Underwater ritual offerings in the Island of the Sun and the formation of the Tiwanaku state

Abstract

Significance
Ritual and religion are significant factors in primary or archaic state formation. These beliefs and practices not only legitimize these new political organizations in their ability to control supernatural forces, but also incentivize intragroup cooperation by punishing freeloading and rewarding cooperative behavior. Recent archaeological excavations from an underwater ceremonial location near the Island of the Sun in Lake Titicaca have revealed the remarkable constituent elements of repetitive rituals practiced by the Tiwanaku state between the 8th and 10th centuries CE. Evidence of animal sacrifice and high-value offerings of vessels, gold, shells, and lapidary stones on a strategically located reef illustrates how power was consolidated in one of the earliest Andean states.

Full text

Underwater ritual offerings in the Island of the Sun and
the formation of the Tiwanaku state
Christophe Delaere
a,b,1
, José M. Capriles
c
, and Charles Stanish
d,1
a
Oxford Centre for Maritime Archaeology, University of Oxford, Oxford OX1 2JD, United Kingdom;
b
Centre de Recherches en Archéologie et Patrimoine,
Université Libre de Bruxelles, 1050 Brussels, Belgium;
c
Department of Anthropology, The Pennsylvania State University, University Park, PA 16802;
and
d
Institute for the Advanced Study of Culture and the Environment, University of South Florida, Tampa, FL 33620
Contributed by Charles Stanish, February 27, 2019 (sent for review December 6, 2018; reviewed by John Janusek and Joyce Marcus)
Considerable debate surrounds the economic, political, and ideolog-
ical systems that constitute primary state formation. Theoretical and
empirical research emphasize the role of religion as a significant insti-
tution for promoting the consolidation and reproduction of archaic
states. The Tiwanaku state developed in the Lake Titicaca Basin
between the 5th and 12th centuries CE and extended its influence
over much of the south-central Andes of South America. We report
on recent discoveries from the first systematic underwater archaeo-
logical excavations in the Khoa Reef near the Island of the Sun,
Bolivia. The depositional context and compositional properties of
offerings consisting of ceramic feline incense burners, killed juvenile
llamas, and sumptuary metal, shell, and lapidary ornaments allow us
to reconstruct the structure and significance of cyclically repeated
state rituals. Using new theoretical tools, we explain the role of these
rituals in promoting the consolidation of the Tiwanaku polity.
Andes
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collective action
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religion
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state formation
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underwater archaeology
The Lake Titicaca Basin covers ∼8,560 km
2
and is among the
few regions in the world that experienced primary state for-
mation (1, 2). Shaped by a geological fault that separates Andean
mountains in two cordilleras, this “inland sea”favored human
settlement by creating a unique ecosystem in the middle of a
semiarid territory (3–5). The Inca (1400–1532 CE) acknowledged
Lake Titicaca as their place of origin, and at the time of the Spanish
conquest, settlements on its shores sustained one of the largest
population densities in the Andes (6). Colonial Spanish chroniclers
documented the vast Inca pilgrimage ceremonial complex built
between Copacabana and the Island of the Sun and compiled sev-
eral legends of underwater deities and offerings (7–10).
Archaeological research conducted over the last century has
helped further explore the deeper history of this region and ex-
amine key periods of cultural change, including the emergence of
agricultural villages (∼1500 BCE), development of regional
polities (200 BCE–500 CE), and formation of the Tiwanaku state
(500–1100 CE) (11–13). A prominent research question that has
framed much of this scholarship is how the archaic state of
Tiwanaku emerged and expanded across the basin during the
first millennium CE (14–17). Although archaeological research
has facilitated a better understanding of the evolution of settle-
ment patterns, social complexity, technology, and human–envi-
ronment interactions over time, the lake level has fluctuated
considerably over time, and a rich archaeological landscape lies
hidden below the water’s surface (18–20).
In this paper, we report recent archaeological research from the
Khoa Reef, a submerged offering location that contains evidence of
Tiwanaku (500–1100 CE) ceremonies (21). We use the evidence
from the Khoa Reef to infer the structure of religious ceremonies
related to Lake Titicaca and discuss the roles of ritual and religion
in integrating and reproducing this primary state formation.
Religion, Collective Action, and the Evolutionary
Significance of Ritual
A substantial body of research identifies repetitive rituals in emer-
gent states as a key factor in the evolution of political complexity
(22–24). The role of religion (belief systems) and ritual (behaviors)
is seen as largely related to controlling and manipulating super-
natural forces, as well as facilitating group cohesion and solidarity
(25, 26). It has been postulated that the greater the power, the
greater the social control by an elite. However, more recent the-
oretical and empirical research into the evolution of religion
suggests a subtler and more critical role played by emergent norms
and values institutionalized by rituals (27, 28). Specifically,
religious-mediated prosociality emerged in the context of in-
creasing population size and social complexity, when decisions
about collective action and opportunities for freeloading be-
havior became common. Religious deities that acted as “super-
natural punishers”provided incentives for individuals to engage
in cooperation and follow specific moral codes. Similarly, those
same supernatural forces could reward individuals who behaved
for the benefit of the community. Costly ritual behavior would
effectively signal intragroup trust. Therefore, religious beliefs man-
ifested in repetitive rituals play a critical role in ensuring intragroup
cooperation, particularly in the absence of more effective secular
norm-enforcing institutions.
Rituals should have a direct role in signaling cooperative in-
tent among group members (29). The cost of the ritual should be
proportional to the effectiveness of norms of trust among group
members. This is particularly significant for group members with
weak or no kinship ties. Ethnographic and experimental cross-
cultural research suggests that the larger the population, the
greater the importance of moralizing deities and, consequently,
the need for costly rituals. Therefore, archaeological evidence of
rituals provides empirical evidence of this process of how religion
Significance
Ritual and religion are significant factors in primary or archaic
state formation. These beliefs and practices not only legitimize
these new political organizations in their ability to control su-
pernatural forces, but also incentivize intragroup cooperation
by punishing freeloading and rewarding cooperative behavior.
Recent archaeological excavations from an underwater cere-
monial location near the Island of the Sun in Lake Titicaca have
revealed the remarkable constituent elements of repetitive
rituals practiced by the Tiwanaku state between the 8th and
10th centuries CE. Evidence of animal sacrifice and high-value
offerings of vessels, gold, shells, and lapidary stones on a
strategically located reef illustrates how power was consoli-
dated in one of the earliest Andean states.
Author contributions: C.D. designed research; C.D. and J.M.C. performed research; C.D.
and J.M.C. contributed new reagents/analytic tools; C.D., J.M.C., and C.S. analyzed data;
and C.D., J.M.C., and C.S. wrote the paper.
Reviewers: J.J., Vanderbilt University; and J.M., University of Michigan.
The authors declare no conflict of interest.
Published under the PNAS license.
1
To whom correspondence may be addressed. Email: delaerechristophe@gmail.com or
stanish@usf.edu.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.
1073/pnas.1820749116/-/DCSupplemental.
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evolved and became a prominent feature of archaic states, fa-
cilitating intragroup cooperation in tasks ranging from organized
intergroup violence to monumental construction (29, 30).
In the south-central Andes, the origins of the Tiwanaku state
are related to the expansion of a religious complex that featured
distinctive art and architectural styles (31). The state iconography
included a rayed front-faced deity holding staffs, often bearing
sharp teeth and fangs and escorted by a series of attendants
bearing either zoomorphic heads or appendages, as well as trophy
heads. At the same time, many monumental pyramids and tem-
ples in the Tiwanaku capital and other regional centers featured
wide-open terraces where multitudes could have participated in
large-scale ceremonies (32). Smaller structures within these larger
buildings suggest that specialized rituals also occurred in closed
settings, possibly for and by an emerging clergy elite.
While Tiwanaku’s iconography could support the notion of a
supernatural punisher, and its architecture the importance of
collective ceremonies and pilgrimage, well-documented evidence
of rituals for making inferences about the content and meaning
of the religious behavior is scarce. Therefore, the evidence rep-
resented in the Khoa Reef reported here provides a singular
example of how in a context of increasing population size and
political complexity, rituals would have emphasized the re-
production of a pan-regional moral code signaling appropriate
civic and economic behavior.
The Khoa Reef
The Tiwanaku capital is located in a valley in the southeastern
portion of the basin. As the state grew, it eventually controlled
the entire Lake Titicaca drainage and beyond (33, 34). The Khoa
Reef is part of an archipelago of small islands on the northwestern
end of the Island of the Sun and as such, has an unobstructed view
of a large portion of Lake Titicaca’s shoreline and surrounding
mountains (Fig. 1A) (35, 36). In September 1977, amateur Japa-
nese divers discovered the reef and retrieved fragments of ceramic
feline incense burners and andesite offering boxes containing
miniature figurines fashioned from shell of the thorny oyster
(Spondylus sp.) (Fig. 1B). A follow-up Bolivian-Japanese expedi-
tion in 1988 found more artifacts, as did a subsequent 1989–1992
expedition sponsored by the National Geographic Society and
directed by Johan Reinhard (36). In total, 385 archaeological of-
ferings consisting of camelid bone, ceramic, stone, gold, and silver
figurines were recovered from the Khoa Reef (37). Whereas the
offerings presented in stone boxes are of clear Inca origin, many
offerings correspond to Tiwanaku, but the specific association of
each was problematic. Moreover, because of sediment accumu-
lation and stone collapse, the reef potentially contained more
offerings deeper within the sediment. In 2013, we conducted a
new phase of underwater explorations reported here (38).
Results
The distribution of archaeological materials in the Khoa Reef covers
an area of ∼2,400 m
2
. In addition to a new topographic survey of the
reef, we conducted three excavations positioned in relation to the
reef’s topography and previous findings. We emphasized areas that
were protected from erosion and thus potentially containing well-
preserved stratigraphy and cultural contexts (Table 1).
Unit 1 (8 m
2
) was situated at 5–7 m below the surface in the
largest fault, located in the eastern sector of the site (Fig. 2). We
completely excavated this unit up to bedrock, and it represents a
relatively undisturbed cultural context associated with Tiwanaku
offerings. The sedimentary accumulation proved to be very dense
and was characterized by a compact agglomerate of collapsing
stones within which the artifacts lay. With the exception of a few
materials, the taphonomy and stratigraphy suggested that the
original offering deposits were structurally affected by cryoclastic
stone collapse and subaquatic erosion but otherwise remained
submerged. Indeed, it seems like the offerings were intentionally
made underwater. With the exception of five modern vasijas
found near the surface, all of the ceramic fragments belonged to
the same vessel type, a Tiwanaku feline (puma) incense burner
(39). At least 13 incense burners were recovered, including a few
semicomplete burners that were too eroded to preserve paint,
slips, or traces of soot on their surfaces. Nevertheless, fragments of
charcoal were present within the excavated deposits.
In these same deposits, we found 10 gold ornaments, including
a pectoral with a Tiwanaku-style ichthyomorphic engraving, a
“massive”square pectoral, a 30-cm-long band, and numerous
small, perforated gold leaves (SI Appendix,Fig.S1A). Some of
these items were found in good contextual association, such as at
the bottom of Unit 1, where underneath a stone collapse lay a
perforated corrugated gold leaf still attached to a leather frag-
ment, fragments of incense burners with well-preserved slip, pol-
ished green-colored glacier moraine stones, and well-preserved
camelid bones, including a possible polished instrument.
The recovered bone specimens included those of camelids,
teal, cormorant, anurans (including Lake Titicaca water frogs),
Fig. 1. (A) Location of the Khoa Reef within Lake Titicaca. (B) Profile of the
reef in relation to Khoa Island. (C) Khoa Reef, including underwater exca-
vations and location of ceramic findings from previous explorations.
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killifish, and catfish (SI Appendix, Table S1) Camelids are the
only species alien to the reef ecosystem. Osteometric analysis
and the presence of diagnostic incisors suggests most of these
correspond to anatomically complete (as most bones were rep-
resented) domesticated llamas (Lama glama), which were likely
killed during deposition. We estimate the presence of at least
one infantile (age ∼6 mo), and three juvenile (age <15 mo)
llamas in the assemblage. Most fish, amphibian, and bird bones
were likely deposited naturally within this submerged ecosystem.
Unit 2 (4 m
2
) was positioned 5.5 m below the surface in a fault
located on the southeastern part of the site, at the junction be-
tween the main massif and the secondary massif. This excavation
proved to be culturally sterile except for a small gold leaf and a
few camelid and frog bones.
Unit 3 (4 m
2
) was located 5.5 m below the surface in the
western flank of the reef, near the base of a steep natural wall
that forms a sedimentary plateau (Fig. 3A). This unit included
two stratigraphically distinct levels separated by ∼30 cm of
mostly sterile sediment. Whereas the upper level contained Inca
materials disturbed by previous divers, the lower level included
mostly Tiwanaku materials located below a stone collapse. These
deposits lay within a plateau at the base of the vertical wall of the
western side of the reef, where a small ditch was formed. Re-
current stone collapses and loose sediment trapped many ar-
chaeological materials in this ditch, including numerous small
metal, shell, and lapidary ornamental artifacts (SI Appendix,
Fig. S2).
All of the ceramic fragments (n=472) correspond to Tiwanaku
feline incense burners, with the exception of two possibly
Late Formative fragments, and suggest the presence of at least
eight distinct vessels. In addition to camelids, aquatic birds,
amphibians, and fish, a possible feline canine was recovered. As
in units 1 and 2, most nonmammalian bones were deposited as
part of natural taphonomic processes, but some fish bones were
burned, suggesting that they might have been consumed as food.
Based on element siding and aging, we estimate that at least
three juvenile llamas were present. The representation of most
skeletal elements suggests that these animals were complete and
possibly killed at the time of deposition.
In total, we recovered 19 metal ornaments, including nine zoo-
morphic llama-puma plaques (commonly referred to as wariwillkas),
a gold medallion, an L-shaped plaque, two thin bands, and several
perforated gold leaves (SI Appendix,Fig.S1B). The medallion is
strikingly similar to another medallion recovered by Reinhard in
the reef (37), and both represent the typical Tiwanaku-style rayed-
face deity (Fig. 3B). The L-shaped plaque, although fragmentary,
contains geometric stepped motifs that end in alternating puma
and condor silhouettes. Five Spondylus shell items, including a
small remarkable camelid figurine and a complete but scraped
thorny oyster clam, were also recovered with these materials. Fi-
nally, we recovered a few semiprecious stone artifacts, including a
green turquoise stone pendant, a small lapis lazuli puma figurine,
and a batch of small green-colored glacier moraine stones.
Eight AMS radiocarbon dates were analyzed from the Khoa
Reef excavations, including four from Unit 1 and four from Unit
3 (Table 2). Four of these dates were on charcoal (which was
relatively common in the deposits), and four were on bone col-
lagen. With the exception of an uncertain date from Unit 1 that
dates a camelid bone to the Late Formative, the overlapping
dates between the two areas verifies that the offerings found in
different parts of the reef were roughly contemporary. More
specifically, Bayesian modeling of the seven dates as part of a
single phase in Oxcal 4.3 (40) using the SHCal13 calibration
curve (41) suggests that the offerings were deposited between
794 ±63 and 964 ±50 CE, a relatively narrow temporal frame
(SI Appendix, Fig. S3). This time frame is consistent with the
expansion of the state during the Tiwanaku IV and V phases, as
well as with the temporal distribution of feline incense burners in
the Tiwanaku capital itself (38, 39).
Discussion
Structure of the Offerings at Khoa. The extraordinarily rich con-
textual associations of the archaeological materials recovered at
Khoa allow us to reconstruct the nature and significance of these
Tiwanaku rituals in relation to state emergence and consolida-
tion. The rayed-face motif on two gold medallions indicates that
the offerings explicitly addressed the main mythical figure in the
religious iconography of Tiwanaku (Fig. 3B). The sumptuary
gold, shell, and lapidary ornaments also highlight the costly
display and disposal of wealth during the ceremonies, because
these materials were among the most prestigious available in the
Andes. For instance, the Spondylus shells had to be obtained by
trade from the warm ocean waters of the Ecuadorian coast,
nearly 2,000 km away. It is likely that these items were attached
to organic textiles, feathers, or leather components as part of
ritual bundles, which were common in burial and other Tiwanaku
ritual contexts (42–44). In fact, leather fragments and dark-color
staining on metals were recovered from the reef, and some of
the perforated gold sheets might have been attached to the
llamas themselves as ear tassels and ritual regalia. Indeed, the
bones of at least seven immature llamas complement the re-
mains of approximately 10 animals recovered from previous
explorations. The stratigraphic and radiocarbon data from these
Table 1. Tiwanaku and Inca offerings recovered from Khoa
Artifacts 1977–1992 Unit 1 Unit 2 Unit 3 Total
Tiwanaku
Ceramic vessels 131 560 0 472 1,163
Camelid bones 184 268 1 115 568
Shell artifacts 6 1 0 5 12
Gold artifacts 4 10 0 19 33
Lapidary artifacts 0 17 0 16 33
Stone anchors 2 1 0 0 3
Subtotal 327 857 1 627 1,812
Inca
Andesite boxes 28 0 0 0 28
Box covers 7 0 0 0 7
Gold artifacts 10 0 1 1 12
Silver artifacts 8 0 0 1 9
Shell artifacts 5 0 0 0 5
Subtotal 58 0 1 2 61
Grand total 385 857 2 629 1,873
Fig. 2. Unit 1 showing the distribution of Tiwanaku incense burner specimens.
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remains verify that most, if not all, of the llamas were deposited
during Tiwanaku times.
Similarly, we retrieved more than 1,000 ceramic fragments
that, along with the 131 (15 kg) whole and fragmented remains
discovered in previous explorations, account for approximately
37 feline modeled incense burners, which together make Khoa
the site with the highest frequency of these vessels in the entire
basin. Previous scholars have argued that unlike the ceramic keru
cup, which is frequently found in burial sites marking expansion
of the Tiwanaku state across a very wide area, the presence of
puma incense burners is one of the most diagnostic traits for the
presence of Tiwanaku within the Lake Titicaca Basin (45–47).
The high frequency along with the restricted technological and
stylistic variability of the paste, temper, and form of the vessels
found at Khoa suggest that they might have originated from
different workshops within the same broad region, verifying that
the puma incense burners are diagnostic of Tiwanaku-related
ritual contexts and direct territorial control within the Titicaca
Basin itself (34, 48, 49).
By comparing Units 1 (well-preserved but heterogeneous as-
sembly) and 3 (fragmentary artifacts but homogeneous assembly)
with the superficial findings (heterogeneous fragmentation and
assembly), we can reconstruct repeated offerings performed at
Khoa during the Tiwanaku period (Fig. 4). The sacrifice of an
immature and possibly decorated llama joined 4 ±1 puma ce-
ramic incense burners and a bundle of small miniature offer-
ings (SI Appendix, Fig. S4). The quantity (n=9) of wariwillka
zoomorphic gold sheets in the excavations is consistent with the
number of identified incense burners and juvenile llamas. The
finding of many semicomplete vessels suggests that the cere-
monies at Khoa occurred above the waterline, followed by ritual
underwater interment. The ritual sacrifice of llamas along with
their ritual interment with high-status goods, such as finely
crafted vessels and miniatures made on exotic materials, were
frequent practices carried out by Tiwanaku and its neighboring
rival state Wari (50–52). In the case of Khoa, officiating au-
thorities likely deposited the offerings during rituals held from
boats, as suggested by the presence of andesite anchors, such as
the one discovered in Unit 1 and four others discovered during
previous explorations. The proximity of all of the components of
the offerings suggests an intention to keep the assemblage as
integrated as much as possible. In this restricted ceremony, there
was no “ritual destruction”of vessels, and the ubiquitous pres-
ence of charcoal in the excavated contexts confirms that the
ceremonies involved burning.
The Meaning of the Offerings: Tiwanaku at the Island of the Sun.
Khoa preserves evidence of activities carried out in relation to
other submerged as well as nonsubmerged spaces. The finding of
contemporary submerged Tiwanaku sites such as Punku, a port
situated in the southeastern shore of the Island of the Sun,
suggests that when the offerings were made, a portion of the
Khoa Reef might have been above water (21). Indeed, the
Tiwanaku’s presence in the Island of the Sun was substantial and
included more than a dozen sites, including Chucaripupata, a
puma-shaped ceremonial complex situated near the northwest-
ern shore (53). On a broader scale, the Island of the Sun and
especially the Khoa Reef are positioned near the geographic
center of the lake, and thus it is not surprising that the emerging
Tiwanaku elite appropriated this space for costly and highly
charged ceremonies. While access to the ceremonies performed
at the reef must have been difficult and reserved for a selected
elite group (given the site’s small, rugged, and probably sacred
nature), residents of surrounding villages might have witnessed
the ceremonies from afar. The construction of buildings in the
Tiwanaku capital and its regional centers resembles this sacred/
profane and public/reserved structuralist dialectic.
The emergence of institutionalized religion in a context of an
expanding state polity often involves the appearance of special-
ized architecture, material culture, iconography, and full-time
religious specialists. Priests controlled the esoteric knowledge of
the meaning of the iconography, the organization of material
culture, and how ceremonies should be officiated (54). The Khoa
offerings are associated with the central figure of the icono-
graphic repertoire, as well as with the attributes of prestige and
power represented in the public spaces and the monumental
complexes of Tiwanaku’s main sites. The process of “sacralizing”
certain components of these spaces is one among many strategies
by which religious authorities orchestrated and legitimized in-
stitutional change. By the time the Tiwanaku state emerged, the
entire shore around Lake Titicaca was densely populated. The
lake was not a border, but rather a vector of communication
between the different parts of the basin. Indeed, people were
Table 2. Accelerator mass spectrometry radiocarbon dates of Khoa
Lab code
14
C BP Error Material Provenience Age cal CE (68.2%) Age cal CE (95.4%)
UBA-23687 1138 26 Charcoal Unit 1, locus 53 898–991 891–1014
UBA-23685 1161 26 Charcoal Unit 3, locus 43 895–980 887–989
UBA-23688 1197 25 Charcoal Unit 3, locus 71 879–968 779–983
UBA-27009 1218 33 Camelid bone (collagen) Unit 3, locus 51 777–956 771–970
UBA-23686 1251 32 Charcoal Unit 1, locus 44 774–880 689–950
UBA-27008 1256 41 Camelid bone (collagen) Unit 3, locus 29 772–880 682–959
UBA-27006 1301 40 Orestias bone (collagen) Unit 1, locus 72 682–843 679–876
UBA-27005 2212 40 Camelid bone (collagen) Unit 1, locus 31 355–148 BCE 367–108 BCE
Note: All dates calibrated using Oxcal 4.3 (40) and the SHCAL13 (41).
Fig. 3. (A) Profile of Unit 3. (B) Metal objects with Tiwanaku iconography.
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boating to the Island of the Sun as early as 2150 BCE and
probably much earlier (55). Within this landscape, certain points
of attraction, such as Khoa in the northwestern extreme of the
Island of the Sun and near the geographic center of the lake,
held strategic positions, acquired sacred roles, and became the
perfect loci for costly religious practices.
Conclusions
Religion and its associated rituals are keystones of emerging
complex societies, providing the moral and institutional structure
for enforcing trust, promoting cooperation, and punishing free-
loading. The emergence and consolidation of the Tiwanaku state
was strongly related to the growth and expansion of a religion
manifested in a specific iconography and architecture and the
rituals that bound them together. More than a mere cult in an
extreme location, the ceremonies at Khoa reflect a complex in-
teraction of being situated at the center of the lake while being
carried out by a small elite group. Given its difficult accessibility
but widespread visibility, it was a privileged and exclusive space
of interaction controlled by a specialized elite class. The quality
and quantity of offerings made at the submerged site placed the
reef at the center of the Tiwanaku people’s beliefs and ritual
landscape. They also emphasize the display of powerful forces,
as the dissemination of rituals focused on the representation of
a rayed-faced deity and smoke-gusting pumas, the sacrifice of
juvenile llamas, and the conspicuous disposal of wealth. Much
like wealth acquisition and transmission, these activities are
profitably understood to represent increasingly institutional-
ized hierarchical relationships that coopted the supernatural
authority to punish while simultaneously encouraging pan-
regional cooperation.
Materials and Methods
Our research at Khoa consisted of 19 days of research between June 26 and
July 27, 2013. This work introduced the first excavations in the lake sediment
itself (38). Fieldwork included sonar scanning and underwater 3D photo-
grammetric mapping of the reef and excavations. The location of Reinhard’s
(36) reference datum (metal stakes: A–F) allowed us to relocate earlier
findings in a geographic information system, as well as to place our three
new excavation units in relation to the materials recovered by previous re-
search (Fig. 1C). At the operational level, the various dives in 2013 were
devoted to determining the morphology of the reef (topography) and the
sedimentary accumulation in relation to the artifacts (stratigraphy). During
the excavations, archaeologists operated a water dredge powered by an
engine pump to excavate the sediment and documented stratigraphic dis-
continuities in deposition. Depths were determined with reference to eleva-
tion 3,809.7 m (lake level). Archaeological materials (e.g., bone, ceramics,
lithics, metal, charcoal), were recorded in situ or retrieved in 1-cm screens and
sorted from natural sediment using a provenience (locus) recording system.
We measured and weighed each archaeological specimen recovered during
excavations. We identified every bone specimen to its most specific taxonomic
and anatomic category and also inspected it for natural and nonnatural modi-
fications (56, 57). We reconstituted the minimum number of individuals for
camelids based on skeletal element side, size, and epiphyseal fusion. We also
determined the minimum number of ceramic vessels by relying on diagnostic
fragments and weight. The incense burners have hyperboloid shapes, annular
bases, and modeled feline zoomorphic heads and tails joined by six scalloped
rim edges. Based on the intact specimens discovered, we estimated the average
weight of a feline incense burner as ∼1,300 g. To refine the chronology of de-
posits, we analyzed both charcoal and bone samples at the KIK/IRPA (Koninklijk
Instituut voor het Kunstpatrimonium–Institut Royal du Patrimoine Artistique)
accelerator mass spectrometry radiocarbon dating facility.
In this project, the notion of space and time is inseparable from the concept
of cultural context. Stratigraphic excavations were aimed at distinguishing the
Tiwanaku, Inca, and other offerings that the site might have received over
Fig. 4. General composition of offerings at Khoa Reef. Image courtesy of Teddy Seguin (photographer).
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time; therefore,it was essential to isolate the Tiwanaku sacred space from that
documentedby subsequent offering practices and to analyze the depositsfrom
both the horizontal spatial distribution and vertical stratigraphic deposition of
the remains (21). Here we focus on the Tiwanaku offerings because these
were recovered within the stratigraphic deposits, whereas the Inca offerings
consisted of an assembly of sealed stone boxes containing miniature figurines,
none of which were recovered during the excavations. The variability of of-
ferings between these two traditions indicates differences not only in the
temporal and stratigraphic dimensions, but also in the rituals and belief sys-
tems associated with these practices.
ACKNOWLEDGMENTS. We acknowledge the support of the authorities of
Lake Titicaca and the Bolivian Ministry of Cultures and Tourism for making
this project possible. We also thank Peter Eeckhout, Ruth Fontenla Alvarez,
Maria Filomena Guerra, Eliana Flores Bedregal, Laurent Masselin, Velia
Mendoza, Marcial Medina Huanca, and the entire team of archaeologists,
divers, conservators, curators, and technicians from Bolivia, Belgium, France,
Spain, and Italy for their help in various stages of our fieldwork and analysis.
Finally, we thank the editors and reviewers of PNAS, including Joyce Marcus
and John Janusek, for their thoughtful comments on an earlier version of
this article.
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