Van den Dries, M. \u0026 Van Gijn, A.L. (1997) The representativity of experimental use wear traces

$Page 1: Van den Dries, M. \u0026 Van Gijn, A.L. (1997) The representativity of experimental use wear traces$
A. RAMOS-MILLAN • Ml! A. BUSTILLO (Eds.)

SILICEOUS ROCKS

AND CULTURE

UNIVERSIDAD DE GRANADA I" ' MONOGRAFlCAARTE YARQUEOLOGIA ;, .,


The Representativity of Experimental U sewear Traces

MONIQUE VAN DEN DRIES and ANNELOU VAN GUN

Instituut voor Prehistorie, Rijksuniversiteit Leiden, Postbus 9515, 2300 RA Leiden, The Netherlands.

RESUMEN

Han existido pocos intentos para cuantificar las huellas de usa obtenidas en l/tiles experimentales. La ausencia de hue lias reconocibles, tales como extracciones del filo, redondeamiento 0 pulido, tiene importantes implicaciones para nuestras inferencias arqueolagicas, de acuerdo con el hecho de que el desarrollo de las huellas de uso varia conforme al material de contacto y la mocian. Por ello, ciertas actividades estarian muy bien representadas en nuestro espectro de resultados mientras que otras estarian ausentes. En este trabajo estimamos los varios aspectos del dana en Ii tiles experimentales a partir del registro de presencias y ausencias de las huellas. De esta manera es posible calcular la representatividad de los datos arqueolagicos. Otro de los objetivos planteados ha sido el examen de la frecuencia de los diversos atributos que resultan en jimcian de los diferentes materiales de contacto y mociones. Segl/n ello, muy pocos atributos son exclusivos de materiales de contacto y mociones especificos. Salo la combinacian de un gran nt/mero de atributos posibilita inferir las sustancias de contacto y las mociones, y este trabajo oji'ece algunas sugerencias de combinaciones significativas al respecto. PALABRAS CLAVE: ANAL/SIS DE HUELLAS DE usa, EXPERIMENTOS CON UTILES DE SILEX, CUANTIFICACION, ATRIBUTOS

DE LAS I-IUELLAS DE usa.

ABSTRACT

There have been very few attempts to quantify the occurrence of wear traces on experimental tools, The absence of recognizable traces, be it edge removals, rounding or polish, has important implications for our archaeological inferences, This is especially so as the development of traces varies with contact material and motion. Certain activities will therefore be overrepresented whereas others will be absent in our spectre of results. In this paper the occurrence of various aspects of damage on experimental tools is counted according to a presencel absence score. In this manner it is possible to calculate the representativity of the archaeological data. Another objective is to examine the frequency of various attributes resulting from different contact materials and motions. It turned out that very few attributes are exclusively linked to specific contact materials or motions. Only by combining a large number of attributes, is it possible to make inferences as to contact substance and motion; the paper provides some suggestions for meaningful combinations. KEYWORDS: USEWEAR ANALYSIS, EXPERIMENTS WITH FLINT IMPLEMENTS, QUANTIFICATION, WEAR TRACE ATTRIBUTES.

INTRODUCTION

\

Usewear analysis of flint tools as a method is ca. 20 years old, but there still seems little consensus as to the exact methodology. Blind tests have pointed out considerable difficulties with both the low- and the high-power approaches (a.o. Newcomer et alii 1986, Unrath et alii 1986). Polishes caused by different contact materials overlap in terms of their constituent attributes, edge damage is not distinctive enough to allow an interpretation, post-depositional surface modifications affect all types of damage much more severely than was previously assumed, and the usage of implements does not always produce recognizable wear.

This paper will address two related issues. First, the absence of traces, be it polish, edge removals or edge rounding, even after considerable use of the experimental implement. It was already recognized by Keeley (1980) that soft materials such as meat do not always result in the development of polishes and most adherents of the high-power approach are aware of the fact that the absence of traces should not lead to the conclusion that the artefact in question has not been used in the past. Low-power approaches generally are less explicit in this regard (but, see Shea 1988). However, there have been very few attempts to quantify the occurrence of

Siliceous Rocks and Culture, 499-513

500 MONIQUE VAN DEN DRIES and ANNELOU VAN GIJN

wear traces on experimental tools. The first objective of this paper therefore is to count absolute presence/absence scores for edge removals, edge rounding and polish.

A second objective is to examine the frequency of various attributes resulting from different contact materials and motions. Fisher et alii (1984) analyzed projectile points, Van Gijn (l986) considered traces of fish polish, whereas Vaughan (1985) and Van Gijn (1990) addressed a variety of materials and motions. Only for quartz as raw material a very detailed quantification of experimental results exists (Knutsson 1988, Sussman 1988). In two separate paragraphs, pertaining to edge removals/rounding and polish respectively, the occurrence of attributes will be presented.

The experimental program on which the present paper is based, consists of301 experiments involving a variety of contact materials and motions. Most of these can be qualified as generalized, but several were directed at a specific task such as the manufacture of a bone harpoon. All implements were examined for the presence of polish, edge removals, striations and edge rounding. Striations are left out of the present analysis because they are only visible within well-developed polish areas and are very difficult to classify. Several variables concerning different aspects of wear were coded and entered into a database, in order to be able to assess the results quantitatively. All experimental pieces were chemically cleaned with Hel and KOH (el Keeley 1980). For a detailed description and a visual presentation of much of the following, the reader is referred to Van Gijn (1990).

A few problems associated with the approach should be mentioned. Some of the experiments were performed by students with little experience, implying less control on the exact course of the experiment; this may be of special importance with regard to the occurrence of edge removals. Also, in terms of cross-tabulations of different variables, many empty cells occur because experiments would run for 30 or 60 minutes, whereas shorter durations are underrepresented. In a sense, this paper therefore is an exploratory one, intended to suggest directions for further experimentation.

PRESENCE/ABSENCE SCORES FOR WEAR DEVELOPMENT

Edge removals

Table 1 shows the frequency of the occurrence of edge removals. Projectile points sustained impact scars on 78% of the tools. Rather surprising are the relatively low scores for bone, wood and antler (66%, 42% and 33%, respectively). If, however, we examine the latter figures per motion, it is evident that longitudinal actions resulted almost inevitably in edge removals: 93% for bone, 88% for wood, and 100% for antler. Transverse motions, in contrast, do not often result in edge removals because they are commonly performed with edges stabilized by retouch and displaying a steep edge angle. This latter observation expiains why contact with hide produced edge removals in only very few cases; most experiments involved a transverse motion.

Edge rounding

Edge rounding is present on 68% of the tools used transversely and on 54% of the implements applied in a longitudinal fashion (table 1). If we examine these figures also per

THE REPRESENTATIVITY OF EXPERIMENTAL USEWEAR TRACES 501

Table I.-Frequency of the occurrence of edge rounding versus edge retouch according to different motions and contact materials. Percentages are listed in parentheses.

longitudinal transverse other total

rounding retouch rounding retouch rounding retouch rounding retouch

hide 7/15 (47) 4/15 (27) 22/28 (79) 0/28 (0) 116 (17) 1/6 (17) 30/49 (61) 5/49 (10)

wood 10/17 (59) 15/17 (88) 19/35 (54) 11135 (31) 2/10 (20) 0/10 ( 0) 31162 (50) 26/62 (42)

bone 1115 (7) 14/15 (93) 12/15 (80) 4/15 (27) 4/23 (17) 17/23 (74) 17/53 (32) 35/53 (66)

antler 2/5 (40) 5/5 (100) 317 (43) 11 7 (14) 11 6 (17) 0/6 ( 0) 6/18 (33) 6/18 (33)

soft silicious plants 14/23 (61) 7/23 (30) - . 111 (100) 0/1 ( 0) 15/24 (62) 7/24 (29)

soft non-silicious plants 4/10 (40)' 3/10 (30)' 1/1 (100) 1/1 (100) - - 5/11 (45) 4/11 (36) ---

cereals 20/20 (100) 6/20 (30) - 0/1 ( 0) 0/1 ( 0) 20/21 (95) 6/21 (29)

- meat 1/4 (25) 2/4 (50) . - - - 1/4 (25) 2/4 (50)

butchering 3/8 (38) 4/8 (50) - - - . 3/8 (38) 4/5 (50)

fish 9/16 (56) 15/16 (94) 3/5 (60) 3/5 (60) 2/6 (33) 2/6 (33) 14/27 (52) 20/27 (74)

projectile - - - - 7/9 (78) 0/9 ( 0) 7/9 (78)

pottery - 6/6 (100) 1/6 (17) 1/2 (50) 1/2 (50) 7/8 (87) 2/8 (25)

shelllstone/teeth 0/3 (0) 3/3 (100) - . 3/8 (37) 5/8 (63) 3/11 (27) 8/11 (73)

soil 4/4 (100) 0/4 ( 0) - - 1/1 (100) 0/1 ( 0) 5/5 (100) 0/5 (0)

total 75/140 (54) 78/140 (56) 66/97 (68) 21/97 (22) 16/64 (25) 26/64 (41) 157/301 (52) 1321301 (44)

* includes the four experiments with roots, involving extensive contact with the soil adhering to the surface.

material, it can be noted that some materials (hide, bone, non-silicious plants and fish) cause significantly more rounding due to transverse motions as compared to longitudinal motions. Wood, on the contrary, causes more rounding with longitudinal motions: 59% versus 54%. Therefore, not only the applied motion is responsible for the development of rounding but also the worked material.

Polish

Table 2 shows the frequency of polish on experimental tools according to contact material and motion. It can be seen that polish develops on a very high percentage of the used implements. Domestic cereals, soil, and pottery even cause polish on a 100% basis. Silicious wild plants, bone, and to a lesser extent wood also score very high (96%, 94% and 86%, respectively). The rather low frequency of hide polish (65%), commonly regarded to develop relatively quickly, is due to several experiments with dyed, modern leather which only in five out of eleven cases yielded polish. Fish produced polish in 67% of the experiments, but this is biased by the fact that in most cases it concerns "bone-polish", whereas traces really characteristic of contact with fish (streaks of polish due to contact with fish-scales) only occurred on 26% of the tools (see also Van Gijn 1986). Among the non-silicious soft-plant implements, experiments with turnip are included; the polish on the turnip-implements is caused by the sand and clay adhering to the root-surface. Omitting these experiments drops the frequency for polish

502

Table 2.-Experimental tools: frequency of the occurrence of polish according to contact material and motion. Percentages are listed in parentheses.

longitudinal transverse boring other total

hide 9/15 (60) 22(1f3 (70) 1/ 6 (17) 32/49 (65)

wood 16/17 (94) 29(35 (83) 3/3 (100) 5/7(71) 53/62 (86)

bone 15/15 (100) 13/15 (87) 3/4(75) 19/19 (100)' 50/53 (94)

antler 5/5 (100) 6/7(86) 3/5(60) 0/1 (0) 14/18 (78)

soft silicious plant 22/23 (96) 1/ 1 (100) 23/24 (96)

soft non-silicious plant 6/10 (60)" 1/ 1 (100) 7/11 (64)

cereals 20/20 (100) 1/1 (100) 21/21 (100)

butchering 6/8(75) 6/8 (75)

meat 2/4 (50) 2/ 4 (50)

fish 12/16 (75) 4/5 (80) 2/6 (33) 18/27 (67)

projectile 6/9 (67) 6/9(67)

pottery 6/6 (100) 2/2 (100) 818 (100)

shell/stone/teeth 1/ 3 (33) 5/8 (63) 6/11 (55)

soil 414 (100) 1/1 (100) 515 (100)

* Concerns carving bone. ** Includes the four experiments with roots, involving extensive contact with the soil adhering to the root's surface.

MONIQUE VAN DEN DRIES anel ANNELOU VAN GIJN

development to 20%. In the case of the shelllstone/teeth-category the relatively low score (55%) is due to the removal of polish by use retouch.

Comparison

It appears that in general polish develops more frequently than edge removals or rounding. This implies that the low-power approach can potentially be missing more used tools as compared to the high-power analyses, which also involve the examination of polishes with incident light microscopy'. However, it should be stressed that polishes are more easily destroyed by post-depositional surface modifications. In addition, the results presented here include those from experiments on a variety of types of flint; if only coarse-grained flint had been used, for

instance, the scores would be much less favourable for the high-power approach, as polish develops only very slowly on such raw material. It is suggested, therefore, that the instances in which used artefacts would be missed in archaeological assemblages should be about equal for both the low- and the high-power approach.

THE QUANTIFICATION OF DIAGNOSTIC EDGE REMOVALS AND ROUNDING

Not only may the presence or absence of edge damage show some patterns, certain variables as scar termination, scar length, and the distribution of these scars along the edge may also vary in a diagnostic fashion. These variables and the development of edge rounding will be discussed in this paragraph. For the purpose of this analysis broad categories of contact substances were further differentiated according to hardness; for instance, wood in soft and hard wood, and bone in soaked and fresh bone.

Termination

Scars can terminate in different ways and it is this variation that may give an indication of the substance on which the edge was used (Odell 1980, Odell and Odell-Vereecken 1981, Shea

I Low-power analyses often include polishes in their inferences as well. However, stereo microscopes do not allow, even if magnifications exceeding IOOx are used, the examination of the same polish features as incident light microscopes.


1991). Odell and Shea make a distinction between harder materials and softer materials. The former is believed to predominantly cause retouch with step- and hinge-terminations, the latter tend to cause feather-terminated retouch. Table 3 shows the scores of their occurrence within this sample 2.

The experimental tools do not display many instances of step-terminations; when they do occur, they are almost exclusively associated with hard animal materials such as bone, teeth and shell. The hinge-type is the most common one and is associated with working hard animal (bone, antler), medium animal (dry hide/leather, fish) and hard vegetal (hard wood) material. Feather-terminations are also abundant, but they seem to be related to use on softer substances, such as meat, fresh hide, soft plants, and cereals. However, they also occur on implements used on soft wood and soaked antler, i. e. material of medium-hardness.

Thus, these termination types may be regarded as diagnostic features of the general hardness of the material worked. However, it should be noted that exceptions will always occur. Working fresh bone and hard vegetal material, for instance, may also cause feather-terminations. In stich instances other factors like the morphology of the working edge angle or the flint's grainsize may be of influence on the wear development. If such is the case with archaeological tools, they may be misinterpreted.

Scar length

Scar length is the second characteristic of the edge-removals that has been quantified (table 4). A few significant features have been noted. For instance, hide working only produces scars with a length up to 250 11, fish processing is associated with scars smaller than 500 11, while edge removals caused by working soft plants generally measure around 200 11, although occasionally they may reach up to 80011 (wild silicious plants such as Phragmites). Cereals only leave scars with a maximum length of 300 11. Meat cutting causes the smallest removals (100 11), as long as

Table 3.--Relationship between contact material and retouch termination, including all applied motions.

step hinge feather

hide 0/5(0%) 2/ 5 (40%) 3/5(60%)

wood 1/24(4%) 15/24 (63%) 8/24 (33%)

bone 9(35 (26%) 23/35 (66%) 3/35 (8%)

antler 0/6 (0%) 3/6 (50%) 3/6 (50%)

soft silicious plant 0/5 (0%) 0/5 (0%) 5/5 (100%)

soft non-silicious plant 0/4 (0%) 2/4 (50%) 2/4 (50%)

cereals 0/6 (0%) 0/6 (0%) 6/6 (100%)

meat 0/2 (0%) 1/2 (50%) 1/2 (50%)

butchering 1/4 (25%) 1/4(25%) 2/ 4 (50%)

fish 0/19 (0%) 8/19 (42%) 11/19 (58%)

pottery 0/2 (0%) 1/2(50%) 1/2 (50%)

shell 2/ 5 (40%) 2/5 (40%) 1/ 5 (20%)

teeth 1/1 (100%) 0/1 (0%) 0/1 (0%)

limestone 0/1 (0%) 0/1 (0%) 1/1 (100%)

total 14/119 (12%) 58/119 (49%) 47/119 (39%)

there is no contact with bone (butchering) or other tough tissue. Although bone worK111g inflicts a wide range of lengths, most of the scars are longer than 500 11. Thus, scar length seems to be a diagnostic feature of the general hardness of the contact substance; motion, on the other hand, does not seem to be of influence on the length of the edge removals.

2 Although each working edge usually shows different termination types, only the predominant type counts. It should be kept in mind that this predominance is always an estimation and therefore subjectively determined. As a consequence, it is possible that one type was sometimes accidently favoured above another while they actually occurred in equal amounts. As a whole these advantages will probably be balanced, but some of the individual cases with unexpected scores may thus be ascribed to a methodological cause. This remark applies to other tables as well.


Table 4.-Relationship between contact material and length Distribution (in 11) of the retouch scars, including all applied motions.

0·250jl. 251-500,," >500jl.

hide 515 (100%) 0/5 (0%) 0/5 (0%)

wood 12/26 (46%) 13/26 (50%) 1/26 (4%)

bone 1/35 ( 3%) 14/35 (40%) 20/35 (57%)

antler 2/ 6 (33%) 3/6 (50%) 116 (17%)

soft silicious plant 4/7 (57%) 1/7 (14%) 2/ 7 (29%)

soft non-silicious plant 2/ 4 (50%) '}J4 (50%) 0/4( 0%)

cereals 516 (83%) 116 (17%) 0/6 (0%)

meat 112 (50%) 1/2 (50%) 0/2 (0%)

butchering 2/ 4 (50%) '}J4 (50%) 0/4 (0%)

fish 1'}J20 (60%) 7/20 (35%) 1/20 (5%)

pottery 0/2 (0%) 2/ 2 (100%) 0/2 (0%)

shell 115 (20%) 4/5 (80%) 0/5 (10%)

teeth 1/1 (100%) Oil (0%) 011 (0%)

limestone 011 (0%) 1/1 (100%) 011 (0%)

total 48/124 (39%) 511124 (41%) 25/124 (20%)

Table 5.-Relationship between motion and distribution of edge removals.

distribution type

total overlapping closel close! widel widel regalar irregular regalar irregular

longitudinal 74 7% 8% 53% 1% 31%

transversal 21 10% 38% 14% 5% 33%

carving 17 65% 17.5% 17.5%

boring 6 67% 16.5% 16.5%

butchering 4 50% 50%

Whereas the variables scar termination and scar length are related to the hardness of the contact materials, the way in which the removals are distributed along the edge is primarily determined by the applied motion (table 5). It may be inferred from this table that overlapping scars are almost exclusively related to carving and boring motions. On 11 out of 17 (65%) carving tools and on four out of six (67%) boring tools this distribution type is present, whereas only five (7%) cutting and two (10%) scraping implements display this feature.

The closelirregular and wide! inegular varieties predominantly result from longitudinal motions (including meat butchering and fish processing). The regular distribution occurs less frequently and seems to be related to a transverse motion: 43% of the transversely used tools displays this feature versus only 9% of the implements used in longitudinal motions. As has been stated earlier in this paper, transverse motions tend to cause less scarring than longitudinal

motions. This observation may explain the scanty occurrence of the regular distribution type. The difference between wide and close distributions does not seem to be related to the

applied motion. Other factors such as the hardness of the contact material, the pressure exerted, or the duration of the experiment may be of importance, but this should be studied further. Finally, it should be stressed that distribution of the edge removals is not the same as their location. The location of the scars on the ventral and dorsal aspect of the implement indeed does relate to motion: despite numerous exceptions, unifacial location is mainly associated with transverse motions, whereas a bifacial location predominantly results from longitudinal motions.

Edge rounding

Above (see table 1) it was concluded that the development of edge rounding not only is a consequence of the applied motion but also of the contact substance. Table 6 displays the relationship between duration of the experiment and contact material for every implement


showing rounding of the used edge. In general, it may be concluded that material of medium hardness (e.g. soaked antler and fish) produces edge rounding more quickly than hard (bone, hard wood) or somewhat softer (fresh hide, soft plant, cereals, or meat) material. However, individual tools can deviate considerably from this general rule; for instance, fresh hide, hard wood or meat can cause edge rounding even after a few minutes work (column "lnin").

The duration of the experiment was also examined for those experimental implements which do not display edge rounding after use. Generally speaking, it is obvious that tools showing edge rounding are used for a longer period than those which still have a sharp edge. However, incidentally edges remain sharp even after more than an hour's work (column "max"). This is the case with a few implements used for scraping fresh hide, cutting soaked antler, and reaping cereals. It is as yet unclear how such deviations may be explained.

Diagnostic combinations of edge damage attributes

As none of the variables are sufficiently indicative of specific motions or material categories, combinations of characteristics were examined for their diagnostic value. One such combination is the presence or absence of edge rounding together with the type of scar termination (fig. 1). This interpretation is preliminary, because more experiments are necessary to see whether these results are replicated.

There seems to be a pattern in the relationship between the kind of

Table 6.-Relationship between the mean duration (in minutes) of the applied work and the development of edge rounding, according to different contact materials.

absent max present min"

hide 22 (396:18) 75 35 (lO71:31) 6

wood 20 (620:31) 55 30 (822:27) 4

bone 18 (658:36) 45 29 (489:17) lO

antler 22 (262:12) 66 23 (138: 6) 15

soft silicious plant 17 (157: 9) 30 33 (502:15) lO

soft non-silicious plant 24 (143: 6) 30 43 (215: 5) 20

cereals 200 (200:1) 200 127 (2538:20) 30

meat 11 (32: 3) 14 45 ( 45: 1) 8

butchering 29 (146: 5) 17 30 ( 90: 3) , 15

fish 13 (171:13) 15 21 (277:13) 6

pottery 7 (7: 1) 7 25 (178: 7) 10

shell 20 (117: 6) 6 12 ( 35: 3) 5

soil 44 (220: 5) 30

* The longest period of work without development of edge rounding or flaking. ** The shortest period of work already causing edge rounding,

step

hinge

rounding

absent

group I

group II

fcather MEDIUM ANIMAL SOFf ANlMAL

soft vegetal

group III

rounding

medium

group IV

medium animal 50ft animal

group V

rounding

heavy

group VI

Figure 1 ,-Relationship between the presence or absence of edge rounding and the kind of termination of the edge removals, according to different materials, Capitals indicate the main constituent of the group in question, whereas the minor constituent is set in lower case,

506 MONIQUE VAN DEN DRIES and ANNELOU VAN GI.IN

worked material and the resulting wear traces. Six groups, each with their own characteristic combination of edge rounding and scar termination, can be distinguished. However, it must be stressed that these groups are partially overlapping.

Group I only represents the traces caused by hard animal materials (fresh bone and shell); edge rounding is absent and the retouch is step-terminated. Group II also contains hard animal material, but in this group hard vegetal substances (hard wood such as oak) appear as well; this group is also characterised by the absence of edge rounding, but the retouch is hinge-tenninated. Group III is dominated by medium (fish) and soft animal material (meat), and still lacks edge rounding but shows feather terminations. The fourth group contains tools showing medium edge rounding together with hinge-terminated retouch; this group represents medium animal (fish and soaked bone) and medium vegetal (soft wood and roots) material. The fifth group predominantly includes medium (soft wood and cereals) and soft vegetal material (soft silicious plants) and, to a smaller extent, medium animal (soaked bone and soaked antler) and soft animal (fresh hide and meat) material. Group VI is a very small group and represents medium vegetal material (cereals) which can cause severe rounding and feather-terminated scars.

Resuming this paragraph, the variables concerning edge removals and edge rounding seem to differentiate mainly in relation to the hardness category of the worked substance. In figure 1 the hard materials and the soft materials clearly belong to different groups, whereas the materials of medium hardness are not so clearly separated. It can also be noted that vegetal substances and animal materials inflict different wear traces. Tools showing either retouch or rounding are mostly employed on animal materials; these are either too soft (fresh hide or meat) to cause retouch, or too hard (fresh bone) to allow rounding. On the other hand, implements displaying both rounding and retouch are predominantly used on vegetal material; the latter substance is resistant enough to inflict (slight) scarring, and soft enough not to continuously retouch the edge and thus allow rounding to develop. Motion is mainly reflected in the distribution of the retouch and to a lesser extent in the development of rounding.

THE QUANTIFICATION OF DIAGNOSTIC POLISH ATTRIBUTES

In this paragraph various polish attributes are examined. Included in the analysis are texture, distribution, brightness, topography, and width. A cross-tabulation was made for these five variables against contact material and motion, to study whether attributes were indicative of a kind of contact material or rather a result of a specific motion.

Polish texture

Table 7 shows that a rough/greasy texture for the most part results from contact with hide. On two implements used for reaping cereals and five for butchering/meat cutting a similar texture was present. The 25 hide-working tools displaying the rough/greasy texture include both cutting, scraping and boring implements. It can be concluded that this texture attribute can mainly be considered diagnostic for hide-working, independent from the motion applied.

The attribute rough/matt, on the contrary, is not mainly indicative of one contact material. Bone-working implements, used in a longitudinal or carving motion, display this feature (48% of the cases). Contact with hide, fish, pottery, soil, and stone/shell/teeth produces a rough/matt texture as well; also in these instances the kind of motion does not seem to be of any influence.


Table 7.-Relationship between worked material and polish texture. The table only involves those experimental implements displaying polish after use.

rough/greasy rough/matt smooth/greasy smooth/matt rough not applicable total (100%)

hide 25 (74%) 9 (26%) - - - - 34

wood - 2 (4%) 3 (6%) 43 (81%) - 5 (9%) 53

bone - 24 (48%) - 26 (52%) - - 50

antler 1 (7%) 1 (7%) - 12 (86%) - - 14

soft silicious plants - 1 (4%) - 22 (96%) - - 23

soft non-silicious plants - 1 (33%) - 1 (33%) 1 (34%) - 3

roots - - - 4 (100%) - 4

cereals 2 (9%) - - 19 (91%) - - 21

butchering/meat 5 (63%) - - 1 (12%) - 2 (25%) 8

fish - 9 (50%) - 6 (33%) 3 (17%) - 18

stone/she11!teeth - 4 (66%) - 1 (17%) - 1 (17%) 6

pottery - 8 (100%) - - - 8

soil - 5 (100%) - - - - 5

total 33 63 3 135 4 8 247

A smooth/matt texture is confined to plant-working tools (96% of the silicious wild plants, 91 % of the cereals), wood-, antler-, and bone-working implements (81 %, 86%, and 52%, respectively), and some fish-cleaning tools displaying patches of "bone-polish" (33%) (see also Van Gijn 1986). Again, motion does not seem to be an influential variable as all motions are represented.

To summarize, the variable polish texture only seems to indicate broad categories of contact materials, a rough/greasy variety being mainly associated with hide, and a smooth/ matt version mainly indicating wood, plants, antler, and less frequently bone. The attribute rough/matt can indicate a large variety of contact substances and cannot be considered diagnostic. Texture does not seem to be greatly influenced by the motion applied.

Polish distribution

From table 8 it can be inferred that the various distribution types which can be differentiated are not linked to specific contact materials, with the exception of the reticulated pattern being exclusively represented on wood-working tools; 21 % of the latter displays this feature. Some tendencies can be noted, however. Isolated spots tend to occur more frequently on bone-working tools (74%), irrespective of the motion involved, whereas a distribution in a band is more often visible on hide-working implements (62%), especially on those used in a scraping motion. Soft silicious plants and cereals cause a distribution in a band or one which is more spread; virtually all these experiments involved a cutting motion. Butchering for the most part only produces a scintillation, which develops in a band after a longer period of use. In contrast, contact with wood results in a variety of distribution patterns,


Table S.-Relationship between worked material and polish distribution. Only those experimental implements are included in the table which displayed polish after use.

scintillated lustre reticulated streaks isolated isolated band spread total spots spots + streaks (100%)

hide 4 (12%) - - 2 (6%) 7 (20%) - 21 (62%) 34

wood 7 (13%) 11 (21%) 1 (2%) 14 (26%) - 17 (32%) 3 (6%) 53

bone 2 (4%) - 37 (74%) - 9 (18%) 2(4%) 50

antler 1 (7%) - - - 7 (50%) - 5 (36%) 1 (7%) 14

soft silicious plants - - - 1 (4%) 2 (8%) - 14 (61%) 6 (27%) 23

soft non-silicious plants - - 1 (33%) - - 1 (33%) 1 (34%) 3

roots - - - 4 (100%) 4

cereals 2 (10%) - - - 1 (5%) - 7 (33%) 11 (52%) 21

butchering 5 (63%) - - 1 (12%) - 2 (25%) 8

fish - 1 (5%) - 3 (17%) 7 (39%) 4 (22%) 3 (17%) - 18

stone/shell/teeth - - 2 (33%) 4 (67%) - - 6

pottery - - - - 2 (25%) - 5 (63%) 1 (12%) 8

soil - - - - - - 5(100%) 5

total 21 1 11 10 82 4 84 34 247

seemingly independent from the motion involved; the same pertains to antler-working tools, albeit to a lesser extent.

It can be concluded that in terms of polish distribution contact with bone, hide, soft silicious plants, and cereals causes a rather uniform pattern. With respect to hide-working implements it can be noted that the characteristic band-distribution occurs more frequently on hide-scrapers than on hide-cutting tools (17 versus 4 cases). Contact with wood and antler, on the other hand, results in a variety of distribution patterns. The variable does not seem to be related to the motion applied. Distribution should not be confused with location of the polish; a bifacial location is predominantly related to longitudinal motions, a unifacial location to transverse motions. It should be stressed, however, that the location of traces on numerous implements deviates from this general rule.

Polish brightness

Table 9 demonstrates that brightness as an independent variable is not sufficiently diagnostic for a statement concerning contact material or motion involved. A very bright or a bright polish is visible on implements used on virtually all substances, a dull hue is confined to a smaller range of contact materials. Motion does not seem to be of any influence. If we examine individual contact materials it can be seen that, although bone, wood and antler for the most part cause a very bright polish, a bright and dull version can result as well. Hide incidentally produces a very bright polish. Polish brightness, therefore, appears to be a slightly problematic variable, which can only be used in combination with other features.


Polish topography

Some topographical features have been considered indicative of specific contact materials. Table 10 shows that only a few phenomena are indeed exclusively confined to certain contact materials. Craters are only seen on hide-working implements, the combination of pits and comet-tails is linked to bone-working implements, a beveled edge to bone-scraping. Other topographical features are more widely represented. Pitting results from hide-, bone-, and antler-contact. A flat topography is visible on tools used on various materials, although it scores highest on cereal-reaping implements (52%), and on tools which have come into contact with soil. A domed

Table 9.-Relationship between worked material and polish brightness. The table only involves those experimental implements displaying polish after use.

very bright bright dull total (100%)

hide 3 (9%) 17 (50%) 14 (41%) 34

wood 30 (57%) 17 (32%) 6 (11%) 53

bone 28 (56%) 18 (36%) 4(8%) 50

antler 9 (64%) 5 (36%) - 14

soft silicious plants 19 (83%) 3 (13%) 1( 4%) 23

soft non-silicious plants 1 (33%) 1 (33%) 1 (34%) 3

roots 3 (75%) 1 (25%) 4

cereals 18 (86%) 3 (14%) - 21

butchering/meat 1 (13%) 2 (25%) 5 (62%) 8

fish 4(22%) 9 (50%) 5 (28%) 18

stone/she11!teeth 5 (83%) 1 (17%) 6

pottery 6 (75%) 2 (25%) 8

soil 5 (100%) 5

total 127 83 37 247

topography is confined to wood- and soft plant-working tools, but can also result from antler; on 29% of the antler-working implements a domed topography can be observed, independent from motion. Topographical attributes are solely related to contact substance, motion being of no influence on their development.

Table IO.-Relationship between worked material and polish topography. Only those experimental implements are represented which displayed polish after use. Percentages are listed in parentheses.

cratered pitted domed corrugated comet tails flat pitted + comet bevel absent/not total tails applicable (100%)

hide 15 (44) 4 (12) - - - - - 15 (44) 34

wood - - 36 (68) 1 (2) 2 ( 4) - - - 14 (26) 53

bone - 2 ( 4) - - 1 (2) 2 ( 4) 22 (44) 7 (14) 16 (32) 50

antler - 3 (21) 4 (29) - - 2 (14) - - 5 (36) 14

soft silicious plants - - 15 (65) 1 ( 4) 2 (9) 2 (9) - - 3 (13) 23

soft non-silicious plants - - 1 (33) - - 1 (33) - - 1 (34) 3

roots - - 1 (25) - - 3 (75) - - - 4

cereals - - 6 (29) - - 11 (52) - - 4 (19) 21

butchering/meat - - - - - - - - 8 (100) 8

fish - - - 1 ( 5) 10 (56) - - - 7 (39) 18

stone/sheWteeth - - - - 1 (17) - - 5 (83) 6

pottery - - - - - - - - 8 (100) 8

soil - - - - 5 (100) - - - 5

total 15 9 63 3 15 27 22 7 86 247

510 MONIQUE VAN DEN DRIES and ANNELOU VAN GUN

Polish width

On every experimentally used tool the extent to which the polish covers the surface (i.e. perpendicular to the edge) was measured (in Il). This measurement may differ between ventral and dorsal surface so the mean was taken for both aspects. Some trends are apparent. It is evident that the width is related to the hardness and resistivity of the contact material. Stone/ shell/teeth, antler and bone cause the narrowest widths, 233, 240 and 286 Il respectively, followed by fish (332 Il). Wood, as a material of medium hardness, induces a width of 645 Il. Plants, on the other hand, cause a much more extensive polish: cereals give a mean width of 3957 ~l, silicious plants 2117 Il and non-silicious plants 2616 Il 3. The difference in width between the tools used on cereals and those on soft silicious plants is due to the fact that the latter category includes implements used on grass. Because grass-stems have a smaller diameter than reeds or cereals, the polish width is much less as well. Contact with pottery and dried clay produces a mean polish width of 3833 ~l (up to 10.000 Il for dried clay), roots result in a width of 5250 Il and soil 20.800 Il. Somewhat remarkable is the rather narrow width caused by butchering and meat cutting (201 Il) and by contact with hide (510 Il). The first may be explained by the slow polish development from contact with meat, whereas the narrow band of hide polish is probably attributable to the somewhat limited pliability (and thus, limited zone of contact with the implement) of a stretched hide.

A difference in polish width between longitudinal and transverse motions could only be observed for the hard materials such as bone and antler; transverse motions induce a width of 87 Il and 162 Il for antler and bone respectively, longitudinal ones 424 Il and 400 Il. This difference virtually disappears for wood (588 Il versus 616 Il) and hide (483 Il versus 536 Il), both being somewhat softer contact materials.

Diagnostic combinations of polish attributes

It can be concluded that a specific polish attribute seldom appears to be confined to just one category of contact material. Only a few distribution patterns (table 8) and topographical features (table 10) are typical for certain worked materials. As we have seen, polish texture and brightness may vary even among implements used in the same fashion on the same material. Reversely, a smooth/matt texture can be found on tools used on materials as diverse as soil, wood, bone, and all plant categories. It is clear that only a combination of attributes will pennit an interpretation as to the contact material involved.

However, even when attributes from all four polish variables are combined, overlap still exists. For example, there is only one attribute which is solely characteristic for wood, i.e. a reticulated distribution pattern, but it developed in only 21 % of the wood-working experiments. If this feature is lacking, wood polish in tenns of texture, brightness, topography and distribution can be identical to bone polish (smooth/matt + bright or very bright + comet tails + isolated spots or band), antler polish (smooth/matt + bright or very bright + domed + isolated spots or band), fish polish (smooth/matt + bright or very bright + comet tails + isolated spots), and to the polishes of all categories of plants, with the exception of roots, as wood polish never displays the flat topography so characteristic for contact with soil. If topographical features

J This mean includes one experiment with celery greens which were covered with dirt. The width of the polish band on this tool amounts to 7000 J.l which is quite out of range with respect to the other two instances.


are not distinctive or the tool is used so briefly that a clear distribution pattern has not yet developed, wood polish may overlap with all other categories as well, for instance hide polish. This may explain why the interpretation of wood-working implements posed so many problems in blind tests (Gendel and Pirnay 1982, Newcomer et alii 1986, Unrath et alii 1986).

The preceding example about the ambiguity of wood polish does not stand alone. If a tool is used only for a short period of time, or slight post-depositional surface modifications have taken place, or the grainsize of the flint is coarse, polish attributes are much less distinctive. Particularly texture and brightness are not very reliable variables in the sense that the same attributes can be related to a number of different contact substances. Therefore, they should only be used in combination with distribution, topography and polish width (or extent). It should also be clear why it is so important in every functional interpretation to include variables pertaining to edge removals and edge rounding, especially since motion does not seem to influence the character of the polish spots, but can only be inferred from indications of directionality within the polished areas. If the polish is not well-developed for whatever reason, such traces are absent and we must rely on the character of the edge removals, most notably retouch distribution, and on rounding, for clues concerning the motion applied.

Generally speaking, the quantification of polish attributes presented in this paragraph is largely in support of much of Keeley's original suggestions (Keeley 1980). However, the picture is much less clear-cut than he initially suggested. Keeley assumed that overlaps between polish characteristics were for the most part limited to bone, antler, and wood versus antler. As has been shown, overlaps can exist between virtually all material categories, especially if one or more polish attributes is not distinctive.

CONCLUSION

The present analysis is only preliminary, but a few conclusions can be drawn. First, it is evident that the absence of certain categories of traces in the archaeological record should 110t lead to the conclusion that the associated activities were not carried out. Next to the absence of traces due to specific contact materials, the character of the raw material and post-depositional surface modifications further complicate the picture.

The absence of recognizable traces, be it polish or edge damage, has important implications for our archaeological interpretions. This is especially so, as the development of traces is differential, and varies depending on contact material and motion. Certain activities will therefore be overrepresented, whereas others will be absent in our spectre of results. Calculations such as presented in this paper provide a clue concerning the percentages of each contact substance potentially to be expected in the archaeological record, thus enabling us to evaluate the range of activities inferred from an archaeological assemblage.

The results of the quantification of wear traces has indicated, once more, that many attributes are overlapping. It is clear that the variation in wear attributes does not match the endless variation possible in contact materials and motions. Only in a few instances are attributes uniquely associated with a specific material category and/or motion, for instance a beveled edge with bone scraping.

Searching for meaningful combinations of attributes is therefore extremely important and should include all aspects of tool damage. The example of combining characteristics of edge removals and rounding may illustrate that such an exercise may be helpful in understanding the patterns in wear traces (fig. 1). However, much more quantitative research is needed to

512 MONIQLJE VAN DEN DRIES and ANNELOLJ VAN GIJN

determine how distinct and consistent these observations are. Also, the interrelationship of various polish characteristics with aspects of edge damage should be subjected to further analysis. We started with simple quantifications, but the next step should be to use some advanced statistics like multivariate analysis.

Another aspect of the quantification of wear traces was to examine the relative importance of motion and contact material for the character of edge removals, rounding, and polish. Edge removals and rounding are determined by both motion and contact material; in addition, the extent of edge rounding is linked to the duration (or intensity) of use as well. However, it was shown that there are no clear relationships, for instance, between longitudinal motions and the development of edge retouch, or transverse motions and edge rounding. Only certain retouch attributes are clearly diagnostic: scar termination and length are determined by the hardness of the contact material, retouch distribution and edge rounding mainly by motion.

The character of polishes, on the other hand, does not appear to significantly change with motion. This is in contrast to earlier observations by Keeley (1980) and Moss (1983), that, for instance, cutting or sawing bone would cause another polish than scraping this material. Motion can only be inferred from the directionality present in the polish spots; if the polish is not well-developed, traces of directionality will not be visible and the only indications to infer motion from are scar distribution and edge rounding and, to a lesser extent, the location of edge removals and polish. This observation may also explain a remarkable result of the Tiibingen blind test: the four analysts involved scored better on contact material than on motion (Unrath et alii 1986). Considering the results of this paper, these scores are not surprising as fewer attributes of wear are indicative of motion than of contact substance.

In this paper emphasis was put on the quantification of various attributes. To enlarge the scope of this exercise in quantification, a next, very important step, should be to examine under which conditions specific attributes occur. Causative relationships with respect to the character of the raw material from which the experimental tool is produced (especially grainsize), the duration of the experiment, and the angle of the used edge should be assessed. This is especially necessary for attributes which are held to be characteristic. For example, polish from wood-working is commonly described in the literature as displaying a reticulated distribution. This was only present on 11 of the 62 experimental implements (53 of which showed polish after use). It turns out that in seven of these 11 cases it concerned very fine-grained northern flint, in the four others medium-fine Rijckholt material. A reticulated pattern does not appear to be an intermediate phase in wood polish development, as the duration of the experiinents producing this feature ranged from 8 to 75 minutes. The edge angle of the implements under consideration does not seem to be a factor either, as this aspect varied from 32 to 80 degrees. The most likely suggestion is, therefore, that a reticulated distribution appears to be related to the somewhat finer grainsize of the raw material.

The investigation ofthese causative relationships, however, can only be fruitfully performed 'vvhen all possible combinations of attributes occur in sufficient numbers. In order to eliminate the "empty cells" in our program many more experiments are needed, a project which has been started recently.

It is our opinion that, although papers like the present one are perhaps somewhat dull to write and read, they are very important for the further development of usewear analysis. Experimental results are seldom published in detaiL In the few cases in which it was done, for example concerning shooting experiments, it turned out that the initial presence/absence scores for wear trace development could be corroborated by further experimentation (Fisher et alii 1984, Odell and Cowan 1986, Van Gijn 1990). Only if more people start organizing their


experiments in terms of quantification of attributes, instead of using them as a mere reference, can we hope to eventually average individual variations. General trends may become apparent, and the highly descriptive, slightly "exotic" terminology which was originally defined by Keeley (1980) and Odell (1977) may obtain a more well-defined foundation going with a better understanding of the causative relationships between various attributes.

REFERENCES

Fisher, A., Hansen, P. V. and Rasmussen, P. (1984). Macro and microwear traces on lithic projectile points. Experimental results and prehistoric samples. Journal of Danish Archaeology 3, 19-46.

Gendel, P. and Pirnay, L. (1982). Microwear analysis of experimental stone tools: further test results. Studia Praehistorica Belgica 2, 251-266.

Gijn, A. L. van (1986). Fish polish, fact and fiction. In Owen, L. R. and Unrath, G. (eds.): Technical aspects of microwear on stone tools, Early Man News 9/10111, Tiibingen, 13-28.

Gijn, A. L. van (1990). The wear and tear of flint. Principles of functional analysis applied to Dutch neolithic assemblages. Thesis Rijkuniversiteit Leiden (also appeared as Analecta Praehistorica Leidensia 22).

Keeley, L. H. (1980). Experimental determination of stone tool uses. A microwear analysis. University of Chicago Press, Chicago.

Knutsson, K. (1988). Patterns of tool use. Scanning electron microscopy of experimental quartz tools. Societas Archaeologica Upsaliensis, Uppsala.

Moss, E. H. (1983). The functional analysis offlint implements. BAR International Series 177, Oxford. Newcomer, M. H., Grace, R. and Unger-Hamilton, R. (1986). Investigating micro wear polishes with blind tests.

Journal of Archaeological Science 13, 203-218. Odell, G. H. (1977). The application of microwear analysis to the lithic component of an entire prehistoric

settlement: methods, problems and functional reconstructions. Thesis Harvard University, Cambridge. Odell, G. H. and Cowan, F. (1986). Experiments with spears and arrows on animal targets. Journal of Field

Archaeology 13, 195-212. Odell, G. H. and Odell-Vereecken, F. (1980). Verifying the reliability of lithic use wear assessments by blind tests:

the low-power approach. Journal of Field Archaeology 7, 87-120. Shea, J. J. (1988). Methodological considerations in affecting the choice of analytical techniques in lithic use-wear

analysis: tests, results and application. In Beyries, S. (ed.): Industries lithiques: traceologie et technologie, BAR International Series 411, (2), Oxford, 65-82.

Shea, J. J. (1991). The behavioral significance of Levantine Mousterian variability. Thesis Harvard University, Cambridge.

Sussman, C. (1988). A microscopic analysis of use-wear and polish formation on experimental quartz tools. BAR International Series 395, Oxford.

Unrath, G., Owen, L. R., Gijn, A. L. van, Moss, E. H., Plisson, H. and Vaughan, P. (1986). An evaluation of micro wear studies: a multi-analyst approach. In Owen, L. R. and Unrath, G. (eds.): Technical aspects of micro wear studies on stone tools, Early Man News 9/10111, Tiibingen, 117-176.

Vaughan, P. (1985). Use-wear analysis offlaked stone tools. University of Arizona Press, Tucson.

Documents

Van den Dries, M. \u0026 Van Gijn, A.L. (1997) The representativity of experimental use wear traces