another.

-[ Speaking native language ] -[ Imitating bird chirping ] -The myth allows us to at least understand this -- the golden age, if you will.

A golden age where animals and plants behaved like humans: cooking, hunting, playing music.

-[ Speaking native language ] -Amazonian mythology is a story that starts from culture and goes towards nature, while we are doing the opposite.

-This singular relationship Amazonians developed with their environment is at the heart of everything they do.

But how long have humans been living in the Amazon rainforest?

Is it possible to trace when these creation myths were first told?

♪♪ A tiny fragment of pottery of inestimable value offers a clue.

-[ Speaking native language ] -This history of ceramics is a long one, with very early origins.

Some of the fragments of ceramics we have here are 7,000 years old.

It is the oldest dated pottery ever found in the Americas.

-[ Speaking native language ] -These fragments come from the Monte Alegre region, in the heart of the Amazon, where this art form was born.

♪♪ Reaching the area requires a 400-mile journey upriver from the mouth of the Amazon, and then a connection with one of the river buses that travel to isolated villages.

Archaeologist Edithe Pereira has been making the trip regularly for more than 10 years.

And each time, it's a journey back to Amazonian prehistory.

♪♪ The very first traces of human settlement can be found here.

Drawings on the rock face that date back to 12,000 BCE.

♪♪ But these decorations, that have lasted millennia, are now in danger.

-[ Speaking native language ] [ Speaking native language ] -The biggest problem here today is wasps.

[ Wasps buzzing ] A type of wasp makes its nest very close to the paintings.

-[ Speaking native language ] -And sometimes on top of the paintings.

-It's a very real risk for the paintings... and for scientists.

Several stings from these large insects can be fatal.

[ Buzzing continues ] No loud talking or sudden movements.

♪♪ These are the only paintings in the area that have been successfully dated, and they are much older than was previously thought.

-[ Speaking native language ] -We carried out a project to try to better understand not only the cave dwellings, but also life in the villages.

We found raw materials for making pigments, with usage marks.

The oldest traces in the shards was dated to some 12,000 years ago.

-They are the oldest observable traces of human presence in the whole of Amazonia.

♪♪ It is further proof that humanity has lived here for thousands of years... in this environment that until only recently, was thought to be completely free from human impact.

But where is the evidence that is usually left behind by thousands of years of human activity and occupation?

And how did the ancient peoples inhabit it?

Finding the answer requires a flight to a point seemingly as far away from any form of human activity as possible -- Nouragues, a CNRS research station set up deep in the heart of this green ocean, accessible only by helicopter.

♪♪ ♪♪ Stéphen has come here to meet ethnobotanist Guillaume Odonne.

-Here we are, in the forest.

We can look around for any signs of human presence, but, at first sight, it's only plants -- lots of different vegetation.

It's tempting to think that it might be very difficult to find any evidence of the presence of Amerindians from 500 or 1,000 years ago.

We have always known that the region around the research station was occupied by Native Americans.

But until now, it was thought that human occupation was rather tenuous, with a low impact.

But in fact, no, this forest has been much more impacted than previously thought.

We have clearly shown that there have been massive occupations over a long period of time.

It is difficult to find sites without any trace of man.

♪♪ -It takes a great deal of work, across multiple fields of research, to achieve results like these.

Guillaume leads the LongTIme project, a wide-ranging multidisciplinary study.

Tropical soil specialists, botanists, ecologists, and anthropologists are all working to identify the plant species living in this corner of the jungle, which could help them find evidence of ancient human presence.

To determine all the species present at this site, Guillaume called on professional climbers.

Their mission is to collect leaves from 130 feet above the ground, so that these giants of the forest can be studied with accuracy.

-The feedback from the botanists will allow the ecologists to say, for example, that in this section, 40% of the trees have edible fruits, or 25% of the trees can provide timber for the construction of traditional houses.

-Mapping the tree species reveals significant concentrations of palm trees bearing edible fruits, like the comous and the patawas.

-All these numbers in red are palm trees.

There are five bacaba, around 50 patawa.

When we scroll the map, we can see that they are very present.

If we go to this other plot, LongTIme 2, there is only one patawa... here.

-The presence, or lack, of certain tree species is a strong indicator as to whether the land was ever occupied by people.

-As you see, we're in this transition zone between the top of the hill, which was occupied, and the bottom of the hill, over there, where there was clearly no occupation.

Back here is the area known as the vine forest.

Lots of tangled vines here.

This is a low-canopy forest, with less than 10 meters of tree height.

Everywhere, we are surrounded by vines.

They are often on the sites of former villages.

♪♪ -When cross-referenced, all this information allows scientists to pinpoint the location of villages and also areas that were set aside for agricultural use, where the vegetation was cleared.

♪♪ -The way it works is, when a village is set up... -[ Speaking native language ] -...little by little, people clear the area around it, where... useful species -- food species -- can be established.

Then, the year after... there will be another clearance, where further species will also become established.

Once the village is abandoned... all that remains are the planted species, or the food species that have become concentrated.

-[ Speaking native language ] -Likewise, they also end up becoming established on the site of the abandoned village.

We then end up with an enriched zone.

-So, we have these changes in vegetation, these developments, these new formations.

Can they be dated?

Can we pinpoint an approximate time when these stages actually occurred?

-From around 50 datings, taken from all the sites, we can identify two main periods of occupation in the area around Nouragues.

The first was between 1,000 and 1,200 years ago; and the second, between 400 and 600 years ago.

-The moment of contact?

-Exactly.

All these phenomena seem to have stopped abruptly at the moment of contact.

-All over the Amazon, we have this proliferation of evidence, particularly in the vegetation, which demonstrates a strong pre-Columbian occupation.

Almost everywhere -- whether along the Amazon, along the Orinoco, in the western Amazon, or the upper Amazon -- we see significant concentrations of human activity.

All the data points towards that.

♪♪ -Analysis shows traces of 83 different species of domesticated native plants... including cassava... coca... and pineapple.

This abundance and diversity has, however, long puzzled researchers.

Most soil in the Amazon is not suitable for agriculture.

And yet the gigantic forest actually thrives, despite very poor conditions.

♪♪ Domestic crops cannot grow in the acidic soil -- a result of heavy rains.

How did the people of the Amazon manage to cultivate food?

Archaeologists have recently discovered that pre-Columbian people in the Amazon developed a method for transforming the soil into very fertile land -- terra preta, or black earth.

♪♪ Brazil is where the most spectacular terra preta sites can be found.

In some places, it is several feet thick and is the subject of serious archaeological excavation.

-We know that this terra preta here formed with this soil.

So, they look very different, and they are very different in a way.

But that's the metric for that.

But we have to have human action interfering in the yellow soil in order to create the terra preta.

-Scientists believe terra preta is an indication of the onset of domesticity.

But how did the uncultivatable soil become something fertile enough to sustain human occupation?

♪♪ Analysis of the soil's composition can provide answers.

♪♪ Researcher Manuel Arroyo-Kalin regularly brings back samples of terra preta for study in his London laboratory.

♪♪ -What I can see here, very clearly, is large quantities of bone fragments.

We can also see here large numbers of fine, rounded fragments of pottery artifacts.

And here it's very interesting because these soils are absolutely full of charcoal.

And that already begins to unravel part of the story.

For one, the large amounts of charcoal have got to be associated to burning -- the sort of thing that you'd find associated to domestic production of food and the large number of fires used to fire the pottery.

And then you have waste-management activities, simply to pile it up and to burn it slowly.

-Indigenous people mixed everyday waste products and other materials into the acidic soil to create terra preta.

But in scientific terms, what makes this mixture so fertile?

-Charcoal helps to attract stuff.

It has a role in contributing to higher organic-matter retention.

-The secret ingredient was the organic matter left after trash was burned.

-All of these fragments of bone, and potentially some of the pottery, is providing a pool of calcium and phosphorus, which act as plant micronutrients that are absorbed by plants.

And so that helps plant productivity.

-The result is a living soil, rich in bacteria, which contribute to the absorption of nutrients by the vegetation and ensures lasting fertility.

♪♪ While the terra preta still has its secrets, pre-Columbian people were able to transform uncultivatable land into one of the world's most fertile soils.

-So, the terra preta is an outcome of a process which, only through various phases of occupation, have created the thick expanses that have subsequently been used as agricultural expanses.

♪♪ They are, at the very least, signatures of higher demography and possibly sedentary settlement in the Amazon basin, probably kicking in around 1500 B.C., and intensifying and growing in population as we go along.

♪♪ -If markers are placed on a map of the Amazon where terra preta has been found, they create an outline of territories known to have been inhabited by Amerindians.

♪♪ Using this data, scientists estimate the total population of the Greater Amazon was somewhere between 8 million and 10 million people when Europeans arrived.

-You have to imagine a very diverse, very populated pre-Columbian Amazon, where all these worlds were interconnected.

They were sedentary populations, but very mobile.

[ Water rushing ] -After seven months of travel, Orellana recorded his final thoughts on the peoples of the forest.

[ Indistinct conversations ] -"As we said, all those we have met on this river are people of great reason and ingenuity, as can be seen from all their works, as well as their vivid drawings and paintings of all colors, which are a wonderful thing to see.

-[ Speaking native language ] -A hundred years later, there was no one left.

What happened?

It's simple.

When the Europeans landed on the continent and came to the Amazon, they brought with them viruses and germs for which the Amerindians had no natural defenses.

These viruses spread, and many Native Americans died before Europeans had even encountered them.

Explorers arrived in villages to find only dead bodies and skeletons in hammocks.

They hadn't even had time to bury their dead.

-With its population decimated by disease, the Amazon was left uninhabited.

A vast land seemingly available for the newly landed settlers.

And a blank page in the history of humanity, that scientists are only now beginning to write.

♪♪ -[ Speaking native language ] -This is a territory of some 7 million square kilometers, which still holds many mysteries for scientists.

We discover new things about the flora and fauna every day.

In the case of human settlements, there are as many discoveries to come as have been made so far, if not more.

♪♪ -Opportunities to explore new territory are often the result of modern development.

♪♪ In northwestern Brazil, deforestation has revealed tiny geometric structures spotted from the air and scattered over tens of thousands of square feet.

♪♪ In Colombia, following the dismantling of the armed groups that occupied the forest, archaeologists discovered a huge wall of pictures -- tens of thousands of paintings -- animals, humans, and non-humans -- at Chiribiquete, which was recently listed as a World Heritage Site by UNESCO -- the first official acknowledgement that these rich and mysterious cultures are part of our invaluable heritage.