The myths of Easter Island – Jared Diamond responds

This week I wrote a blog post re-examining the historical evidence for the view that what happened in pre-historic Easter Island is a classic story of ecological ‘collapse’ and thereby holds lessons for us all. Jared Diamond, who used the Easter Island story as the lead case study in his 2005 book ‘Collapse’, responds to the charge below. I am happy to publish his comments in full, including links to two scholarly articles that Jared also supplied.

Jared Diamond writes:

This website has posted comments on Hunt’s and Lipo’s book about Easter Island, which claims to show how those authors’ recent archaeological studies overturned orthodox conclusions derived from a century of previous extensive archaeological research by many scholars.  Among Hunt’s and Lipo’s main conclusions, they say that Easter Island was deforested by rats, not by Polynesian settlers; that settlement was not until AD 1200 rather than earlier as widely assumed; that the tall stone statues of up to 90 tons were not transported horizontally, but were “walked” upright; that the collapse of Easter society was due to European impact, rather than to impacts of the settlers themselves before European arrival; and that the view of Easter society’s collapse as a self-inflicted ecological catastrophe is flawed.

Unfortunately, the web postings don’t recognize the compelling reasons why Hunt’s and Lipo’s conclusions are considered transparently wrong by essentially all other archaeologists with active programs on Easter Island.  I’ll summarize the reasons, for readers interested in these issues:

Rats.  The initial reason for positing a role of rats in Easter’s deforestation was that some preserved seeds of Easter’s extinct palm tree, found in caves, show marks of gnawing by rats; and that a study of Hawaii attributed deforestation there to rats.

However, evidence that rats played no significant role in Easter’s deforestation includes the following.  Rats occur not only on Easter but also on every other one of the hundreds of other Polynesian islands, most of which nevertheless did not end up deforested.  Over 90% of preserved palm seeds outside caves were not gnawed by rats.  Easter’s forest consisted not only of the palm but also of at least two dozen other species of trees and other plants, all of which also became extinct on Easter although most of them are not known to suffer seed predation by rats and continue to exist in the presence of rats on other Polynesian islands.  The Hawaii study does not demonstrate, but merely speculates about, a role of rats in deforestation on Hawaii.  Had rat predation on seedlings caused deforestation on Easter, there should then have been no regeneration of young palm trees, but continued survival of mature palms capable of living for many centuries.  Instead, palm trees continued to regenerate for centuries in the presence of rats, but eventually all palms, young and old, disappeared by AD 1600.  The reason for their disappearance is obvious: they were cut and burned by humans, as shown by burned palm stumps, cleanly-cut-off palm stumps, burnt palm leaves, and burned soil in many parts of Easter Island.  See the attached paper by Mieth and Bork, which Hunt and Lipo did not even cite in their book.

Settle a date. On the basis of radiocarbon dates of AD 1200 for a few wood samples from a surface at Anakena taken to represent the first settlement on Easter Island, Hunt and Lipo concluded that settlement was not until around AD 1200.  They rejected all of the many older radiocarbon dates obtained by other authors.  However, the Anakena surface occurs at a gap in soil deposition layers (an “unconformity” in geological terms), indicating that archaeological layers corresponding to an unknown number of centuries are missing (blown or dug or washed away) below that surface.  The surface thus provides no evidence about first settlement.  See the attached book review by Paul Bahn and John Flenley, two of the leading experts on Easter Island.

Statue transport.  How could tall 90-ton statues have been dragged over unpaved hilly terrain?  The only reasonable solution, to avoid their tipping and breaking during transport, is to transport them horizontally and then lever them into an upright position.  Jo Anne Van Tilburg, the leading scholar of Easter statues, who has spent decades cataloging the hundreds of statues, carried out an experiment in which Easter Islanders demonstrated for her their horizontal transport and levering-up of a model statue.  But Hunt and Lipo claim that statues were transported vertically.  This seems an implausible recipe for disaster.  Imagine it yourself: if you were told to transport a 90-ton statue 33 feet high over a dirt road, why would you risk tipping and breaking it by transporting it vertically with all its weight concentrated on its small base, rather than avoiding the risk of tipping by laying it flat and distributing its weight over its entire length?

Collapse only after European impact. Hunt and Lipo, relying partly on a paper by Peiser (written apparently without first-hand experience of Easter Island), claimed that Easter’s collapse was due to European impact, and that the islanders were coping successfully before European arrival.  No one disputes that European impact did devastate what was left of indigenous Easter society, especially by introduced diseases and by a slave raid.  However, to blame it all on Europeans dismisses all the convincing evidence that Easter society had been collapsing well before European arrival: evidence such as the near-completion of deforestation (attested by the disappearance of forest pollen and of forest plant remains), the evidence of widespread warfare (from detailed oral accounts and preserved weapons and skeletal injuries), the cessation of carving statues, the disappearance of oceanic fish and mammals from the diet (because of no trees to build canoes to harpoon them), and the desperate resort to sugarcane scraps for fuel (because of disappearance of native plant fuel).  These and other types of evidence that have built up our current understanding of Easter Island history are denied.

The lesson of Easter Island. Sometimes, a new study does result in previously unappreciated facts and interpretations, which eventually convince experts in the field.  But we learn to be suspicious when a highly selective book claims to present an “iron-clad case” for a “definitive solution” that has hitherto escaped all experts, and when the book’s dust-jacket quotes and favorable reviews are not by experts in the field.

Some of us may be eager to embrace claims that those native Easter Islanders really were innocent wise stewards of their environment, and that evil Europeans destroyed their paradise.  But research on Easter Island published since my 2005 book, and now fairly summarized in Bahn’s and Flenley’s just published new third edition of their standard source book Easter Island, Earth Island, enrich and don’t overturn our previous understanding of Easter Island.  The islanders did inadvertently destroy the environmental underpinnings of their society.  They did so, not because they were especially evil or deprived of foresight, but because they were ordinary people, living in a fragile environment, and subject to the usual human problems of clashes between group interests, clashes between individual and group interests, selfishness, and limited ability to predict the future.  Does that remind you of any problems that we ourselves face today?  That’s why we find Easter’s story so gripping, and why it may offer us lessons.  You’ll find good coverage in Bahn’s and Flenley’s new book.

© Mark Lynas
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