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Journal of Archaeological Science 39 (2012) 3361e3370

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Journal of Archaeological Science

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Taphonomic analysis of Bronze Age burials in Mongolian khirigsuurs

Judith Littleton a,*, Bruce Floyd a, Bruno Frohlich b, Michael Dickson a, Tsend Amgalantögs c,Sarah Karstens a, Kristen Pearlstein b

aAnthropology Department, University of Auckland, Auckland, New ZealandbAnthropology, National Museum of Natural History, Washington, DC, USAcMongolian Academy of Sciences, Institute of Archaeology, Ulaanbaatar, Mongolia

a r t i c l e i n f o

Article history:Received 4 August 2011Received in revised form4 June 2012Accepted 8 June 2012

Keywords:Human taphonomyKhirigsuursBronze AgeMongoliaMortuary practice

* Corresponding author. Anthropology DepartmePrivate Mail Bag 92019, Auckland, New Zealand. Te93737441.

E-mail address: j.littleton@auckland.ac.nz (J. Little

0305-4403/$ e see front matter � 2012 Elsevier Ltd.http://dx.doi.org/10.1016/j.jas.2012.06.004

a b s t r a c t

The role of the distinctive Mongolian Bronze Age mounds (khirigsuurs) has been debated for many yearswith authors divided over their funerary role. Interpretation of the presence or absence of human bonehas been central to this debate. In this paper, we undertake a systematic analysis of human taphonomy atthe Khövsgöl site to explain why mounds appear “empty”. In doing so we demonstrate a strong statisticalrelationship between the preservation of human bone and intrinsic circumstances related to the moundlocations and the age of the deceased. In contrast, patterns of disarticulation are strongly correlated withhuman disturbance of graves post-mortem. We argue that statistical analysis of burials, recognising thecontinuity of potential preservation from nil to complete serves to explain the relative importance oftaphonomic agents but allows for predictive analysis of where remains are most likely to be preserved.Such approaches are important in shifting studies of human taphonomy from a descriptive to analyticalendeavour.

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1. Introduction

From the related fields of “anthropologie de terrain” (Duday,2006) and forensic taphonomy (Haglund and Sorg, 1997a,b), therehas been a growing body of work dealing with increasinglyexacting descriptions of mortuary practices and post-mortemmanipulation. However, one of the major difficulties dealing withburials and with human remains is how to interpret their absence.This seems like a simple issue: a grave after all is generally fora body but as archaeologists have pointed out there are cenotaphs,the empty graves of Scandinavia (Haringe-Friberg, 2005), a range offunerary and extra-funerary process (Weiss-Krejci, 2011) and, evenmore commonly, structures which, while appearing monumentalin purpose, have an uncertain primary function. It is this later classof structures that we address in this paper.

While khirigsuurs, the distinctive stone built mounds of theMongolian steppe, are the fundamental monument associated withthe late Bronze Age, there has beenmore than 20 years of argumentoverwhether thesemonuments are purelymonumental orwhethertheir primary function, and hence their symbolic resonance, is as

nt, University of Auckland,l.: þ64 93737599; fax: þ64

ton).

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burial places (Cybiktarov, 2003; Jacobson, 1993). In this paper weuse an approach proposed by Lieverse et al. (2006) to demonstratethe primary funerary function of khirigsuurs and to explain howsuch contradictory interpretations have arisen froma complex set oftaphonomic processes. In doing so,wepropose a systematic analysisof skeletal preservation that recognises the continuum in potentialpreservation fromnil to complete. Undertaking such an analysis notonly highlights the relative role of human, animal and physicalinfluences on remains but also allows for predictive analysis ofwhere remains are most likely to be preserved.

1.1. Khirigsuurs, dating and distribution

Khirigsuurs are built stone mounds sometimes incorporatingadditional features such as fences and pavements (Wright, 2007).They are distributed across northern, central and westernMongoliaand the Baikal region of Siberia (Fig. 1). They are part of a larger,long-lived Northeast Asia tradition of monument building datingfrom between 5000 and 1000 BC and share features with thekurgan mounds which comprise a wooden roof chamber coveredby an earthen or stone mound in the Eurasian steppe (Cybiktarov,2003).

The khirigsuurs are built of local stone and vary greatly in size,many less than 10 m square in total foot print (Fig. 2) but witha high variability of associated structures such as fences and

Fig. 1. The distribution of khirigsuurs (based on Cybiktarov, 2003) and provincial locations of their excavation in Mongolia. Khirigsuurs are not found in eastern or the very north ofMongolia.

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e33703362

external mounds, which can cover many hectares (Fitzhugh, 2009;Wright, 2007). The study of khirigsuurs, however, is madecomplicated by a confusing terminology. Some authors (e.g. Allardand Erdenebaatar, 2005; Cybiktarov, 2003; Houle, 2010) restrict theterm to larger mounds with satellite structures compared tosmaller mounds which may simply have a central mound andclosely associated ringwall (Houle’s slope burials, Cybiktarov’sbarrows of the Mogun-Tagai). Other authors (e.g. Frohlich andBazarsad, 2005; Frohlich et al., 2008, 2009; Wright, 2007) refer toall structures with central stonemound and ringwall as khirigsuursbut then make their own internal divisions based on architecture(elaborate vs. simple; Wright, 2007) or on size and elevation(Classes 1e3; Frohlich and Bazarsad, 2005). In this paper we willuse the term khirigsuurs in the inclusive sense of Wright andFrohlich given the commonality in structure (central chamber,stone mound and fence), the continuous distribution in size (in the

Fig. 2. Large khirigsuurs with external structures including fence and satellite mounds.

Khövsgöl the range is from four sq m to more than 100 sq m), and,as we will argue, the initial function of the mounds.

Dates attributed to the mounds vary considerably. Cybiktarov(2003) cites dates from mid-second to third millennia BC until the6th to 8th centuries AD. Most interest has focussed, however, onthose of the late BronzeAge and themounds considered in this paper(whether from our excavations or others cited) date from c3500 to2700 BP (calibrated radiocarbon) years (Frohlich et al., 2009).

1.2. Interpretations of their role

The contrast between the apparent external monumentality ofthe mounds (particularly the large structures) and their apparentemptiness has made them a particular interpretative puzzle.Models of their function (whether symbolic or pragmatic) can beseen as a continuum from those arguing for purely non-funeraryfunctions to those arguing for a primarily funerary purpose.

Given the apparent lack of artefacts and human remains in themounds, particularly when compared to the kurgans further west,Jacobson (2002) suggested that they could be usefully conceived ofas altars e centres of collective activity on the part of pastoralists. Asimilar interpretation was proposed by Beljinski (cited in Wright,2007).

Wright, while acknowledging that occasional khirigsuurscontain burials, argues that they are monuments ‘constructed withrelatively regular frequency by a consistently sized group and usedfor group-oriented activities’ (Wright, 2007: 350). Given this focuson the group any associationwith between the site and the identityof the person buried is discounted. This interpretationwith its focuson collective activity is supported by Honeychurch (Honeychurchand Amartuvshin, 2007; Honeychurch et al., 2009) who arguesthat khirigsuurs are neither consistently nor universally burials butprimarily evidence of symbolic group activity.

Allard and Erdenebaatar (2005), on the other hand, argue thatthe khirigsuurs may have a dual purpose, ceremonially as altars and

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functionally as burial places. They suggest that the mounds withremains be treated as burial places while those without remainswere altars or ritual sites. Even when excavated mounds werefound to contain the architecture of burial (stone cists for example)Allard and Erdenebaatar (2005) still refer to them as altars.

While Allard and Erdenebaatar (2005) are interested in theastronomical alignment of large khirigsuur complexes, Houle(2010) focuses upon the role of elaborate khirigsuurs as symbol-ising the power of individual leaders and providing ritual foci. Hepostulates that empty tombs could represent cenotaphs but pointsto the possibility of poor preservation as a cause of the emptiness.

In contrast to these non-funerary or conditionally funeraryinterpretations, others suggest that they represent primarilyfunerary monuments. Cybiktarov (2003) in a survey and excavationof structures in southern Siberia and northernMongolia argues thatthe khirigsuurs represent the burials of an elite group dating tobetween themid-secondmillennium and early first millennium BC.Tombs of lower social strata were described as barrows of themongun-taiga type. In his view the khirigsuurs represent theintroduction of an elite into the central Mongolian steppes.

Takahama et al. (2006) excavated mounds in the Khövsgölaimag down to the ground surface finding stone cists in four of thefive mounds. They identified a multiphase building programme ofwhat they consider are primarily burial mounds. Empty mounds,they suggest, are due to the action of burrowing animals.

Erdenebaatar (2004), Amartuvshin (2007) and Frohlich et al.(2009, 2010) all argue, based on their finds of human remains,that the khirigsurrs are primarily burials mounds. Erdenebattar hasworked in the Khövsgöl and Arkhangi regions, Amartuvshin in theAltais and Frohlich in the Khövsgöl and Khovd aimags (Fig. 1).

The arguments about the significance of khirigsuurs as funeraryvs. non-funerary monuments are presented irrespective of howmany bodies are found during excavation (Table 1). For example,Wright describes the results of Cybiktarov’s excavation: “only [italmine] half the sites contained any skeletal remains at all” (Wright,2007: 352). While Japanese researchers, equally convinced that allmounds are funerary, only found human remains in one of the twokhirigsuurs they excavated (Takahama et al., 2006). Simply findingremains is not sufficient in sorting out this argument; what isrequired is an explanation for why remains may not be founddespite the best efforts of their excavators.

2. Materials and methods

2.1. The Khövsgöl region mounds

The khirigsuurs analysed here have been excavated by a jointSmithsonian InstitutioneMongolian Institute of Archaeologyexpedition between 2006 and 2009 (Frohlich et al., 2009, 2010). Theexcavation has been part of a larger survey of khirigsuurs within an

Table 1Percentage of mounds with human remains from a range of studies, compared to thepercentages in sites with defined burial chambers.

Site Numberexcavated

% with humanremains

Source

MongoliaEgiin Gol,

Khövsgöl9 11.1% Honeychurch et al. (2009)

Ulaan Uushig,Khövsgöl

2 50.0% Takahama et al. (2006)

Mongolia &Lower Baikal

58 41.4% Cybiktarov (2003)

Khanuy Valley,Arkhangi

6 (includesslab burials)

50.0% Houle (2010)

Khövsgöl aimag 35 82.9% This study

850 square kilometre area of the Khövsgöl aimag located in northcentralMongolia in the steppe (Fig.1; Frohlich et al., 2009). Over thisentire area an estimated two thousandkhirigsuurs (Fig. 3) havebeenidentified lyingon the valleyfloor, lower andupper slopes of the lowranges between the valleys (Frohlich et al., 2009). Excavation hasconcentrated on sampling different topographic zones within thearea, establishing the validity of the survey data, the chronologicalposition of themounds, the level of architectural variability, and theprimary function of the mounds. In total 43 mounded structureshave been excavated and a subset of 35 that met criteria describedbelow are the basis for analysis within this paper.

2.2. Methods of recording and analysis

Given the focus on maximizing recovery of remains biologicalanthropologists were directly involved in field recording andrecovery. Our aim was to maximise the quality and quantity ofosteological data recovered. Each khirigsuur was exposed in itsentirety. Excavation initially cleared the surface of the mound todefine any external fence, pavement, and themound perimeter. Thenext stage of excavation involved identifying the central chamberand any capstones (whether disturbed or in situ). At each stage thestructure was mapped and photographed as well as geo-referenced. The capstones were removed while minimizingdisturbance to the structure. This was difficult in the case of verylarge capstones where the stones had to be towed away by vehicle.

The area of the central pit was then excavated in arbitrary spits.Particular attention was paid to defining and clearing the pit walls.In above ground structures this was relatively easy but moredifficult when the pit was partly subterranean. In these instancesthe distinction between wall and pit fill was a matter only of thedifferent density of the granular soil. During excavation attentionwas paid to any signs of animal activity (particularly burrows oranimal bones) and to the presence of plant roots.

Any human remains found were completely exposed and asmuch information as possible recorded in situ including

Fig. 3. Aerial photograph of Khövsgöl region showing location of excavation areas.

Table 2Definition of predictor variables considered in analyses.

Variable Definition

IntrinsicAge Age as estimated using criteria in Bass (2005);

ranked initially in seven categories ranging from1 (<5 years) to 6 (>50 years) or 7 (adult, toofragmentary to estimate); later collapsed into two(<10 years and >10 years; see text for details)

Sex Sex identified using criteria in Bass (2005)Area One of 6 geographic areas excavated from

2006 to 2009Size Size of mound as measured by extent of

unexcavated mound, treated both as continuousvariable (m)

Above orbelow ground

Measured dichotomously and as depth fromsurface of mound.

Slope The slope of the land surface the tomb is found onranked initially in four categories ranging from1 (valley floor) to 4 (moderately steep upslope);later the two flat or shallow sloped categories(1 and 2) were collapsed as were the two steepercategories (3 and 4).

ExtrinsicAnimal modification Evidence of animal tooth marks (Haglund and

Sorg, 1997a,b; Klippel and Synstelein, 2007)(Yes or No)

Burning Evidence of human bones being burned (Yes or No)Burrowing Evidence of burrowing within the burial

chamber (Yes or No)Capstone Disturbed Evidence that a tomb’s capstone had been

disturbed (Yes or No)Roots Evidence of roots in a tomb (Yes or No)

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observation of completeness, articulation, indictors of age and sex(following Buikstra and Ubelaker, 1994), and measurements of thelong bones. Other characters recorded included burial integrity,body position and orientation, burial dimensions, and any evidenceof taphonomic processes. Detailed photographs were taken at eachstage.

After documentation remains were carefully removed from thegrave pit, packed, labelled and returned to camp. Here they wereunpacked, inventoried again, and recorded with photography ofeach element. A third final recording of all material was undertakenin Ulan Baatar in 2010 when earlier observations were doublechecked as well as more detailed recording of non-metric traits andpathological lesions was undertaken.

The attributes recorded for each element were the percentage ofskeletal element recorded (Brickley and McKinley, 2004; Buikstraand Ubelaker, 1994) and degree of articulation (close articulation,disarticulated but in expected position, disarticulated anddisplaced).

People involved in the field recording varied by season butrecording in Ulan Baatar was undertaken by Sarah Karstens (SK)and Kristen Pearlstein (KP). In order to improve inter-observerreliability assessment of the amount preserved was undertakenby SK and KP with JL on a set of three individuals. We found a highlevel of reliability between observers who followed a consistent setof rules e in particular, a complete element scored 100%, anelementmissing a small part of bone (10% of less) scored 90%. Theserecords were checked against the field recording and then againstthe excavation photograph so that by triangulationwe could assureconsistency with the field recording while taking into accountpotential damage that occurred during the transport of remains toUlan Baatar.

Following Bello and Andrews (2006), we used two measures ofbone presence and condition: the bone representation index(Dodson and Wexlar, 1979) which is the absolute presence orabsence of individual skeletal elements compared to the expectednumber of elements given the minimum number of individuals(MNI); and the anatomical preservation index which assesses thepercentage of each element preserved (not including smallergrouped elements such as phalanges and carpals).Weathering statewas used in one analysis of the data (Dickson, 2010) but it is tightlycorrelated with degree of preservation so was not included in thisanalysis.

Rather than undertaking subsequent analysis by element asLieverse et al. (2006), this analysis was aimed at understanding thecausal relationships between external conditions and the preser-vation or articulation of the remains of each human interred. Forthis reason we initially calculated two summary measures ofpreservation: a score based on the number of elements presentgiven a maximum of 73 major elements or groupings (e.g. bones ofthe hand) and a mean preservation score which was an average ofthe anatomical preservation index of all skeletal elements for eachbody. In this sample these two scores were very highly correlated(n ¼ 35, r ¼ 0.98). It would be conceivable in some circumstancesfor them not to be, for example where there are high levels offragmentation of undisturbed remains (where there would be highnumbers of elements present but low preservation) but frag-mentation in this sample was relatively low. Given this highcorrelation our subsequent analyses used mean preservation asthe primary criterion variable. Articulation, treated as a separaterank order criterion variable here, was similarly summarised asa composite measure for the skeleton ranging from complete e

remains present completely articulated (i.e. in correct anatomicalposition accounting for gravity; Duday, 2006), high e articulatedwith the exception of one bodily segment (e.g. hand, foot, or arm),fairly high e articulated with the exception of two bodily

segments, moderate e half articulated (frequently upper or lowerbody only), low e partial articulation of a quarter or less of theskeleton, absent e complete disarticulation.

Table 2 shows predictor variables considered. Variables weredefined as intrinsic to a burial (i.e. dependent upon the particularnature and location of a grave and identity of an individualinterred) and extrinsic (i.e. related to human or animal activity andsubsequent disturbance of the burial as reflected by capstonedisturbance, burrowing, burning, roots or tooth marks). Nodistinction in this analysis was made between rat and largermammal tooth marks although these are different processes ofscavenging because of the co-existence of rodent gnawing marksand pedestalling with evidence of larger animals (as judging byscalloping and other large tooth marks). Preliminary analysesconsidered the pattern of presence/absence of skeletal elements,altogether and by age. The percentage of variance in mean preser-vation accounted for by individual predictors was then evaluatedusing one-way ANOVA. Subsequently we considered whichpredictors and interaction terms best accounted for variance inmean preservation score using multiple regression analysis. Testassumptions were confirmed by examining whether residuals weredistributed approximately normally with similar variance acrossthe range of estimated values.

Rank order differences in the extent of articulation were alsoassessed using non-parametric KruskaleWallis One-Way ANOVA.All analyses were accomplished using SYSTAT v. 10.

3. Results

The 43 excavated structures varied in size from 2 to 60 m indiameter. Of the total number three (7%) were mounds of a laterdate with distinctively different architecture, two (5%) were naturalfeatures, and one was a subterranean squared structure probably

Table 3All ‘mounds’ excavated in the Hovsgol aimag (2006e2009). Those included in thisanalysis (because of the time period) identified by ‘b’ under Period.

Area Season Mound Period Age Sex Bonerepresent.index

Anatom.preservat.index

A 2006 1 b 18e25 M 57.5 80.0A 2006 2 b 10e15 35.6 33.4

A 2006 3 b 5e9.9 26.0 27.82006 4 Incomplete 0.0 0.02006 5 Subsid 0.0 0.0

C 2006 6 b 26e50 M 52.1 67.62006 6a Late Adult 5.5 3.9

C 2006 7 b >50 M 57.5 81.4C 2007 8 b >50 F 57.5 80.5C 2007 9 b 10e15 M 75.3 81.5

C 2007 10 b 26e50 M 80.8 96.02007 11 Natural2007 12 Late 26e50 F 42.5 43.8

B 2007 13 b <5 1.4 0.0B 2007 14 b 26e50 F 38.4 31.0B 2007 15 b 0.0 0.0B 2007 16 b 16e25 M 57.5 61.0B 2007 17 b >50 F 60.3 69.3B 2007 18 b 26e50 F 50.7 45.8

B 2007 19 b 0.0 0.02007 20 Natural 0.0 0.02007 21 Non mound

B 2007 22 b 10e15 68.5 74.8B 2007 23 b 16e25 M 80.8 92.4B 2007 24 b >50 M 79.5 80.8B 2007 25 b >50 F 76.7 86.8B 2007 26 b 0.0 0.0B 2007 27 b 10e15 24.7 34.4B 2007 28 LateF 2008 40 b <5 4.1 2.8F 2008 41 b 5e9.9 15.1 3.8F 2008 42 b 0.0 0.0F 2008 43 b <5 5.5 3.3F 2008 44 b 26e50 M 28.8 29.8F 2008 45 b 0.0 0.0F 2008 46 b Adult 4.1 3.0D 2009 51 b <5 1.4 0.5D 2009 52 b 16e25 M 34.2 36.8D 2009 52a Late <5 1.4 1.5D 2009 52b Late Adult 1.4 0.5D 2009 52c Late 5e9.9 5.5 2.8D 2009 53 b >50 F 16.4 14.9D 2009 54a Late 16e25 54.8 56.8D 2009 54b Late Adult 9.6 9.0D 2009 54d b 26e50 M 65.8 84.9D 2009 54e Late Adult 2.7 1.0D 2009 54f Late <5 2.7 0.5D 2009 54g Intrusive 1.4 2.5D 2009 55 b 16e25 31.5 29.8D 2009 56 b 0.0 0.0E 2009 57 Late 1.4 0.5E 2009 58 b <5 35.6 38.0

Fig. 4. Excavated khirigsuur showing internal cist and partly disarticulated skeleton.

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e3370 3365

later and distinctly different from the Bronze Age mounds (Table 3).Of the remaining 37 structures one was a small external mound,part of the surrounding subsidiary burials around a large mound (itcontained a horse’s head), and in one (a very largemound) the floorof the chamber was not reached during excavation. Large bouldersmade ongoing excavation impossible. This means there were a totalof 35 khirigsuurs completely excavated. Their characteristics arelisted in Table 3 (further data in the supplementary table).

Human remains, when identified were primarily within theburial chamber. These were primary burials of single fully

articulated bodies, placed into the pit partly rolled onto theirside (left or right) with the face oriented upslope. Arms wereslightly bent and placed in front or just over the hips, legs,particularly lower legs one over the other (Fig. 4). The pattern ofcollapse of elements (e.g. clavicles down into chest cavity, handsinto the pelvic cavity, head backwards) support the identificationof these as primary inhumations with no evidence of secondaryburial.

3.1. Presence or absence of human remains

Of khirigsuurs considered here, 83% (29/35) contained humanremains (Table 4). This is significantly more than in some of theother areas of Mongolia prompting the suggestion that Khövsgölrepresents a particular form of usage of khirigsuurs (Honeychurchet al., 2009). However, this high percentage masks significantvariation in preservation within and among different geographicareas excavated in different field seasons.

3.2. Bone representation

This distinction becomes clearer once the extent of preservationis examined. Fig. 5 shows the percentage of the graves containingparticular elements (bone representation). This is a simple measureof presence/absence (combining left and right sides and groups ofelements e.g. cranial bones, tarsals) and demonstrates the distinctdifferences in preservation by bone type.

Bones of crania are amongst the best preserved elements inparticular the larger elements of the occipitals and parietals relativeto the much more fragile bones of the face. In general, the repre-sentation of bones can be seen to link with their overall size (Fig. 5).Apart from the larger bones of the crania, the bones with a rangebetween 40 and 60% representation are the long bones generally inorder of their length and robusticity (i.e. femur, tibia, humerus,ulna, radius, fibula) as well as the large flat bones: the innominateand the scapula. This is despite the relative fragility of the scapularand iliac blades. The sacrum and lumbar vertebra fall within thisgroup but the other vertebrae fall within a group of elements wherebetween 20 and 40% are preserved. These comprise small butrelatively robust elements such as the vertebrae, the tali and cal-caneii, the patellae, along with the ribs and the clavicles. Again sizeseems an important determinant. For example, the preservation ofthe vertebrae sorts according to size with lumbar more likely to bepreserved than thoracic and than cervical. The least well preservedelements are the smallest: the coccyx, the carpals, tarsals, meta-carpals, metatarsals, and the phalanges.

Table 4Presence or absence of human remains in tombs by excavation season.a

Excavation season No human remains Human remains found

N % N %

2006 0 0.0% 5 100.0%2007 3 18.8% 13 81.2%2008 2 28.6% 5 71.4%2009 1 14.3% 6 85.7%

Total 6 17.1% 29 82.9%

a No significant difference was found in overall presence or absence of remains inmounds excavated in different field seasons (X2 ¼ 1.75, df ¼ 3, P ¼ 0.63).

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e33703366

While there is no difference in the degree of representationaccording to sex (see Table 5) age does play a significant role. Theremains of those less than ten years at the time of death wereconsistently less frequently represented and there appeared to bea natural split point at c10 years of age so that the remains ofadolescents and adults were better preserved (Fig. 6A). The singleadult with poor preservation is an individual who could only beaged as ‘adult’ (therefore by their very classification they are pre-dicted to be poorly preserved). The rank order correlation ofpercentage of potential elements represented across skeletalelements of those under 10 years of age as compared to adults washigh (r ¼ 0.84) though showing a similar pattern of preservationbut major difference in degree (Fig. 6B).

3.3. Anatomical preservation

Bone representation, however, tends to give an incompleteimpression of the degree of preservation since it does not takeaccount of how much of an element is preserved. It is only whenaccount is taken of the degree of preservation that the poor pres-ervation of bone in some areas and tombs becomes fully apparent.As indicated in Fig. 7, preservationwas exceptionally good in Area Cexcavated in 2006 and the early part of 2007 but much morevariable in Areas B and D excavated in 2007 and 2009, respectively.Area F, excavated in 2008, had consistently poorer preservation. As

Fig. 5. Bone representation shown by the elements as a per

is clearly indicated, field season and area excavated overlapsubstantially. Field season was excluded from further analyses asarea was the stronger predictor reflecting the influence of localtopographic characters.

Empty tombs are part of a continuum rather than a discretephenomenon. While empty tombs form 17% (6/35) of the totalnumber of mounds, a further six had less than 5% preservation e

these were represented by an individual deciduous tooth in Burial13, or bone fragments in grave chambers of Burials 40, 41, 43, 46and 51. Mounds such as these may be identified as “empty”withoutcareful excavation and sieving.

3.4. Predicting preservation

The results of univariate least squares regression modelscomparing each variable with preservation are summarised inTable 5. Four intrinsic measures, age, area, size and slope, allaccounted for a highly statistically significantly portion of thevariation, however, sex and whether the grave was cut into theground surface or above ground did not. In order to maintainadequate cell size in regression models that included interactionswith age, this variable was consolidated as two groups using anestimated age of 10 years as the split point. Two of the extrinsicvariables, animal modification and burrowing, were also individ-ually statistically significant.

In addition to age and area, slope proved to be strongly associ-ated with variation in preservation (Table 5). The 23 mounds in thevalley floors or lower shallow slopes (which tended to be largermounds on average) had markedly better preservation(53.01 � 6.08% SE). Mounds positioned upslope had poorer pres-ervation in general (12.51 �8.42% SE). The effect of size was closelyrelated to slope since smaller mounds are on the upper slopes,larger in the valley floors. The correlation of size only to meanpreservation was less than that of slope only.

Burrowing was statistically significantly, but less strongly,associated with preservation. Animal burrowing, particularly bymarmots (based on burrow size and animal bone inclusions), wascommon occurring in 33% of the mounds (11/33). Our impressionwas that burrowing may contribute to elements missing from

cent of the expected minimum number of individuals.

Fig. 6. A. Mean preservation by age group demonstrating major difference between the less than 10 yr age group and older adults. B. Bone representation compared between eightsubadults (<10 years of age) and 18 adults (three individuals with estimated age between 10 and 15 years not included here).

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e3370 3367

tombs which might sometimes be found outside the chamber.However, the association of burrowing with preservation wasopposite to that predicted. Mean preservationwas actually better inthose tombs where burrowing or animal modification wasobserved. This might be an artefact of the process of recording.

Fig. 7. The distribution of mean preservation in each excavated khirigsuur by field season athe burial.

Burrowing can be difficult to identify particularly in tombs thathave earthen walls, a possible contributor to poor preservation.Animal tooth marks are easier to discern on more completeremains. Whatever the underlying explanation, these significantdifferences in preservation are inconsistent with ideas that animal

nd area excavated calculated by averaging the preservation score for each element in

Table 5Results of univariate least squares regression models accounting for variation inmean preservation (significant results shown in bold). Pearson’s correlations are alsoshown in brackets for the continuous variables of depth from surface of mound.

Predictor variable Categories(N)

Multiple R2 F P N

AgeInitial 7 0.554 4.553 0.004 29Consolidated 2 0.417 19.337 0.000 29

Sex 2 0.117 1.989 0.179 17Area 6 0.436 4.484 0.004 35Size of burial mound 0.136 5.056 0.032 34

SlopeInitial 4 0.352 5.612 0.003 35Consolidated 2 0.317 15.286 0.000 35

Above or below ground 2 0.035 (0.231) 0.029 0.866 (0.315) 30Animal modification 2 0.107 2.992 0.096 27Burning 2 0.009 0.228 0.638 26Burrowing 2 0.264 11.114 0.002 33Capstone disturbance 2 0.006 0.193 0.664 33Roots 2 0.007 0.224 0.639 33

Fig. 8. Significant interaction between age and slope accounting for variation inpreservation (P ¼ 0.003) is explained by a much greater contrast between categories ofslope among adolescent and adult remains.

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e33703368

activity is a major contributor to poor preservation in khirigsuurs.Significant, but as yet unmeasured, differences in temperature andmicroclimate may have important influences on preservation. Thisrequires further investigation.

The variables without any statistically significant associationwere burning (only one occurrence), the presence of roots, andcapstone disturbance. While roots were not associated with theoverall mean preservation, plants (particularly thistles) with longextensive root systems were observed to have caused fragmenta-tion of remains. Capstones were either partially or fully disturbedon 12 of the 33 mounds that could be confidently assessed (twomounds were indeterminate). Capstones could be either missingentirely or tipped on the side. Given their large size (frequentlymore than 1 m in width) it is assumed their movement was causedby humans trying to get access to the grave. Preservation was quitevariable among both disturbed and undisturbed burials. Whilemean preservation was lower in burials where the capstones hadbeen disturbed (38.0% vs. 43.6%), differences were not statisticallysignificant in a univariate model.

As reported in Table 6, the simpler of two models consideredincluded age, slope and their interaction effect. This model, withage and slope variables dichotomised, accounted for 74% of thevariance in mean preservation. There was a significant interactioneffect between age and slope. Subadult preservation is poorregardless of slope while adult preservation is particularly good inkhirigsuurs placed on relatively flat ground but much poorer whenremains were buried on somewhat steeper slopes (Fig. 8).

The modestly better fitting model, however, confirmed throughboth forward and backward stepping methods, was one thatincluded the intrinsic features of age and slope with capstone

Table 6Simplest effective model accounting for variation in mean preservation.

Criterion: Mean preservation; N: 29; Multiple R: 0.861; Squared multipleR: 0.741

Analysis of variance

Source Sum-of-squares df Mean-square F-ratio P

Slope 3145.75 1 3145.75 10.15 0.004Age 5529.20 1 5529.20 17.85 0.000Slope * Age 3245.02 1 3245.02 10.48 0.003Error 7744.89 25 309.80

disturbance (Table 7). Size was initially included in this model butits contribution became statistically insignificant once slope wasentered confirming the interactions between these two variables.In this model 75% of total variation in mean preservation wasaccounted for. Running the simplest model on the same 27 moundsdemonstrates that the ‘best model’ accounts for about 4% morevariance than a model without the variable, capstone disturbance.Unlike in the univariate analysis, capstone disturbance was a nearstatistically significant contributor in this model. This is because ofthe influence of age category. Among the 21 burials with adolescentor adult remains, capstone disturbance was associated withsignificantly poorer preservation (45.6 � 7.8% SE vs. 73.3 � 7.4% SE,P ¼ 0.019).

3.5. Explaining articulation

In contrast to preservation, the extent of disarticulation ofremains was harder to predict, in part because it was treated asa rank order variable. Apart from area, capstone disturbance wasthe only variable that was near statistically significant (Table 8 andFig. 9). Remains in khirigsuurs with evidence of disturbedcapstones had fewer completely articulated remains, and more

Table 7The “best” fitting model judging from forward and backward stepping regression.

Criterion: Mean preservation; N: 27; Multiple R: 0.864; Squared multipleR: 0.747

Analysis of variance

Source Sum-of-squares df Mean-square F-ratio P

Slope 1554.47 1 1554.47 5.37 0.030Age 3983.84 1 3983.84 13.76 0.001Capstone disturbed? 873.95 1 873.95 3.02 0.096Slope * Age 2247.57 1 2247.57 7.76 0.011Error 6368.37 22 289.47

Table 8Results of rank order tests of each predictor on extent of articulation.

Predictor variable Categories (N) Test statistic df P N

Age e Consolidated 2 71.5 1 0.614 27Area 6 14.3a 5 0.014 27Slope e Consolidated 2 81.0 1 0.536 27Animal modification 2 106.0 1 0.191 27Burning 2 12.0 1 0.946 27Burrowing 2 102.0 1 0.493 27Capstone disturbance 2 120.0 1 0.074 27Roots 2 59.5 1 0.153 27

a Represents a KruskaleWallis test statistic; all others are ManneWhitney U tests.

Fig. 9. Disturbed capstones may be associated with reductions in the extent of artic-ulation of remains (P ¼ 0.074, or if those <10 years excluded, P ¼ 0.057).

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e3370 3369

with low or no segments articulated. Area was a significantpredictor of extent of articulation entirely because remains in AreasA and F were consistently very high and low, respectively. Distri-butions of articulation in other areas were similar.

4. Discussion and conclusion

Construction features of the mounds such as the central cistcovered with capstones to make an empty container suggests thatthe primary function of the khirigsuurs was as a place for burial. It isthe lack of human remains that has provided the basis for disputes.However, the percentage of empty tombs found in the Khövsgölmounds is a relatively poor indicator of the pattern of preservationin khirigsuurs. Preservation in these mounds is muchmore variableand much more subject to the local environment than has beenpreviously recognised. While in the region evaluated here, 83% ofthe khirigsuurs excavated yielded human remains, the percentageelsewhere has been lower (Table 1). This analysis demonstrates theinteraction of factors that can contribute to this variability.

The pattern of preservation as shown by element is determinedby the nature of the bone itself and in particular bone size anddensity. The representation of elements reported on here (Fig. 5)bears striking similarity to that observed by Bello and Andrews(2006) for a series of sites from historic France and Englandwhere the largest and most dense bones or parts of bones arepreserved (see also Lieverse et al., 2006; Willey et al., 1997). Thispattern may be characteristic of sites where there is relatively littlemechanical disturbance to remains which has the potential tofragment large flat bones such as the innominate and scapula (e.g.Waldron, 1987). In the mounds analysed here, however, such largeflat bones were well represented.

This shift in the extent of preservation seems to occur in earlyadolescence and is likely linked to increases in cortical bone aroundthat age. It may be that the relatively good preservation of cranialbones amongst the children is because the cranial bones containa relatively large proportion of the denser inner and outer tables

relative to diploe. Here, as also observed by Bello and Andrews(2006), the significant change in bone density occurs aroundadolescence so that preservation of adolescent remains is verysimilar to that of adults.

Extending the analysis to concentrate on the interrelationshipsbetween mean preservation and intrinsic and extrinsic factorsalso demonstrates which factors are significant and which are not.Takahama et al (2006) for instance postulated poor preservationdue to animal disturbance but it is clear that in this region at least,animal disturbance, while it occurs, does not contributesubstantially to poor preservation. In this instance the factorsmost clearly related to preservation are the age of the deceased (inparticular whether the occupant was an infant or child), thephysical environment, particularly slope, and whether the gravehas been disturbed particularly through movement of thecapstones. This raises the question of what was the purpose ofdisturbing graves through capstone removal. Those doing thedisturbing clearly did not set about to destroy the remains,although some loss of preservation following disturbanceoccurred. However disturbed graves do tend to have more disar-ticulation. Further analysis on patterns of disarticulation andmovement of elements needs to be undertaken to disentangledeliberate human and animal activities.

The diversity in preservation between different locations in theKhövsgöl area helps explain the diverse results from the smallernumber of mounds excavated elsewhere in Mongolia. In particular,it needs to be remembered that even in a region with a relativelyhigh yield of human remains, a majority of these burials are onlyevidenced by fragments of remaining bone or teeth. It is unsur-prising given the difficulty of identifying chamber walls and floors,levels of disturbance, and properties of the physical environmentthat some excavations have failed to yield human remains or onlyyielded low proportions. Importantly, bone preservation isa continuous variable. Analyses that begin with subdividing gravesor mounds into those that have bones and those that do not andthen categorising site function accordingly (Allard andErdenebaatar, 2005) fail to understand how the preservation ofbone proceeds and how contingent it can be.

Assuming a funerary function for khirigsuurs does not negatethe hypotheses about their symbolic function but it does rathersimplify the landscape of north Asia in the Bronze Age placingcentral Mongolia and its khirigsuurs in a consistent position withthe surrounding people who also symbolize and monumentalizetheir burials whether as kurgans or slab burials. The analysis alsoprompts us to remember Duday’s (2006) warning that burialinterpretation relies upon a sample not a singularity and thatanalysis of taphonomy beyond the descriptive gives us bothexplanatory and predictive power.

Appendix A. Supplementary material

Supplementarymaterial associatedwith this article canbe found,in the online version, at http://dx.doi.org/10.1016/j.jas.2012.06.004.

References

Allard, F., Erdenebaatar, D., 2005. Khirigsuurs, ritual and mobility in the Bronze Ageof Mongolia. Antiquity 79, 547e563.

Amartuvshin, C., 2007. Archaeology and Cultural Resource Management inMongolia 2003e2008. Preservation Sector of the Institute of Archaeology,Ulaanbaatar.

Bass, W.M., 2005. Human Osteology: a Laboratory and Field Manual, fifth ed. Mis-souri Archaeological Society, Columbia.

Bello, S., Andrews, P., 2006. The intrinsic pattern of preservation of human skeletonsand influence on the interpretation of funerary behaviours. In: Gowland, R.,Knüsel, C. (Eds.), The Social Archaeology of Funerary Remains. Oxbow, Oxford,pp. 1e13.

J. Littleton et al. / Journal of Archaeological Science 39 (2012) 3361e33703370

Brickley, M., McKinley, J., 2004. Guidelines to the Standards for Recording HumanRemains. British Association of Burial Archaeologists and Osteoarchaeologists,Southhampton.

Buikstra, J., Ubelaker, D., 1994. Standards for Data Collection from Human SkeletalRemains. Arkansas Archeological Society, Fayetteville.

Cybiktarov, A.B., 2003. Central Asia in the Bronze and Early Iron Ages. Archaeology,Ethnology and Anthropology of Eurasia 1, 80e97.

Dickson, M., 2010. Not just monuments? Mongolia’s khirigsuurs as burial places andthe nature of skeletal disturbance. Master of Arts in Anthropology, University ofAuckland.

Dodson, P., Wexlar, D., 1979. Taphonomic investigations of owl pellets. Paleobiology5, 275e284.

Duday, H., 2006. L’archaeothanatologie ou l’archaeologie de la mort (Archae-othanatology or the Archaeology of Death). In: Gowland, R., Knüsel, C. (Eds.),The Social Archaeology of Funerary Remains. Oxbow, Oxford, pp. 30e56.

Erdenebaatar, D., 2004. Burial materials related to the history of the Bronze Age inthe territory of Mongolia. In: Linduff, K. (Ed.), Metallurgy in Ancient EasternEurasia from the Urals to the Yellow River. Edwin Mellen Press, Lewiston, NY,pp. 189e223.

Fitzhugh, W.W., 2009. Stone Shamans and Flying Deer of Northern Mongolia: DeerGoddess of Siberia or Chimera of the Steppe? Arctic Anthropology 46, 72e88.

Frohlich, B., Bazarsad, N., 2005. Burial Khirigsuurs in Khövsgöl aimag, NorthernMongolia: preliminary results from 2003 to 2004. In: Fitzhugh, W.,Bayarsaikhan, J., Marsh, P. (Eds.), The Deer Stone Project. AnthropologicalStudies in Mongolia 2002e2004. National Museum of Natural History, Wash-ington, DC, pp. 57e88.

Frohlich, B., Amgalantugs, T., Littleton, J., Hunt, D., Hinton, J., Batchatar, E.,Dickson, M., Frohlich, T., Goler, K., 2008. Bronze Age burial mounds (Khir-igsuurs) in the Hovsgol aimag, Mongolia: a reconstruction of biological andsocial histories. Studia Archaeologica Instituti Archaeologici Academiae Scien-tiarum Mongolicae VI (XXVI), 92e114.

Frohlich, B., Amgalantugs, T., Littleton, J., Hunt, D., Hinton, J., Goler, K., 2009. Bronzeage burial mounds in the Khövsgöl aimag, Mongolia. In: Bemmann, J.,Parzinger, H., Pohl, E., Tseveendorch, D. (Eds.), Current Archaeological Researchin Mongolia. Vor- und Frühgeschichtliche Archäologie Rheinische Friedrich-Wilhelms-Universität, Bonn, pp. 99e116.

Frohlich, B., Amgalantugs, T., Littleton, J., Ganbat, G., Hunt, D., Nittler, E., Karstens, S.,Frohlich, T.E.B., 2010. An overview of theories and hypotheses pertaining toMongolian Bronze Age khirigsuurs in the Hovsgol aimag. Studia ArchaeologicaInstituti Archaeologici Academiae Scientiarum Mongolocae IX (XXIX), 123e143.

Haglund, W., Sorg, M., 1997a. Forensic Taphonomy: the Postmortem Fate of HumanRemains. CRC, Baton Rouge.

Haglund, W., Sorg, M. (Eds.), 1997b. Forensic Taphonomy: the Postmortem Fate ofHuman Remains. CRC Press, Boca Raton, Fla.

Haringe-Friberg, K., 2005. Where are the dead? Empty graves early Iron Age Upp-land. In: Artelius, T., Svanberg, F. (Eds.), Dealing with the Dead. ArchaeologicalPerspectives on Prehistoric Scandinavian Burial Ritual. Riksantikvarieambetet,Lund, pp. 143e158.

Honeychurch, W., Amartuvshin, C., 2007. Hinterlands, urban centres and mobilesettings: the “new” old world archaeology from the Eurasian steppe. AsianPerspectives 46, 36e64.

Honeychurch, W., Wright, J., Amartuvshin, C., 2009. Re-writing monumental land-scapes as inner Asian political process. In: Hanks, B.K., Linduff, K.M. (Eds.),Social Complexity in Prehistoric Eurasia: Monuments, Metals and Mobility.Cambridge University Press, New York, pp. 330e357.

Houle, J.-L., 2010. Emergent Complexity on the Mongolian Steppe: Mobility, Terri-toriality and the Development of Early Nomadic Polities. Graduate Faculty ofArts and Sciences, University of Pittsburgh, Pittsburgh.

Jacobson, E., 1993. The Deer Goddess of Ancient Siberia: a Study in the Ecology ofBelief. E.J. Brill, Leiden.

Jacobson, E., 2002. Petroglyphs and the qualification of Bronze Age mortuaryarchaeology. Archaeology, Ethnology and Anthropology of Eurasia 3, 32e47.

Klippel, W., Synstelein, J., 2007. Rodents as taphonomic agents: bone gnawing bybrown rats and grey squirrels. Journal of Forensic Sciences 52, 765e773.

Lieverse, A.R., Weber, A.W., Goriunova, O.I., 2006. Human taphonomy at Khuzhir-Nuge XIV, Siberia: a new method for documenting skeletal condition. Journalof Archaeological Science 33, 1141e1151.

Takahama, S., Hayashi, T., Masanori, K., Matsubara, R., Erdenebaatar, D., 2006.Preliminary report of the archaeological investigations in Ulaan Uushig I(Uushigiin Ovor) in Mongolia. The Bulletin of Archaeology, University ofKanazawa 28, 61e102.

Waldron, T., 1987. The relative survival of the human skeleton: implications forpalaeopathology. In: Boddington, A., Garland, A., Janaway, R. (Eds.), Death, Decayand Reconstruction. Manchester University Press, Manchester, pp. 55e64.

Weiss-Krejci, E., 2011. The formation of mortuary deposits: implications forunderstanding mortuary behavior of past populations. In: Agarwal, S.C.,Glencross, B. (Eds.), Social Bioarchaeology. Blackwell Studies in GlobalArchaeology. Wiley-Blackwell, Chichester, pp. 68e106.

Willey, P., Galloway, A., Snyder, L., 1997. Bone mineral density and survival ofelements and element portions in the bones of the Crow Creek massacrevictims. American Journal of Physical Anthropology 104, 513e528.

Wright, J., 2007. Organizational principles of khirigsuur monuments in the lowerEgiin Gol valley, Mongolia. Journal of Anthropological Archaeology 26,350e365.