Breakage Patterns of Human Long Bons

Paola Villa Mumm, Campus Box 315, University of Colorado, Boulder, Colorado 80309-0315, U.S.A.

Eric Mahieu

Etudes et Prospectives Archblogiques, 265 rue Paradis, 13006 Marseille, FWZce

Received 20 December 1989 Revision received 10 September 1990 and accepted 1 December 1990

X-crwords:bone breakage, taphonomy, burial, marrow fracturing, sediment pressure.

Breakage patterns of human long bOn8S

In the study of fragmented human remains the plausibility of a cannibalism hypothesis rests primarily on the correct identification of the cause of breakage. Here the use of fracture morphologies and fragmentation indices for distinguishing green from postdepositional bone breakage is assessed using three assemblages of human bone broken by unique and well known causes, i.e., marrow fracturing of green bone, sediment pressure and impact on subfossil bone. Of the tested attributes, five appear to have diagnostic value at the statistical, assemblage level: fracture outline, fracture angle, shaft circumference, shaft fragmentation and breadth/length ratios of shaft splinters.

Journal of Human Evolution (199 1 I 21,27-48

Introduction

Distinguishing natural fractures from deliberate breakage by humans to extract marrow is an

important issue in the study ofhuman long bone assemblages when cannibalism practices are

suspected. Hammerstone-produced features such as bone microflakes* attached to the shaft

at points ofimpact and marks such as pits and striations (Blumenschine & Selvaggio, 1988, in

press; Turner, 1983, Figures 7 and 8) are diagnostic of marrow fracturing, especially if

potential overlap with carnivore activity can be excluded by other variables or specific

attributes (Blumenschine & Selvaggio, 1988; Brain, 1981, p. 141; Potts, 1982, p. 216).

However, these traces are not constant properties of all bones broken by hammerstone. The

first criteria have been shown to occur in relatively low frequencies in both animal and

human bone assemblages (23% and 10%; Binford, 1981, p. 165; Villa et al., 1986a, p. 436).

Frequencies of the second group of criteria in animal assemblages are similarly not very high

(e.g., 20.496 at FLK ,?jnzanthropus; Blumenschine et al., 1990) though somewhat higher in experimental samples. More importantly, both kinds of features may be obliterated or

difficult to identify in bone assemblages that have undergone sediment attrition or post-

depositional chemical deterioration and do not have well preserved cortical surfaces. Long

bone breakage morphologies and fragmentation indices can provide additional lines of evi-

dence concerning fresh versus subfossil bone breakage. The purpose of this paper is to

evaluate a number of criteria that are at present poorly developed and considered less

diagnostic than others.

Methodological approach

In recent years breakage patterns of animal bones have been the subject of actualistic

research, especially conc,erning carnivore and hammerstone fracturing of fresh bone

*Lhis term refers to incompletely detached small flakes normally associated with zones of impact; they run through the bone thickness and their platform is bounded by arcuate fissure lines behind the point ofimpact (Bunn, 1981, Figure 4; Villa, 1986a p. 436, 19866 Figure 16). Microflakes form on long bone shafts where cortical bone is relatively thick. Hammerstone blows on articular ends, where the cortical bone is thinner and supported by cancellous tissue, will produce depressed margins described by Binford (1981, p. 164, Figure 4.53 and Table 4.06; Villa 19866, Figure 16.2). All these hammerstone traces were first replicated and defined by French archaeologist Henri Martin more than 80 years ago (1910).

0047-2484/91/070027 +22 $03.00/O 0 1991 Academic Press Limited

28 P. VILLA AND E. MAHIEU

(Binford, 1981; Blumenschine, 1988; Blumenschine & Selvaggio, 1988, in press; Bunn, 1983; Haynes 1983a,b, 1988; Johnson, 1985; Lyman 1987; and older references cited in these papers). Less is known about dry, subfossil or mineralized bone breakage since studies done in controlled situations are few or limited in scope (Bonnichsen, 1979; Davis, n.d.).

Although various kinds of bone damage (e.g., morphology of cutmarks, impact scars and gnaw marks) are essentially independent from species-specific bone morphology, other characteristics such as the relative size and shape of diaphyseal fragments or different sus- ceptibility to fragmentation and destruction are more likely to be influenced by specific characters. Thus detailed knowledge of human long bone breakage morphologies should be developed directly from studies ofhuman bone assemblages. Actualistic research, however, is limited by difficulties in obtaining large samples for replicative experiments and by culturally restricted chances for taphonomic observations. In fact, there is little published information on characteristics of post-mortem human bone breakage aside from general observations of fractures intuitively ascribed to sediment pressure or rock fall (Trinkaus, 1985) and studies of gnaw marks on recent or archaeological bone, which have provided no data on diaphyseal splintering (Haglund et al., 1988; Horwitz & Smith, 1988; Milner & Smith, 1989).

Under special conditions it is possible to derive diagnostic criteria from archaeological assemblages. Sites and assemblages that are in pristine condition, represent single events or a simple series ofsingle events, and have been meticulously excavated and recorded, contain a lot of information about context; their formation processes can be controlled and recon- structed with confidence. If the cause of fragmentation of an assemblage is unique and securely identified, it is possible, by studying attributes that were not used in the original diagnosis, to define other criteria that may have diagnostic value with respect to the process under study. In other words, if sites can provide unambiguous information on the effects of certain taphonomic processes, this information can then be used at other sites with a strong degree of confidence. This approach is especially useful when long-term processes, such as sediment compaction acting on progressively weakened bones, are involved: such processes are characteristic of the archaeological record but are clearly difficult to replicate.

The level of precision and confidence achieved is lower than that obtained in laboratory experiments, where the process can be produced and replicated at will, but is comparable to the one provided by natural environment research where the process may not have been observed while happening yet relations between cause and effect can be established beyond reasonable doubt (Bonnichsen, 1982; cf. actualistic case studies such as Haglund et al., 1989 and Haynes, 1983). An approach similar to ours has been used by Oliver ( 1986; Lewin, 1984) in the study of cutmark mimics in a natural trap cave and by Myers et al. ( 1980) on spiral breaks in paleontological assemblages.

The assemblages

Three archaeological sites in Southern France have provided assemblages of human long bones broken by unique and securely identified causes. Two of these sites have been excavated with exceptional care; the third is a special case. They are:

1. Sarrians, a collective burial with bones broken by sediment pressure. 2. Fontbrtgoua, a cave site with an assemblage of cannibalized long bones broken for

marrow extraction, that is by impact on green bone. 3. Bezouce, another collective burial with bones broken by the pick and shovel of the

land owner and amateur archaeologist. Thus the cause of breakage is impact on desiccated,

BREAKAGE PATTERNS OF HUMAN LONG BONES 29

subfossil bone. The bones were collected by professional archaeologists who excavated what was left of the site. This kind of breakage can be compared to that caused by rock fall at archaeological cave sites.

These sites allow us to study the products ofgreen versus subfossil bone breakage, that is to distinguish the effects ofburial from pre-burial processes. The main features and taphonomic significance of these assemblages are summarized below.

Sarrians

The site (its precise name is hypogte des Boileau) is located in the Vaucluse, near the village of Sarrians and is under current excavation by Eric Mahieu ( 1987a). Its age, indicated by a few grave goods, is Late Neolithic, approximately 2500 B.C.

The site is an oval chamber dug out in soft sandstone on a hill slope. In an area of 12 m2 150 individuals (1989 estimate) were tightly packed and piled on top of each other, forming a layer which is more than 40 cm thick (Figure 1). The excavation is done with microspatulas with blunt, rounded edges, to avoid moving or marring the bones; the sediment is gently removed with vacuum cleaners. Photogrammetry, small scale maps and B/W photos are used to produce exact distribution plans of the bones (Mahieu 1986, 19876). These records show that bones were broken in situ; fragments of the same bone lie adjacent to each other, incomplete fractures prolonged by fissure lines are occasionally present, breakage occurs in bones resting on convex or concave surfaces (Figure 2). Breakage is clearly due to a process of dew compaction and void filling, folowing organic decay, in the pile of bodies which were buried under a sand layer varying in thickness from 50-60 cm at the edges to 100 cm in the center and against one wall. The presence ofincomplete fracture lines suggests that breakage was a long-term process acting on diagenetically altered and progressively weakened bones.

Our sample includes the long bones of 14 individuals (10 adults, three adolescents, one child) for a total of 32 1 specimens ofwhich 281 are broken shaft or end plus shaft* fragments. All bones come from articulated skeletons or articulated anatomical segments, in one case from a bundle of bones of the same individual, aligned near the wall. All fractures are in situ i.e., pieces were found in contact with their conjoinable counterparts. A few excessively cornminuted bones or fracture margins have not been considered.

Sarrians is exceptional because it provides a large assemblage of articulated long bones in absolutely pristine context, in good state of preservation and with extensive excavation records, which prove that only sedimentary pressure and no other breakage process has affected these bones. Bones are not permineralized but have no collagen content, as indicated by chemical analysis of a long bone fragment by Margaret Schoeninger (pers. comm.). They are brittle and less resistant to breakage than bones of the other two sites, but not friable; the cortical surfaces are well-preserved with no traces ofsubaerial weathering nor postdepositional corrosion. The present state ofpreservation ofthese bones is related to the end, not the beginning of the breakage process, which probably started long ago, after flesh decay created voids and zones of differential pressure in the mass of bodies and sand.

Fontbrtfgoua

This cave with a 3-m deep Early and Middle Neolithic sequence, is under current excavation by Jean Courtin ofthe French C.N.R.S. The sample studied consists of 156 shaft and end plus

*End plus shaft are specimens consisting ofepiphysis and attached complete or partial diaphysis.


Figure 1. Sarrians (Vaucluse, Southern France). This collective burial, dated to the third millennium B.C. is under current excavation by Eric Mahieu.

shaft fragments? belonging to a minimum of six individuals (three adults, two children/

adolescent and one individual ofindeterminate age). This assemblage was found in a shallow

hollow, 80 x 40 cm and 15 cm deep which also contained bones of the axial skeleton, to the

exclusion of cranial parts (Figure 3). This cluster of bones, called feature H3, is dated to

3930 + 130 B.C. (uncalibrated 14C date on bone collagen by the Lyon laboratory, Ly 3748).

All visible objects were plotted with three Cartesian coordinates, and all sediment was

water screened, allowing the recovery of many small bone chips (Villa et al., 1986a, note 18);

34% of the pieces have been refitted.

Our argument in favor ofcannibalism has been published (Villa et&., 1986a,b, 1987, 1988)

and will not be repeated here. Evidence oflong bone breakage by percussion on green bone is

based on several lines of evidence:

1. A 20% frequency of impact notches, half of which have microflakes adhering to the impact point.

2. Bone surfaces are unweathered, uneroded and have sharp fracture edges.

3. Breakage by sediment pressure is excluded by horizontal (Figure 4) and vertical (Villa

et al., 1986a, Figure 2) maps showing the position of each bone fragment. Refitting links indicate that fragments ofthe same bone were not found adjacent to each other (as expected if

they have been broken in place by pressure or a falling rock) but were separated by distances

of up to 50 cm within the feature. The few refitting pieces that have been found adjacent to

tThis sample includes 50 long bone fragments that can be assigned to the genus Homo with a good degree of confidence; these fragments were not included in the H3 sample of Villa et al. ( 1986a,b, Tables 2 and 3) comprising only bones that can be identified with total confidence.


Figure 2. Bones broken in situ at Sarrians

each other (see short links in Figure 4; six cases in total) were either superimposed or head to

tail, as shown by detailed maps drawn during excavation.

4. Breakage by trampling (which would tend to disperse the bones) is excluded by the

sharp horizontal boundaries of the bone cluster. Ten other clusters containing butchered

animal bones and very similar in size and shape to H3 have been found and have similarly

sharp horizontal and vertical boundaries (Villa et al., 1985, 1986aJ).

5. Carnivore gnawing is excluded by: a. total absence of tooth marks, b. the repetitive

shape and size ofthe human and animal bone clusters and c. their homogeneous and species-

specific content (Villa et al., 1985, 1986a,b). These facts are incompatible with a carnivore

origin ofthe features and prove that the H3 cluster is intact and man-made. Again, the spatial

distribution ofrefitting fragments shows that the bones were broken before being thrown into

the hollow.

Cutmarks made by stone tools are found on 30% of the bones. These marks are not recent

scratches: excavation tools used at Fontbregoua are small putty trowels with round ends that

cannot produce cutmark mimics, bones are not covered with preservatives, have not been

restored and craniographs have never been used (White & Toth, 1989). SEM photos show

encrusted sedimentary matrix covering the tool marks thus supporting their antiquity (Villa

et al., 19866, Figures 10:3-4; Villa et al., 1987, p. 51). Cutmarks are not randomly placed (Olsen & Shipman, 1988) but are found in locations predicted by modern butchery studies,


Figure 3. Feature H3: cluster of cut-marked and broken human bones in Fontbrtgoua Cave (Provence, Southern France) Photo courtesy ofJean Courtin, director ofexcavations.

0 25 50

L 13

.

t _*

75 cm

L 12

.

. bones m stone ax

A fragments of bracelets

Figure 4. Feature H3: horizontal plan and refitting links between conjoinable pieces.

and comparisons with fauna1 assemblages (Villa ei at., 19866, 1988). Some marks go across a fracture line separating two conjoined fragments found at different locations (Villa et al., 19866, Figure 1 I:5 and 6) proving that bones were cut-marked before being broken. In sum,


there is no doubt that these bones document butchery and breakage by hammerstone blows,

to the exclusion of other processes.

Fontbrkgoua is one of the extremely few well-documented cases ofprehistoric cannibalism.

In the Old World there are no undisputed archaeological assemblages that have provided a

relatively large sample of human long bones demonstrably broken by percussion when fresh.

To our knowledge, no ethnographic assemblages of this kind have ever been analysed or

collected. Only in the New World have comparable assemblages of cannibalized bones been

reported by Turner (1983) for the American Southwest.

Like Sarrians but unlike many other archaeological assemblages, the FontbrCgoua bones

have been found in pristine conditions and have undergone only one cycle ofbreakage. Their

state of preservation is excellent: cortical surfaces are compact with a dense texture, fracture

surfaces have fresh, sharp edges, allowing easy diagnosis and attribute description. Collagen

content is high with values ranging from 24.6, to 14, 13.5 and 2.7O/b on four samples analysed

by Margaret Schoeninger (in fresh bone collagen is about 257,). Since bones were broken

when fresh, their present state of preservation is only a measure of ease in morphological

analysis.

Bqouce

Like Sarrians, this is a collective burial, although a smaller one with 22 individuals (MN1

based on humeri; Mahieu, 1990). The surrounding area is flat, so the chamber was built with

stones (Roudil, 1984). The color of fracture surfaces shows that these bones have undergone

two cycles of breakage. The first cycle with patinated fracture surfaces is old; it is probably

due to roof collapse and sediment pressure. The second cycle is due to the violent excavation

methods of the land owner; fracture surfaces are white. The analysed assemblage is composed

of shaft and end plus shaft fragments: 99 have recent fractures, 114 have one recent and one

old fracture, and 204 have old fractures only. Our analysis concerns only pieces with recent

fractures because their cause of breakage is well established by oral information. The total

number of pieces with recent fractures is actually 261 but to enhance comparability with

Fontbrkgoua (see section on length of analysed sample) we restricted the analysis to pieces

longer than 3.9 cm, except for conjoinable fragments. Thus, although screening procedures

were less meticulous than at the other two sites, they do not affect the analysis. As at Sarrians

breakage affected desiccated, brittle bones, but here it was a dynamic rather than a static

process.

This assemblage is remarkable in a negative sense, in having such a large proportion of

excavators breaks on robust bones. Bones are not permineralized; although brittle, they are

more resistant to breakage than those from Sarrians. Cortical surfaces have no traces of

subaerial weathering but show abundant root etching. Collagen content is fairly low (3.4O/,,;

Schoeninger, pers. comm.). In this case the present physical state ofbones and their breakage

process are contemporaneous.

Analytical procedures

We have looked at the following features: fracture angle, fracture outline, fracture edge, shaft

circumference, shaft fragmentation and shaft length. Attribute states are described under the

appropriate heading. These attributes have been defined by other workers (Bonnichsen,

1979; Bunn, 1983; Johnson, 1985; Morlan, 1984) but there is very little quantitative infor-

mation on frequencies of these attributes in assemblages of known origin, with the exception


ofBunns paper which provides data on shaft circumference and shaft length frequencies for two assemblages of animal bones.

Each fragment is identified to body part, segment and portion (Gifford & Crader, 1977); other recorded attributes are side, age, length, breadth (only when the shaft diameter is less than half the original), and refitting group, in addition to provenience information. Excluding indeterminate cases, most bones belong to adults: 73% at Sarrians (206 of 281), 94% at Bezouce (92 of98) and 77% at Fontbregoua (56 of73). Epiphyseal fragments without diaphysis have not been considered because epiphyses break differently from diaphyses and there are insufficient isolated epiphyses in the Fontbregoua and Sarrians samples to make a separate study worthwhile. The Fontbregoua and Bezouce samples do not contain complete bones; there were 19 complete long bones in the original Sarrians sample; they have been excluded from all analyses, including that of shaft circumference.

Fracture angle

This is the angle formed by the fracture surface and the bone cortical surface. Obtuse or acute angles are commonly associated with green bone fractures while, right angles are said to be preferentially associated with dry or permineralized bone fractures (Johnson, 1985; Morlan, 1984). Recorded attribute states are: 1. oblique (i.e. obtuse or acute); 2. right; 3. oblique and right (for fractures that have variable angles). Angles have been assessed visually, as in Bonnichsen (1979, p. 221). This description is used for proximal and distal fractures (Figure 5). Juvenile or thin cortical bone have not been considered.

Figure6 shows a very clear contrast between Sarrians and Bezouce on one hand with only 8.2 and 10.7% ofoblique angles and Fontbregoua on the other with 65.5%. Chi square values are very high for Fontbregoua vs. Sarrians ( 164.08) and for Fontbregoua vs. Bezouce ( 140.25; in both cases P


SAR (269)

BE2 (253)

FE (174)

Fracture angle

m Oblique

0 Right q Oblique and right

Figure 6. Relative frequencies of fracture angles. Absolute frequencies for oblique, right, and oblique and right angles are as follows: Sarrians 22, 176, 71; Bezouce 27, 174,52; Fontbrkgoua 114,47, 13.

36

e Figure 7. Examples of curved (a, b, c and e, left), transverse (d) and V-shaped (e, right) fractures from Bezouce (a, b, d), Sarrians (c) and Fontbrkgoua (e).

category represents complex, multidirectional morphologies, in clear opposition to simple transverse, rectilinear morphologies; and 3. intermediate which includes fractures that have a straight morphology but are diagonal, and fractures with a stepped outlinePthis category has the same function as the miscellaneous, divers and sundry tools categories of traditional lithic typologies, i.e., it acts as a catch-all for all those cases that do not fit neatly

SAR (358)

BEZ (287)

FB (2611

BREAKAGE PATTERNS OF HUMAN LONG BONES

Fracture outline

m Transverse

17 Curved/V-shaped

q Intermediate

Figure 8. Relative frequencies of fracture outlines. Absolute frequencies for transverse, curved and V- shaped, and intermediate fractures are as follows: Sarrians 193, 74f 32, 59; Bezouce 144, 59+23, 61; Fontbregoua 92.42 +92,35.

37

Figure 9. Jagged fracture surfaces (Sarrians) For an example of smooth surfaces see Figure 5b.

into the transverse, curved or V-shaped classes. Its purpose is to reveal patterns by

limiting analytical noise. Lateral fractures* and fractures on or near epiphyses have not been

considered.

*The term longitudinal fractures is often used to describe lateral breaks parallel to the shaft long axis; by extension, the term is applied to subrectangular shaft splinters produced by such breaks. Longitudinal fractures seem to be common in dry or subfossil bone; however, experiments show that lateral breaks in fresh bones are often more or less parallel to the shaft long axis. Following previous analysis (Bonnichsen, 1979) we classified lateral breaks as either parallel or oblique but we soon found these categories unsatisfactory because of intergradation between the two attribute states. Thus we decided to quantify the overall shape of a fragment through the shaft circumference attribute only; in other words, longitudinal fractures are represented by fragments with shaft circumference 1. In the course of the analysis we noticed that some fresh-fractured shaft splinters at Fontbregoua have twisted profiles that do not occur in postdepositionally broken bones. In the future we should develop a systematic description of lateral breaks that would separate such diagnostic byproducts of green bone breakage from other non-diagnostic morphologies.


SAR (358)

BEZ (287)

FB (261)

Fracture edge

m Smooth r- .Innnrr4

Figure 10. Relative frequencies of fracture edges. Absolute frequencies for smooth and jagged fracture surfaces are as follows: Sarrians 111,247; Bezouce 158, 129; Fontbregoua 163,98.

Shaft circumference

SAR (226)

BEZ (93)

FB (151)

Figure 11. Relative frequencies of shaft circumference. I = circumference is i; 3 = complete. Absolute frequencies for the 1,2,3 categories are as follows: Sarrians 16, 10,200; Bezouce 33, 0,60; Fontbregoua 115,23, 13.

Figure 8 shows again a contrast between Sarrians and Bezouce on one hand, both with a majority of transverse fractures, and Fontbrtgoua on the other, with a majority of curved fractures. Chi square values are as follows: Sarrians vs. Fontbregoua 30.74; Bezouce vs. Fontbregoua 30.46 (PO.30, not significant). It is clear that breakage outline, like fracture angle, is dependent on bone

Table 1 Body part frequelIcics


Sarrians (0)

Bezouce

(0)

Fontbrtgoua

(A)

Femur 20.4 38.7 IO.6 Tibia 15.9 18.3 18.5 Fib& 22.1 7.5 3.4 Humerus 12.8 9.7 13.3 Radius 13.3 3.2 Ulna 15.5 5.4 8.6

Indeterminate long bone 17.2 45.0 ,I 226 93 151

Percentages of body part representation in the shaft circumference and shaft fragmentation samples, which exclude all fragments shorter than 4 cm. See section on length of analysed fragments for explanation.

Figure 12. (a J Cylinders from Bezouce. (b) Elongate splinters (twisted profiles to the right) from Fontbrkgoua.

40 I. VILLA AND E. MAHIEU

Table 2 Combined tabulation of abaft length and circumfertncc

Length

Circumference 1 2 3 4

1 2 3 Total

I

2 3 Total

I 2 3 Total

Sarrians 16 0 0 0 9 1 0 0

66 60 62 12 91 61 62 12

&ZOUCC

31 2 0 0 0 0 0 0

30 25 4 I 61 27 4 1

Fontbr@ua 77 32 5 I 6 8 5 4 2 5 4 2

85 45 14 7

physical conditions (fresh, old), thus grouping together Bezouce and Sarrians, in contrast to FontbrCgoua.

The occurrence of spiral fractures on desiccated, subfossil bone comes as no surprise to taphonomists; we note however that spiral fractures with offsets (i.e. a spiral outline displaced by right-angie offsets, due to the presence of drying cracks; Mot-Ian, 1980, Figure 3.2 and Haynes, 19836, Figure 2) are present in the Bezouce and Sarrians samples (6.8% and 17.0% ofcurved outlines, that is four of59 and 18 of 106) but totally absent at Fontbrtgoua.

Fracture edge

This attribute refers to the aspect or texture of the fracture margin: smooth or jagged (Figure 9). Green bone breakage is said to be characterized by smooth margins and surfaces; jagged edges are found on dry bone (Johnson, 1985; Morlan, 1984). Figure 10 shows a significant difference between Sarrians and Fontbrtgoua. Unexpectedly Bezouce has a majority of smooth surfaces, like FontbrCgoua and unlike Sarrians. Chi square values are: Sarrians vs. Fontbrkgoua 59.24; Sarrians vs. Bezouce 35.90 (P< O-001 in both cases); Bezouce vs. FontbrCgoua 3.10 (not significant). We conclude that this attribute will not discriminate between aid and fresh bone breakage. Perhaps the kind offorce (dynamic versus static force) is more important than whether the bone is old and desiccated or fresh.

Shaft circumference This is an attribute developed by Bunn (1983) who used it to differentiate a bone assemblage accumulated by a hyena (characterized by a majority of specimens with complete shaft diameter) from bones broken by hunter/gatherers (with a majority of splinters). Attribute states are:

1. Bone circumference is less than half of the original (e.g., Figure 7b). 2. Circumference is more than half in at least a portion of the bone length. 3. Complete circumference in at least a portion of the bone length (Figure 7a, c).


As explained below (cf. Length of analysed shaft fragments), samples used in this and

following analyses (shaft length and B/L ratios) do not include fragments shorter than 4 cm.

This restriction should be taken into account in the following discussion.

Bezouce and Sarrians (Figure 11) have a large majority of specimens with complete

diameter (64.5 and 88.5)) at Fontbrtgoua splinters predominate (76.2%). Chi square values

are: Sarrians us. Fontbrtgoua 231.80; Bezouce us. Fontbregoua 83.15; Sarrians vs. Bezouce

23.57 (P< 0.001 in all cases). In this test the 1 and 2 categories have been combined because

Bezouce has zero frequencies for shaft circumference 2 and the chi-square test requires cell

frequencies greater than 1 (Siegel, 1956, p. 110). The higher frequencies of shaft circumference 1 at Bezouce (where violent excavation methods were used on already broken bones)

account for the relatively high value of the chi-square for Bezouce us. Sarrians; however,

their divergence is much smaller than with Fontbregoua. Clearly, of the two assemblages

with postdepositionally broken bones, Sarrians with its intact context and meticulously

excavated bones provides the most robust pattern. Still, it is remarkable that after two

breakage cycles specimens with complete shaft diameters still outnumber shaft splinters at

Bezouce.

High frequencies of complete shaft diameters are not, as one may suggest, the effect of

disproportionate numbers of bones with small diameters and/or thick cortical walls, such as

fibulae, radii and ulnae. Table 1 shows that at Bezouce and Fontbregoua fibulae and arm

bones occur in comparable frequencies, yet there is great disparity in the relative frequencies

of complete diameters. Fibulae and arm bones are, however, more resistant to splitting, as

obser\:ed by Trinkaus ( 1985) : at Sarrians 98 ?a of these bones preserve complete diameters, but only 73.9:!, of the tibias do so.

In sum, high frequencies of complete diameters appear to characterize assemblages of

postdepositionally broken bones. There is potential overlap with carnivore-generated

features, since fauna1 assemblages produced by carnivores appear to be characterized by

some cylinders (i.e. complete shafts or shaft segments without epiphyses) and by high

frequencies of articular ends with attached shafts preserving complete diameters in at least

one portion of their length (Binford, 1981, pp. 171-173; Bunn, 1983; Todd & Rapson,

1988). This ambiguity can easily be resolved by observing the incidence of other variables

such as tooth marks (Blumenschine, 1988; Todd & Rapson, 1988). Moreover, the overall

morphology of the Sarrians and Bezouce cylinders is quite different from those produced by

carnivores: compare Figure 12 showing cylinders bounded by transverse or stepped frac-

tures with Figure 4.57 in Binford (1981) with cylinders characterized by denticulated,

irregular, scalloped edges. We note that at Sarrians gnaw marks are completely absent; at

Bezouce two possible gnaw marks have been observed on a total of 444 recorded long bone

specimens.

Shafttfkagmentation

This attribute, based on a combined tabulation of shaft circumference versus shaft length,

appears to provide the most diagnostic pattern. Shaft length is categorized as follows:

1. corresponds to shafts that are less than one-fourth the original length (length here refers

to shafts only, the articular end is not taken into account);

2. is a length comprised between one-fourth and one-half.

3. is between one-half and three-fourths.

4. is more than three-fourths, essentially a complete or almost complete shaft.

Sarr~ans 12261

2G

10 -__._,

I 2 3 4

Shaft length (0)

Shaft length ibl

,=OfltbrigOUO (Itif)

Shaft length

(cl


This classification is more detailed than the one devised by Bunn (1983) which had

only three categories; however our data can be compared to his by lumping our 1 and 2

together.

Table 2 and Figure 13a-c indicate that Bezouce and Sarrians consist essentially of tubular

pieces of various lengths, from 4 to 1, while all splinters, that is fragments with shaft circum-

ference = 1 or 2, are very short, almost all shorter than one-fourth the original length. In other

words, at both sites breakage affects more the length than the circumference of the shaft. At

Fontbregoua breakage affects both aspects.

Particularly interesting is the presence at Fontbregoua of 25.296 of splinters that are

long and narrow, relative to the original bone shape (shaft circumference= 1 and shaft

length = 2-4). If we include fragments with shaft circumference 2, all of which are splinters

that preserve a larger diameter only on a small part of their length, frequencies go up to

36.4O,,. At Sarrians and Bezouce this class is essentially absent (frequencies are 0 and 2.1 no

respectively). These elongate splinters are the product ofwhat has been called longitudinal

diaphyseal splitting. In the past this breakage pattern was considered diagnostic of humanly

broken bones (Breuil & Weidenreich cited in Binford, 1981, p. 12); more recently Binford has challenged this view showing that this pattern occurs in bones broken by gnawing dogs

(1981, p. 56). Inalaterpaper thesameauthor (Binford & Ho, 1985, pp. 414and437) hasalso

suggested that breakage of longitudinally split human bones from Zhoukoudian was due to

weathering cracks and has labelled the idea that longitudinal splitting is indicative ofhuman

action an ancient folk belief .

Yet at Fontbregoua Cave bones show no traces at all of subaerial weathering, have no

deterioration cracks and were not chewed by dogs. Clearly elongate splinters can be a product

ofpercussion on green bone. Sarrians and Bezouce, on the contrary, show that subfossil bone

tends to break in short splinters. We note that at Fontbrigoua two-thirds of the elongate

splinters have curved end fractures and oblique angles; some are characterized by twisted,

helicoidal profiles (Figure 12) that do not occur in the other two assemblages, which are

characterized by splinters with parallel or subparallel lateral breaks (see footnote, p. 37).

Length of analysed shaft fragments

The number ofobservations falling into the category shaft length = 1 depends on the smallest

absolute length of the long bone fragments the analyst chooses to consider and/or is able to

assign to the genus Homo, ifnot to body part, without doubt. The archaeological context plays

a role in this problem.

Sarrians and Bezouce were not habitation sites and contained no fauna. Since bones at

Sarrians were broken in situ, even minute fragments could be assigned to species and body

part without hesitation; thus the original Sarrians sample contains 51 shaft fragments

between 1 and 4 cm long. At Bezouce there are also no species identification problems and all

small splinters can be securely attributed to Homo. On the other hand, Fontbregoua is an

habitation site. Although feature H3 was clearly made to contain only human postcranial

bones, the cave sediment is rich in animal bones; their fortuitous presence around and in the

sediment that covered and fihed the feature is not surprising and several were found at the

Figure 13. (a)- ic) Three-dimensional bar diagrams showing relative frequencies of shaft length by shaft circumference. Shaft length categories are: 1 = : or complete. Absolute frequencies are provided in Table 2.


Breadth/ length

0 20 40 % 0 20 40 % ,,,I,, III4II

0

0. I

0.2

0.3

0.4

0.5

0.6

0.7

0.0 Ber (33)

I- I

r-

SClr

Bez

Fb --LF t

L 1 I I I I I I I 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.6

- 0.r.

0 S.d.

W 95% confidence interval

1 Mean

Figure 14. Comparisons of breadth/length ratios of shaft splinters. Abbreviations: o.r. =observed range; s.d. =standard deviation. The 95% confidence intervals ofthe mean overlap for Sarrians and Bezouce and separate these two sites from Fontbrigoua.

periphery of the feature. Shaft splinters smaller than 4 cm are often impossible to separate

from animal bone fragments; thus they are under represented (n=5) in the Fontbrtgoua

sample which does not include fragments non-identifiable to species. To eliminate this dis-

parity between assemblages we have established a cut-off point for absolute length: all shaft

fragments smaller than 4 cm are excluded from the shaft circumference, shaft fragmentation

and breadth/length samples. Inclusion offragments I-3.9 cm long in the sample would have

the effect of increasing the category circumference 1 and length 1 of a few percentage

points at Sarrians and more than doubling its frequency at Bezouce* but it would have no

effect on the relative frequencies of elongate splinters, which are absent at Sarrians and

Bezouce.

Breadth/length ratios. Samples include only shaft splinters with length >4 cm (see previous

section) and breadth smaller than the original shaft diameter. End plus shaft fragments are

excluded. This greatly reduces the size of the Bezouce and Sarrians assemblages although

their comparisons still retain information value. Figure 14 shows that the Fontbrtgoua

assemblage has lower breadth/length ratios than the other two sites. This difference is

independent from types oflong bone present. Logically larger bones such as femurs and tibias

will tend to yield fragments with greater breadth/length ratios than narrower bones such as

fibulas and radii. In fact, mean B/L ratios offemurs are 0.39 at Sarrians and 0.40 at Bezouce

while FontbrCgoua has a mean ratio of0.26; for tibias ratios are 0.3 1 and 0.42 for Sarrians and

Bezouce, O-19 for Fontbrkgoua; for indeterminate long bones ratios are 0.34 at Bezouce and

*At Sarrians the increase would be from 16 (as in Table 2) to 50 (7.1 to 17.9%); at Bezouce from 3 1 to 190 (33.3 to 75.496).


0.22 at Fontbregoua (this class is not represented at Sarrians). Students t-values are high for all cases and P varies between 0.02 and < O+OOl . The Sarrians and Bezouce samples are too small and other types of bones cannot be compared; but the previous figures clearly suggest

that mean B/L ratios are consistently smaller at Fontbrtgoua* and are not determined by

differences in body part representation.

Results

Fracture angle, fracture outline, shaft circumference, shaft fragmentation and B/L ratios are

criteria of diagnostic value with respect to breakage processes and can be used to separate subfossil bone breakage from hammerstone breakage of green bone. These criteria are useful

at the statistical, assemblage level but are not diagnostic for individual pieces. Individual

pieces can be identified as the result of hammerstone breakage only if they preserve impact

notches with incompletely detached microflakes, possibly in association with percussion pits

and grooves, or if the archaeological context points unequivocally to that interpretation.

This situation finds a parallel in the diagnosis ofearly stone or bone artifacts. These too can

be unequivocaly identified as man-made only by a combination of attributes (multiple flake

scars in an orderly pattern, recurring shapes and clear bulbs ofpercussion) at the assemblage

level. Isolated pieces pose serious problems unless they have naturally improbable shapes

(e.g., an elaborate biface shape) or are found in an unambiguous man-made context and

association (like the wooden spear embedded in an elephant thoracic cage at Lehringen).

Based on knowledge of animal bone fracture patterns, we expect carnivore breakage of

green human bone to resemble in part hammerstone breakage. However, high frequencies of

tooth marks, distinctive patterns of destruction and specific morphologies of gnawed edges

are to be expected in carnivore-modified assemblages (Blumenschine, 1988; see also Horwitz

& Smith, 1988; Milner & Smith, 1989).

Applications

Fracture morphologies and shaft fragmentation indices should be used in the study of the

Neandertal bones from Krapina, where the hypothesis ofcannibalism remains controversial.

Russell (1987a) studied the Krapina bones to see whether their breakage was natural and due

to sediment pressure and rock fall, as Trinkaus had suggested in 1985, or due to marrow

fracturing, i.e., for cannibalism. She argued that the strongest indicators ofhuman percussion

on green bone shafts are microflakes adhering to the point ofimpact (see LiIntroduction and

footnote therein).

Russell did not find such features on the Krapina bones and therefore she argued that

breakage was natural and there had been no cannibalism at Krapina, only geological break-

age of bones that had been given secondary burial.

If she is right, it cannot be for the reasons given. First, microflakes adhering to the impact

point are not common features. At Fontbrigoua they are found on only 10% of the long

bones. Comparable percentages have been provided by Binford (1981) for reindeer bones

broken by the Nunamiut for marrow extraction (see Introduction).

*Although we cannot test mean differences in breadth/length ratios for splinters shorter than 4 cm in bones broken when fresh or broken after burial, we suspect that such differences would vanish as length decreases. Breadth cannot decrease with the same gradient as length because very thin splinters become comminuted into bits too minuscule for analysis; thus splinters shorter than 34 cm will have similar breadth/length ratios in all kinds ofassemblages.


Not only are microflakes rare, they are also very fragile and easy to detach from the bone.

One cannot reasonably expect to find them preserved on bones that have undergone even

slight mechanical attrition in sediments, bones made fragile by post-burial chemical alter-

ation and bones that have been handled and shifted in drawers for a long time, as the Krapina

bones. Clearly incompletely detached spalls are easy to detach; these features can be pre-

served only on bones in pristine conditions. * This is not the case for the Krapina bones which

were very fragile and had to be preserved with shellac, had been vertically displaced in the

sediment, as indicated by refitting offragments from different levels, and have been handled

for many years.

In sum, the absence of particular impact scars carries no positive significance in the case

of assemblages with a complex taphonomic or post-excavation history, i.e., bones that do

not have well-preserved cortical surfaces and have undergone sediment attrition or post-

depositional deterioration. The criteria we have developed in this paper should be used in

the absence of hammerstone-produced features, or as a complement to them, because they

provide an additional and significant line of evidence. The Krapina materials should be

re-evaluated using these patterns.?

The applicability of these criteria to the study of fauna1 bones should be tested through

analysis of archaeological and paleontological assemblages. Since fracture morphologies and

*Microflakes can also become detached during transport as experience with shipping Hadza assemblages of percussion-broken bones shows (Larry Bartram, pers. comm.).

tThe refutation of cannibalism at Krapina rests also on Russells study of cutmarks, but the cutmarks data she used are equally unsuitable for the purpose (Russell, 19876). She compared cutmark frequencies from Krapina, Juntunen (a North American ossuary dated to 132Ok 75 A.D. containing bonesdefleshed for secondary burial) and Combe Grenal (a French Mousterian site where reindeer bones were processed for food). In frequency and location ofcutmarks Krapina is very similar to Juntunen, and both are different from Combe Grenal where cutmarks are said to be fewer and differently placed. Since defleshing for meat at Combe Grenal seemed to produce few marks, she suggested that high frequency of marks at Krapina were the result of bone cleaning practices related to secondary burial. We question this interpretation for the following reasons:

1. Combe Grenal is not a valid sample. Russell used data published by Binford (1981, Table 4.03). Unfortunately, Binfords table includes only articular ends, not limb shafts; Binford himselfexplains that limb shaft fragments were not routinely saved at Combe Grenal ( 1981, pp. 99, 134). Since the incidence of cut marks can be very high on limb shafts (Bunn, 1986, p. 437; Marshall, 1986, p. 664, Tables 1 and 2), the reported cutmark frequency at Combe Grenal is likely to be lower than in the original assemblage. Limb shafts are present in the Krapina and Juntunen assemblages (to which Combe Grenal is compared) and typically carry many defleshing marks (Russell, 19876 Figures 3,4,6 and 7) In sum the omission oflimb shafts from the Combe Grenal assemblage undermines its value for comparative purposes, both in term of cutmark frequencies and locations (for the latter Russell could only use descriptions of isolated examples by Binford and by Henri Martin who in reality described La Quina, not Combe Grenal). Interestingly, chi-square tests based on data published by Chase (1986, pp. 62-65 and Tables A22A5) indicate no significant differences for tibias and humeri between Krapina and Combe Grenal (chi-square values are 2.19 and 2.35, not significant at the 0.05 level for df= 1).

2. Several fauna1 assemblages show the high frequency of cutmarks and the kind of defleshing marks Russell associates with secondary burial; but in fauna1 assemblages secondary burial is out of the question. For instance, we may compare frequencies of marks on Krapina humeri, femora, tibiae, and scapulae with values published for Ngamuriak large bovids (Marshall, 1986, Table 2) and the animal sample from Fontbregoua (sheep and wild boar; Villa er al., 1986a, Table 4). For Krapina, Juntunen, Ngamuriak and the Fontbregoua animal sample, in this order, percentage values are: humerus 45.8,351,54.7, and 40.0; femur 66.7,36.4,30.8 and 41.4; tibia 20.0,20.0,19.7 and 40.0; scapula 47.4, 44.1, 46.1, 44.4. Chi-square tests on raw frequencies show no significant differences for any of these elements in all four assemblages; chi-square values are all smaller than 3.84. In addition, locations of marks reported by Russell at Krapina and Juntunen are very similar to those found on the Fontbregoua human and animal bones (Villa, in prep.).

In sum, Russells data are inadequate to prove the thesis of secondary burial and to refute the cannibalism hypothesis. In principle the Krapina fauna1 collection should be used in comparisons with the human bones. But the Krapina fauna is selected and incomplete, and information on mode of bone disposal is lost; thus only bone breakage can provide a significant argument.


fragmentation indices are constant properties ofbroken bone, they can be studied even when

the bone cortical surfaces would not allow reliable identification of various impact traces.

Acknowledgements

We thank Margaret Schoeninger for doing analyses of collagen content. We also thank her,

Larry Bartram, Jim Oliver, Nick Toth and one journal referee for very useful, critical

comments.

References

Binford, L. R. (1981). Bones: Ancient Men and Modern Myths. New York: Academic Press. Binford, L. R. & Ho, C. K. (1985). Taphonomy at a distance: Zhoukoudian, The Cave Home of Beijing Man.

Curr. Anthrop. 26,4 13-439. Blumenschine, R. J, (1988). An experimental model of the timing of hominid and carnivore influence on archaeo-

logical bones assemblages. 3. Archaeol. Sci. 15,483-502. Blumenschine, R. J. & Selvaggio, M. M. (1988). Percussion marks on bone surfaces as a new diagnostic ofhominid

behavior. Nature 333,763S765. Blumenschine, R. J. & Selvaggio, M. M. (in press). On the marks ofmarrow bone processing by hammerstones and

hyaenas: their anatomical patterning and archaeological implications. In J. D. Clark, Ed.), XIth U.I.S.P.P. Congress, Early Man Symposium Maim: Romisch-Germanisches Zentralmuseum.

Blumenschine, R. J., Bunn, H. T., Selvaggio, M. M. & Saanane, C. (1990). Site formation and hominid behavior at FLK


Mahieu, E. (1987a). Lhypogte des Boileau. Vers une meilleure connaissance des rites funeraires du Neolithique proven9al. Bull. Sot. Prihist. Fran+sc 84,5-l.

Mahieu, E. (19876). Lhypogie des Boileau: approche mithodologique. Act. Rencont. Nkolith. Rhke-A&s 3,97-102. Mahieu, E. (1990). La sepulture du Mas St. Andre a Bezouce (Gard). Etudes des restes humains. Paper presented at

the meeting Le Chalcolithique en Languedoc. Hommage au Dr. Arnal, St. Mathieu de Treviers, Sept. 1990. Martin, H. (1910). La percussion osseuse et les esquilles qui en derivent. Bull. Sot. Prihist. Fran+re 7,299%304. Marshall, F. (1986). Implications of bone modification in a Neolithic fauna1 assemblage for the study of early

hominid butchery and subsistence practices. J. hum. Euol. l&661-672. Milner, G. R. & Smith, V. G. (1989). C arnivore alteration of human bone from a late prehistoric human site in

Illinois. Am. J. Phys. Anthrop. 79,43-49. Morlan, R. E. ( 1980). Taphonomy and Archaeology in the Upper Pleistocene of the Northern Yukon Territory: .4 Glimpse of the

Peopling of the New World. Ottawa: National Museum of Man Mercury Series. Morlan, R. E. (1984). Toward the definition ofcriteria for the recognition ofartificial bone alterations. Quntern. Res.

22,160-171. Myers, T. P., Voorhies, M. R. and Corner, R. G. (1980). Spiral fractures and bone pseudotools at paleontological

sites. Am. Antiq. 45,483-490. Oliver, J. S. (1986). The taphonomy and paleoecology of Shield Trap Cave (24CBSI), Caribou County, Montana. MS

Dissertation, University of Maine at Orono. Olsen, S. L. & Shipman, P. (1988). Surface modification on bone: trampling versus butchery. 1. ,4rchaeol. Sci. 15,

535-553. Potts, R. B. (1982). Lower Pleistocene siteformation and hominid activities at Olduuai Gorge, Tanzania. Ph.D. Dissertation,

Harvard University, Massachusetts. Potts, R. B. (1988). Earb Hominid Actiuities at Olduuai. New York: Aldine de Gruyter. Roudil, J. L. (1984). Informations archtologiques, Circonscription du Languedoc-Roussillon. Gallia Prdhist. 27,363. Russell, M. D. (1987~). Bone breakage in the Krapina hominid collection. Am. J. Phys. Anthrop. 72,373-379. Russell, M. D. (19876). Mortuary practices at the Krapina Neandertal site. Am. J. Phys. Anthrop. 72,381-397. Siegel, S. (1956). Nonparametric Statisticsfor the Behavioral Sciences. New York: McGraw-Hill. Todd, L. C. & Rapson, D. J. (1988). Long bone fragmentation and interpretation offaunal assemblages: approaches

to comparative analysis. 3. Archaeol. Sci. 15,307-325. Trinkaus, E. (1985). Cannibalism and burial at Krapina. 3. hum. Evol. 14,203-216. Turner, C. G. II (1983). Taphonomic reconstruction of human violence and cannibalism based on mass burials in

the American Southwest. In (C. M. LeMoine & A. S. MacEachern, Eds) Carnivore~,HumanScavengersandPredator~: A Question of Bone Technology, pp. 219240. Calgary: Archaeological Association of the University of Calgary.

Villa, P. ( 1983). Terra Amata and the Middle Pleistocene Archaeological Record of Southern France. Berkeley and Los Angeles: University of California Press.

Villa, P., Helmer, D. & Courtin, J. (1985). Restes osseux et structures dhabitat en grotte: Iapport des remontages dans la Baume Fontbregoua. Bull. SOL. Prihist. Fran&se 85,398-42 1.

Villa, P., Bouville, C., Courtin, J., Helmer, D., Mahieu, E., Shipman. P., Belluomini, G. & Branca, M. (1986~) Cannibalism in the Neolithic. Science 233,43 l-437.

Villa, P., Courtin, J., Helmer, P., Shipman, P., Bouville, C. & Mahieu, E. (19866). Un cas de cannibalisme au Neolithique: boucherie et rejet de restes humains et animaux dans la grotte de Fontbregoua 1 Salernes (Var). Gallia PrLhist. 29, 143% 17 1.

Villa, P., Courtin, J. & Helmer, D. (1987). Le cannibalisme prehistorique. Archiologia 223,4&52. Villa, P., Courtin, J. & Helmer, D. (1988). Cannibalism in Old World prehistory. Rivista di Antropologia (Roma)

66(Suppl.), 4764. White, T. D. & Toth, N. (1989). Engis: preparation damage, not ancient cutmarks. Am. 3. Phys. Anthrop. 78,

361-367.

Breakage Patterns of Human Long Bons

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