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The ‘Walking’ Megalithic Statues (Moai) of Easter Island
Carl P. Lipo, Terry L. Hunt, Sergio Rapu Haoa
PII: S0305-4403(12)00431-1
DOI: 10.1016/j.jas.2012.09.029
Reference: YJASC 3443
To appear in: Journal of Archaeological Science
Received Date: 25 July 2012
Revised Date: 20 September 2012
Accepted Date: 20 September 2012
Please cite this article as: Lipo, C.P., Hunt, T.L., Haoa, S.R., The ‘Walking’ Megalithic Statues (Moai) of
Easter Island, Journal of Archaeological Science (2012), doi: 10.1016/j.jas.2012.09.029.
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Graphical Abstract
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Highlights
We show how Easter Island statue variability is explained by transport in a
vertical position
We ‘walk’ a precise road statue replica demonstrating how form enables
vertical transport
‘Walking’ multi-ton statues did not require timber and could be
accomplished by relatively small groups
*Highlights
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`Title: The ‘Walking’ Megalithic Statues (Moai) of Easter Island
Authors: Carl P. Lipo1*, Terry L. Hunt2, and Sergio Rapu Haoa3
1IIRMES and Department of Anthropology, California State University Long Beach,
1250 Bellflower Blvd., Long Beach, CA, USA 90840
2Department of Anthropology, University of Hawai’i, 2424 Maile Way, Saunders Hall
346, Honolulu, HI, USA 96822-2223
3Instituto de Estudios Oceanicos, Hangaroa, Rapa Nui/Isla de Pascua, Chile
*Correspondence to: carl.lipo@csulb.edu
Abstract: Explaining how the monumental statues (moai) of Easter Island were
transported has remained open to debate and speculation, including their resource
expenditures and role in deforestation. Archaeological evidence including analysis
of moai variability, particularly those abandoned along ancient roads, indicates
transport was achieved in a vertical position. To test this proposition we
constructed a precise three-dimensional 4.35 metric ton replica of an actual statue
and demonstrate how positioning the center of mass allowed it to fall forward and
rock from side to side causing it to ‘walk.’ Our experiments reveal how the statue
form was engineered for efficient transport by a small number of individuals.
*Manuscript
Click here to view linked References
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1. Introduction
The ancient Polynesians of Easter Island carved nearly 1000 massive statues
(moai) from volcanic hyalotuff bedrock and transported about 500 along roads
traversing a rugged landscape to monumental sites around the island, some as far as
16-18 km distance (Fig. 1). The largest of these statues is over ca. 10 m tall, weighs
approximately 74 metric tons and was moved over 5 km. Early European visitors
and later researchers have assumed moai carving and transport required a large
labor force, a correspondingly large population, and a substantial expenditure of
natural resources such as agricultural surplus and trees for rollers or other
transport devices. The notion of an irrational statue cult fueled by overpopulation
and overexploitation of resources has formed foundations of arguments for
“ecocide” and seemed to provide a coherent model for Easter’s prehistory
(Diamond, 2005, 2007). However, recent research and new evidence calls into
question the longstanding notions of “ecocide” and population collapse before
European contact (Hunt and Lipo, 2011).
Understanding the role of carving and transporting hundreds of multi-ton
moai remains central to the island’s prehistory. In this paper, we draw on detailed
analysis of ancient statues (n=961 total; see Torres Hochstetter et al. 2011), with a
focus on those abandoned along roadways (Lipo and Hunt 2005; n=62 statues; see
Table S1) during their transport. Based on our research, we show that movement in
a vertical ‘walking’ motion explains systematic variations in moai found in the
quarry, on ancient roadways, and those found on platforms (ahu). To test a
proposition for vertical transport, we used a precisely scaled five-ton road-statue
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replica and show experimentally how relatively few people achieve movement in a
‘walking’ motion. Our new explanation of statue transport accounts for systematic
variability in the statues and highlights the remarkable engineering skills of the
prehistoric Easter Islanders.
2.1 Previous Investigations
The question of how the multi-ton moai of Easter were transported has
puzzled visitors and researchers for centuries. No visitors to the island ever
witnessed the process, leaving much to an array of speculations. The islanders’ oral
traditions have long recounted that the statues ‘walked’. Thomson (1889), for
example, was told the statues were “endowed with power to walk about in the
darkness.” Metraux (1940:240) recounts, “the huge blocks walked for a distance and
then stopped.” However, oral tradition offers no detailed explanation of how this
‘walking’ was achieved or to what degree it was meant metaphorically.
Modern experiments began with Heyerdahl’s efforts in the 1950s, including
simply dragging them (Heyerdahl 1989a). To resolve problems of friction and
damage to statues, later efforts employed wooden sledges, pods, rollers, and sliders
in various configurations. Among those proposing use of wooden devices, the debate
focused on whether statues were moved in a horizontal or vertical position (Love
2000; Van Tilburg and Ralston 2005). In contrast, Pavel (1995; Heyerdahl Skjølsvold
and Pavel 1989) attempted to move a statue in a vertical position using only ropes
and padding in a fashion in which the statue was “wiggled” from side to side. While
more realistic than horizontal arrangements, his attempt met with limited success
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given the statue’s unsuitable form, vertical instability, and great friction quickly
causing damage to its base. The most recent attempts have employed a wooden
sledge with moai in horizontal (prone or supine) positions pulled over logs in a
sliding motion (Van Tilburg and Ralston 2005). A conclusion favoring horizontal
movement of moai in prone or supine positions on wooden sledges slid over logs
has seen some favor, appearing to fit the assumed impact the statue cult played in
the island’s deforestation (Diamond 2005, 2007). While experimental attempts
highlight the plausibility of methods that could have been used to move statues, they
have overlooked systematic variation in the statues and their broader context in the
archaeological record.
2.2 Roads and Statues
Despite longstanding questions of how statues were moved, surprisingly
little attention has been paid to the archaeological record directly related to
transport or variability in the statues. In 2004, we undertook a study of prehistoric
roads constructed as paths for the transport of moai (Lipo and Hunt 2005; Fig. 1).
First noted in 1917 by Routledge (1919), these paths form linear features
approximately 4.5 m wide extending out from the quarry at Rano Raraku. Over 25
km of these roads remain visible on the landscape and in satellite images (Lipo and
Hunt 2005). These roads provide direct information about some of the physical
parameters necessarily involved in statue movement. For example, a long stretch of
moai road along the south coast has uphill gradients as steep as 13 degrees with an
average of 2.9 degrees, and downhill slopes of 16 degrees with an average of 2.8
degrees (Fig. S1). Excavations of segments of the moai roads by Love (2001) also
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show that the roads are concave in cross section, a configuration that largely rules
out use of transverse rollers.
During field research on moai roads, we documented 62 statues located on
and parallel to road features (Table S1). These moai can be explained as those in the
process of being moved, but transport failed and they were abandoned. The
explanation relies on several lines of evidence. First, the statues lay in a direction
parallel to the road direction that runs away from the main quarry at Rano Raraku,
an orientation consistent with transport. Second, these moai are not associated with
platforms (ahu) where they would be erected at their destinations. Third, like the
statues remaining at the quarry, none had eye sockets carved in them, in contrast to
those erected on platforms. Prehistoric islanders inserted into these eye sockets
coral “eyes” with obsidian or red scoria pupils. As with the crowning of red scoria
hats (pukao) for many statues, adding the eyes was a final step in completing moai
with emplacement on platforms. None of the road statues in our analyzed set has
these eye features, defining their incompleteness and status as in transit when
abandoned.
The statues found along the roads have shapes that also distinguish them
from those statues erected on ahu. The road moai have statistically wider bases
when measured relative to shoulder width than ahu moai (Fig. S2). Once statues
arrived on platforms, prehistoric carvers modified the statues to decrease the width
of the base relative to shoulder. In addition, while ahu moai stand in an upright
fashion with their mass located well over their base, road moai show a distinctive
angled base that would cause the statue to lean significantly forward, often more
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than 10 degrees. Indeed such forward lean means that most could not stand upright
on their own. The reduction of the base width is thus related to changing the vertical
orientation of the statue from a forward lean to a more stable upright position (Fig.
2).
Finally, three additional observations of the road moai inform on their
transport. Thirty-seven percent of road moai are broken into two or more fragments
consistent with breakage that resulted from falling from a vertical position (e.g., Fig.
S3). In addition, on the south coast road are two examples of moai that did not
break and were partially buried at their base and can be explained by ancient
workers who attempted to re-erect them by excavating a pit to restore them to an
upright position to be ‘walked’ out on a ramp (e.g., Figs. S4 and S5). Second, 70% of
road moai exhibit evidence of fracture caused by force being applied in inverse
vertical fashion along the lateral edges of the base. These fractures form broad
shallow concave scars from which a wide pressure flake was removed. Third, the
positions of fallen statues are statistically non-random (p<0.05) with respect to the
slope on which they lay (Table S2). The majority of statues are found facedown
when the road slopes downhill, and often on their backs when going uphill.
These road and statue observations are explained by the hypothesis that
moai were transported in a standing position and some fell en route. Significantly,
hypotheses for horizontal transport using wooden devices cannot account for these
archaeological observations. Moreover, the field evidence clearly shows that statues
were lowered down into trenches from their quarry bedrock sources above to the
base of Rano Raraku where their backs were completed and other details carved,
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and then moved upright out of these trenches remaining in a vertical position,
including their final placement on ahu (Fig. 3). Otherwise, the logistics of lowering
and later raising tall multi-ton moai make little sense and imply they remained
vertical. Statues found along the roads that fell during transport were often not re-
erected given breakage or the difficulty of raising them. However, the question
arising from Pavel’s (1995) attempt at vertical transport remained unanswered:
how would damage to the statue base from friction be minimized? If a short
distance of vertical transport (in ‘wiggling’ or ‘shuffling’ as Pavel did) significantly
damages the base, it seems improbable that the statues could have been moved
several kilometers without causing catastrophic damage.
3.1 Evaluating the ‘Walking’ Moai
To address detailed problems of statue transport, we constructed a three-
dimensional model of an actual road moai (Fig. 4). The original moai (12-220-01) is
located along the ancient roadway on the south coast of the island and is 7.35
meters in height and 2.83 meters in width. It had been transported ca. 3.54 km
southwest from the Rano Raraku quarry before it fell on its back intact on an uphill
slope of a south coast moai road.
The 3D models of moai allowed us to measure the center of mass along each
of three spatial dimensions. The center of mass was located in the middle of the
statue in terms of its width as the statues are generally left/right symmetric. The
height of the center of mass is also approximately in the center of the statue,
midway between the base and the top of the head. But the center of mass in the
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depth dimension is remarkably forward relative to the base of the statue. This
peculiar configuration cannot be explained by a hypothesis of horizontal transport.
In horizontal transport, one would expect to find the center of mass toward the base
to facilitate raising the statue back up to its vertical orientation when placed on the
ahu.
The 3D model provides a means of evaluating how forces acting on it would
result in motion. Like other road moai, this statue has a distinctive forward lean and
exhibits flaking on the lateral portions of the base. The plan view shape of the
statue’s base is also like other road moai with a dorsal edge is relatively straight and
a ventral edge is broadly rounded. This rounded front edge is shaped in such a way
that it provides a continuous surface across which the statue can roll as it is tilted
from side to side.
Inspection of the 3D digital model revealed that the moai would not stand
upright on its own. For the moai replicated, like others that were in transit, the
center of mass is positioned just over the point of the front edge and standing the
statue on its base would cause it to tip forward. Modification of the base for
standing on an ahu, therefore, would have been necessary had the statue reached its
destination, explaining the difference in the base to shoulder ratios we document.
The basal flaking and forward lean point to how the statue was ‘walked’ in an
upright position without significant wear to the base caused by twisting on its basal
surface as in Pavel’s earlier attempts. Rather than twisting in place, moai were tilted
to the side and allowed to fall forward in the direction of their lean. With a slight tilt
to the side, the statue then falls forward toward its inherent front lean. As it falls, the
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moai rolls across its front edge and rotates slightly to the opposite side. In this way,
friction between the base and the ground is minimized allowing for the conservation
of energy, increasing overall efficiency and removing the potential for damage as the
statue ‘walks.’
The difference between road moai and those that reach their ahu
destinations is significant, though previous experiments overlooked the systematic
variations. Van Tilburg and Ralston (2005), for example, created a “statistically
average moai” thereby masking statue variability and modeling transport by
confounding forms designed to 'walk’ versus those modified to stand erect on ahu
platforms. Significantly, a “statistically average moai” replica would not be capable
of transport by ‘walking’ since the vast majority of statues were prehistorically
modified to stand stably on platforms.
3.2 Demonstration of Moai ‘Walking’
To test the dynamics of motion and the practical constraints involved with
walking a moai, we constructed a scaled replica of a size sufficient to represent real-
world challenges in moving these monumental figures. Despite previous
experiments, ours is the first use of a precise proportionally scaled replica of an
actual road moai shaped appropriately for transport, rather than standing erect on
an ahu.
In four days of field trials in June and November of 2011 at Kualoa Ranch,
Hawai`i, a team of volunteers experimented with placement of ropes (1” hemp),
cooperative tactics, and other logistical details (Fig. 5; Video S1; Figs. S6-S10). Initial
vertical placement of the replica using a crane confirmed that the moai could not
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stand on its own without inserts under the front edge sufficient to tilt the center of
mass back over its base. ‘Walking’ the replica statue demonstrated that road moai
can be moved efficiently and with minimal friction and resulting wear (Fig. 6). The
statue’s shaped features are integrated into the range of motion enabling ‘walking.’
Using the fewest inputs possible, we found that three ropes attached around the
statue’s head were sufficient to initiate forward motion. We attached one rope near
the top of the head at the eyes of the moai and stretched it behind the direction of
travel. This rope kept the statue position leaning slightly forward on its front edge,
preventing it from falling too far forward. Tied to the same location at the eyes, we
stretched two additional ropes perpendicular to the statue’s direction of travel.
These lines were pulled in alternating fashion to ‘rock’ the statue from side to side.
As the statue began to rock, it rolled forward along its front edge. Each roll caused
the statue to take a ‘step.’
When the center of mass is positioned in the center of the statue in the
vertical direction, rocking the statue back and forth is relatively easy: the taller the
moai, the greater the leverage enabling handlers to initiate its rocking. The width of
the statue and the elongated head provides the statue the lateral stability and shape
similar to a bowling pin. With such a shape, the statue we modeled can be tilted
laterally as much as to 26 degrees from vertical. The tilting to each side provides
clearance on the opposite base edge for steps to be taken in an uphill fashion. By
tilting the statue to one side, we could lift a lateral edge over 60cm in height before
the statue would fall sideways. The degree to which the statue can be tilted to the
side provides the clearance necessary for the moai to climb uphill as well as
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provides the dynamic energy involved in each step. Downhill motion was also
demonstrated, though we did not explore the potential for moving the statue
backwards while descending steep slopes (although no direct archaeological
evidence suggests this was attempted).
Describing the moai movement as ‘walking’ is conceptually consistent with
our own pedal locomotion. Statue ‘walking’ and our own steps represent mechanics
that can be modeled an inverse pendulum: a simple pendulum that is turned upside
down so the mass swings back and forth from a fixed base. Pendulums conserve
energy and can remain in motion for some duration as long as there is minimal
friction during each swing. When moving to walk forward, one pivots on their foot
placed on the ground. From that pivot point, our center of mass—located along the
vertical centerline of one’s belly—follows the path of an arc as we lift our opposite
hip and swing a leg forward. One’s forward foot eventually hits the ground and the
arc slows to a stop in that direction. At that point kinetic energy is at a minimum,
but potential energy on that side is at a maximum. As one falls forward into the next
step, potential energy is converted back into kinetic energy, and continues move
forward. This is the basic physics of walking.
Moving large moai takes advantage of the same principle. During forward
movement the statue tilts sequentially in opposite directions. The transfer of energy
back and forth, however, does not involve the high friction “wiggle” motion as
proposed by the Pavel (1995) method. Rather, road moai are designed so that the
when the statue rocks from one side to the other it also falls slightly forward and
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rolls across its front edge. In this way, once the moai is set in motion it efficiently
maintains the energy invested in the initial tilting. Energy is smoothly converted
from potential energy at the point of the statue’s greatest tilt to kinetic energy as it
swings back to the other side. Through this rocking and rolling motion, the statue
takes incremental steps and moves forward. Once in motion, relatively small
amounts of energy must be added to the system through gentle tugs on opposite
sides.
This system of transportation is only possible, however, because the statute
is shaped to move in this fashion. Two factors are essential. First, the statues must
lean forward so that they fall forward and any rocking motion also results in the
statue rolling on the front edge. Second, the statue bases must be shaped in a way to
provide an edge across which the statue can roll. The outlines of the bases for road
moai have a flat back edge and distinct rounded front edge (Fig. S11). Once moai
reached their final locations, however, prehistoric reshaping was necessary to allow
them to stand upright in a stable fashion on their constructed stone platforms.
Consequently, completed statues at the ahu could no longer be ‘walked.’
‘Walking’ the moai was achieved by creating inherent instability with its
forward lean. In transit, statues would not be able to stand on their own, and
without ropes or left stationary, they required stones, for example, wedged under
them to balance the center of mass. This observation seems to explain stone
arrangements discovered in excavations at the bases of moai on roads (see
Heyerdahl et al. 1989; Richards, et al. 2011). Thus, moai left standing along roads
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would have been highly unstable and prone to fall without significant further
modification of their form.
This observation rebuts early (Routledge 1919) and recently elaborated
(Richards et al. 2011) speculations that road moai are not fallen attempts at moving
a statue, but deliberate placements that mark a ritual path. The notion of a ritual
path, however, bears no impact on the issue of how the statues were transported,
since it has no direct empirical implications. Nor does such speculation explain why
road statues have their characteristic shape and lack eye sockets as found in all ahu
moai. Indeed, the presence of stones near the base of some of the road moai
locations is easily explained as relating to the process of transport. Since few statues
could have been moved from quarry to ahu in a single day, most would have had to
have been left standing between moving efforts. With the instability inherent in the
shape of statues and the relatively soft ground, this situation would have required
stabilization around the base as has been noted in excavations.
In our experiments, remarkably small teams were easily able to initiate
‘walking’ the 4.35 metric ton road statue replica. Even with our limited practical
experience moving the statue, a minimum of only 18 people could achieve ‘walking.’
The lower limit for the number of individuals derives from the number needed on
the sides to initiate rocking. The greatest initial energy input is the initiation of
rocking of the statue from a static upright position. We achieved this with four
individuals on each lateral rope. Once the statue began rocking, however, relatively
little input was required from each team of lateral rope handlers as the statue
motion conserved energy in its repeated transitions from kinetic to potential to
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kinetic energy. Ten people were needed to maintain the rear rope allowing the
statue to lean forward, but not fall to the ground. We were also able to easily ‘walk’
the statue uphill and downhill slopes as great as 6 degrees, turn and change
directions, as well as rotate the statue 180 degrees, requiring little, if any, more
space than its own base. While several near-falls were averted by quick cooperative
action of the rope handlers, we did drop the statue (face-forward) several times and
re-positioned it vertically using a large hydraulic crane. It would have been
impossible to resurrect the statue by the handlers using ropes alone. The great
difficulty of raising a fallen statue may explain why so many were abandoned along
the roads even though they were not broken.
The ‘walking’ covered ground rapidly. In one continuous effort we were able
to move the statue about 100 m in just 40 minutes. In contrast, Heyerdahl and Pavel
(Heyerdahl et al. 1989) estimated that a highly experienced crew might “wiggle” a
moai 100 meters in a full day. The relatively rapid rate we achieved in ‘walking’
suggests that statues could have been moved several kilometers across the island in
only a matter of weeks or months. It also follows that investment in statues was
likely a part-time effort requiring relatively small groups of people.
While large, our experimental moai replica is slightly smaller than the mean
size for statues across the island (ca. 4m). Many examples of moai that were
successfully moved are much larger, with the largest moved measuring about 10 m
in height. Unlike methods of movement using sleds, however, the ‘walking’ transport
method scales well as statues get larger. Larger statues are also taller, thus
providing proportionally greater leverage for the rope handlers on the sides. At the
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same time, taller statues become narrower overall and have increasingly longer and
thinner heads relative to their bodies (Fig S12, S13). This “bowling pin” shape not
only gives moai their characteristic look, but it also means their volume is decreased
more than if they were scaled proportionally in all dimensions and had a lower
center of mass. Each of these features reduces the effort that is required to tip the
statue enough to initiate its rocking and thus ‘walking’ motion.
Indeed, the larger the statues, the less likely they could have been moved in
any way other than ‘walking.’ The fact that statues get thinner with longer heads
means that they become more fragile and prone to breakage at the neck, as evident
by frequent neck breaks among the fallen road moai. Transporting large statues in a
horizontal fashion would put stress on the weakest point of the statue. The hyalotuff
that composes the statues is a relatively low-density material (Gioncada et al. 2011)
that has good compressive strength, but low shear strength. Thus, while vertical
objects can be successfully made from the hyalotuff, horizontal shapes would be
more prone to breakage. Even greater stresses would be placed on moai if they also
had to be levered up to a vertical position after transport. In this way, the shapes of
the road moai are clearly inappropriate for transport methods other than ‘walking’
upright.
4.1 Conclusions
The successful transport of hundreds of multi-ton statues on prehistoric
Easter Island has puzzled observers for centuries. Modern research has focused on
attempts such as hauling statues in horizontal positions on log contraptions with
accompanying rollers or sliders. Significantly, such efforts have ignored systematic
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variations in moai form. Statues were designed for movement and those fallen on
roads would have been further modified had they reached their destinations at ahu.
Moai patterns of breakage and wear, and positions on roads relative to slope are
also explained by a hypothesis of vertical ‘walking’ transport. As our research and
experiments illustrate, these observations explain the archaeological record for
transport, and allowed us to deduce a falsifiable hypothesis for how the statues
were moved.
In contrast to popular notions of sledges, rollers or sliders of trees, the
evidence shows that moai were specifically engineered to ‘walk’ in an upright
position achieved using only ropes, human labor, and simple cleared pathways. A
relatively small number of people are capable of moving a statue; just 18 rope
handlers could ‘walk’ a statue weighing more than 4.35 metric tons. The statue
evidence does not imply that a large population once existed on Easter, contrary to
earlier and now popularized notions (e.g., Brown 1924; Diamond 2005, 2007). Apart
from labor and engineering expertise, statue transport required only ropes; few if
any trees were required in statue transport. In fact, the primary vegetation on the
island was the now extinct palm, Jubaea chilensis or a close relative, and given palm
structure would likely not have been suitable for use in building contraptions or
making rollers that could support a great amount of weight. Material for ropes,
however, was abundant on the island as they were made from a woody shrub
(Triumfetta semitrioba that grows in disturbed habitats, see Metraux 1940).
Consequently, statue making and transport cannot be linked to deforestation, nor
can forest clearance for extensive cultivation of agricultural surplus to feed
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thousands of statue workers, as some have supposed (see Diamond 2005, 2007; Van
Tilburg and Ralston 2005:299). The evidence for moai carving and transport points
to activities by small-scale social groups rather than the product of laborers unified
under a powerful centralized chiefdom. Here monumentality does not imply large-
scale social organization as assumed for many cases worldwide. Instead, we see
moai carving and ‘walking’ as vivid expressions of costly signaling and evolutionary
bet hedging in a competitive environment. Multiple lines of evidence, including the
ingenious engineering to ‘walk’ statues, point to Easter Island as a remarkable
history of success in a most unlikely place.
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Acknowledgements
Funding for this project was provided by a grant from the National Geographic
Expeditions Council. We thank Pacific Islanders in Communications and Nippon
Television for their additional support. We thank the National Park staff on Rapa
Nui for assistance in the field. We thank Hannah Bloch and Fernando Baptista at
National Geographic Magazine for their excellent work on the July 2012 cover story
and artwork. We also thank Maria Awes, Andy Awes, the staff at Committee Films,
Max Beach, John Bredar, Robert DiNapoli, Brian Fagan, John Francis, Herman Ika,
Marc Kelly, John Morgan (Kualoa Ranch), Alex Morrison, John O’Connor, Ted
Ralston, Sergio Rapu, Jr., Timothy Rieth, Damion Sailors, Deborah Schechter, Sheela
Sharma, Francisco Torres Hochstetter, Enrique Tucki and Janet Wilmshurst for their
encouragement and generous support of our research. Finally, we thank the many
energetic, patient, and enthusiastic volunteers who helped us ‘walk’ a moai for the
first time in centuries.
Figures
Fig. 1: Moai and moai roads of Easter Island.
Fig. 2: Differences between road moai (in transit) and those modified moai found at
ahu. Road statues have a distinctive forward lean that places the center of
mass close to or slightly over the front edge. In addition, shoulder width
relative to the width of the base is close to 1.0 giving the statue a lower
center of mass. Ahu moai, in contrast, have a center of mass closer to the
center of base. Shoulder widths for ahu moai tend to be wider than the base
width, making the statue more top-heavy.
Fig. 3: Quarrying and positioning of moai. (A) On the upper slopes of Rano Raraku,
an extinct volcanic vent, bedrock hyalotuff is carved into a moai. The figure is
usually shaped from the top down leaving a narrow ‘keel’ connecting it to the
bedrock. (B) To move the statue from its quarried location, carvers broke the
keel and slid the moai downhill. Moai were then placed into standing
positions in pits excavated near or at the base of the slope. Here, carvers
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finished removing material from the back of the moai and prepared statues
for movement. (C) Statues were ‘walked’ out of the pit through excavated
openings to moai roads. (D) Not all statues were removed from pits; many
were left and following sedimentation only the heads and shoulders of these
are now visible on the quarry slopes. Statues were moved along road
features (E) that were prepared in advance. These roads often have a
concave shape that matched the arc of the front edge of the moai base. The
concavity of the roads provides constraints to keep the statue moving in the
intended direction. Occasionally, the roads have stretches of “curbstones”
(F) that line their edges. These stones may serve to keep sediment from
filling in the concave roadbed. Along the roads are found examples of statues
that failed in transport (G). These are often on the sides of roads
demonstrating that the roads are realigned for statue transport as needed.
Roads are kept relatively flat through the infilling of low areas and (H) and
carving through hills and ridges. Once at their destination statues are walked
up temporary ramps made of stone (I). The remains of these stone ramps
were often used to form “wings” on the lateral edges of the platform. Upon
reaching the top of the platform, the moai then are turned 180 degrees (J) to
face the ceremonial area that lay in front of the ahu. The moai are complete
once they are reshaped to make them stand upright and their eye sockets are
carved for coral insets.
Fig. 4: 3D model of a road moai reconstructed using structure from motion
algorithms in Microsoft Photosynth. The first step involves taking
uncontrolled overlapping photographs of the moai from as many points of
view as possible. Second, the photos are synthesized to form a single
representation of the moai surface using Microsoft Photosynth. The 3D
models are constructed using point cloud data extracted from the completed
photosynth.
Fig. 5: Scaled 3 m tall, 4.35 metric ton moai-replica ‘walking’ with teams handling
three ropes at Kualoa Ranch, Hawai`i. Using a mold created from the 3D
model, the replica is formed of a density-corrected concrete and retains the
same mass configuration as the road moai on which it is based.
Fig. 6: (A). Moai movement propelled by forward lean and side rocking using three
ropes; solid lines with arrows show force of ropes; dashed lines show
directions of movement. (B). Overhead view of moai walking motion.
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Supplementary Materials
Fig. S1: Terrain and moai along the south coast moai road. The top graph shows
the relative elevation of 7 km of mapped moai roads with the location and
position of statues. The bottom graph shows the relative slope of the
moai roads as measured using a 10-meter DEM derived from ASTER data
(http://www.gds.aster.ersdac.or.jp/gds_www2002/service_e/inq.c_e/set
_inq.c_e.html).
Fig. S2: (A) Comparison of the ratio of base width to body width for road moai
and those found at ahu. (B) Comparison of the ratio of base width to
shoulder width for road moai and those found at ahu.
Fig. S3: Moai broken in fragments as a result of falling. Note that the head is
detached from the body in a way that is consistent with falling over from
a standing position.
Figs. S4 and S5: Moai along a south coast road that fell and it appears that attempts
were made to re-erect them by lowering them into an excavated trench
and then ‘walking’ them out on a ramp. The moai, as a result, are now
found partially buried and at a forward angle.
Fig. S6: Replica moai being placed at Kualoa Ranch, Hawai’i for the experiment.
Fig. S7: Rope positions used for ‘walking’ the replica moai. Three ropes were
used, one in the back to manage the forward lean and two on the sides of
the statue to put the moai into motion.
Fig. S8: Replica moai being ‘walked’ by rope handlers at Kualoa Ranch, Hawai’i.
Fig. S9: Side view of replica moai during ‘walking.’ Note the forward lean of 9.5
degrees for the statue. This forward lean is caused by position of the
center of mass for the statue and is integral to its dynamic walking
motion.
Fig. S10: Tracks of the moai created during its ‘walking.’
Fig. S11: Outlines of the bases of road moai that are visible and for which total
height can be measured. The front of the statue is oriented up. The total
height of the statue is listed for each base outline.
Fig. S12: Ratio of head length to body length relative to overall statue height.
Heads become increasingly long and thin relative to bodies, as statues get
taller.
Fig. S13: (A) Left ear length as a function of overall statue height. As statues get
taller, heads become increasingly longer as a function of the shape
required for transport. (B). The ratio of left ear length relative to the total
height of road moai. Although statues are often described as having
extremely “long ears” indicative of an extinct cultural group, the length of
statue ears is simply a function of statue size and not a cultural feature.
Video S1: Video of Moai replica ‘walking,’ Kualoa Ranch, Hawai`i.
Table S1 Moai data. This table contains a list of positions and photos for all
identified road moai and their locations. Data were compiled by Zoe
Schumaker (A Geo-Spatial Database of the Monumental Statues (Moai) of
Easter Island, Chile, Unpublished MA Thesis, Department of Geography,
California State University Long Beach, Long Beach, CA) from survey
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work conducted by the authors and Britton L. Shepardson (Explaining
Temporal and Spatial Patterns of Energy Investment in the Prehistoric
Statuary of Rapa Nui. Unpublished Ph.D. Dissertation, Department of
Anthropology, University of Hawai'i at Manoa, 2006; Moai of Rapa Nui
(Easter Island, Chile), http://www.terevaka.net/dc, 2009).
Table S2: Position of moai relative to road slope for 51 of the road moai identified
on Easter Island. 1
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5.1 References
Brown, J.M. 1924. The Riddle of the Pacific. T. Fisher Unwin, London.
Diamond, J., 2005. Collapse: How Societies Choose to Fail or Succeed. Viking, New
York.
Diamond, J., 2007. Easter Island Revisited, Science 317, 1692.
Gioncada, G., Gonzalez-Ferran, O., Lezzerini, M., Mazzuoli, R., Bisson, M., and Rapu, S.,
2011. The Volcanic Rocks of Easter Island (Chile) and their Use for Moai
Sculptures. European Journal of Mineralogy 22, 855-867.
Heyerdahl, T., 1989. Easter Island: The Mystery Solved. Souvenir Press, London.
Heyerdahl, T., Skjølsvold, A., and Pavel, P., 1989. The ‘walking’ moai of Easter Island.
Occasional Papers of the Kon-Tiki Museum 1, 55.
Hunt, T.L., and Lipo, C.P., 2011. The Statues That Walked: Unraveling the Mystery of
Easter Island. Free Press, New York.
Lipo, C.P., and Hunt, T.L. 2005. Mapping prehistoric statue roads on Easter Island.
Antiquity 79, 309-317.
Love, C. 1990. How to make and move an Easter Island Statue, in State and
Perspectives of Scientific Research in Easter Island Culture, H. M. Esen-Bauer,
Ed. Courier Forschungsinstitut Senckenburg, Frankfurt, pp. 139-140.
Love, C., 2001. The Easter Island Moai Roads: An Excavation Project to Investigate
the Roads along which the Easter Islanders moved their Gigantic Ancestral
Statues. Unpublished report on File at the P. Sebastian Englert Museum of
Anthropology, Isla de Pascua, Chile.
Metraux, A., 1940. Ethnology of Easter Island. Bishop Museum, Honolulu.
Torres Hochstetter, F., Rapu Haoa, S., Lipo, C. P., and Hunt T.L., 2011. A Public
Database of Archaeological Resources on Easter Island (Rapa Nui) Using
Google Earth, Latin American Antiquity 22, 385-397.
Pavel, P. 1995. Reconstruction of the Transport of the Moai Statues and Pukao hats.
Rapa Nui Journal 9, 69-72.
Thomson, W.J., 1880. Report of the U.S. National Museum for the Year Ending June 30,
1880. U.S. Government Printing Office, Washington, D.C., pp. 497
Richards C., Croucher, K., Paoa, T., Parish, T., Tucki, E., and Welham, K., 2011. Road
My Body Goes: Re-creating Ancestors from Stone at the Great Moai Quarry
of Rano Raraku, Rapa Nui (Easter Island). World Archaeology 43, 191–210.
Routledge, K. The Mystery of Easter Island. Stifton, Praed & Co., London, (1919).
Van Tilburg, J. and Ralston, T., 2005. Megaliths and Mariners: experimental
archaeology on Easter Island, in Onward and Upward! Papers in Honor of
Clement W. Meighan, K. Johnson, Ed. pp. 279-303.
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Fig. 1: Moai and moai roads of Easter Island.
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Fig. 2: Changes between road moai (in transit) and modified moai found at ahu.
Road statues have a distinctive forward lean that places the center of mass close to
or slightly over the front edge. In addition, shoulder width relative to the width of
the base is close to 1.0 giving the statue a lower center of mass. Ahu moai, in
contrast, have a center of mass closer to the center of base. Shoulder widths for ahu
moai tend to be wider than the base width, making the statue more top-heavy.
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Fig. 3: Quarrying and positioning of moai. (A) On the upper slopes of Rano Raraku,
an extinct volcanic vent, bedrock hyalotuff is carved into a moai. The figure is
shaped from the top down leaving a narrow ‘keel’ connecting it to the bedrock. (B)
To move the statue from its quarried location, carvers broke the keel and slid the
moai downhill. Moai were then rotated into standing positions in pits excavated at
the base of the slope. Here, carvers finished removing material from the back of the
moai and prepared statues for movement. (C) Statues were ‘walked’ out of the pit
through excavated openings to moai roads. (D) Not all statues were removed from
pits; many were left and following sedimentation only the heads and shoulders of
these are now visible on the quarry slopes. Statues were moved along road features
(E) that were prepared in advance. These roads often have a concave shape that
matched the arc of the front edge of the moai base. The concavity of the roads
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provides constraints to keep the statue moving in the intended direction.
Occasionally, the roads have stretches of “curbstones” (F) that line their edges.
These stones may serve to keep sediment from filling in the concave roadbed. Along
the roads are found examples of statues that failed during transport (G). These are
often on the sides of roads demonstrating that the roads are realigned for every
statue transport. Roads are kept relatively flat through the in-filling of low areas
and (H) and carving through hills and ridges. Once at their destination statues are
walked up temporary ramps made of stone (I). The remains of these stone ramps
were often used to form “wings” on the lateral edges of the platform. Upon reaching
the top of the platform, the moai then are turned 180 degrees (J) to face the
ceremonial area that lay in front of the ahu. The moai are complete once they are
reshaped to make them stand upright and their eye sockets are carved for coral
insets.
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Fig. 4: 3D model of a road moai reconstructed using structure from motion
algorithms in Microsoft Photosynth. The first step involves taking uncontrolled
overlapping photographs of the moai from as many points of view as possible.
Second, the photos are synthesized to form a single representation of the moai
surface using Microsoft Photosynth. The 3D models are constructed using point
cloud data extracted from the completed photosynth.
2. Structure from
motion algorithms
used to extract point-
cloud data of moai
surface.
3. Three dimensional
model of Moai
12-220-01.
1. Digital photos of Moai
12-220-01 taken in an uncon-
strained but overlapping
fashion.
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Fig. 5: Scaled 3 m tall, 4.35 metric ton moai-replica ‘walking’ with teams handling
three ropes at Kualoa Ranch, Hawai`i. Using a mold created from the 3D model, the
replica is formed of a density-corrected concrete and retains the same mass
configuration as the road moai on which it is based.
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Fig. 6: (A). Moai movement propelled by forward lean and side rocking using three
ropes; solid lines with arrows show force of ropes; dashed lines show directions of
movement. (B). Overhead view of moai walking motion.
A B
