The Mystery of Rapa Nui - What caused the fall of Easter Island?

[narrator] Once, this was a paradise under palm trees, out in the Pacific Ocean. A jungle on a tiny island at the end of the world, its coasts lined by hundreds of giant statues. The Moai, a unique array of man-made sculptures.

[blowing shell] When European sailors discovered Easter Island in the 18th century, not a single palm tree was left, and the statues had been toppled. Archaeologist Sonia Haoa is a descendant of the few indigenous inhabitants who had survived slavery and deportation. She comes across traces of cannibalism.

For years, researchers from all fields of science have been competing for explanations. Why did the civilization of the enigmatic Moai perish? And why did the enormous forest of palm trees vanish so suddenly?

Two German researchers find amazing evidence which contradicts all prior hypotheses. [narrator] Hans-Rudolf Bork and Andreas Mieth are on the way to a mysterious place. They're eco-archaeologists, specialists in exploring islands around the globe.

Yet there's none comparable to this one, nor any as remote from civilization. Easter Island, or as the indigenous population called it, Rapa Nui, lies in total isolation in the South Pacific, almost 4,000 kilometers from the coast of Chile. On its easternmost tip, on the peninsula of Poike, a dramatic process has left its mark.

Rain has been cutting deep ravines into the soil and turned it into a red desert where hardly a plant survives. There is no other island in the world being explored as intensively as Rapa Nui, and no other divulging as little of itself. For the researchers, it's a race against time.

Erosion will soon have done away with the last areas of fertile soil, and with them, all evidence of an era when Poike, too, was still a green paradise will be lost. Each new soil sample bears witness to a once-intact ecosystem. [man speaking German] The older layers show seed holes and remains of excellent humus that was used by the original inhabitants for sustainable gardening.

Where today there is nothing but desert, back then their plants had grown under a shady roof of palm trees. [speaking German] [interpreter 1] Just imagine, there weren't just two or three trees here. .

. [interpreter 2] This whole area once was a forest with more than a thousand palm trees per hectare. [narrator] Mieth and Bork have calculated that more than 16 million palms had kept this landscape a blossoming oasis in the middle of the Pacific Ocean for centuries.

[man speaking German] [interpreter] And one day the whole forest vanished in no time. [narrator] Researchers are still puzzled by the question, who or what might have brought about the destruction of this paradise? The last palm tree must have been felled about 1600 AD, almost the exact time that the Moai civilization ended.

When Dutch seafarers discovered the island on Easter Sunday 1722, most of the statues had been toppled from their ceremonial platforms, or "ahu," and the landscape had been deforested. At the stone pits, there were still dozens of colossal statues to be seen which had been left unfinished. Rapa Nui emerged from the lava of three volcanoes.

It encompasses only 160 square kilometers. It's the loneliest inhabited island of the world. For 120 years now, it's been part of Chile.

Most of the 5,000 islanders live by fishery and tourism. About half of them are Chileans, the others are descendants of the indigenous population. Most of them have their homes in Hanga Roa, the only present-day settlement and capital of Rapa Nui.

A team of local researchers is on their way to work. Led by archaeologist Sonia Haoa, they're heading for the north coast of the island. Sonia is a true-born Rapa Nui.

Her forefathers were among the few natives who survived lethal diseases, deportation and enslavement under successive colonial regimes. She wants to understand how her people lived before and after the protective forest of palms disappeared. Her team examines the ruins of hundreds of settlements, measuring and indexing each stone.

Time and again they come across stone graves, carefully piled up slabs which were supposed to protect the bones of the dead from wind and inclement weather. To Sonia, her scientific brief is closely linked to a very personal quest. Whatever she finds here inevitably opens a door into her own past.

Down there lie the bodily remains of her ancestors. [speaking Spanish] [interpreter] It's the skull of an adult woman and that of a tiny child. [narrator] As so often, the researchers merely find skulls and ribs of the dead.

The longer, stable bones of their arms and legs had been used to carve filigree tools like these fish hooks. There just wasn't any better material. No one on Rapa Nui likes to talk about it, but under the many stone heaps also lie victims of cannibalism.

[speaking Spanish] [interpreter] Given the situation they were in, it didn't matter whether it was the bone of their grandfather or of some other member of their family. To them, eating the flesh of their dead was a necessity if they wanted to survive. [narrator] Who were these people who lived on this remote island?

And how did they get here in the first place? It's the only stretch of sand beach on Rapa Nui, the small bay of Anakena on the north coast. American anthropologist Terry Hunt is convinced that the first settlers could only have landed here.

Most experts agree that they arrived between 400 and 900 AD. DNA samples of their descendants showed that they must have been Polynesians. [chanting] Yet one day, while excavating at the beach, Hunt came across a strange find which made him doubt conventional chronology.

[Hunt] At the very bottom, we found charcoal, obsidian artefacts, rat bones, the first signs of human evidence. We have pieces like this radiocarbon-dated and it turned out to be only 800 years old. We were very surprised because this made the chronology of this island 400 or maybe even 800 years shorter than we thought.

[narrator] But how, in fact, did the first settlers reach Rapa Nui? The answer to this question can be found at the other end of the Pacific Ocean on Big Island in Hawaii. From here the Polynesians set out, probably using wooden precursors of a double-hulled canoe such as this.

Captain Kalepa Baybayan ranks as a past master of the ancient ways of navigation. In 1999, he and his crew embarked on the most daring voyage of their lives. Without any modern equipment, they sailed 2,800 kilometers across the open Pacific, from the Polynesian island of Mangareva to Rapa Nui.

Yet what may have caused their ancestors to venture into the unknown? Well, whatever motivation, whether they were forced to go out and explore because of conditions on their islands or whether it was just, um, what I like to think is the reason, is that they were just curious explorers and the fact that they sailed in all directions is an indicator and proof of people that were curious about the world they lived in. [narrator] It's an experiment for all of them.

A nautical challenge, its outcome uncertain. No compass, no GPS, no radar. Just as their ancestors, they rely solely on observing nature to help them find their way.

As for navigational aids, there'll be the stars, the wind and the waves, or even the smell of the ocean. At times, they're near exhaustion. Yet only 19 days out from Mangareva, they can hardly believe their eyes.

At dawn, there is land looming over the horizon. They have made it. They have reached Easter Island, having used nothing else but the expertise and know-how of the ancient mariners.

[Baybayan] What was surprising was that when we began our land search, we actually found the island on our first tack, which is 12 hours into our purposeful land search, and we saw the island at sunrise. And that was-- for us that was, um, astonishing. The degree of accuracy that we had navigated to Rapa Nui with and the degree of luck that afforded us the favorable winds to take us almost on a straight line to Rapa Nui.

[narrator] Hawaii is also the perfect place to comprehend how the stars might have guided seafarers back then. Four thousand two hundred meters above sea level. The Mauna Kea.

On the highest peak of Big Island, scientists from eleven nations operate some of the most powerful telescopes on earth. The data they provide are also used by a researcher at the foot of the mountain. The planetarium of Hilo University is the workplace of astronomer Shawn Laatsch.

At his command post under the dome, Shawn, a descendant of German immigrants, is master of time and space. He can turn back the clock to any specific day of the era when the Polynesians reached Rapa Nui. It's the very night sky the ancient seafarers would have seen.

What did it tell them? And how could they navigate by what they observed up there? There's a group of stars that's rising up on our horizon over here, which to us we call Scorpius in Western society.

Throughout Polynesia it was known as "Maui's fishhook. " The Polynesians basically would look for groupings of stars and by watching those different groupings and their position versus the horizon, they could tell their latitude north or south. They looked for patterns of stars and they knew that they would tra-- you know, they knew by watching the sky, that they would travel across the sky from east to west daily, and they knew that if they move north or south, these patterns would shift in their height above the horizon.

[narrator] The Polynesian navigators knew more than 200 stars, as well as their orbits. Yet there was one star that was of paramount importance to them. So they observed it each night, especially the point where its orbit came closest to the horizon.

Their extensive knowledge of the Pacific Ocean and the stars had carried the first settlers to this uninhabited island. Could it be that their relation to the sea was also the deciding factor for the sites they chose for their cult figures, the Moai? Was this the reason why they erected those giant statues of up to ten meters high and with their incredible weight of 80 tons nearest to the coast?

Might they even have regarded the Moai as a kind of link to the night skies? Many myths have grown around the enigmatic monuments. There's speculation that they may have been used for astronomical purposes, as a virtual observatory.

[Laatsch] There's a pretty good chance that they aligned their buildings and their monuments with the sky, because many cultures did. Potentially having them face either sunrise or sunset or face a position where certain stars would rise or set because of their significance. [narrator] Yet who were the enigmatic Moai?

There are nearly 1,000 of them with varying facial expressions. Sonia Haoa assumes that they were images of divinified ancestors. Their builders adorned them with bright colors and even put stone hats on some of them, each weighing several tons.

Where there are mere gaping holes today, their eye sockets were once filled with white coral and irises of black obsidian. It wasn't until the end of the 20th century that they were re-erected, facing landward, as if watching over the inhabitants of the island like back then. Yet their time was up when the forest of palm trees disappeared.

Those few palms standing today had only been planted a few decades ago. Terry Hunt believes to have found a spectacular explanation for the demise of the forest. His evidence: palm nuts with gnaw marks.

[Hunt] The ancient palm trees of Easter Island almost certainly disappeared with the effects of introduced rats. We know from ecological studies that when rats are introduced to islands with no predators, they eat the seeds of native trees and plants. Those trees and plants can't regenerate and deforestation occurs.

[narrator] The barrenness of the land already amazed the latter-day discoverers. Their oldest map, dating from the 18th century, shows an island without any trees. Yet were they really devoured by rats?

Hans-Rudolf Bork and Andreas Mieth are on a track that's literally hot and points to an altogether different sequence of events. They've found considerable remains of charcoal, which to them are proof that the trees had been felled by human hands from the middle of the 13th century onwards and then put to the fire. [man speaking German] [interpreter] Here we see a thin layer of ash.

It's evidence of a drama. When the palm forest was cut down and burned, the soil lost its protection and was washed away, as these strata clearly show. The people lost their basis of existence.

Any fertile soil has disappeared. [narrator] Yet why did the inhabitants willfully destroy their paradise? The evidence is overwhelming.

The island of the stone giants fell victim to a large-scale slash-and-burn operation. The eco-archaeologists are probing further sites in the eastern part of Rapa Nui, and here too, they hit upon dead black layers of charcoal almost everywhere, silent witnesses of a devastating fire. And within those layers, there are carbonized palm nuts.

There's one point where Mieth and Bork agree with their American colleague. The first settlers not only brought along chicken but also rats, obviously a favorite part of their diet, which then multiplied rapidly. Yet did the rodents really destroy the palm nuts, as Terry Hunt assumes?

In the evening, Andreas Mieth analyses their finds. In fact, hardly any of the fragile pieces are still intact. Yet were they really crunched by rats?

-[man speaking German] -[interpreter] These palm nuts haven't been gnawed by rats. We have examined hundreds of them, and almost none of them bears traces of the teeth of the Polynesian rat. [narrator] Terry Hunt, however, is far from convinced.

To widen his research, he intends to get a broader view of the human inhabitants of Rapa Nui from high above. A gas-filled balloon is being prepared to provide an outline of human settlements on the north coast of the island. If all goes well, they will reap several hundred photographs from the three cameras of their airborne scout.

It's one of the few days when wind conditions will allow an ascent. Terry hopes that structures on the ground will be much more easily discernible from high up. For instance, the alignments of tiny villages with their buildings.

The settlers obviously had a special relationship to the sea, so they erected their tent houses in a boat-shaped fashion. There was a roof of leaves held by a wooden frame of several dozen poles fixed by stone settings. Terry Hunt also uses a mobile X-ray spectroscope.

It will tell him the exact make-up of natural substances. He wants to find out which kind of stone the builders used for the foundations of their houses. He can determine from which quarry they collected their material and even which rocks were reprocessed.

Using these data, Terry will try to establish a migration pattern of specific groups moving from one site on the island to another. If he succeeds, he may even be able to outline boundaries between clans or tribes. The Americans have set up a provisional lab in a storage room of the local museum.

A mobile 3-D scanner allows the scientists to capture and analyze the structures of even the largest rocks. This way, they have already digitalized the surface geometry of a Moai. [man] You can actually see the arm here.

[narrator] Yet Rapa Nui divulges its secrets only hesitantly. And to some questions, there isn't any answer at all, despite the most modern equipment available. [indistinct chatter] I came to this island thinking that we knew, through the work of many years of research, that we knew a lot about this island.

I began to find out that we didn't know very much about this island. And I think it's a dangerous perception to say that we know what happened here. We actually don't understand very well what happened here, and we have years of research ahead of us to answer very basic questions.

Our work is just beginning, it's not over. [narrator] Meanwhile, Sonia Haoa keeps on searching for traces of her ancestors. She and her team have discovered a multitude of caves.

This one is special. Its walls and ceilings are littered with petroglyphs, images carved into the surface of the stone. Dozens of them show the highest deity of the Rapa Nui, the masklike face of Makemake.

Obviously, this subterranean location was dedicated to him. [Sonia speaking Spanish] [interpreter] Apparently, the cave was used by human beings as a site for ceremonial purposes over a long period of time. It's the only one of its kind in the area, and we think that it was in continuous use for a very long time.

Presumably, it was a socially highly organized society. No one would come here by chance and scratch a Makemake. This was definitely a place reserved for religion and belief.

[narrator] The archaeologists have discovered hundreds of well-hidden caves that once served as habitations for the islanders. This one is only accessible by a narrow crevice. Inside there are several large rooms, and one of them offers a breath-taking view.

A window over the sea. It's a perfect look-out. Especially after the palm forest had vanished, many islanders sought shelter in the caves since the Pacific gales were now sweeping the island with unhindered force.

Yet the caves also provided shelter from raiding neighbors. There are countless legends telling of bloody clashes among rivalling clans. To Sonia, however, the biggest sensation lies on and above the ground.

Millions of stones, apparently strewn around at random. Yet their pattern is anything but accidental. Andreas Mieth and Hans-Rudolf Bork meet their local colleague for some on-site inspection.

By combining their research, they hope to get some clues about the secret this barren grassland has kept for centuries. For Andreas and Hans-Rudolf, too, these inconspicuous stones count among the most spectacular finds on Easter Island. In fact, they might have been the islanders' last resort after the palm forest had been felled.

To keep the soil of their fields from being washed away by torrential rains, the islanders laid out stone gardens. The stones served as a protective layer, like a coat of mulch, keeping the soil in place as well as storing the warmth of the sun, next to perfect conditions for arable farming. To the archaeologists, the stone gardens are a stroke of genius, a fascinating technical and logistical achievement.

[man speaking German] [interpreter] We have extrapolated that more than a billion stones must have been moved to create the gardens. The amount of work involved was much greater than the sculpturing and the transporting of the Moai. [narrator] A volcano that has been long extinct.

Once this was the workplace of the stone masons. All Moai originated from this crater. It took months to break just one statue out of the tuff.

For centuries, the echo of the chisels could be heard from several kilometers away. Yet one day, this all ended, almost as if someone had pulled the plug. Throughout the huge crater, there are hundreds of statues ready for transport, next to others which have only been partially cut from the rock.

Today, the Rano Raraku is a cemetery of stone giants. Hans-Rudolf Bork and Andreas Mieth investigate the soil inside the crater. And they find another hint contradicting Terry Hunt's rat hypothesis.

[man speaking German] [interpreter] Here we see the tubes of a palm root. This particular tree grew after the razing of the palm forest. The tubes are in perfect condition.

So, rats couldn't have been the cause for the destruction of the forest. [narrator] Over a period of 400 years, the people of Rapa Nui felled almost 16 million palm trees, literally uprooting the eco-system of their island. Yet, it didn't collapse, thanks to the stone gardens.

But where did the know-how of such a sophisticated technology come from? [speaking Spanish] [narrator] Time and again, Sonia Haoa and her team come across ceremonial sites amidst the black volcanic rocks marked by images of the Birdman. [man speaking Spanish] [narrator] The petroglyphs indicate the beginning of a new cult immediately following the end of the Moai era.

Close to the ancient settlement of Tongariki lies the largest ceremonial site of the western hemisphere, abounding with magnificent images of the mythical Birdman. [man speaking German] [interpreter] There are heads, a beak, stretched-out arms, all clearly distinguishable. [narrator] An analogous symbol was an integral part of the Inca culture in far-off Peru.

And the best-preserved ahu, too, closely resembles Inca structures. Not even the blade of a knife will fit between the blocks, as shown on original drawings from the Incan Empire. Just a coincidence?

Or could it have been that other settlers had reached the tiny island in the Pacific Ocean after the Polynesians? The Inca were famous for their highly productive agriculture and most skillful in exploiting even the tiniest piece of ground. Digging sticks might be evidence of their presence on Rapa Nui.

European sailors still saw them in use when they discovered the island in the 18th century. It's a fact that the sophisticated exploitation of the soil prevented the ecological collapse on Rapa Nui. [shell call blaring] And there actually are sources referring to an expedition of the mighty Inca at the end of the 15th century, which is said to have set course for the Easter Islands under the command of Prince Tupac Yupanqui.

He was renowned as a conqueror, ever eager to expand the realm of his empire. A Spanish chronicler, Pedro Sarmiento de Gamboa, recorded the accounts of 40 contemporary witnesses of their long and arduous voyage. According to them, Yupanqui and his men had sailed on a fleet of balsa rafts and made landfall at Easter Island after months of braving the high seas.

Yet, to this day, no positive evidence has come to light that the Inca really did reach Rapa Nui. However, the option remains that the Polynesians didn't always have the island all to themselves. [in German] We can't exclude the possibility of a second wave of settlers.

[speaking German] [interpreter] By people who brought with them other experiences and crafts as well as other models of land use. [narrator] Did the Moai fall victim to new cultural and religious concepts? There is no proof for this hypothesis yet.

What lies hidden inside the ahu, those platforms made up of 9,000 tons of stone? Mieth and Bork are hoping for new insights by taking a closer look at one of them. Maybe they'll even find additional evidence in relation to the demise of the palm forest.

The researchers discover numerous rounded white objects. They're corals, which once were precious burial objects. -[man speaking German] -[interpreter] These were chipped by man.

[narrator] And they remind of an old ritual that was described by the islanders to the white discoverers. [shell blowing] It's a most solemn ceremony. Ho!

[narrator] A chosen group of men invokes the gods for urgently needed rain. First, they dig an earth hole close to the coast. Then the high priest buries a freshly cut coral wrapped in algae.

[thunder crashes] [narrator] When rain fell, the crater lakes of the three volcanos on Rapa Nui served as cisterns for the vital fresh water. But did they always provide sufficient amounts for all islanders? [chanting] Perhaps the coral sacrifice did not always find favor with the gods.

[thunder crashing] However, there are times when rain can be rather unwelcome. The Rano Kau volcano at the southwestern tip of Easter Island on a day when weather conditions are too adverse for field research. On the rim of the crater lies the ceremonial village of Orongo.

From the 16th century onward, this was the site of the legendary cult of the Birdman. When the palm forest had been almost obliterated, young men of different tribes gathered here to take part in a do-or-die contest. Each year in August, they had to descend 300 meters down the cliff and swim a mile through the cold, shark-infested sea to reach the island of Motu Nui.

He who returned first with an undamaged egg of a tern became the new Birdman for a year and would also hold the position of high priest. Today, the dangerous stretch of water off Motu Nui is the islanders' fishing grounds. These fishermen, too, are descendants of the original Rapa Nui.

It's the same spot where, back then, many young men perished in their quest. According to the fishermen, this is the only place on the planet where stones are used to haul in the catch. They fasten their bait to pieces of rock and throw them overboard.

[laughs] A practice which seems only consistent on an island where even the gardens are covered by stones. Whether the story is true or not, the method works. [narrator] Andreas Mieth and Hans-Rudolf Bork carry on with their survey of Easter Island, probing ever deeper layers of earth in their search for an explanation why the inhabitants began felling the palm forest.

From time to time, their efforts are rewarded by a find, even if it's not instantly evident whether it will lead to anything. It's a lance tip made of obsidian. A weapon like this could cause severe or even deadly gashes.

Poike, the eastern part of the island, is of special interest to researchers. If erosion of the soil goes on at the current rate, the peninsula will simply be washed away. It's here that the archaeologists come across a most interesting object.

At first glance, it just seems to be an ordinary middle-sized boulder. [in German] Do you have a sec? I think we haven't seen anything like that yet.

Fantastic. -This can't be natural. -Absolutely unique.

[narrator] The boulder is made of basalt and was carved into a kind of bowl with an opening at the side, as if it had been intended to collect and then re-distribute liquid substances. [speaking German] [narrator] Mieth and Bork are speculating whether the bowl might have served to collect juice from the palms, which then could have been filled into other bowls or containers. What if the location of the settlements might have something to do with the use of objects like this?

Many of the islanders had to undertake long walks to collect their water from the crater lakes. Could this explain the sequence of sites where the palms were felled? -[speaking German] -[interpreter] There were three lakes.

Some of the villages were at a considerable distance, and so their inhabitants quite early on began to use palm juice as a substitute for water, which was too far away, and it might have meant too much of an effort to transport it. [narrator] After years of research, Mieth and Bork finally seem to have found the solution. The islanders felled their palms to procure water more quickly and to escape the consequences of a drought, if, in spite of all sacrifices to their gods, the rains did not bring sufficient water.

Then they started fires to destroy stumps and leaves. Yet this wholesale clearing caused a dramatic change in the landscape of the island. And in view of the now-barren ground, they laid out stone gardens.

The coat of stones was the only means to protect what was left of arable soil. If the giant images of their ancestors were to have guarded the living, did they fail in the end? [speaking German] [interpreter] It may well be that the traumatic ecological change caused a loss of faith in the force of the Moai in the Rapa Nui people.

So, in their disappointment, they overturned them, took their eyes out and destroyed them. [speaking German] [interpreter] And maybe it was the immense effort that had to be invested into the stone mulch civilization that caused people to abandon the gigantic Moai. You couldn't invest into two megalith civilizations at the same time.

So, they gave up the Moai civilization and turned to the stone mulch civilization instead. [narrator] This would mean that, by their new ways of living, the inhabitants of Rapa Nui brought about a sea change. And in the new era, there was no use for the Moai anymore.

[crowd chanting prayer] Each year in July, today's islanders pay homage to the patron saints of the fishermen. Their Christian belief is another legacy from the white occupants of Easter Island, who also brought lethal diseases and slavery. [singing] On their final day, Andreas Mieth and Hans-Rudolf Bork take part in one of the festive highlights on Rapa Nui.

The great communal feast of the Curanto, a huge cooking pit around which everyone meets. Like hundreds of years ago, volcanic rocks are heated and buried in a pre-dug hollow. Beneath them, vegetables, fish and meat are stewed for several days and then, along with some fruit, distributed to the crowd that has been waiting patiently for hours.

A copious meal on an otherwise barren island which never made it easy for its inhabitants to survive in the vastness of the Pacific Ocean. And yet the island might look like this even today. Sonia Haoa's private garden is proof that the soil on Rapa Nui still has the potential to bring forth a blossoming Eden.

Sonia has achieved a botanic sensation. The growth of a toromiro sprout. The legendary tree grew solely on Easter Island and was long said to be extinct.

From its wood, the Rapa Nui carved artful tools and ceremonial objects such as this fish. It bears an inscription in Rongorongo, a language nobody can read anymore, written many centuries ago when Rapa Nui was still covered by a jungle of palms. Sixteen million trees on a tiny spot of earth.

To know how they vanished is an important step in understanding the fate of Rapa Nui. Easter Island will remain a fascinating object of research for scientists from all over the world, as an example of a drastic upheaval of a biosphere caused by man, even if they may have escaped the worst through their own ingenuity. [speaking German] [interpreter] The palm forest may have collapsed, but the society as such did not, nor did the overall civilization of the Easter Islands.

The people who lived here were incredibly gifted in technical matters and highly inventive. And they adapted to the change they themselves had brought about in most skillful ways. [narrator] A lost paradise that represents earth in miniature as a telling memento.

Except that the inhabitants of Rapa Nui, back then, did not know the consequences their actions would have on their environment. [speaking Spanish] [interpreter] This is a big chance for us to get an insight into history, and to learn from this tiny island in the Pacific Ocean practically everything about our own existence. [narrator] Can the story of Rapa Nui serve as a simile for a global disaster?

The Easter Island syndrome? It illustrates the fate of an isolated planet from which there was no escape and whose inhabitants only changed their way of thinking when it had been almost too late. Maybe that's it, the secret message of Rapa Nui.