Tuesday, December 27, 2011

Pocket Magnetometer?: A Holiday Break Experiment

I've often wondered whether the magnetometer built into the iPhone is sensitive enough to be used as a remote sensing device.  At CSULB we use a Geometric 858 cesium vapor magnetometer to map subsurface deposits.  This ca. $25K instrument provides very fast and high precision measurements of the earth's magnetic field.  Collecting 10 readings a second, the 858 is capable of measuring differences as small as 0.008 nanoteslas (gammas).  While this precision is fantastic, often the variability we are interested in (e.g., hearths, organic deposits, etc) varies substantially more than that from the background magnetic field.  When mapping a large area, it isn't uncommon to see lots of noisy measurements at 1-10s of nanoteslas with features of interest showing variation in the 100s of nanoteslas. Of course, one's ability to measure differences in subsurface magnetics depends largely on the degree of variability of the background. The noisier the background (i.e., larger the highs and lows), the bigger the signal must be from the feature of interest. Using a gradiometer (i.e., two sensors and subtracting the difference) greatly aids in filtering out noise -- more on that in a bit.

The iPhone's magnetometer is reported to be sensitive to changes as small as 0.1 microteslas.  That is 100 nanoteslas (gammas). This means that the differences detected have to be pretty large, but also that it is not too far off from where we want to be.  It can report values as fast as once per 0.01 seconds.

To check out how the iPhone might work, I wrote a quick app that polls the magnetometer.  For simplicity, I also had it poll the GPS for locational information. I say simplicity since this has a number of consequences.  One the one hand one gets X and Y locations for each magnetic value.  One the other hand, the rate of update is slowed to one reading per second - which seems to be about the limit of the iPhone for producing locational values. I'll have to check on this though.  Using the iPhone GPS also introduces locational error since the phone is a pretty basic GPS w/ 2-5 meter error (at least).  The app creates a text file with the three values -- X, Y, and mag.  Oh, and for the mag value, I calculated the overall magnitude of the field at each position.  This is because the built in magnetometer actually returns values in 3 dimensions (x,y,z) which is cool, but means that small shifts in the orientation of the iPhone will be detected.  To calculate the overall magnitude, I simply stored the  sqr(x^2 + y^2 + z^2).

A more elaborate app would probably include a couple of features -- first, it would have one define transects in some systematic way and then have a way of marking the beginning and ending of the transects in the file.  Second there would be some way of placing markers in the file for indicating intervals.  These two bits of data would be useful for stretching the values for each transect in an fashion that would best represent the survey.  This might even not use GPS at all (though one would then have to layout and map a grid, and then georeference that later).  One might also make use of 2 iPhones to create a gradiometer -- or even take an Arduino Uno ($50) and 2 magnetometer sensors (maybe something like this or http://microcontrollershop.com/product_info.php?products_id=4565 -- $15/each) to construct a mini-gradiometer(space the sensors about 1 meter apart with one close to the ground and one at waist level).   For kicks, maybe add a gps -- http://microcontrollershop.com/product_info.php?products_id=2768 ($60) at the same time and some kind of analog input for adding markers ) Add this for data logging:http://microcontrollershop.com/product_info.php?products_id=4526 ($25.00). One could make a pretty slick little measurement device and data logger for doing mag/gradiometer surveys for under $200. Add in additional mag sensors to create an "array" and one can get pretty serious.

But there is still a concern -- is the basic magnetometer sensitive enough to changes subsurface changes in composition?  With my quick iPhone app, I did a quick survey in the park across from my house. This was a number of transects (up and down) that were done perpendicular to the curb of the circular park.  I uploaded the data into Surfer to and then added the file into QGIS so I could have the output georeferenced over a satellite image.  Below is what I ended up with.  In the image dark colors are low magnetic values, white colors are higher values.

 

NewImage

Pros:

-- It was certainly fast and cheap. The quick app worked with minimal pain.

-- The data definitely characterizes the curb edge of the park.

-- There may be other subsurface structures as apparent from the data.

 

Cons:

-- The one-second update rate for the location is a bit slow for getting mag points. A dedicated gps card (as described above) would be a huge advantage as these cards can usually produce location at 5-20Hz.  With the mag producing values at 0.01 seconds, you would have far more dense data to produce a map.

-- I'm not sure why the other structures are apparent in the data.  These are possibly due to subsurface pipes and whatnot. The lack of even data points across the survey area, however, is probably most likely to blame.  I didn't mark out my transects ahead of time (which is always a good idea) so I know I didn't walk in straight parallel lines.  An interface on the app might provide "steering" to keep on on a transect - that would help.  Also, having markers would enable one to ensure the data are distributed correctly across each transect (provided motion was constant).  Combining both the gps data (direction, speed, location) with some kind of marker system for end/middle/beginning of lines would probably provide a low-cost but reasonably reliable solution.

GPS Precision

It would be great to be able to post-process the GPS data to correct them for atmospheric error and reduce the uncertainty. There have been some successes in doing post processing of consumer grade gps units.  Most notably, garmin gps units can be coaxed into producing pseudo-range and carrier phase data (see:http://www.fig.net/pub/cairo/papers/ts_03/ts03_02_schwieger_glaser.pdf http://gpsinformation.info/harris/gpspostprocessing.html http://www.gps-forums.net/impressive-resolution-garmin-etrex-gps-using-gringo-t35448.html). The 12-Channel Lassen IQ receiver (http://www.sparkfun.com/products/163) ($50.00) might be just the thing as it produces RTCM output in addition to standard protocols. Some thing to look into, for certain. Additional discussion of the Lassen IQ is here: http://forum.sparkfun.com/viewtopic.php?t=809. Actually, that should be possible according to the reference manual. http://www.sparkfun.com/datasheets/GPS/Lassen%20iQ_Reference%20Manual.pdf.  The TSIP protocol can be set to output raw measurements and raw pseudo ranges (though the default is off). See page 112 for the TSIP protocol. This could mean a really cheap post-processing capable GPS!  Sweet.

This project - Kinematic -- has done much of the research -- but seems to be dead. http://web.archive.org/web/20090202200458/http://www.precision-gps.org/ It suggests that the Lassen is capable of producing 20-50cm precision since it lacks carrier wave information. Hell, that would be awesome.

Wednesday, November 2, 2011

Response to Paul Bahn in Nature

 

We just published a small comment back to Paul Bahn in Nature today. It is short (given the Correspondence format) but at least points out some of the major problems with Paul Bahn's "review" of our work.  You can read an online version of the comment here:

 

http://csulb.academia.edu/CarlLipo/Papers/1110216/Statues_Walking_Easter_Islands_Complex_History#

Tuesday, November 1, 2011

Hotu Iti: The Next Steps

We are headed back to Kualoa Ranch on the north shore of Hawai'i this week for another round of moai walking.  This event is sponsored by National Geographic and NipponTV and will (possibly) produce footage for the already-filmed Nat Geo documentary as well as a new one for NipponTV.  The NipponTV version will have its own host - as I understand it - a Japanese movie star or some other notable figure.

The stakes have been raised for this round of experiments.  Now that we know the basics of walking the moai we are challenged to walk it further, walk it uphill and downhill and to demonstrate how it can be maneuvered in tight quarters.  I think we can accomplish that but given the fact we have to learn everything as we do it (there is no off-camera prep time) it could be hairy.  Moving it 100 meters should be a no brainer as our experiments showed that this is really very simple -- its just a matter of time - very little in the way of brute strength.

I'd also like to see how few people we need to move the statue.  I suppose the way to do that is start with our existing number and then eliminate individuals systematically until we can't get it to move any more. This should give us a better idea of the investment constraints when moving the statue (the lower end that is, since more people can always be added on). There are upper limits to the contribution adding "more people" have on the movement process -- at some point no additional individuals will make a measurable difference.

I am also going to pay more attention to the steps the statue takes -- how high are they, how far forward does it rock when it takes a step, etc.  It'd be good to see if the curvature of the front edge predicts the size of the step taken (I suspect it does given the physics involved).  That way we can then model statues of different sizes and shapes in terms of the characteristics of their walks.  Perhaps there are different kinds of steps done by different statues perhaps intended by their carvers. That could be an interesting stylistic aspect of statue walking to explore.

It's going to be a busy weekend - and rainy it seems.

Friday, October 7, 2011

Diamond attempts to defend myths of Easter Island: Lipo and Hunt respond

 

Author Mark Lynas (The God Species: How the planet can survive the age of humans, Six Degrees, High Tide) recently posted a discussion of The Statues That Walked on his blog (www.marklynas.org) -- The myth of Easter Island’s ecocide.  In his essay, Lynas agrees with the basis of our research and concludes:

Like all of us, modern Easter Islanders are inter-dependent with the rest of the world. Perhaps the more recent studies of their history will help challenge the Hobbesian and pessimistic view that human nature necessarily tends towards destruction and violence. Resilience and sustainability are just as likely outcomes, even over the longer term. This, I think, is the true lesson of Easter Island.

His essay states, as we do in TSTW, that ecocide - at least on Easter Island - is a myth and that the evidence contradicts claims made by Jared Diamond (and others).  Interestingly, Jared Diamond (Collapse, Guns, Germs and Steel) chose this forum as a platform to argue against our research and conclusions.  Diamond's letter to Mark's posting is posted in full here.  Below is our response to Diamond's comments.  We have cross posted this here and on Mark Lynas' blog.  Enjoy!

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Diamond attempts to defend myths of Easter Island:  Lipo and Hunt respond

 

We are hardly surprised that Jared Diamond would write that we are “transparently wrong” about Easter Island.  He has a vested interest in defending his “ecocide” storyline published back in 1995 in Discover Magazine and again in his bestselling book Collapse. We acknowledge that Diamond has much at stake here.  But so do the Easter Islanders.  So too does the field of archeology.  And so too does the truth.

Diamond’s thesis about what happened on Easter Island is not new, building as it did on presumptions originally offered by the first Europeans to set foot on the island in the early 18th century. Sadly, this thesis was not challenged because it so conveniently confirmed 18th century prejudice about superior (European) and inferior (everyone not European) societies. Thor Heyerdahl expanded the story and added a further racist twist about lighter-skinned people who accomplished much, and darker-skinned people who incited rebellion, warfare, and ruin.  Diamond simply continues the tradition by reworking the tale to remove the racist elements, relying instead upon an environmental twist put forth by popular writer Paul Bahn and palynologist John Flenley.

An important role of scholarship is to examine long-held myths and see if they hold up under modern scientific tests.  The original Easter Island thesis, in any of its iterations, including Diamond’s, does not.  Let us point out that we didn’t go to Easter Island to tear down Diamond’s thesis. We went there to support it by filling in the missing archeological data. It was only when we convinced ourselves that any iteration of that original story, including Diamond’s, had no archeological evidence to support it and much to contradict it that we began to see where the research was leading us.

It is also important to note that Diamond is not an archaeologist and has not done archaeological or palaeoecological research in Polynesia. We have been doing research and primary archaeological field work on Easter since 2000. One of us (TH) has worked in Pacific Island archaeology for nearly 40 years and taught at University of Hawaii for 23 years.  On Easter Island we have done more field work and covered a greater breadth of archaeology than anyone else in the past two decades.  Our work has been peer-reviewed and published in science’s most selective and prestigious journals.  We outline in detail the evidence from our work and that of scores of colleagues working on the island in our book The Statues that Walked.  Diamond would have readers believe that the majority of archeologists who have studied Easter Island support his thesis.  It is simply not true. The new evidence that we and other serious scholars have provided over the past decade not only contradicts the old story that Diamond has so heavily invested in, but has led to a new consensus among the majority of scholars around our work.

Now, let us deal with the four or five major points of contention.

 

Deforestation

 

Everyone agrees that Easter Island was almost completely deforested by the time Europeans first visited in 1722.  The key issue is causation. In the absence of evidence to refute the facts we lay out, Diamond chooses either to ignore or misrepresent what we do argue. We never argued that rats were the sole cause of deforestation.  As the evidence shows and as we argued in our book, deforestation was a cumulative process that took centuries.  It resulted from rat predation of seeds and from people using fire to clear vegetation for agriculture.

To defend his position that rats played no significant role in deforestation, Diamond cites a study by Mieth and Bork.  Setting aside the fact that even if only a fraction of palm nuts were destroyed by rats, the cumulative effect would have been significant, let’s examine this study on its merits.

We were well aware of the work of Mieth and Bork as we did our work. But we were also aware of the fact (which Diamond fails to point out) that Mieth and Bork based their claim on nut fragments, not whole nuts. Before we rejected this study, we took the time to  experiment ourselves with 25 modern rat-gnawed palm nuts from mainland Chile that we broke into fragments of the sizes resembling those reported by Mieth and Bork.  This sample of 100% whole rat-gnawed nuts--when broken and then counted by their fragments--became a much, much smaller percentage. This shows the problem using Mieth and Bork whose estimate of 10% rat gnawed fragments implies that most nuts (if they were counted whole) were actually gnawed by rats.

Indeed, there is an extensive scientific literature on the impact of rats in island ecosystems that Diamond is either unaware of or simply doesn’t want readers to know about, such as one example from Lord Howe Island, where ecologists point out that without massive programs of rat eradication, the native palms on the island will go extinct. And rats have been on Lord Howe only since 1918, when a steamship ran aground!  Diamond himself, in his own writing, has referred to rats as “agents of extermination” (Diamond 1985).

Bottom line: Diamond needs to explain how, in the absence of predators and with an almost unlimited supply of food, the rat population would have remained small and had no impact on native plants and animals.

Next, Diamond makes the argument that even if rats could do this type of damage, the particular type of trees on Easter Island was not vulnerable to rats. The facts are as follows: Of the 17 major woody species identified from charcoal found in ancient cooking fires, 14 are documented to have seen major rat impacts elsewhere, or to be edible and highly vulnerable.  Furthermore, because the Jubaea palms were slow growing and did not fruit until about 70 years of age, they were particularly vulnerable. Some fraction of new palms would grow, but not enough to replace an entire forest over time.  Older trees would die, many were lost to fire, and in the end it was a losing battle; not enough young seedlings made it to reproductive age.

As for Diamond’s notion that palms were not diminished by rats, but taken down the islanders for rollers to move statues or to carve into canoes, enabling deep-sea fishing, anyone who has seen a palm tree cross-section with its thin, brittle bark and soft fibrous interior would quickly recognize these would not be suitable. Nor frankly would they have been capable of supporting the weight of multi-ton statues as rollers.

As for his allegation that palms were an important part of the islanders’ subsistence, there is overwhelming evidence that the islanders didn’t think so.  As we document in The Statues That Walked on research conducted by Joan Wozniak (2003), Chris Stevenson (Stevenson et al 2002, 2006; Ladefoged  et al. 2005, 2010) and  Hans-Rudolf Bork (Bork et al. 2004) lithic mulch gardens, along with stone-walled gardens known locally as manavai, provided the basis for the islander’s subsistence soon after the island was settled.  Palms provided no direct, long-term benefit so their loss had few if any consequences.

Chronology—When exactly was the island colonized?

One of our most important findings resulted from excavation and radiocarbon dating to establish the date of settlement as 300-800 years later than Diamond’s thesis requires. Diamond insists on missing evidence to argue for a longer chronology.  His argument asks us to accept on faith the notion that “the evidence must be there, we just can’t find it.”  That wouldn’t stand up in court, and it certainly doesn’t stand up in science.  Until such time as serious scientists prove otherwise, there are no reliable radiocarbon dates that support settlement of Easter Island before 1200 A.D. (Hunt and Lipo 2006). To argue otherwise ignores more than 2,000 radiocarbon dates from multiple archipelagos that provide overwhelming evidence that all of the eastern Pacific Islands were settled only over the past thousand years (Rieth et al 2011;Wilmshurst et al 2011), with Easter settled around 1200 A.D.  Even the most skeptical archaeologists working in the Pacific are now quibbling about chronological differences of only 50 to 100 years, not several centuries as Diamond imagines.

Statue Transport---Did the states move horizontally or vertically?

 

Diamond’s thesis hangs on the need for logs to “roll” the statues from the quarries to their final destinations.  In support of his thesis, he asks the reader to “imagine it yourself.”  Surely, he implies, it would be crazy to move a multi-ton statue in a standing position.  And if all you are solely relying upon is your own imagination, it may sound like a scary proposition. But that’s not reason enough to declare some past event as impossible.

But readers need to keep in mind that Diamond’s collapse thesis relies heavily on how the statues were moved.  To sustain his thesis regarding the eventual “collapse” of the ancient society, he needs statue movement to be the “engine” that caused the loss of trees. Decouple the loss of trees from moving statues and the “collapse” story looses steam. Thus, we are not surprised that Diamond holds so tenaciously to old beliefs and discredited claims.

But one has to wonder if Diamond has read The Statues that Walked.  In the book we discuss how fallen statue positions, kinds of breakage, statue shapes with a forward center of mass, as well as statue modifications made between quarry and placement on platforms can only be explained by vertical movement.  As archaeologist and colleague on the island Sergio Rapu (who has studied statues his whole life and has a M.A. degree in archaeology) taught us, the statues were “engineered to move.”  Oral traditions have long insisted that they “walked.” And while some have shown that it is possible to move a statue horizontally on a contraption of logs, (as Diamond posits they were moved) such a method completely ignores the direct and unambiguous evidence provided by the statues themselves.

But there is much better news awaiting readers who might want “to imagine it” themselves.   In recent experiments funded by National Geographic and fully filmed, we “walked” a multi-ton replica of an actual statue (one found along an ancient transport road).  Moving a statue in a standing position is not only possible; it’s relatively easy and can be done with a small group of people using only ropes.  Our experiment will be highlighted in a forthcoming NOVA-National Geographic television special to be broadcast on PBS in the spring of 2012.  Then the rest of the world will see what we have seen—the statues of Easter Island walking upright! Stay tuned!

 


Collapse only after European Contact

 

Again Diamond makes an appeal to authority in lieu of reference to evidence.  He mistakenly says we relied on only one source (Peiser, who does not even appear in our book’s bibliography—again, did he read our book?) who, he points out, has not done any work on the island.  Let us also note once again that Diamond has not conducted any field work on the island.  Nor to our knowledge has one of Diamond’s proclaimed “leading experts,” Paul Bahn, done any field studies on the island.

As we show in The Statues that Walked, rather than repeat assumptions and claims made in the past, we sought direct evidence with no preconceived ideas we needed to defend.  In that frame of mind, what the evidence kept pointing to is that many of the “facts” offered up by so-called “experts” were simply claims repeated over and over and nothing more. The island was certainly transformed over the course of human history (including the dramatic impact of more than 100 years of sheep ranching once the Chileans took control of the island.).  But what is Diamond’s evidence that prehistoric loss of the forest led to cultural and demographic collapse? There is none other than the assumption that losing trees is bad for people living on this island.  Is there evidence of soil erosion? Yes, but it shows re-deposited soils were successfully cultivated. In addition, radiocarbon dating and modern observations show that the most dramatic soil erosion occurred in post-contact and modern times (i.e., largely the results of sheep ranching).  Would the loss of trees have resulted in a critical shortfall of food and/or necessary materials?  The answer is a resounding “no.” Could the palm tree have provided a vital food source for people in the form of nuts? Yes, however, the introduction of tree-dwelling rats meant that these pests would have consumed most of the nuts first.

Diamond repeats a number of traditional notions about the island’s history.  In particular, he cites “evidence of widespread warfare” based on “oral accounts and preserved weapons and skeletal injuries.”  Let’s examine this so-called evidence. First, oral traditions were collected in the 20th century, almost 200 years after European contact.  Alfred Metraux, an anthropologist who studied the islanders’ oral traditions, concluded that they were most likely of very recent origin (Metraux 1940). Katherine Routledge, who worked on the island in the early 20th century, also describes how unreliable and contradictory she found the oral traditions. Our work does not draw upon oral traditions, given their uneven and unknown reliability. Some traditions may well be consistent with what actually happened in the past. In other cases they may not.  It is impossible to evaluate them on their own merits and independent lines of evidence are necessary (e.g., statues “walking” had to be evaluated in terms of evidence beyond just oral traditions).

Diamond’s “preserved weapons,” the mata’a, are agricultural tools that he has chosen to describe as “weapons.”  Their design alone, a rounded to irregular shape, should have been enough to make him question their purpose. But if he had read the microscopic studies reporting edge damage on thousands of these artifacts, he would have seen that the damage they show is consistent with their role in cutting and scrapping plant material (e.g., Church and Ellis 1994).  Indeed, our field studies show that they are found in the greatest concentrations in the lithic mulch gardening areas, right where one would expect to find them. And the island has no fortifications, such as those we see on other Polynesian islands where warfare was frequent.

Diamond points to evidence of violence in human skeletal remains.  However, the published data reveal there are only two cases in which violence appears to have resulted in death, and one of these was an individual who suffered a bullet wound to the head.  The skeletal evidence shows injuries and as we explain in The Statues that Walked, the ancient islanders engaged in some conflicts with one another. But as we outline in our book, statues were a focus of competitive signaling that staved off lethal violence.

Finally, Diamond ignores field research reporting dated domestic habitation sites (see Hunt and Lipo 2009 for discussion). When the habitations are plotted in fifty-year intervals, the number of those occupied clearly shows that the first and only sustained decline, as a relative measure of the population, began only in the first interval following European contact.  Before contact the data show a population that is growing and stabilizing, as reflected in their habitations across the landscape.  There is no evidence of population decline, let alone “collapse” until after European contact.  Indeed, there is direct, abundant evidence that population numbers grew, stabilized, and then fell only after European contact beginning in 1722.

 

The Lesson of Easter Island

 

Rather than address the evidence, Diamond attempts to deride our work by claiming that the people on the dust jacket are not experts in the field.  Diamond is certainly no expert in the field of Easter Island archaeology, regardless of his popularity. The individuals who commented on our book are experts in the areas of human and environmental change, including extensive research in the Pacific Islands.  These well-qualified, highly respected individuals know how science works and are directly engaged in research on ecology, evolution, and environmental change. Lacking quotes by “experts” who we have necessarily challenged in our research (perhaps such as Diamond?)  is certainly no reason for suspicion. The truth of the matter rests in the hands of the reader and the factual evidence outlined in The Statues that Walked.

There are those such as popular writer Paul Bahn and and palynologist John Flenley who continue to push the old doomsday, “ecocide” scenario.  But recent work has shown the central significance of lithic mulch (e.g., Bork et al. 2004; Stevenson et al. 2005; Ladefoged et al. 2010; Wozniak 1999, 2003), the lack of evidence for a 1680 AD “Collapse” event (e.g., Mulrooney et al. 2009, Lipo and Hunt 2009), that mata’a are not developed weapons (Church and Rigney 1994; Church and Ellis 1995), the lack of structural integrity of palms to serve as rollers or use as canoes (e.g., Bork and Meith 2003), the lack of evidence for cannibalism (e.g., McLaughlin 2005), the shorter chronology for colonization not just for Easter, but for the entire eastern Pacific (e.g., Kennett et al. 2006; Reith et al. 2011; Wilmshurst et al. 2008, 2011), the devastating effects that rats have on island environments (e.g., Athens 2009), details about the impact that Europeans had on historic populations (e.g., Fischer 2005), direct evidence about statue transport based on analysis of moai roads (e.g., Lipo and Hunt 2005; Love 2001), the inherently nutrient poor state of soil on Rapa Nui (e.g., Ladefoged 2005) and more.  These findings point to the growing body of evidence that falsifies the basic claims made in favor of “ecocide.” And based on this evidence, the majority of archaeologists working on Easter and elsewhere in Polynesia now reject the notion that the island suffered a pre-European collapse.

Our work in The Statues that Walked brings a wide range of current research into focus and combines more than a decade of our own field and related Easter Island research to form a coherent picture that is the basis of a new scientific consensus.  Easter Island was a story of remarkable success. And as young Native Islanders have told us, knowledge of their ancestors’ success, not failure, matters greatly to them. The “collapse” story for Easter Island is a convenient and popular parable used for shocking the public about the dangers of over-exuberance and environmental disregard.  However, as we describe in our book, the island’s collapse came only with the germs, guns, and enslavement brought by the outside world.  Given what is at stake in terms of lessons to be learned about long-term survival on an isolated and resource poor location, the truth matters.  Indeed, we have much to learn from Easter Island.

References

Athens, Stephen

2009 Rattus exulans and the catastrophic disappearance of Hawai'i's native lowland forest. Biological Invasions 11: 1489-1501.

 

Auld T.D., Hutton I., Ooi M.K.J., Denham A.J.

2010 Disruption of recruitment in two endemic palms on Lord Howe Island by invasive rats. Biological Invasions 12: 3351-3361

 

Bork, Hans-Rudolf, Andreas Mieth, and Bernd Tschochner

2004 Nothing but stones? A review of the extent and technical efforts of prehistoric stone mulching on Rapa Nui. Rapa Nui Journal 18(1): 10-14.

 

Butler, K. R., C. R. Prior, and J. R. Flenley

2004 Anomalous radiocarbon dates from Easter Island. Radiocarbon 46(1): 395-405.

 

Campbell, D. J., Atkinson, I. A. E.

2002 Depression of tree recruitment by the Pacific rat (Rattus exulans Peale) on New Zealand’s northern offshore islands. Biological Conservation 107:19-35.

 

Church, Flora, and Grace Ellis

1996 A use-wear analysis of obsidian tools from an Ana Kionga. Rapa Nui Journal 10(4): 81-88.

 

Church, F., and J. Rigney

1994 A microwear analysis of tools from site 10-241, Easter Island--An inland processing site. Rapa Nui Journal 8(4): 101-105.

 

Diamond, J.

1985 Rats as agents of extermination. Nature 318: 602-603.

 

Drake, D.R. and T. L. Hunt

2009 Invasive rodents on islands: integrating historical and contemporary ecology. Biological Invasions 11: 1483-1487.

 

Fischer, Steven R.

2005 Island at the End of the World: The turbulent history of Easter Island. London: Reaktion Books.

 

Hunt, T. L., and C. P. Lipo

2006 Late colonization of Easter Island. Science 311(5767): 1603-1606.

 

Hunt, T.L. and C.P. Lipo

2009 Revisiting Rapa Nui (Easter Island) “Ecocide.” Pacific Science 63: 601-616.

 

Kennett, Douglas, et al.

2006 Prehistoric human impacts on Rapa, French Polynesia. Natural History 80 (October 2004): 340-354.

 

Ladefoged, T. N., C. M. Stevenson, S. Haoa, M. Mulrooney, C. Puleston, P. M. Vitousek and O.A. Chadwick

2010 Soil nutrient analysis and Rapa Nui gardening. Archaeology in Oceania 45:80-85.

 

Lipo, Carl. P., and Terry L. Hunt

2005 Mapping prehistoric statue roads on Easter Island. Antiquity 79:158-168.

 

Lipo, C. P. and T. L. Hunt

2009 AD 1680 and Easter Island Prehistory.  Asian Perspectives. 48(2): 309-317.

 

McLaughlin, S.

2005 Cannibalism and Easter Island: Evaluation, Discussion of Probabilities, and Survey of the Literature on the Subject.  Rapa Nui Journal 19(1): 30-50.

 

Métraux, Alfred

1940 Ethnology of Easter Island. Honolulu: Bulletin, 160, Bernice P. Bishop Museum.

 

Mulrooney, M. A., T. N. Ladefoged, C. M. Stevenson, and S. Haoa,

2009 The Myth of AD 1680: New Evidence from Hanga Ho‘onu, Rapa Nui (Easter Island). Rapa Nui Journal 23(2): 94-105

 

Owsley, Douglas W., George W. Gill, and Stephen D. Ousley

1994 Biological effects of European contact on Easter Island. In In the Wake of Contact: Biological Responses to Conquest. C.S. Larsen and G.R. Milner, eds., pp. 161-177. New York: Wiley-Liss.

 

Reith, Timothy M., Terry L. Hunt, Carl P. Lipo, Janet M. Wilmshurst

2011 The Thirteenth Century Polynesian Colonization of Hawai‘i Island Journal of Archaeological Science 38(10): 2740-2749

 

Steadman, David W., Patricia Vargas Casanova, and Claudio Cristino Ferrando

1994 Stratigraphy, Chronology, and Cultural Context of an Early Faunal Assemblage from Easter Island. Asian Perspectives 33(1): 79-96.

 

Stevenson, Christopher M., Thegn Ladefoged, and Sonia Haoa

2002 Productive Strategies in an Uncertain Environment: Prehistoric Agriculture on Easter Island. Rapa Nui Journal 16(1): 17-22.

 

Stevenson, C. M., S. Haoa, T. N. Ladefoged, M. A. Mulrooney, P. M. Vitousek, O. A. Chadwick, and C. Puleston

2010 Evaluating Rapa Nui Prehistoric Terrestrial Resource Degradation. Rapa Nui Journal 24(2): 15-16.

 

Wilmshurst, J.M., T.L. Hunt, C.P. Lipo, and A. Anderson

2011 High precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia. Proceedings of the National Academy of Sciences USA 108 (5):1815-1820.  http://www.pnas.org/cgi/doi/10.1073/pnas.1015876108

 

Wilmshurst, J.M., A.J. Anderson, T.F.G. Higham, and TH Worthy.

2008 Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat. Proceedings of the National Academy of Sciences USA 105 (22) 7676–7680. www.pnas.org/cgi/doi/10.1073/pnas.0801507105

 

Wozniak, Joan A.

1999 Prehistoric horticultural practices on Easter Island: lithic mulched gardens and field systems. Rapa Nui Journal 13(3): 95-99.

 

Wozniak, Joan A.

2003 Exploring Landscapes on Easter Island (Rapa Nui) with Geoarchaeological Studies: Settlement, Subsistence, and environmental changes.  Ph.D. Dissertation. University of Oregon, Eugene.

Jared Diamond attempts to defend the myths of Easter Island—
Carl Lipo and Terry Hunt Respond
We are hardly surprised that Jared Diamond would write that we are “transparently wrong” about Easter Island.  He has a vested interest in defending his “ecocide” storyline published back in 1995 in Discover Magazine and again in his bestselling book Collapse. We acknowledge that Diamond has much at stake here.  But so do the Easter Islanders.  So too does the field of archeology.  And so too does the truth.
Diamond’s thesis about what happened on Easter Island is not new, building as it did on presumptions originally offered by the first Europeans to set foot on the island in the early 18th century. Sadly, this thesis was not challenged because it so conveniently confirmed 18th century prejudice about superior (European) and inferior (everyone not European) societies. Thor Heyerdahl expanded the story and added a further racist twist about lighter-skinned people who accomplished much, and darker-skinned people who incited rebellion, warfare, and ruin.  Diamond simply continues the tradition by reworking the tale to remove the racist elements, relying instead upon an environmental twist put forth by popular writer Bahn and palynologist Flenley.
An important role of scholarship is to examine long-held myths and see if they hold up under modern scientific tests.  The original Easter Island thesis, in any of its iterations, including Diamond’s, does not.  Let us point out that we didn’t go to Easter Island to tear down Diamond’s thesis. We went there to support it by filling in the missing archeological data. It was only when we convinced ourselves that any iteration of that original story, including Diamond’s, had no archeological evidence to support it and much to contract it that we began to see where the research was leading us.
It is also important to note that Diamond is not an archaeologist and has not done archaeological or palaeoecological research in Polynesia. We have been doing research and primary archaeological field work on Easter since 2000. One of us (TH) has worked in Pacific Island archaeology for nearly 40 years and taught at University of Hawaii for 23 years.  On Easter Island we have done more field work and covered a greater breadth of archaeology than anyone else in the past two decades.  Our work has been peer-reviewed and published in science’s most selective and prestigious journals.  We outline in detail the evidence from our work and that of scores of colleagues working on the island in our book The Statues that Walked.  Diamond would have readers believe that the majority of archeologists who have studied Easter Island support his thesis.  It is simply not true. The new evidence that we and other serious scholars have provided over the past decade not only contradicts the old story that Diamond has so heavily invested in, but has led to a new consensus among the majority of scholars around our work.
Now, let us deal with the four or five major points of contention.
Deforestation
Everyone agrees that Easter Island was almost completely deforested by the time Europeans first visited in 1722.  The key issue is causation. In the absence of evidence to refute the facts we lay out, Diamond chooses either to ignore or misrepresent what we do argue. We never argued that rats were the sole cause of deforestation.  As the evidence shows and as we argued in our book, deforestation was a cumulative process that took centuries.  It resulted from rat predation of seeds and from people using fire to clear vegetation for agriculture.
To defend his position that rats played no significant role in deforestation, Diamond cites a study by Mieth and Bork.  Setting aside the fact that even if only a fraction of palm nuts were destroyed by rats, the cumulative effect would have been significant, let’s examine this study on its merits.
We were well aware of the work of Mieth and Bork as we did our work. But we were also aware of the fact (which Diamond fails to point out) that Mieth and Bork based their claim on nut fragments, not whole nuts. Before we rejected this study, we took the time to  experiment ourselves with 25 modern rat-gnawed palm nuts from mainland Chile that we broke into fragments of the sizes resembling those reported by Mieth and Bork.  This sample of 100% whole rat-gnawed nuts--when broken and then counted by their fragments--became a much, much smaller percentage. This shows the problem using Mieth and Bork whose estimate of 10% rat gnawed fragments implies that most nuts (if they were counted whole) were actually gnawed by rats.
Indeed, there is an extensive scientific literature on the impact of rats in island ecosystems that Diamond is either unaware of or simply doesn’t want readers to know about, such as those from Lord Howe Island, where ecologists point out that without massive programs of rat eradication, the native palms on the island will go extinct. And rats have been on Lord Howe only since 1918, when a steamship ran aground!  Diamond himself, in his own writing, has referred to rats as “agents of extermination” (Diamond 1985).
Bottom line: Diamond needs to explain how, in the absence of predators and with an almost unlimited supply of food, the rat population would have remained small and had no impact on native plants and animals.
Next, Diamond makes the argument that even if rats could do this type of damage, the particular type of trees on Easter Island were not vulnerable to rats. The facts are as follows: Of the 17 major woody species identified from charcoal found in ancient cooking fires, 14 are documented to have seen major rat impacts elsewhere, or to be edible and highly vulnerable.  Furthermore, because the Jubaea palms were slow growing and did not fruit until about 70 years of age, they were particularly vulnerable. Some fraction of new palms would grow, but not enough to replace an entire forest over time.  Older trees would die, many were lost to fire, and in the end it was a losing battle; not enough young seedlings made it to reproductive age.
As for Diamond’s notion that palms were not diminished by rats, but taken down the islanders for rollers to move statues or to carve into canoes, enabling deep-sea fishing, anyone who has seen a palm tree cross-section with its thin, brittle bark and soft fibrous interior would quickly recognize these would not be suitable. Nor frankly would they have been capable of supporting the weight of multi-ton statues as rollers.
As for his allegation that palms were an important part of the islanders’ subsistence, there is overwhelming evidence that the islanders didn’t think so.  As we document in The Statues That Walked on research conducted by Joan Wozniak (2003), Chris Stevenson (Stevenson et al 2002, 2006; Ladefoged  et al. 2005, 2010) and  Hans-Rudolf (Bork et al. 2004) lithic mulch gardens, along with stone-walled gardens known locally as manavai, provided the basis for the islander’s subsistence soon after the island was settled.  Palms provided no direct, long-term benefit so their loss had few if any consequences.
Chronology—When exactly was the island colonized?
One of our most important findings was excavation and radiocarbon dating to establish the date of settlement as 300-800 years later than Diamond’s thesis requires. Diamond insists on missing evidence to argue for a longer chronology.  His argument asks us to accept on faith the notion that “the evidence must be there, we just can’t find it.”  That wouldn’t stand up in court, and it certainly doesn’t stand up in science.  Until such time as serious scientists prove otherwise, there are no reliable radiocarbon dates that support settlement of Easter Island before 1200 A.D. (Hunt and Lipo 2006). To argue otherwise ignores more than 2,000 radiocarbon dates from multiple archipelagos that provide overwhelming evidence that all of the eastern Pacific Islands were settled only over the past thousand years (Rieth et al 2011;Wilmshurst et al 2011), with Easter settled around 1200 A.D.  Even the most skeptical archaeologists working in the Pacific are now quibbling about chronological differences of only 50 to 100 years, not several centuries as Diamond imagines.
Statue Transport---Did the states move horizontally or vertically?
Diamond’s thesis hangs on the need for logs to “roll” the statues from the quarries to their final destinations.  In support of his thesis, he asks the reader to “imagine it yourself.”  Surely, he implies, it would be crazy to move a multi-ton statue in a standing position.  And if all you are solely relying upon is your own imagination, it may sound like a scary proposition. But that’s not reason enough to declare some past event as impossible.
But readers need to keep in mind that Diamond’s collapse thesis relies heavily on how the statues were moved.  To sustain his thesis regarding the eventual “collapse” of the ancient society, he needs statue movement to be the “engine” that caused the loss of trees. Decouple the loss of trees from moving statues and the “collapse” story looses steam. Thus, we are not surprised that Diamond holds so tenaciously to old beliefs and discredited claims.
But one has to wonder if Diamond has read The Statues that Walked.  In the book we discuss how fallen statue positions, kinds of breakage, statue shapes with a forward center of mass, as well as statue modifications made between quarry and placement on platforms can only be explained by vertical movement.  As archaeologist and colleague on the island Sergio Rapu (who has studied statues his whole life and has a M.A. degree in archaeology) taught us, the statues were “engineered to move.”  Oral traditions have long insisted that they “walked.” And while some have shown that it is possible to move a statue horizontally on a contraption of logs, (as Diamond posits they were moved) such a method completely ignores the direct and unambiguous evidence provided by the statues themselves.
But there is much better news awaiting readers who might want “to imagine it” themselves.   In recent experiments funded by National Geographic and fully filmed, we “walked” a multi-ton replica of an actual statue (one found along an ancient transport road).  Moving a statue in a standing position is not only possible; it’s relatively easy and can be done with a small group of people using only ropes.  Our experiment will be highlighted in a forthcoming NOVA-National Geographic television special to be broadcast on PBS in the spring of 2012.  Then the rest of the world will see what we have seen—the statues of Easter Island walking upright! Stay tuned!
Collapse only after European Contact
Again Diamond makes an appeal to authority in lieu of reference to evidence.  He mistakenly says we relied on only one source (Peiser, who does not even appear in our book’s bibliography—again, did he read our book?) who, he points out, has not done any work on the island.  Let us also note once again that Diamond has not conducted any field work on the island.  Nor to our knowledge has one of Diamond’s proclaimed “leading experts,” Paul Bahn, done any field studies on the island.
As we show in The Statues that Walked, rather than repeat assumptions and claims made in the past, we sought direct evidence with no preconceived ideas we needed to defend.  In that frame of mine, what the evidence kept pointing to is that many of the “facts” offered up by so-called “experts” were simply claims repeated over and over and nothing more. The island was certainly transformed over the course of human history (including the dramatic impact of more than 100 years of sheep ranching once the Chileans took control of the island.).  But what is Diamond’s evidence that prehistoric loss of the forest led to cultural and demographic collapse? There is none other than the assumption that losing trees is bad for people living on this island.  Is there evidence of soil erosion? Yes, but it shows re-deposited soils were successfully cultivated. In addition, radiocarbon dating and modern observations show that the most dramatic soil erosion occurred in post-contact and modern times (i.e., largely the results of sheep ranching).  Would the loss of trees have resulted in a critical shortfall of food and/or necessary materials?  The answer is a resounding “no.” Could the palm tree have provided a vital food source for people in the form of nuts? Yes, however, the introduction of tree-dwelling rats meant that these pests would have consumed most of the nuts first.
Diamond repeats a number of traditional notions about the island’s history.  In particular, he cites “evidence of widespread warfare” based on “oral accounts and preserved weapons and skeletal injuries.”  Let’s examine this so-called evidence. First, oral traditions were collected in the 20th century, almost 200 years after European contact.  Alfred Metraux, an anthropologist who studied the islanders’ oral traditions, concluded that they were most likely of very recent origin (Metraux 1940). Katherine Routledge, who worked on the island in the early 20th century, also describes how unreliable and contradictory she found the oral traditions. Our work does not draw upon oral traditions, given their uneven and unknown reliability. Some traditions may well be consistent with what actually happened in the past. In other cases they may not.  It is impossible to evaluate them on their own merits and independent lines of evidence are necessary (e.g., statues “walking” had to be evaluated in terms of evidence beyond just oral traditions).
Diamond’s “preserved weapons,” the mata’a, are agricultural tools that he has chosen to describe as “weapons.”  Their design alone, a rounded to irregular shape, should have been enough to make him question their purpose. But if he had read the microscopic studies reporting edge damage on thousands of these artifacts, he would have seen that the damage they show is consistent with their role in cutting and scrapping plant material (e.g., Church and Ellis 1994).  Indeed, our field studies show that they are found in the greatest concentrations in the lithic mulch gardening areas, right where one would expect to find them. And the island has no fortifications, such as those we see on other Polynesian islands where warfare was frequent.
Diamond points to evidence of violence in human skeletal remains.  However, the published data reveal there are only two cases in which violence appears to have resulted in death, and one of these was an individual who suffered a bullet wound to the head.  The skeletal evidence shows injuries and as we explain in The Statues that Walked, the ancient islanders engaged in some conflicts with one another. But as we outline in our book, statues were a focus of competitive signaling that staved off lethal violence.
Finally, Diamond ignores field research reporting dated domestic habitation sites (see Hunt and Lipo 2009 for discussion). When the habitations are plotted in fifty-year intervals, the number of those occupied clearly shows that the first and only sustained decline, as a relative measure of the population, began only in the first interval following European contact.  Before contact the data show a population that is growing and stabilizing, as reflected in their habitations across the landscape.  There is no evidence of population decline, let alone “collapse” until after European contact.  Indeed, there is direct, abundant evidence that population numbers grew, stabilized, and then fell only after 1722.
The Lesson of Easter Island
Rather than address the evidence, Diamond attempts to deride our work by claiming that the people on the dust jacket are not experts in the field.  Diamond is certainly no expert in the field of Easter Island archaeology, regardless of his popularity. The individuals who commented on our book are experts in the areas of human and environmental change, including extensive research in the Pacific Islands.  These well-qualified, highly respected individuals know how science works and are directly engaged in research on ecology, evolution, and environmental change. Lacking quotes by “experts” who we have necessarily challenged in our research (perhaps such as Diamond?)  is certainly no reason for suspicion. The truth of the matter rests in the hands of the reader and the factual evidence outlined in The Statues that Walked.
There are those such as popular writer Paul Bahn and and palynologist John Flenley who continue to push the old doomsday, “ecocide” scenario.  But recent work has shown the central significance of lithic mulch (e.g., Bork et al. 2004; Stevenson et al. 2005; Ladefoged et al. 2010; Wozniak 1999, 2003), the lack of evidence for an 1680 AD “Collapse” event (e.g., Mulrooney et al. 2009, Lipo and Hunt 2009), that mata’a are not developed weapons (Church and Rigney 1994; Church and Ellis 1995), the lack of structural integrity of palms to serve as rollers or use as canoes (e.g., Bork and Meith 2003), the lack of evidence for cannibalism (e.g., McLaughlin 2005), the shorter chronology for colonization not just for Easter, but for the entire eastern Pacific (e.g., Kennett et al. 2006; Reith et al. 2011; Wilmshurst et al. 2008, 2011), the devastating effects that rats have on island environments (e.g., Athens 2009), details about the impact that Europeans had on historic populations (e.g., Fischer 2005), direct evidence about statue transport based on analysis of moai roads (e.g., Lipo and Hunt 2005; Love 2001), the inherently nutrient poor state of soil on Rapa Nui (e.g., Ladefoged 2005) and more.  These new findings point to the growing body of evidence that falsifies the basic claims made in favor of “ecocide.” And based on this evidence, the majority of archaeologists working on Easter and elsewhere in Polynesia now reject the notion that the island suffered a pre-European collapse.
Our work in The Statues that Walked brings a wide range of current research into focus and combines more than a decade of our own field and related Easter Island research to form a coherent picture that is the basis of a new scientific consensus.  Easter Island was a story of remarkable success. And as young Native Islanders have told us, knowledge of their ancestors’ success, not failure, matters greatly to them. The “collapse” story for Easter Island is a convenient and popular parable used for shocking the public about the dangers of over-exuberance and environmental disregard.  However, as we describe in our book, the island’s collapse came only with the germs, guns, and enslavement brought by the outside world.  Given what is at stake in terms of lessons to be learned about long-term survival on an isolated and resource poor location, the truth matters.  Indeed, we have much to learn from Easter Island.
References
Athens, Stephen
2009 Rattus exulans and the catastrophic disappearance of Hawai'i's native lowland forest. Biological Invasions 11: 1489-1501.
Auld T.D., Hutton I., Ooi M.K.J., Denham A.J.
2010 Disruption of recruitment in two endemic palms on Lord Howe Island by invasive rats. Biological Invasions 12: 3351-3361
Bork, Hans-Rudolf, Andreas Mieth, and Bernd Tschochner
2004 Nothing but stones? A review of the extent and technical efforts of prehistoric stone mulching on Rapa Nui. Rapa Nui Journal 18(1): 10-14.
Butler, K. R., C. R. Prior, and J. R. Flenley
2004 Anomalous radiocarbon dates from Easter Island.  Radiocarbon 46(1): 395-405.
Campbell, D. J., Atkinson, I. A. E.
2002 Depression of tree recruitment by the Pacific rat (Rattus exulans Peale) on New Zealand’s northern offshore islands. Biological Conservation 107:19-35.
Church, Flora, and Grace Ellis
1996 A use-wear analysis of obsidian tools from an Ana Kionga. Rapa Nui Journal 10(4): 81-88.
Church, F., and J. Rigney
1994 A microwear analysis of tools from site 10-241, Easter Island--An inland processing site. Rapa Nui Journal 8(4): 101-105.
Diamond, J.
1985 Rats as agents of extermination. Nature 318: 602-603.
Drake, D.R. and T. L. Hunt
2009 Invasive rodents on islands: integrating historical and contemporary ecology. Biological Invasions 11: 1483-1487.
Fischer, Steven R.
2005 Island at the End of the World: The turbulent history of Easter Island. London: Reaktion Books.
Hunt, T. L., and C. P. Lipo
2006 Late colonization of Easter Island. Science 311(5767): 1603-1606.
Hunt, T.L. and C.P. Lipo
2009 Revisiting Rapa Nui (Easter Island) “Ecocide.” Pacific Science 63: 601-616.
Kennett, Douglas, et al.
2006 Prehistoric human impacts on Rapa, French Polynesia. Natural History 80 (October 2004): 340-354.
Ladefoged, T. N., C. M. Stevenson, S. Haoa, M. Mulrooney, C. Puleston, P. M. Vitousek and O.A. Chadwick
2010 Soil nutrient analysis and Rapa Nui gardening. Archaeology in Oceania 45:80-85.
Lipo, Carl. P., and Terry L. Hunt
2005 Mapping prehistoric statue roads on Easter Island. Antiquity 79:158-168.
Lipo, C. P. and T. L. Hunt
2009 AD 1680 and Easter Island Prehistory.  Asian Perspectives. 48(2): 309-317.
McLaughlin, S.
2005 Cannibalism and Easter Island: Evaluation, Discussion of Probabilities, and Survey of the Literature on the Subject.  Rapa Nui Journal 19(1): 30-50.
Métraux, Alfred
1940 Ethnology of Easter Island. Honolulu: Bulletin, 160, Bernice P. Bishop Museum.
Mulrooney, M. A., T. N. Ladefoged, C. M. Stevenson, and S. Haoa,
2009 The Myth of AD 1680: New Evidence from Hanga Ho‘onu, Rapa Nui (Easter Island). Rapa Nui Journal 23(2): 94-105
Owsley, Douglas W., George W. Gill, and Stephen D. Ousley
1994 Biological effects of European contact on Easter Island. In In the Wake of Contact: Biological Responses to Conquest. C.S. Larsen and G.R. Milner, eds., pp. 161-177. New York: Wiley-Liss.
Reith, Timothy M., Terry L. Hunt, Carl P. Lipo, Janet M. Wilmshurst
2011 The Thirteenth Century Polynesian Colonization of Hawai‘i Island Journal of Archaeological Science 38(10): 2740-2749
Steadman, David W., Patricia Vargas Casanova, and Claudio Cristino Ferrando
1994 Stratigraphy, Chronology, and Cultural Context of an Early Faunal Assemblage from Easter Island. Asian Perspectives 33(1): 79-96.
Stevenson, Christopher M., Thegn Ladefoged, and Sonia Haoa
2002 Productive Strategies in an Uncertain Environment: Prehistoric Agriculture on Easter Island. Rapa Nui Journal 16(1): 17-22.
Stevenson, C. M., S. Haoa, T. N. Ladefoged, M. A. Mulrooney, P. M. Vitousek, O. A. Chadwick, and C. Puleston
2010 Evaluating Rapa Nui Prehistoric Terrestrial Resource Degradation. Rapa Nui Journal 24(2): 15-16.
Wilmshurst, J.M., T.L. Hunt, C.P. Lipo, and A. Anderson
2011 High precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia. Proceedings of the National Academy of Sciences USA 108 (5):1815-1820.
www.pnas.org/cgi/doi/10.1073/pnas.1015876108
Wilmshurst, J.M., A.J. Anderson, T.F.G. Higham, and TH Worthy.
2008 Dating the late prehistoric dispersal of Polynesians to New Zealand using the commensal Pacific rat. Proceedings of the National Academy of Sciences USA 105 (22) 7676–7680. www.pnas.org/cgi/doi/10.1073/pnas.0801507105
Wozniak, Joan A.
1999 Prehistoric horticultural practices on Easter Island: lithic mulched gardens and field systems. Rapa Nui Journal 13(3): 95-99.
Wozniak, Joan A.
2003 Exploring Landscapes on Easter Island (Rapa Nui) with Geoarchaeological Studies: Settlement, Subsistence, and environmental changes.  Ph.D. Dissertation. University of Oregon, Eugene.

Thursday, June 23, 2011

Hoto Iti 3: 7:19PM

DSCF4354

It's now 7PM and the day is finished.  What a day it was... The rain kind of blew our plans for the original location we had scouted on Sunday.  Instead, we ended up moving down the valley. This area was flat but regularly invaded by buses and ATV tours for tourists viewing the sets of Lost and other movies.  We found a flat stretch that was off the main road. The Kualoa Ranch folks were kind enough to bring up a backhoe/grader to flatten this stretch by removing the small humps of grass in the center. This part of the valley was a bit drier relative to the upper end due to the lack of an orographic effect. We had a small army of volunteers for the "pulling" jobs and we all huddled underneath a small shelter while small squall blew through. It wasn't long, however, before the crane and then the statue arrived.  The statue showed up on a flatbed truck bearing a monster wooden crate. Huge.

The crane lowered the crate to the ground and the freight moving folks opened up. Holy friggin'-cow. This is a huge statue. Both Terry and I felt sick to our stomachs at the idea of moving this massive monolith. What had we gotten ourselves into? 10,000 lbs?

DSCF4349

It was only a bit latter when the statue was lifted up and set on the ground that we realized that we had a serious problem -- the statue would not stand on its own.  Blargh!  The angle of the base is correct and the statue is a direct copy of the digital model I sent.  However, I had to wonder whether or not I had made a mistake somewhere. This was, of course, an eroded statue laying on the road.. and there had clearly been post-falling modifications made to it (cupules on the top of the head, for example).  Perhaps there was material lost on the bottom edge that was critical to the movement -- but now lost? We can't stick anything back on! Or perhaps we scaled something incorrectly. Or we had it all wrong to begin with.  I have to say, my head started to spin with possibilities... all dark and gloomy.

We took a break for lunch and thought about the problem.  There are a couple of scenarios that we could imagine.  First, it is entirely possible that statues that had fallen were somehow modified to make it impossible for anyone else to move them and therefore "cheat" the signal that the statues represent. After all, if you had moved a statue 4 miles and it fell just before you had it on the ahu, you wouldnt want someone to jack your statue and make away with all the effort you put into getting the statue that far... This kind of modification would help ensure the "signal" is honest --- a statue that made it to the ahu would be guaranteed to be transported from the quarry (or be substantially smaller if somehow the material were "reused").

Evaluating this idea requires looking in detail at all the road moai -- if they have some kind of modification that is consistent with prohibiting further transport, then this might be the case.

The only problem, though, is that the modifications that would have been necessary to make this statue lean at a crazy steep angle (20 degrees) did not appear to be some kind of hack-job. Instead the front edge (the part that presents the point at which the center of mass is behind (letting the statue stand) or in front of (causing the statue to fall) is uniformly curved and well shaped.  So if someone removed material, they did so with an eye to preserving the shape of the base).

The second idea - and one I think might be ultimately the case -- is that the statue were made purposely leaning forward beyond the point of vertical stability.  This might seem surprising but from the point of view movement it makes sense that the statue remain in a constant "unstable" state with rope restraints used to hold it back from tipping.  This way, the folks allowing the statue to move forward would simply allow forward movement and not have to "catch" the statue as it transitioned from its stable upright position to a forward falling one.  If the angle of the ropes were correctly positioned it wouldnt take an excessive amount of force to keep the statue tipped back. In fact, the flat nature of the back edge of the base is consistent with this idea -- the flat edge is perfectly shaped to provide a leverage point for the statue to be tilted backwards.  Given that we consistently see this shape, and that the shape is more pronounced on bigger statues (and since they could have made the back base shape in any way they wanted) the back edge goes along with this idea.

We also noted that the difference between standing and falling forward is small - just a single 2x4" piece of lumber is adequate to hold the statue upright  - the difference between vertical stability and falling forward is just a matter of inches. so perhaps... perhaps, the statues in transport were made to be unstable and that stability -- putting it upright for standing was done with a couple of flat stones wedged under the front.  In fact, we find such stones along the roads -- poro stones that are flat that could serve this function.  And the presence of such stones underneath statues (as noted by Heyerdahl during his excavations at the quarry in the 1980s) helps support this notion.

We rigged a rope around the statue's head so that we had an attachment point along the plane of the eyes -- this gave us the maximum leverage to restrain the statue.  The crane operator released the tension on the straps and we had 12 folks pulling back to hold the statue. It worked.  We played a bit with the angles and the pulling to see if we could get the statue to rock and tilt side to side -- this also was successful.  So we might be okay.  In fact, thinking about it I had to remind myself that the prehistoric Rapanui moved this exact statue (or rather a 2x version of this statue) about 3 miles from the quarry before fell. Sure, it might have fallen, but the shape was adequate to get it that far. So in many ways, we need to remember that the shape the statue has is a product of prehistoric Rapanui engineering -- the shape is not from our imagination but theirs -- and they were able to move them.  Our problem is simply figuring out how this might be done given the form of the statues as we see them.

It is certainly easy to forget this point when you are looking at giant 10,000 lb (well, 9,600 lbs according to the crane operator) cement statue towering over one's head.  It is easy to doubt that the shape is "correct" -- but there is really no reason to think that it isn't. Trust in the ancestors.

Tomorrow we will do some rope configuration -- likely we will move the ropes to attach along the upper chest area.  This wide point will provide us leverage to rotate the statue as we tilt it.  We might need more than 2 ropes but that will be our starting point. We can start from there.

It is now.. of course... beverage o'clock.  At times like this, I find a bit of Bombay and Tonic to be quite efficacious.

Hotu Iti 2: 10AM

The weather is pretty rainy. Its now 10AM and and everyone is struggling to get things set up. Mata'u is desperately trying to construct an umu -- digging a hole and finding rocks. Of course, the rain is filling the hole and it is unlikely to hold a fire hot enough to cook chicken.  Raw chicken, blargh. As Mike Pfeffer once said "the short-lived life of the chicken sashimi chef..."

 

Hoto Iti

Kualoa Ranch

We arrived. It's a rainy, misty day.  The clouds are low and sweep past the rugged volcanic cliffs that make up the valley walls. Someone left the gate open last night so the area we are supposed to use has a herd of moo-ing cows.  Our rope "pullers" from UH, the local Navy base and elsewhere are showing up sporadically  The crew has set up a tent for the group of pullers - craft services and what not.  The rain, though, is coming down sideways so the tent is barely a shelter.  A typical scene of chaos, really.

The schedule for today is supposed to go something like this:

8:00am Arrive at Kualoa Ranch (Crew, Terry, Carl)

9:00am EMT, Volunteers arrive

10:00am SHOOT: Test walking with Pullers, Carl, Terry

11:00am Hotu Iti arrives at site

Crane arrives at site

Blessers arrive, SHUTTLE to site

11:30am Unloading of Hotu Iti

SHOOT: Unload and Blessing Ceremony at site

1:00pm LUNCH

2:30pm SHOOT: Test walking with Hotu Iti

3:30pm SHOOT: Re-group for Hero walk

4:00pm SHOOT: Hero walk

6:00pm END DAY 1

Wheels up for hotel… (Possible Sunset B-roll)


The first part of the day is dedicated to getting the folks who are going to be pulling the ropes to move the statue up to speed about about how we believe the statues were moved. We also need them to be able to work as teams. So we will get them doing some tug-of-war exercises that will lead to some practice events. First, we will get them to simply work as independent teams - tugging against each other in typical tug-of-war fashion. Then we will have them work on pulling and coordinating their efforts -- getting the center of the rope to move in different directions.  Once those tasks seem easy, we have a large 10' log that we will stand upright.  The ropes will be tied to the log and we will have the teams attempt to lean the logs in different directions (left, right, forward,back) to simulate the coordination required to tilt the statue.  This should give them some idea of what is required to work as a united whole and as separate groups. Or at least, that is the hope.

The statue - Hotu Iti - is scheduled to arrive @ 11AM.  I havent seen it yet -- While I have footage of the mold being carved back at Janicki in Sedro Wooley, I have yet to see the finished concrete product.  As I understand it, the statue was placed in a crate that was then put in a container. The container was put aboard a cargo ship and sailed to Honolulu where it has been sitting since arriving last week.  Today a truck will bring it to the film location along with a crane to extricate Hoto Iti from the container/box.  It must be a fairly large crane as the statue weighs nearly 12,000 lbs.  That is about the weight of 4 average sedan type cars.  Blargh. Fortunately we have an EMIT on site.

There are some blessings to take place - Rapa Nui and Hawaiian.  Sergio/Mata'u is going to construct an umu to do a traditional ceremony that precedes most Rapanui events.  I saw him digging the hole down by the road stretch we hope to move the statue along.  Physics aside, we need, I suppose, all the good fortune we can get - so bring on the blessings.

We are planning two kinds of "walks" today. First, we will work with the statue while it is still attached to the crane. I'm not sure exactly how we will attach the rope but somehow we will make sure that the statue can move yet not fall over. This will allow us to let evaluate how far we can tilt the statue before it hits it's tipping point.  While I have models to show us what we believe will be the point, these are based on assumptions of homogeneity of the material.  I'd like to actual view the tipping points for the statue so that we can visually assess the angles that are required for moving. Without doing so, I suspect we will be overly conservative and not let the statue tip far enough.  Given the mass of Hoto Iti, it would be easy to be scared of it falling.

If we can get that worked out we will do some "walking" tests with the crane rope attached. Once we get the "hang" of it, we will then remove the crane rope and do what Mata'u calls the "Hero walk."  I guess we will be heroes if we can make that happen -- compressing generations of Rapanui experimentation into a few short hours. Whoohooo!

 

 

The Plan for Hoto Iti: The statue that walks

Today is the big day.  The statue will walk (or it won't).  We head out to Kualoa Ranch momentarily.

Monday, June 20, 2011

Hoto Iti: The Statue That Walks

NewImageI left Long Beach on Saturday for Honolulu and the site of our Hoto Iti moving attempt.  This next phase of the NOVA filming will, hopefully, demonstrate how an actual moai can be moved in a standing position using its own distribution of mass and shape to facilitate its "walking."  Earlier this spring I created a 3D model of a "road" moai (i.e., one that was abandoned after falling during transport) that was then used by Janicki Industries in Sedro Wooley, Washington to fabricate a mold that was then used to create a 5-ton 10-foot tall cement replica.  This was then shipped to Honolulu on a container ship and now rests at the port of Honolulu.

Committee Films (the production company) has arranged to have Hoto Iti brought to Kualoa Ranch.  Kualoa Ranch is an enormous chunk of Oahu located out the northeast side of the island.  It's a stunning valley with massive cliffs and the classic "Polynesian-style" spire top mountains associated with young volcanic landscapes. The ranch is about 4,000 acres and was historically used for sugar cane cultivation (and prehistorically there were fishponds, terraces and pond-fields up in the upper part of the valley).  The ranch seems to be largely used for filming these days -- Jurassic Park, 50 first dates, Godzilla, Mighty Joe Young, Windtalkers, Pearl Harbor, Lost, Stargate Atlantis and, of course, Hawaii 5-O (and more) were all filmed there. So it seems oddly familiar.

We all (the Committee Film folks - Maria, Andy, Ben, Bo, Matu'a, Meghan and Terry, Marc and Hotu the dog) met at the Ranch on Sunday afternoon to "scout" out the location. Earlier this spring Terry and Alex Morrison had measured some of the slope features of the road that stretches along the valley floor to find a suitable stretch that might work for our statue movement attempt.  We need some place that has slopes that are no steeper than 3 degrees going uphill and 6 degrees going downhill. These slope constraints are based on measurements of actual moai roads on Rapa Nui -- the south coast road stretch has such parameters.

KualoaRanch

 

We found what looks like a suitable place in the upper part of the valley, below the location of what we think is the "Stargate Atlantis" set.  Its a fairly flat stretch that has enough space on the sides of the road for the team of rope pullers to work. It also appears to be accessible for the giant truck and crane that will carry Hotu Iti to the location.   There are some undulations in the road and of course the notion of moving a giant 5 ton statue across this surface will be complex.

I have to admit that the movement attempt fills me with more than a little bit of anxiety.  Will it fall over and break into 10 pieces? will it just sit there as we pull on the ropes?  Can we figure out generations of learned information in just a few short days? I guess we will see!

 

 

Sunday, May 29, 2011

Arrival!

Friday afternoon and after ca 36 hours of flying and waiting we are back on Rapa Nui. I've got my old room ... 22, purportedly where Heyerdahl slept back in 1986. No ghosts though. The weather is superb...warm with light breezes, soft air. I can hear the rollers down in the harbor and see the cargo ship in the bay. Right now I'm sitting outside my room. Terry and marc have gone off to find wine...



Location:Chile

Thursday, May 26, 2011

NOVA II

It is the third day of shooting for the NOVA documentary that is being shot by Committee Films about The Statues that Walked.  So far so good.  Fortuitously, the several cop

Book

ies of the book arrived! We got 3 advance copies that we are going to take to Rapa Nui (arriving Friday).  I am very happy for that as we can give a copy to Sergio, Francisco and others who have worked with us -- as well as donate a copy to the museum.  The last two days were spent filming in the LA area -- first at CSULB (in our archaeology lab) and then over in Culver City where Max Beach works.  Max Beach has been leading the animation efforts for demonstrating how the statues work.  His office (IDA design) kindly supported this work and our intrusive filming.  I spent a lot of time the first day providing "head shot" interview material.  Ben Awes (the Director) had a long list of great questions that I was asked to answer.  I have no idea how I did: I cobbled responses together as best I could.  We will see...

Right now we are in Miami waiting for the flight to Santiago, Chile.  It's an overnight flight so somewhat brutal. i hope to sleep through much of it.  Once we get to Santiago, its a simple 5 hour flight to Rapa Nui!