What Really Happened on Easter Island

On Easter Sunday in 1722, a Dutch ship made Europe's first contact with a remote island in the South Pacific, halfway between Pitcairn and Chile. They found a mountainous green land, which would have been a paradise had it not been mysteriously stripped of all the palm trees that had once covered it. Even more strange were the great stone heads, up to ten meters high, so famous today; nearly 900 of them in all, standing tall and staring silently across the landscape. A few thousand indigenous people remained; and beyond these meager facts, the Dutch could learn little. What has followed has been centuries of study and conjecture over what happened on Easter Island: Rapa Nui to its natives, Isla de Pascua to today's Chileans.

The central reason for our lack of knowledge is that the Rapa Nui had no written language, and after European contact their population declined into the mere double digits, which effectively caused the irretrievable loss of any oral histories. Thus, the only records which survive of the history of Rapa Nui prior to European contact are a very few incomplete and poorly documented oral histories as interpreted by the earliest European visitors. As far as providing serviceable history, these unreliable snippets are as close to useless as can be. And so the task of learning what happened on Rapa Nui has fallen to archaeologists, anthropologists, botanists, paleodemographers and ethnographers, soil chemists and geologists, and later geneticists. The picture they've collectively painted has evolved and gradually come into better focus, and along the way, has resulted in some very popular misinformation.

Addendum: A glyph system called rongorongo does exist on Rapa Nui, known only from 24 examples carved in wood. It may have been proto-writing. It has never been deciphered, and has been described as "probably used as a memory aid or for decorative purposes, not for recording the Rapanui language of the islanders." So a more accurate statement than the above would be that Rapa Nui had no decipherable written language, and certainly no written history. —BD

For much of the history of Rapa Nui studies, research focused on the deforestation and the stone heads, called moai. Early on, we learned that nearly all the moai came from a single quarry, and were then somehow transported overland (many more than 10 kilometers) to their erection sites. No evidence at all survives to tell us which of the many possible methods were used, but the assumption was that the island's trees were mainly cut down to make rollers, levers, and skids to facilitate the moving. This deforestation had a dramatic unintended consequence: famine and starvation, which triggered warfare and even cannibalism. Obsidian points found all over the island, called mata'a, were thus determined to be weapons, which fell neatly into place supporting the warfare theory. Taking everything into account, the consensus was that the Rapa Nui had numbered perhaps 15,000 at their peak, give or take; and beginning with the loss of their life-giving palm trees, had starved and murdered one another until just a few scant thousand remained by that momentous Easter Sunday in 1722.

This is the story as you've heard it before. Not only was it an ecological cautionary tale along the lines of Dr. Seuss' The Lorax, by the end of the 20th century it was also a pretty robust theory. It had even enjoyed a massive pop-culture boost by the famous Norwegian adventurer Thor Heyerdahl, who in 1947 had built a raft named the Kon-Tiki and successfully sailed it from South America to Polynesia. His intention was to prove that South Americans accounted for at least some of the Polynesian population throughout the South Pacific. He then led a large Norwegian scientific expedition to Rapa Nui in the 1950s and detailed it in his 1957 international bestseller Aku-Aku, which he followed with other books in later decades. Heyerdahl firmly implanted into the popular consciousness the image of Rapa Nui's dramatic moai, and an equally dramatic story of a population — a mixture of Polynesian and South American heritage — fighting one another to near extinction. In recent decades, this idea has been given a loftier and more intellectual and academic boost by the author Jared Diamond.

Jared Diamond is an interesting character. He's best known as a bearer of the problematic label "public intellectual". Nominally he is a geographer and a professor of geography at UCLA, but substantially he is an award-winning author of mass-market nonfiction books — including a Pulitzer Prize for his 1997 book Guns, Germs, and Steel. It became an international bestseller and had a National Geographic TV series based on it. Like most of his books, it was essentially about environmental determinism, the idea that geography and the natural environment are the primary drivers of the trajectories of human societies. In a chapter of a subsequent book, 2005's Collapse: How Societies Choose to Fail or Succeed, he applied environmental determinism specifically to Rapa Nui. This book was similarly successful, and it is largely what propelled into the pop mainstream the idea that the Rapa Nui extinguished themselves mainly through deforestation and its inevitably resulting starvation and conflict. Ecocide is what he called it. Subsequent promotion of this theory by documentary filmmakers and the mass market has made it virtually the only story of Rapa Nui that anyone knows.

But while Diamond's writing has resounded successfully among laypeople and the television networks, acceptance from academia and career researchers in the relevant fields has been far more elusive. Diamond's theories have sometimes contradicted well-established theories in archaeology, anthropology, genetics, and other fields he has strayed into in support of environmental determinism. Anthropologist Christopher Kavanagh wrote:

Diamond is a controversial figure, especially among anthropologists (a 2013 paper was titled "F**k Jared Diamond"), and he has repeatedly been accused of misrepresenting facts to fit his grand narratives... Diamond's narrative can be (uncharitably) presented as a case of academic elites blaming powerless victims, largely due to the unreliable reports of racist European sailors, in order to generate a modern ecological morality tale for a modern Western audience.

The appeal of the alternative account to current political palates is precisely why caution is warranted: a narrative's popular appeal is a poor indicator of its truth.

Why the animosity? Because by now, everything you thought you knew about Rapa Nui — and most of Diamond's fundamental points — have been largely displaced by newer (and incompatible) theories. As the sciences of genetics, chemical analysis, Bayesian statistical inference, and others have improved, we've found that earlier work was wrong on so many points. This has most prominently been demonstrated in a series of publications over the years by anthropologist Carl Lipo and archaeologist Terry Hunt, though most of these newer hypotheses have their roots way back in the 20th century. Let's go through some basic bullet points.

1. Did the Rapa Nui deforest their island? They did, and one way we've confirmed they did it within only about four centuries is through pollen analysis that tells us how much was around when. Though we don't know for sure the reasons, there are plenty of rational alternatives. Boatbuilding, slash and burn clearing for agriculture (we've been able to radiometrically date plenty of charcoal), construction, and tools for moving moai are all possibilities. But there may have also been another major pressure on the palms that had nothing to do with humans: the rats the first Polynesians are known to have brought to Rapa Nui in the 1200s. In this new environment free of any predators, the rats' population could have grown to as many as several million, and among their favorite natural food sources were palm nuts and palm saplings. The cause of the deforestation was almost certainly multifactorial.
   
   
2. Did they need the trees to move the statues? They did not, although logs clearly offer a number of ways to move stones. Many moai that have been completely excavated show wear consistent with them having been "walked" from the quarry to their sites. With lots of people and ropes, the moai can be rocked side to side and stepped forward. It's far faster and much more energy efficient than using log rollers or levers.
   
   
3. Did they turn to violence and cannibalism as they ran out of food? First of all, it turns out we have no evidence that they ever ran out of food. They were skilled at agriculture, even having enriched the soil of their farmlands with volcanic minerals. Isotopic analysis of early Rapa Nui remains show that they relied on seafood in their diet more than previously thought. And study of their skeletons found that only 2.5% died bearing wounds consistent with the use of weapons, and of those, the majority had healed, indicating the wounds were not fatal. Evidence of cannibalism is nonexistent; it was merely early conjecture based on those fragments of oral history.
   
   
4. What was their population really? This we simply don't know, the bottleneck after European contact was so small that we just can't do some of the genetic tests that would have helped with this. The founding population of Polynesians was obviously quite small, and it was in the range of several thousand when first encountered in 1722. Most modern estimates range from 4,000 to 9,000. But we don't have any evidence that there was a significant population decline prior to contact. Modern Bayesian analysis of the data we have tells us the population likely grew quickly at first but then remained relatively constant for most of the society's history, likely due to the small island's limited resources, with no catastrophic declines. The big decline in their population took place only after European contact, and was largely due to imported disease.
   
   
5. What about the mata'a? Though these obsidian blades are indeed found in vast numbers, they are not consistent with spearheads or other weapons as previously claimed. They come in all shapes and sizes, and probably represented common hand tools, cutting implements, and even fine tools for creating body art via scarification.
   
   
6. Did the Rapa Nui have any South American heritage? Nope. Genetic testing of skeletal remains has conclusively disproven this; the indigenous Rapa Nui were all Polynesian. However, South American genetic markers became abundant once more regular transportation between South America and Rapa Nui began.

It's fair to point out that no one of these newer conclusions is undisputed. Many in the field still cling to the older interpretations of one or more of them, but from a survey of the current literature, it is clear that the majority of the new conclusions now enjoy consensus status in the field. So yes, you will find even current publications casting doubt on each of these points. But they are now in the minority.

It should also be stressed that while the names of Jared Diamond, Carl Lipo, and Terry Hunt have dominated reporting about Rapa Nui in recent decades, they are only three among a vast army of important researchers who have done important work on the island and its history. Turn to the end of any academic paper on the island, and you'll find pages of citations of published work by countless scientists in many disciplines. Make no mistake, the volume of science supporting the current theory is vast, diverse, and robust, with credit due to all involved.

So here, in a nutshell, let's summarize the most probable and best-accepted theory of Rapa Nui. The island was originally settled by a small number of Polynesians sometime after the year 1200 CE, who brought with them plant crops, rats, and chickens. They probably played a large role in the deforestation of the island over about 400 years, and the flourishing rat population probably prevented the trees from growing back. Luckily the Rapa Nui were skilled at agriculture and fishing, which they refined as the number of palm trees shrank to zero. They erected the moai. Any fighting among themselves was limited; rather, their society flourished. Over the centuries their population probably remained relatively constant until their first contact with Europeans in 1722, who estimated their population at two to three thousand, but it may have been higher. After this contact, disease killed off many. Then, for reasons that remain unclear but were probably the result of internal conflicts, the Rapa Nui toppled nearly all of their ancestors' moai over the course of about 60 years, completing this destruction in the 1830s. Then in the 1860s, slave traders took about half the remaining population, and spread tuberculosis, smallpox, and dysentery to the rest. And that brings us up to the established modern history, a patchwork of missionaries and plantations and eventual annexation to Chile. Fewer than 100 Rapa Nui remained on the island at their lowest point.

The old idea as espoused by Diamond — that they killed themselves off through deforestation — is now essentially obsolete in light of this much better informed, newer theory.

It's easy to dismiss Diamond's version as "a modern ecological morality tale for a modern Western audience" as Kavanagh did, but my personal judgement call doesn't go quite so far as to impugn Diamond's motives. When he wrote Collapse, a lot of this newer research was just getting started; and really all he did was to expand on an existing theory that had as much support as any other. Nowhere in Diamond's work will you find the kind of outright fabrications we see from other authors who promote fringe perspectives. He was applying his jam — geography and environmental determinism — to a long-standing theory that hadn't yet been invalidated. Diamond is a skilled and persuasive writer, and with the success he'd found as a public science communicator with his books, it's no wonder that his ecocide theory completely took over the public understanding of Rapa Nui. And since the ecocide theory is "a modern ecological morality tale for a modern Western audience" — whether he intended it that way or not — its success was guaranteed in a marketplace always hungry for ecocentric narratives.

And so let us put to bed the Lorax-like notion that the Rapa Nui traded their lush forests for a shortsighted passion for erecting moai. It may be a fashionable story, but it's almost certainly false.

By Brian Dunning
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