A Most Mysterious Island
The old net is laid aside; a new net goes a-fishing.
Mention Easter Island to just about anyone and "mystery" immediately comes to mind.The Mystery of Easter Island is the title of untold books and modern film documentaries. The mystery surrounds how so few people on a remote, treeless, and impoverished island could have made and transported hundreds of the eerie, gargantuan statues—calledmoai—for which the island is so famous. The awe-inspiring, multi-ton stone statues, some standing nearly forty feet high and weighing more than seventy-five tons, were carved out of the island's quarry of compacted volcanic ash and then somehow transported several miles over the island's rugged terrain. Not all of them survived the journey. Many lie scattered across the island, some broken, never to take their intended places on platforms along the shoreline or elsewhere throughout the island. To see these statues, many of them situated upon equally impressive platforms called ahu, is to sense a hidden drama of compelling human proportions calling out for explanation. Facing inward, rather than out to sea, they seem to be gazing back in a vain search for the noble society that created them.
As we were archaeologists who had studied other parts of Polynesia, when we began our work on the island the statues were somewhat familiar. Similar religious statuary are found elsewhere in Polynesia. And on other islands, statues were also moved significant distances. The moai, like the elaborate carved wooden images from the Hawaiian Islands, or the stone tiki of the Marquesas, while much bigger, represented the same deified ancestors so important in Polynesian religion and cosmology. That themoai were religious images explains why the vast majority face inland, watching over their descendants day after day. With their backs to the sea, themoai had not been carved as sentries, warding off potential intruders, as with the Colossus of Rhodes.
Had the islanders carved and transported just one or two of these statues, the accomplishment would have been noteworthy, but not surprising. But our count for Rapa Nui suggests that the islanders carved something well over 950 statues, and of those, more than 500 were transported considerable distances, appearing in every corner of the island. Nowhere else in Polynesia is such a creative and monumental legacy found. Why did it emerge only on this tiny island, whose population should have, by all accounts, been focused solely on where to find the next meal?
Since Easter Sunday 1722, when the first European accidentally sighted this isolated speck in the vast South Pacific, Easter Island has presented a seemingly intractable dilemma for explorers, scientists, and curiosity-driven tourists. By comparison to the cultural and physical richness of such storied Polynesian islands as those of the Tahiti and Hawaii archipelagos, Easter Island seems a poor setting—almost mocking—for one of the great achievements of early Polynesian history. The island itself, which today Polynesians call Rapa Nui (the people who live there are called the Rapanui), is almost a moonscape in appearance, little more than a barren lump of lava-covered terrain. Lacking the deep valleys, steep mountains, lush streams, and beautiful waterfalls typical of many of the volcanic islands of Polynesia, Rapa Nui is characterized by a modest landscape of rolling hills. The island was born less than a million years ago when the coalescing eruptions of three seafloor volcanoes reached the surface. One searches in vain here for a refreshing stream, let alone a flowing river. Most of the water is found in lakes formed in the three volcanic cones, though some also trickles out of a number of small springs.
Nor does fruit fall from the trees here, as it does on so many other Polynesian islands. From the mid-eighteenth century onward, seamen, explorers, Christian missionaries, and other visitors remarked consistently on the pitiable and "wretched" lives of the island's native inhabitants. Swedish botanist Carl Skottsberg, who compiled the first natural history of Rapa Nui, wrote that "there is in the Pacific Ocean no island of the size, geology and altitude of Easter Island with such an extremely poor flora and with a subtropical climate favorable for plant growth, but nor is there an island as isolated as this, and the conclusion will be that poverty is the result of isolation."1
Those who settled Rapa Nui had accomplished a remarkable feat of seamanship, perhaps the most daunting of the whole colonization of the Polynesian islands, only to have arrived at a desperately inhospitable new home.
The story of the Polynesian migration is staggering in its sweep.
Seafaring colonists known by their distinctive pottery called Lapita, who had set out from the shores of the western Pacific, reached the islands of Tonga and Samoa by 800 BC. It must have seemed to be the edge of the world. Verdant Samoa is today considered the heart of Polynesia, but at that time, there on the eastern frontier of their rapid dispersal to hundreds of islands, Lapita stopped dead in its tracks. Maybe Samoa was just too luxurious for them to leave. We don't currently know why they stopped, but we do know that no islanders ventured farther into the Pacific for nearly two thousand more years.
It was in the Polynesian homelands of Tonga and Samoa that the earliest forms of Polynesian monumental architecture emerged, by about AD 1000. When the islanders began migrating again, sometime around AD 1100, they brought their ritual architecture with them, including religious courtyards made of stone and upright stones, conceived of as backrests for the gods. In some places these "backrests" were transformed into elaborate carved human figures, like those found in the Marquesas, Hawaii, the Australs, and, ultimately, Rapa Nui.
Those migrating across the eastern Pacific first reached the spectacular islands of the archipelago of Tahiti. Voyaging in large double-hulled canoes soon after AD 1200, in less than a century, the islanders had discovered just about every island in the eastern Pacific, including the far-flung Cooks, Tuamotu atolls, Marquesas, Hawaii, Australs, Gambiers, Rapa Nui, New Zealand, and even the frigid islands of the sub-Antarctic.2 They also reached South America, where they fetched the sweet potato and perhaps introduced the humble chicken.3 Their colonization over this vast region was remarkably fast; they had traversed thousands of miles of turbulent seas, and had done so against prevailing winds and currents.
Discovering Rapa Nui, the most remote of these outposts, was particularly improbable. The territory over which Polynesia spreads is truly vast: about equivalent to the size of the entire North Atlantic Ocean. Roughly 99.5 percent of Polynesia is ocean, and 92 percent of the tiny fraction of land is New Zealand's whopping 112,355 square miles. Beyond the central archipelagos of the Societies, Tuamotus, and Marquesas lies a wide-open expanse along Polynesia's southeastern edge, where the minuscule islands of Rapa Iti, Pitcairn, Henderson, and finally Rapa Nui are found.
Ordinary maps can't convey Rapa Nui's true remoteness. One of the old names recorded for the island, Te Pito o te Henua, translates as the "navel of the world," or perhaps more aptly, theend of the world. The island's geographic isolation is magnified many times over by its extreme windward position. Sailing to Rapa Nui from central Polynesia, as the islanders likely did, meant pushing directly into the prevailing east-southeasterly trade winds and correspondingly strong currents of the South Pacific. Doing so would have required tacking, which would have made the journey approximately four times farther than the straight-line distance. If, for example, the islanders had left from the island of Rarotonga, in the Southern Cook Islands, the tacking distance to Rapa Nui would have been a staggering 12,500 miles.
The trick would be to find enough days of consistent westerly winds. They may well have been aided by El Niño, which reduces the average strength of the east-southeasterly trade winds in the area, bringing westerly wind reversals. Paleoclimatic studies show that about the time the islanders probably set out, El Niño appeared on average about once every four years, so the Rapa Nui settlers may have ridden one of the gusts of regular westerlies that would have been generated.
To have spotted the tiny island was nonetheless quite a long shot. Rapa Nui is tiny, one of the smallest inhabited islands in the Pacific. The total island area measures about sixty-three square miles. The longest east-west axis is just over fourteen miles; the maximum width north-south is less than eight miles. It is possible to walk around the entire island in a day, albeit a long one. This is surely why, as the evidence convincingly shows, the island was colonized only once. Probably traveling in two, or even more, large double-hulled canoes, some thirty to fifty, or perhaps as many as about one hundred men, women, and children embarked on the voyage.
The oral tradition of the island credits the discovery to a chief named Hotu Matu'a. The first signs of land probably came not with actual sighting of the island, but with seabirds returning to their nests flying off to the east at dusk. A lone palm nut or a tree branch floating in the water might have alerted experienced navigators that land was somewhere nearby. They had defied great odds, but their struggle had only begun. The voyagers would have brought with them the critical plants of Polynesian life, including taro, breadfruit, coconut, yams, bananas, sugarcane, turmeric, and kava as well as chickens and small Polynesian rats (Rattus exulans), the latter either invited passengers—it is speculated that they were eaten—or as tenacious stowaways drawn to the provisions. Pigs and dogs may also have been on board, although archaeology reveals they didn't make it to the island. The travelers were to face a challenge, though, in bringing their traditional foods to the island. With such scant water for irrigation, which islanders elsewhere in the Pacific used to cultivate taro, the mainstay of their diets, some of the other crops the settlers brought with them could not be grown on the island. Establishing the way of life the islanders were accustomed to would have been a great challenge. And yet this tiny, relatively impoverished island was to become host to the astonishing population of monoliths so admired still today. Here on Rapa Nui, more than a thousand miles from another Polynesian island, more than two thousand miles from the coast of Chile, apparently without influence from any other culture, a prehistoric society emerged that produced some of the most compelling monuments and feats of engineering in all of Polynesia, and perhaps the world. How could that be?
This has been the question sailors, Christian missionaries, self-styled adventurers, scholars, and a slew of other investigators have been asking since the mid-eighteenth century. Over time a consensus developed around the idea that something dramatic had occurred in the past, long before the island was discovered by Europeans, that would account for the miserable state the society was thought to have been in at the time of European contact. A society that had created such monumental statues, the argument went, must surely once have been more noble. But what was that event? When did it happen? And why? With what seemed increasingly compelling evidence, a theory developed that pointed to horrible conflict and twisted priorities within ancient Rapanui society. Modern writers refer to ecological suicide or "ecocide" in their speculations of what unfolded.
The first Europeans arrived on Easter Sunday 1722, when Dutch explorer Jacob Roggeveen sighted the island. The Dutch encountered a treeless island covered with hundreds of giant statues and a population estimated to be about three thousand, described as healthy. The next European visitors arrived forty-eight years later, in 1770, in the form of a Spanish expedition under the order of the viceroy of Peru, which provided little detail about the state of the island other than that there was very little wood. Then, in 1774, the English arrived under Captain James Cook, probably the best-known explorer to have sailed the Pacific. His fame comes in part from the great details of his observations and those of his crew.
The British mission in the Pacific was colonial, and thus economic. Like the other European nations, Britain had aspirations of finding the great southern continent, and as things unfolded, a northwest passage as well. In Cook's first voyage, on theEndeavour, he charted much of the Australian and New Zealand coastlines and collected a wealth of information about these southern lands. In July 1772 he set sail from Plymouth, England, for his second expedition, with two ships, theResolution and the Adventure. This would be a final search for the elusive southern continent, Terra Australis, and indeed, this voyage was to furnish once and for all proof that it did not exist. On board were German-born naturalist Johann Reinhold Forster and his nineteen-year-old son, Georg, as well as artist and engraver William Hodges.
Searching the frigid waters of the far southern Pacific for about two months, Cook crossed the Antarctic Circle, and as he expected, no great continent awaited their discovery. By March of 1774, the crew, badly in need of provisions, headed north to Easter Island. His men were exhausted and suffering the debilitating effects of scurvy. Cook knew of the voyage of English buccaneer Edward Davis in the 1680s with mention of an island in the vicinity, he had read Carl Behrens's report of the Dutch visit in 1722, and he had learned of the Spanish expedition. On March 11, he and his crew finally sighted Rapa Nui.
Cook and his men described the island as barren, lacking wood and fresh water, and noted, "Nature has been exceedingly sparing of her favours to this spot."4 On this visit, the expedition's naturalist, Forster, recorded that
the most diligent enquiries on our part have not been sufficient to throw a clear light on the surprising objects which struck our eyes on this island. We may however attempt to account for those gigantic monuments, of which great numbers exist in every part; for as they are so disproportionate to the present strength of the nation, it is most reasonable to look upon them as the remains of better times. The nicest calculations ... never brought the number of inhabitants in this island beyond 700, who, destitute of tools, of shelter, and clothing, are obliged to spend all their time in providing food to support their precarious existence. ... Accordingly we did not see a single instrument among them on all our excursions, which could have been of the least use in masonry or sculpture: We neither met with any quarries, where they had recently dug the materials, nor with unfinished statues which we might have considered as the work of the present race. It is therefore probable that these people were formerly more numerous, more opulent and happy, when they could spare sufficient time to flatter the vanity of their princes. ... It is not in our power to determine by what various accidents a nation so flourishing, could be reduced in and degraded to its present indigence.
This concept of flourishing times on the island followed by indigence took a new twist with French explorer La Pérouse. Visiting for a just single day in April 1786, he speculated that at some very distant time Easter's inhabitants unwisely cut down all of the island's trees. La Pérouse observed that the loss of the forest
exposed their soil to the burning ardor of the sun, and has deprived them of ravines, brooks, and springs. They were ignorant that in these small islands, in the midst of an immense ocean, the coolness of the earth covered with trees can alone detain and condense the clouds, and by that means keep up an almost continual rain upon the mountains, which descends in springs and brooks to the different quarters. The islands[,] which are deprived of this advantage, are reduced to the most dreadful aridity, which, gradually destroying the plants and scrubs, renders them almost uninhabitable. Mr. de Langle [naval commander, explorer, and second in command of the La Pérouse expedition] as well as myself had no doubt that these people were indebted to the imprudence of their ancestors for their present unfortunate situation.5
In this manner, the notion of the imprudence of the islanders' ancestors entered the Western discourse of Rapa Nui's sorry fate, a theme that would be revived in the twentieth century with the beginnings of scientific expeditions to the island.
Best known for his Kon-Tiki adventures, Norwegian explorer Thor Heyerdahl brought contemporary archaeological research to Rapa Nui. Born in 1914 in Larvik, Norway, Heyerdahl began his studies as a zoologist and traveled to the Marquesas as part of a school project to learn how animals arrived on these remote Pacific islands. This interest in colonization led him to an interest in human migrations, specifically those of the Polynesians and, ultimately, the Rapanui. Heyerdahl believed that ancient Americans first populated the Pacific islands, and he set out to prove his theory in adventurous fashion.
In 1947 Heyerdahl led the Kon-Tiki expedition, a daring experiment, drifting on a balsa wood raft from South America into the Pacific, as some Spanish accounts had asserted the Inca had done. The expedition succeeded in making land, washing ashore on the reef off the coast of the island of Raroia in the Tuamotu Archipelago, and generated a storm of media attention. In 1955 Heyerdahl and an international team of scientists began extensive field research on Rapa Nui. William Mulloy, an American archaeologist, was part of the team. Based on his analysis of the evolution in style of the island's monumental architecture and the island's first radiocarbon dates, Mulloy proposed three periods for Rapa Nui prehistory: the Early Period, AD 400–1100; the Middle Period, AD 1100–1680; and the Late Period, AD 1680–1868.6 Heyerdahl and his colleagues regarded the Late Period as a time of collapse for the Rapanui civilization; the Early and Middle phases reflected two distinct traditions in an enduring episode of cultural splendor expressed in monuments and colossal statues.
Heyerdahl drew upon the island's oral history for his conjectures, including accounts collected in the late nineteenth and early twentieth centuries.7 Much of this material was collected by Katherine Routledge, who spent seventeen eventful months on Rapa Nui between 1914 and 1915. Routledge focused much of her research on collecting oral history and observing the islanders' way of life. When writing of her interviews of elder native inhabitants on the island, Routledge remarked with some frustration that it is "even more difficult to collect facts from brains than out of stones."8 Many of the stories they told have nonetheless been treated as factual by subsequent researchers.
In the oral traditions recorded by Routledge, the island was subject to intense competition between two groups, the so-called "Long Ears" and "Short Ears." In his interpretation of this legend, Heyerdahl argued that the initial colonists of Rapa Nui arrived from South America early in the first millennium AD.9 At some later, uncertain point in time a second wave of migrants arrived from Polynesia. For Heyerdahl, the South Americans represented a superior "lighter-skinned" population who maintained a tradition of artificially distending their earlobes and thus were known as the Long Ears, while the Polynesians, who did not share this tradition, were the Short Ears. According to Heyerdahl, the early South American settlers also brought with them a specific cultural tradition of highly specialized masonry art. Heyerdahl states in his book The Art of Easter Island, "The remarkable expertness of the first settlers suggests a long tradition in stone-shaping technique ... [and] it is logical to assume that the Early Period settlers brought the art of stone sculpture with them."10 It was these South American settlers, the Long Ears, Heyerdahl argued, who were responsible for the firstahu and moai construction.
These opposing tribes, Heyerdahl further conjectured, had clashed in an epic battle around AD 1680, which has come to be known as the "AD 1680 Event," killing all but one individual of the Long Ear tribe. Heyerdahl wrote: "The collapse of the totalitarian hierarchy must have taken place before the arrival of the first Europeans. No supreme sovereign ceremonially received Roggeveen or the Spaniards when they landed. The fact that the Dutch found that peace and apparent equality had been reestablished appears to indicate that the collapse of the organized monarchy must have taken place well before 1722."11
Heyerdahl's putative AD 1680 Event still represents a pivotal point in the conventional narrative for Rapa Nui. The great battle of AD 1680 is said to mark the tipping point of environmental and demographic collapse.12 Heyerdahl's seemingly precise date of AD 1680 comes from a single radiocarbon date that roughly corresponds to an account offered by Father Sebastian Englert, a Catholic priest and researcher who lived on the island from 1935 to 1969. Englert estimated AD 1680 from genealogical records in concert with an array of suppositions. Since the AD 1680 Event derives from little more than interpretations from legends, most contemporary researchers do not believe the story has much in the way of veracity. Nonetheless, incarnations live on in support of the ecocide thesis.
Today the best known is Jared Diamond's popular account in his book Collapse. Diamond asserts that Rapa Nui was first settled by Polynesians, around AD 900, or perhaps a bit earlier, and taking account of the most modern analysis of pollen grains preserved in the island's lakes, it was covered in luxuriant forest, a virtual Garden of Eden. Giant palms (Jubaea chilensis or a close relative) dominated the forest which, along with the other trees that once thrived on the island, are now extinct.
A complex, hierarchical chiefdom developed on the island with a religion focused on ancestor worship. As things went from bad to worse, religious and political pressure, fueled by greed and shortsightedness, led to more and more statues being carved and transported. The same fervor led to larger and larger statues. Thousands of the giant palm trees were cut down to construct sleds or other contraptions essential to move ever more statues. Thousands more were cut and burned in order to make more room for more and more agricultural fields to feed the hundreds of statue workers. A centralized political authority held a ruthless stranglehold on the island's people and was in charge of the work of the statue cult. Diamond believes the population grew out of control, and by about AD 1600 had reached a staggering 10,000, 15,000, or maybe even 20,000 or 30,000, greatly overtaxing the island's resources.
When the island's resources had become so diminished that food had become scarce, statue making stopped abruptly—dead in its tracks. Statues were left unfinished in the quarry and many were abandoned along the transport roads en route to display, vivid snapshots of the moment the glory ended. Crisis ensued. Obsidian spear points were manufactured in huge numbers to arm islanders in the fierce battles that broke out in a vicious cycle of violence. Chickens were kept in fortified compounds to stop thieves. Because the forest had been decimated, no canoes could be made for obtaining supplies from other islands. Apart from fish, the only significant source of protein was human flesh, and cannibalism became rampant, further fueling the cycle of warfare.
A great civil war ensued, with thousands killed. To insult their enemies, and perhaps the ancestral gods who had forsaken them, the warring parties toppled the giant statues of their opponents in fits of rage. The real end came when someone cut down the last tree. They knew it was the last tree, and they cut it down anyway. Finally, there was no place to run. The islanders had sentenced themselves to a prison of their own making.
Diamond sees Rapa Nui's demise as "the clearest example of a society that destroyed itself by overexploiting its own resources."13 Deforestation coupled with environmental fragility and human recklessness brought cultural collapse, and this horrific history is held up as a cautionary tale of environmental ruin that serves as a parable for our own time.
When we began our work on the island, we fully expected our findings to corroborate this account. After all, Rapa Nui is one of the most intensively studied specks of land anywhere in the world. We thought that doing additional field research on the island might add a few details to the already known prehistory, but not much more.
Our first years of fieldwork on Rapa Nui were from 2001 to 2003, when we focused on a large-scale survey of archaeological stone structures and artifacts found on the surface. Our mission was simply to document these remains—many in danger of destruction from land use changes, vehicles, and tourists—while also training our students how to map, photograph, and write detailed descriptions of findings. It wasn't until our fourth field season, in 2004, when we conducted excavations on Anakena Beach, that our understanding of the island's archaeology and prehistory began to change.
Anakena Beach is probably Rapa Nui's most photographed location, a beautiful strip of white sand along a crescent-shaped bay of turquoise water lined with rugged black volcanic rocks. Anakena is splendid by any standard, but the majestic stone platforms known as Ahu Ature Huke and Ahu Nau Nau, both now restored and crowned with well-carved and almost perfectly preservedmoai, make it an awe-inspiring setting like nowhere else on earth.
In the oral tradition, Anakena was said to be the settlers' landing site, and according to legend, it became the royal residence of Hotu Matu'a, which meant that the beach area would likely be full of records of ancient activity. We expected to find plentiful artifacts, such as fragments of fishhooks, obsidian flakes, and shaped tools, as well as stone adzes and fragments of stone that chipped off during their use. We also anticipated that the calcareous beach sands provided the perfect conditions for the preservation of bone. One of our students doing her doctoral work, Kelley Esh, hoped to study the record of consumption of fish, seabirds, chickens, and perhaps also rats, evaluating how people had changed their diet as resources diminished.
As we expected, the dune deposits were beautifully stratified, with layer after layer of sand periodically interrupted by volcanic mud that had eroded off the slopes above. The stratification formed by consecutive, undisturbed layers of sand and earth meant that we could be confident that the bits and pieces we found in a layer had been deposited together.
Digging in sand dunes is a challenge, because nothing much holds the uppermost sand of a dune in place. The deepest layers in our 2004 excavations were more than ten feet deep, and tourists standing near the edge of our pits to peer down on what we were doing invoked some genuine fear in us. The other excitement would come when our Rapanui friends would gallop their horses over the beach and up dunes. Down in the pits we could hear them coming as sand grains began to fall all around us. We had to continually build wooden frame reinforcements around the sides of our pit.
The work paid off, though, as we found abundant artifacts and bones, an archaeologist's dream. In 2005 we returned to Anakena and renewed our work, this time in an area that had the same layers, but where they could be found much closer to the surface. Again the ancient sandy layers offered up thousands of small bones—from birds, fish, rats, and chickens, and fragments from sea mammals such as dolphins—as well as obsidian flakes and some ground and polished stone adze fragments.
In both the 2004 and 2005 excavations we eventually reached a dense, compact clay layer, in which we could see charcoal bits, obsidian flake artifacts, and bones, mostly from rats and fish, clear evidence of human habitation, as none of these things would be embedded in this ancient surface naturally. But as we excavated below that level, we found none of that: no charcoal, no obsidian flakes, and no bones. We did see small tubular casts in the clay that we quickly recognized as what are called root molds, empty voids preserved where the roots of ancient plants once grew. These root molds provided direct evidence of the storied giant palms. We had uncovered the soil in which the palms grew when people first set foot on the island.
On a sunny and windy day, as our work was winding down, we cleaned the sand and any debris away from the clay layer in preparation for carefully taking samples for radiocarbon dating. Painstakingly we collected small bits of charcoal from the ancient soil, expecting that these samples would date back to about AD 700 to 800, based on the chronology we believed was well established for the island.
Some archaeologists still accepted Heyerdahl's earlier date of AD 400 for colonization, but we, like a growing number of others, saw serious problems with Heyerdahl's date. No one had been able to replicate it from charcoal samples taken from the same layer Heyerdahl had taken his samples from. And worse, Heyerdahl's AD 400 date was measured from a sample of unidentified wood charcoal, which probably led to what radiocarbon experts refer to as the "old wood" problem: because the rings of a tree's interior are older than those of the exterior, the parts of the wood dated can produce different ages. This is why we now date wood charcoal from short-lived trees or short-lived parts such as twigs or seeds. The emerging consensus was for a colonization date at least a few hundred years later than Heyerdahl had thought.
Months passed and finally the radiocarbon report arrived. The results were consistent, the statistical errors were small, and the laboratory reported that everything had proceeded normally. But there was a problem. The oldest layers at the base of Anakena were only around eight hundred years old. Eight hundred years? That would mean that the colonizers had arrived much later than even the newly accepted later date, of AD 700 to 800, thus in the neighborhood of only about AD 1200. Had something gone wrong? We were disappointed. Feeling puzzled, we set the report aside and went on to other tasks. But before long we began to rethink what the evidence might be telling us. Could this "late" date be correct? Was Rapa Nui settled centuries later than everyone had assumed? We e-mailed Atholl Anderson, a leading expert on the cultures of the Pacific islands, asking him what he thought, and he responded that a date of about AD 1200 would actually fit the picture emerging for the wider settlement of East Polynesia much better than the consensus older dates. He also added words of sage advice: "trust the hard evidence more than your preconceptions."
But if our radiocarbon dates were right, then what about the older ones that existed for Rapa Nui? Were there problems that had been overlooked in obtaining these dates? Were some of those charcoal bits perhaps also actually portions of ancient trees that began their life hundreds of years before humans arrived? We decided to conduct a critical evaluation of all of the more than 120 radiocarbon dates published for Rapa Nui,14 excluding dates measured from any problem materials such as unidentified wood charcoal. We also excluded marine samples such as shell, fishbone, coral, and even seabird bones, because sea creatures often feed in the areas of oceans where upwellings from the deep open create high nutrient levels, which means that they absorb ancient dissolved carbon dioxide that has been released into those upwellings. Consuming this old carbon makes marine samples appear older, sometimes by centuries.
Our analysis showed that all of the reliable dates—those from short-lived materials—fit with our new evidence. Several pieces now fell into place supporting the AD 1200 chronology for settlement. Recently acquired dates from new pollen studies on the island had shown the first signs of human presence to be at about the same time,15 and recent studies also showed sudden environmental changes around AD 1200. New research was also confirming later chronologies across Polynesia, in Tahiti, the Marquesas, New Zealand, and Hawaii.16 We knew that our results were important, and we immediately wrote a paper introducing them, which within a matter of weeks appeared in the journalScience. On Rapa Nui, as elsewhere in Polynesia, shorter chronologies meant rapid disappearance of the native forest occurred soon after colonization. With careful dating, the major changes in island vegetation and the first—independent—signs of human presence were closely contemporaneous. The emerging evidence pointed to significant forest loss on the scale of decades, not centuries. For Rapa Nui and other Pacific islands, this evidence raised questions about how the forest could decline so rapidly. We grew skeptical that the efforts of making and moving the giant statues explained much about forest depletion on Rapa Nui.
If something as fundamental as the dating of first colonization of the island had been wrong, even several hundred years off, what else didn't we know? Critical thinking had led us to doubt a few details, but the shortened chronology now undermined our confidence in just about everything. It felt as though what we knew, or thought we knew, had been pulled out from under us.
We realized that there was a lot of work to do, and that things might just turn out quite differently than we had assumed. As we began to study what was actually known, versus speculation that had been passed off as certainty, we began to suspect that the story needed revision.
We had no question that deforestation had transformed Rapa Nui, but we now wondered how and why this deforestation occurred and whether it had actually caused a population collapse. That was to be our next focus of investigation.
© 2011 Terry Hunt and Carl Lipo