Was Jared Diamond right about the collapse of Easter Island?

The excellent Charles C. Mann reviews a new book on the history of Easter Island, The Statues That Walked, excerpts:

“Rather than a case of abject failure,” the authors argue, “Rapa Nui is an unlikely story of success.” The islanders had migrated, perhaps accidentally, to a place with little water and “fundamentally unproductive” soil with “uniformly low” levels of phosphorus, an essential mineral for plant growth. To avoid the wind’s dehydrating effects, the newcomers circled their gardens with stone walls known as manavai. Today, the researchers discovered, abandoned manavai occupy about 6.4 square miles, a tenth of the island’s total surface.

More impressive still, about half of the island is covered by “lithic mulching,” in which the islanders scattered broken stone over the fields. The uneven surface creates more turbulent airflow, reducing daytime surface temperatures and warming fields at night. And shattering the rocks exposes “fresh, unweathered surfaces, thus releasing mineral nutrients held within the rock.” Only lithic mulching produced enough nutrients—just barely—to make Rapa Nui’s terrible soil cultivable. Breaking and moving vast amounts of stone, the islanders had engineered an entirely new, more productive landscape.

Mann sums up:

People have done lots of environmentally destructive things, heaven knows. But there are surprisingly few cases in which societies have permanently laid waste to their own subsistence. The history of Easter Island suggests that humans generally do have a long-term capacity to work with natural systems, even in extreme cases.

I just bought the Easter Island book, Mann’s new book, which I devoured immediately, is out soon.


Diamond's Collapse was an intellectual embarrassment and primarily a product of its times -- an age of religious eco-hysteria. It capitalized on the hysteria, but is about as informative as a book advocating Spiritualism in 1920s England.

Charles Mann is da man.
In the article, it's funny how you can see Diamond's treatment of Easter Island simply as an update of Hyerdahl, simply changing the narrative to fit the new flavor of intellectual empty calories.
I can't wait for Mann's new book.

Yay! After we trash the environment we can continue to eek out an existance! Wahooo.

Such sarcasm betrays some poor reading comprehension. Part of the point here, which you've clearly missed, is that the island's environment was already "trash" when the first people arrived, and not as a result of anything they did, contra Diamond. Further, what they did was not simply further "trash" their already bleak environment, but rather render it more fertile. If you want to dispute the truth of these claims and defend Diamond's interpretation, go ahead, but your comment above in no way accomplishes that, but simply misinterprets what was said.

If you knew a little about the actual facts, you would know that the Island had one crucial resource when humans arrived - giant palm trees suitable for making the key technology of the Polnysian settler - ocean going canoes. Diamond pointed out that the people cut down the last of these, thereby greatly impoverishing their technology and way of life.

MD is correct. CIP--YOU'VE got the facts wrong. Read the new book by Hunt and Lipo. They explain and provide ample evidence to show Diamond hasn't got a clue!

Nothing that I stated contradicts what you suggest. That is, the proposition that the settlers cut down all their trees is not mutually exclusive with the proposition that the "mulching" practices discussed in the article actually enhanced the soil's fertility to a level above what it was prior to their arrival. If you wish to place an emphasis on the importance of ocean travel that's fine for your own purposes, but it doesn't contradict anything I've said.

CIP, where is your evidence that the natives cut down the trees? The inhabitants were enslaved, and their trees cut down by raiders. When the first Europeans arrived, the trees were still there.

The deforestation of Easter Island was caused by rats. Diamond was also wrong about Greenlanders refusing to eat fish.

TGGP, that's pretty interesting: according to analysis of the isotopes in Greenland Norse bones,

The diet of the first settlers consisted of 80% agricultural products and 20% food from the surrounding sea. But seafood played an increasing role, such that the pattern was completely turned around towards the end of the period — from the 1300′s the Greenland Norse had 50-80% of their diet from the marine food chain. In simplified terms: they started out as farmers but ended up as hunters/fishers.

I'd add that the Norse had lactase persistence and undoubtedly other genetic adaptations to at least pastoral agriculture. These adaptations were almost surely gained at the cost of no longer having genetics optimized for hunting, gathering, and fishing. During the harsh Greenland winters of the 14th century, they lost the benefits of the pastoral adaptations when they switched from raising cattle to to hunting and fishing. But they did not have time to genetically re-adapt to hunting and fishing, and thus were overwhelmed by the Inuit who had been hunters and fishers all along, and for over a millenia in such harshly cold climates.

The lactase persistence gene is pretty well known, but I don't know of what adaptations for fish are uncommon or would be selected against with other diets.

We've barely scratched the surface on discovering the various genetic adaptations to agriculture. We only understand the very straightforward ones like the regulatory gene that keeps lactase being manufactured as an adult (instead of terminating some time after weening as it normally does in mammals, including most humans).

Even if lactase persistence were the only pastoral adaptation my reasoning still applies. Conservation of mass says if a metabolism is manufacturing lactase, it must be making less of something else. Energy is also being consumed making lactase instead of something else. Presumably that "something else" had some useful function, at least in the hunter-gatherer environment. Suddenly remove milk from the adult diet and the metabolic advantage is lost, but the metabolic handicap remains. The Inuit, who didn't have the chemical handicap of diverting their bodies' scarce resources into making a now-useless enzyme, would have had a metabolic advantage.

That kind of tradeoff generally applies to other possible genetic adaptations to agriculture.

I find your reasoning plausible despite the lack of specific evidence.

If there's a problem, it's only that you state it as if it's known to be true, when from what I know it is only plausible.

I would assume that lactase persistence would be regulated so that lactase wouldn't actually be produced unless lactose was present the way the lactose operand works in bacteria and how we don't produce a mass of antibodies for mumps after getting a mumps vaccine until the mumps microorganism is present. In which case the penalty is pretty minimal.

Please, no one follow tggp's link "caused by rats." It links to one of his own posts which asserts that in one sentence in the third long paragraph and links to a) a broken link and b) a long comment of his with the same assertion in the sixth long paragraph and the same broken link. What a waste of our time.

Here's the actual paper (and the source of the above quote) TGGP is indirectly referring to:


That's about Greenland & fish, Noumenon is talking about Easter Island and rats.

Yes, I hadn't checked the link in a while and just lazily did a search on my blog and linked thsoe posts. After commenting here I checked and found the American Scientist link had rotted, so the currently working link is below.

I'm with Mr. Brak on this one. None of this casts any doubt on the fundamental narrative Diamond laid out: deforestation, whether caused by the islanders religious conflicts or the rats they brought with them, destroyed an economy dependent on the sea, and reduced the inhabitants to a miserable subsistance.

No, the authors' thesis is that the society whose remains impress us existed for several centuries _after_ the palm trees had already been destroyed. The making and moving of the statues, the writing system, etc. all occurred almost entirely after that destruction, which occurred in the first century after the Polynesians arrived. They were able to adapt to the lack of palms with lithic mulching.

The "ratpocalypse" -- rats that stowed with the Polynesians eating palm seeds and shoots, destroying the palm forests quite early in Rapa Nui's history -- seems quite a bit more probable than Diamond's account where the increasingly scarce trees don't become valuable enough to merit preservation or replanting. If the founding human population was small, they wouldn't have had the resources to save the palms from the far faster growing population of rats.

It's also quite likely that, as with the rest of the Americas, Rapa Nui's population was devastated by disease upon contact with Europeans. We should be able to test this theory via DNA evidence. Scarce farm labor due to disease and wool as an export crop (exchanged in part for food to feed the greatly reduced population) would have made sheep replace the traditional agriculture after Europeans introduced them.

The benefits and drawbacks of "lithic mulching", or creating a pebble or gravel surface layer, are still not well understood, so that theory while promising needs further experimental research. Lithic mulching was also occasionally practiced by the Maori, the Incas, and a few others. It can reduce soil evaporation (important in the windy climate after the palm trees were destroyed) and reduce soil temperature extremes via radiative heating at night and thermal inertia. But it's pretty labor intensive, especially without draft animals or the wheel. The possibility that, even with the rocks so crudely split, lithic mulching might add phosphorous to a very phosphorous-poor soil is also very interesting but also needs work. During the British agricultural revolution, a key breakthrough was grinding bones, which exposes orders of magnitude more phosphorous-rich surface area to the soil than just splitting rocks or gravel.

These guys do seem to demonstrate a greater knowledge of agriculture than Diamond.

Terry Hunt, who put forward the rat theory*, also thinks the arrival of Europeans brought about downfall.

*Apologies for an old link via a previous comment having succumbed to linkrot.

There is still a mystery here. If Easter Island was so unsuitable for habitation, why was it settled in the first place? If it became unsuitable later, why didn't the inhabitents leave?

Easter Island was not unsuitable for habitation, but it was isolated and somewhat fragile. There is plenty of seafood in the seas around it to support a fairly varied diet. Once the one large species of Palms disappeared (cut down to make statues or why ever), the islanders lost the ability to build seagoing canoes - a catastrophic loss for the greatest seagoing people of all time. Imagine us minus electricity and internal combustion - some might survive, but we would be vastly diminished.

Easter Isaland was very isolated and somewhat ecologically fragile. It was a fantastic feat for the Polynesians to arrive there at all, but once there, they may have been stuck. As long as they had their big canoes, they still had access to abundant, protein rich seafood and sea shell with phosphorus for their gardens. Loss of the one species of large Palm from which canoes could be made destroyed their ability to go to sea, a catastrophe for the greatest navigators of all time.

Like us losing electricity and the internal combustion engine.

Did they lose their abiility to put to sea in the shallows around the island (where they could fish, etc.), or to travel hundreds of miles across the open ocean? There were other trees on the island, as late as the 1700s, so couldn'lt they have made smaller craft for short-distance fishing trips?

Relevance to the original post?

From the Amazon editorial review:
"their statue building was actually integral to their ability to achieve a delicate balance of sustainability"

Uh-huh, I smell BS. The number of statues and their size clearly borders on insane. That Hunt & Lipo were the first ones to do radiocarbon analysis or that everyone before them got the dates so horribly wrong is very, very doubtful... Something's not right here. The "lithic mulching" narrative sounds suspicious, too. Control of evaporation and temperature - well, maybe okay, but adding "nutrients" sounds like a BS. What are the nutrients that have to come from inside of basalt rocks? And how come there was enough phosphorus in the soil for palms but not for anything else? And "walking", while plausible, has to account for going down the slopes. Not likely to be very successful endeavor considering the size. Finally, rats are eatable - not a bad thing if agriculture does not yield much. And there are plenty of oral accounts of fighting - not exactly consistent with the idyllic picture painted (good parts of the book are available on Google Books).

It should go without saying that like all other cultures the Rapa Nui fought. What there's no evidence for is that they fought much more than other cultures, making fighting a special causative factor in their collapse.

Palms almost surely had deeper roots than the other plants on Rapa Nui, and so could get phosphorous from soil that hadn't been depleted by other plants.

As for statues going down slopes, why not just roll them down? Where their account may go wrong is in implying that rollers or similar ground transport was the only role the palm played in transporting the statues. The statues were almost entirely erected within a few hundred feet of the coast, all around the island. The vast majority of the distance from quarry to site must have been covered by boat, which would have cost far less than transport over ground. Just one sufficiently large catamaran would have been enough to transport all those statues over the several centuries they were made. Just as elsewhere in Polynesia canoes transported the Yap stones.

They had to have a source of material to repair the boat, and a small grove of palms would have been sufficient for this. Indeed, pollen and charcoal records show that quite a few palms existed up until the early 17th century, and the palm only went extinct in 1650. The statues also stopped being quarried and moved about that same time. This suggests my own theory of the collapse:

(1) The rats did destroy most of the palms in the 13th century, but as they got scarce the Polynesians intervened to grow some new young palms in constructions protected from rats, replanting them in groves when mature enough to withstand the rats' depredations.

(2) The European-originated plagues that wiped out 90% of the native Americans also reached Rapa Nui, well before the first direct European contact in 1722. There are good reasons to believe there were some non-European trade contacts between Rapa Nui and South America, for example the spread of the American sweet potato to Polynesia.

(3) The late 16th or early 17th century plagues on Rapa Nui greatly increased labor costs relative to the costs of building materials, so that it was no longer worthwhile expending the greatly reduced amount of labor to protect the remaining palms from the rats. Nor was there any longer sufficient population to produce a labor surplus for making or moving statues.

(4) Thus, the Rapa Nui society remained vibrant right up to the arrival of European diseases, probably in the early 17th century.

Re: The European-originated plagues that wiped out 90% of the native Americans also reached Rapa Nui, well before the first direct European contact in 1722.

How? The people on the island weren't going anywhere and apparently no one else was visiting them. Diseases don't leap thousands of miles of open on their own.

(1) Spanish ships were regularly plying the west coast of South America by the late 16th century. On top of that, taking the Straights of Magellan into the Pacific was a commonly used route for anybody wanting to avoid the Portuguese control of the Indian Ocean, and also used by pirates and privateers (Drake et. al.). Records of these voyages are very incomplete.

(2) There might have been some non-European trade between Rapa Nui and South America. Somehow the sweet potato got from South America to Polynesia, and via Rapa Nui would be an obvious route.

DNA testing, as was recently done for the European Black Plague, should be able to discover when and to what extent European diseases reached Rapa Nui.

The people on the island weren’t going anywhere and apparently no one else was visiting them.

This is one of those assumptions I wonder about. It's the way the story has consistently been told, but how would we know?

A 19 day trip to the nearest polynesian island. Closer in miles to the mainland than to that island. Why would nobody visit them?

1. Maybe they were poor and had nothing to trade. The way after awhile nobody visited nordic greenland.

2. Maybe they got a reputation. "People who go there don't come back."

3. Maybe there was thriving trade after all.

Did polynesians trade with the mainland? They knew it was there. Easter Island might be a natural way station. This is something that could probably be known. The Easter Island inhabitants suffered repeated population near-extinctions, and probably lost a lot of history. Other polynesian populations may perhaps remember visiting them.

On-topic, polite, well-argued, funny - comment of the month!

I suspect your prediction is wrong. Why not just spend time worrying about truth rather than momentum?

Why not just spend time worrying about truth rather than momentum?

I've done that. And the problem with it is, that truth does not pay off in the short run.

And every single day is the short run.

If you want results, go with momentum. Just be careful not to zig when momentum zags or you'll get creamed. But if you don't go with momentum you'll get creamed both ways.

Thanks Lemmus. - dirk (aka the anonymous drunk who blogs at ahappinessexperiment)

Positive group identification is just as wrong as negative group identification. It may make you feel warm and fuzzy but it provides a permanent market for the other side.

I have no idea why this disproves Diamond's thesis. If Easter Islanders could eek out an existence using their innovative cultivation methods, why could they no do it do it in perpetuity? There must have been a sustainable production level from these methods, which they must have exceeded.

Mann's conclusions completely contradict the above quoted passages- "...humans generally do have a long-term capacity to work with natural systems, even in extreme cases". Shouldn't it read " humans generally do have a short-term capacity to work with natural systems, even in extreme cases"?

They could have done it in perpetuity, were it not for the European invasions. (I'm not sure how they account for the fact that, while most of the palms were destroyed in the 13th century, the extinction of the palms and the end of statue making doesn't occurs until the mid-17th century, but still decades _before_ first known European contact in 1722. I account for this above by arguing for the existence of non-European trade routes between Rapa Nui and South America which could have spread the European plagues. DNA from Rapa Nui remains can test such theories).

It's also possible that the first actual European contact predates the first known one by a considerable margin of time.

Yes. There was much Spanish shipping up and down the west coast of South America during the period.

Its pretty certain that someone in Polynesia had contact with South America even in pre-Columbian times. the sweet potato, a South American plant, abruptly spread all over Polynesia by 1000 AD (though that's too early for European plagues), and not just the plant itself but the Quechua name for ("kumar" in Quechua; "kumara" is the general Polynesian name)

Didn't they do it right up until they were enslaved by Europeans and shipped away?

So it was rats, not axes. I guess that means that they accidentally wrecked their environment by accident (by transporting rats), rather than accidentally wrecked their environment on purpose (by logging). Yay?

Thank you for another document to put into my "crooks and fallacies" file. What about the serious business - who has demonstrated that the downfall of Easter Island is all the fault of the USA?

Why wasn't there phosphorous from sea bird poop?

Yeah? alot of remote pacific islands were mined for phosphorous back when mining phosphorous was profitable. They were heaped with phosphorous. They were like little hershey kisses of phosphorous sitting midst an empty carpet than men called the Pacific Ocean. Why is Easter Island different?

Yes, that's my question too. Why was Easter Island so different? Why didn't rats kill the palms everywhere else? Why didn't people cut down all the trees anywhere else?

From Wikipedia:
A 1999 voyage with reconstructed Polynesian boats was able to reach Easter Island from Mangareva in 19 days.

Easter Island could have been part of a trade group, if they had anything to sell. They could have bought boats made elsewhere, if anybody wanted to sell them boats. They could have bought palm seedlings. (Though the palm that people talk about may have been unique to Easter Island and may have have taken over 100 years to reach maturity. It would take long-term thinking to raise them.)

Basalt is generally poor in potassium and phosphorus. But hawaiite has some olivine. It would weaken the fertilizer claim if it turned out that random rocks were used in gardens, and not carefully-chosen rocks.

Again from Wikipedia:

In 1786 Jean-François de La Pérouse visited Easter Island and his gardener declared that "three days' work a year" would be enough to support the population.

Rollin, a major in the Pérouse expedition, wrote, "Instead of meeting with men exhausted by famine... I found, on the contrary, a considerable population, with more beauty and grace than I afterwards met in any other island; and a soil, which, with very little labor, furnished excellent provisions, and in an abundance more than sufficient for the consumption of the inhabitants."

Various Wikipedia quotes like this give me the strong impression that the collapse on Easter Island may have been something like european diseases, or european technology introduced by polynesian traders. Something pretty recent, anyway.

I can understand why people are down on Jared Diamond. He published daring hypotheses and gave the impression he had overwhelming evidence behind them, while most of his evidence turns out to be disputed. But why are they so down on Thor Heyerdahl? He led an expedition with real scientists, they did real archeology, and they listened to the stories the people who lived on Easter Island told them. He wrote a popular book based on those stories, but so what?

(1) The Easter Island palm was descended from palms in Chile rather than Polynesia, and so might have been less well adapted to the Polynesian rat.

(2) Good point about the choice of rocks.

"But why are they so down on Thor Heyerdahl? "

One account I read said the his great Kon-Tiki expedition was a fake. The currents along the coast of S America were so strong that he couldn't get his raft out into the Pacific, and in the end simply had it towed out a few tens of miles offshore. That makes a mockery of his theory of the settlement of the Pacific.

And then there's Margaret Bloody Mead - does the Pacific unduly attract intellectual crooks?

Thor Heyerdahl is considered a pseudo-scientist by many, and genetic evidence shows his theory about the origin of Polynesians to be wrong. And the credibility of Mead's debunker, Derek Freeman, has taken a hit recently.

Thor Heyerdahl is considered a pseudo-scientist by many, and genetic evidence shows his theory about the origin of Polynesians to be wrong.

So he was wrong about something. If I never took a chance on being wrong I wouldn't get much done.

And so OK, he didn't understand the currents close to shore in south america, but south american sailors would have. He didn't do badly for 1947. Similarly, his Easter Island stuff wasn't bad for 1956 and the scientists who came with him apparently did some good work even if he lacked training to do anything in particular.

I read his Easter Island book in high school and don't remember all that many details. I vaguely remember him as being as contentious and absolutely certain he was right as Diamond, so I guess it's understandable that people would want to knock him down.

Blow me down, WKPD has got the goods on him.

"The Kon-Tiki left Callao, Peru, on the afternoon of April 28, 1947. It was initially towed 50 miles out — allowing it to bypass the treacherous currents close to shore (something any pre-Columbian sailors would have had to deal with) — by the Fleet Tug Guardian Rios of the Peruvian Navy. Having skipped what was arguably the most difficult part of the voyage, the ship sailed roughly west carried along on the Humboldt Current."

From my recollection of "The Kon Tiki Voyage", Heyerdahl's argument was that as spanish explorers had encountered rafts in the open ocean out of the influence of the land currents, there was no need to prove that a raft could leave the shore into the open ocean. Assuming this is correct, this seems like a reasonable argument - after all he was trying to prove that a raft could get from South America to Polynesia which is what everyone said was impossible.

From the Amazon editorial review: “their statue building was actually integral to their ability to achieve a delicate balance of sustainability”

I also smell poppycock. It seems much more likely that a declining resource base led to wars, which led to statues commemorating fallen warriors. In turn this may have inspired more fighting, as young men grew up in an environment that offered little except the chance to match the glory of their fathers.

Let's all make up crazy stories!

Lots of us already do. Jared Diamond was by no means the first.

"But there are surprisingly few cases in which societies have permanently laid waste to their own subsistence."

So the conclusion is that our society can do its best to lay waste to its own subsistence, taking comfort in the fact that history says it won't get
into any trouble? Methinks there is a flaw in that conclusion...

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