Pregunta 2, del examen aplicado en la secundaria matutina del BINE

A number of the sites reviewed above had metric data available. These metric data are now described and the variation within sites and between sites discussed. The metric data are listed in Tables 1-9 in Appendix B. The data are presented in various ways (Figures 22-2.1) depending on how they are presented in publications. For those studies in which the material had been separated into wild, domestic, and undetermined groups, the abbreviations ‘W ’, ‘D ’, and ‘?’ have been used respectively in Appendix B. In Figures 2.2-2.1 these are denoted by three different symbols shown in the key to symbols.

Comparing published measurements of Sus material was difficult because the different archaeological samples allowed different measurements to be taken. This means that the number of different sites between which a specific dimension can be compared is limited. Frequently recorded dimensions are plotted in Figures 2.2-2.1. Each figure shows the range of variation in the measurements of one dimension, drawing on data from a number of sites.

Key to sites and phases for Figures 2,1-12______________________________________

l=Endrod 119, 2=Padina all phases, 3=Padina phase 1,4=Padina phase HI, 5=Starcevo pits, 6=Starcevo III, 7=Starcevo II, 8=Starcevo 1,9=Starcevo Trench A, 10=Starcevo Trench B, ll=Starcevo 69/70,

12=Selevac, 13=Achilleion I, 14=Achilleion II, 15=Achilleion HI, 16=Achilleion IV, 17=Uzzo meso 2, 18=Uzzo meso/neo, 19=Uzzo neo 1, 20=Uzzo neo 2, 21=Arene Candide all phases, 22=Arene Candide early neo, 23=Arene Candide mid neo 1, 24=Arene Candide mid neo 2, 25=Arene Candide late neo, 26=Arene Candide copper/bronze, 27 Svaerdborg I, 28=Yvonard IV all phases, 29=Yvonard IV Horgen, 30= Yvonard IV Lurschez, 31=Vlaardingen, 32=Hekelingen I, 33= Hekelingen III, 34= Swiferbant, 35=Hazendonk (Vlaardingen lb), 36=Hazendonk 3, 37=Star Carr, 38=Thatcham, 39=Mount Pleasant neo, 40=Mount Pleasant beaker, 41=Durrington Walls, 42=Windmill Hill

Key to symbols used in Figures 2.2-2.T

■ wild • domestic

X unknown A not separated

Figure 2.2 Distal Breadth o f Humerus for example European sites 60 5 5 -- 50 - - Q S. 45 2 I 40 13 3 5 -- 3 0 -- 25 20 0 1 2 3 4 5 6 7 8 9 1011 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 2 0 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 2 9 3 0 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 3 9 4 0 4 1

code for site/phase

In Figure 2.2 the measurement data for the distal breadth of the humerus are plotted. Most of the sites produced material which was then interpreted as either

domestic or wild. A few, however, have been interpreted as comprising two populations within the Sus scrofa sample e.g. Swifterbant (34). The problem which arises is that the mean values for these two ‘populations’ differ by only nine millimetres, which is smaller than the entire wild range, for example, at Yvonard IV(28). In many cases the

measurements could only be taken on a very small number of humeri from each site; with very small sample size the potential for the recognition of the range of variation within the population from which the sample is derived is somewhat limited. At Vlaardingen (31), two ranges are seen which have been interpreted as specimens from separate wild and domestic populations (Clason 1967). The difference between the smallest domestic specimen and the largest wild one is so great that these are unlikely to have been derived from the same population.

Another dimension frequently recorded is that of the breadth of the distal tibia, present in more reports than any other dimension. The ranges for what have been interpreted as domestic and wild specimens vary greatly between sites. Some of the values from Starcevo for so-called domestic specimens are considerably larger than those from the British Neolithic sites, also termed domestic. The range given for domestic pigs at Yvonard IV (28) is considerable. The inference that this represents a single

population (Clutton-Brock 1990) could be questioned. However, it is very difficult to be confident that a sample is representative of two populations unless the range of variation that constitutes a single population can be established. It should be remembered that some dimensions are more variable than others, both within and between populations.

Figure 2.3 Distal breadth o f tibia for example European sites

45 40 -- 35 -- 30 -■ 20 - - 15 A A

ii..

Figure 2.4 Lateral Length o f astragalus for example European sites 60 5 5 -- 50 -- 2 45 £ 4 0 -- 3 5 - 30 25 I I "

" II

code for site/phase

Figure 2.5 Greatest length of calcaneum for example European sites

IS O 140 -- g 130 + - 120 E

I

:iii

code for site/phase

Two Other skeletal elements which are often measured are the astragalus and the calcaneus. The metric data for these elements are shown in Figures 2.4 and 2.5. The lateral length of the astragalus (Figure 2.4) shows some overlap between the ranges of those interpreted as either wild or domestic, particularly if comparisons between sites are

calcaneus is considered the difference in size between the smaller wild and largest domestic specimen is so small as to cast doubt on the suggestion that two separate breeding groups are represented (Figure 2.5). The assumed wild and domestic ranges for the calcaneus at Starcevo, when combined, would not be so large as to exceed the variation expected within a single population. Although at nearby Padina one individual appears to have a truly huge calcaneus. The evidence of bimodality in the Arene Candide measurements for the bronze age is noticeable for this dimension.

In addition to the skeletal dimensions discussed above, measurements are also available for the dentition. Teeth may be well-preserved on sites where bone is quite degraded due to the hardness of enamel as compared with bone. The length of the check teeth has been of most interest in zooarchaeological studies, in particular the length of the lower third molar. This dimension has often been used in the separation of wild from domestic pig remains. Clason (1967), after examining a great number of Dutch

assemblages from sites in many location and of different dates, drew up a table of parameters for wild and domestic Sus skeletal and dental measurements which included the M3. This is shown in Table 2.7.

Table 2.7 Metrical parameters in mm for Sus scrofa dental and skeletal

M easurem ent N am e Sus d o m esticu s Sus scro fa

Maxilla

len gth m olar row 7 8 -9 0

len gth 4 1 -5 0

Mandibular

length o f the sym p h ysis 9 5 -1 2 0 length o f the m olar row * 2 0 L 3 6 f/g& f 3 6 -4 5 len gth M3 2 3 - 4 0 * 4 0 -4 9

Scapula

h eigh t o f the neck 13-29

Humerus

distal w idth 2 8 -4 5 4 6 -5 7

Radius

proxim al w idth 2 4 -3 2 3 8 -4 2

Ulna

w idth o f the articular surface 16-25 2 6 -3 0

Pelvis length o f acetabulum 14-35 3 6 -4 4 Femur proxim al w idth 4 8 -5 2 7 3 -7 8 distal width 3 0 -5 0 6 0 -6 4 Tibia distal w idth 2 4 -3 5 3 7-43 hted).

The M3 length, as seen in Figure 2.6, has a considerable range of variation, and there is also overlap between ranges given for specimens interpreted as wild and

domestic. The Endrod 119 (1) data, for example, includes small individuals which have been identified as domestic, whilst the larger ones are described as wild boar (Bokdnyi 1972). A single Sus specimen from this site, has an intermediate size between the two groups, and is interpreted as possible evidence for local domestication {ibid..\2\9). It could, however, equally be the case that there are missing values in this size category, which could unite the two ranges and thus remove the bimodality, and this would

indicate one rather than two breeding populations (contributing to the sample seen in this assemblage). The entire range, however, is no greater than that seen for the group identified as wild from Starcevo. The data from Selevac (12) is rather more convincing. Two clusters of points, each showing a range of variation, suggest that the sample may include specimens from two populations rather than a single one (Legge 1990). This conclusion is questioned, however, by the presence of a value which falls midway between the two clusters.

Figure 2.6 Length of lower third molar for example European sites

55 50 -- B S 40

I

The specimens from Endrod 119 are closer in size to the ‘wild’ specimens from all the other sites, although they were identified by Bokonyi (1992) as domestic. At

Figure 2.7 Length of upper third molar for example European sites 46 44 -- 42 -- 40 38 -- t 3 6 - = 3 4 - O) 32 - 30 -- 28 -- 26 -- 24

•Ii

The measurements from Starcevo show quite a difference between the wild and domestic specimens but the sample is rather small. The Arene Candide

measurements for the bronze age levels (21) appear to have a wide range. This variation may indicate the presence of individuals from more than one breeding group, the points are trimodal rather than bimodal. For Yvonard IV (28) there is a lot of overlap between the wild and domestic ranges. Hekelingen m (33) has material identified as both wild and domestic but the difference is not great and the sample small.

In the figures above the presence of an ‘unknown’ category is a constant reminder of the problems which surround the separation of wild from domestic groups within Sus scrofa assemblages. The fact that domestication and a decrease in size are often linked can be misleading as many factors other than selection by humans can lead to a change in animal body size.

There have been many suggestions that mammalian body size (within a species) can decrease through time with a change in climate. Davis (1981) found that several Near Eastern mammals decreased in size throughout the Late Pleistocene, as

temperatures generally rose, although interestingly, some did not (see also Ducos and Horwitz 1998). A size decrease within some taxa has been noted particularly with

populations on islands (e.g. Lister 1989, Purdue and Reitz 1993), which has been attributed variously to the lack of predators, a change in environment, and a decrease in forage. Therefore, it should be kept in mind that changes relating to the ecology of a taxon can affect body size, although there are no simple generalisations (Dayan et a l

1991).

The particular strategy for assigning a specimen to the wild or domestic category

for Sus scrofa varies between authors. For example Prummel (1987) compensates for

the small number of measurable specimens by comparing her sample with values given for other assemblages, and in cases of ambiguity she classifies the specimens from the overlap as domestic. The justification for this, according to Prummel, is that this practise would minimise the risk of exaggerating the proportion of wild specimens. What, one wonders, is to be done about the exaggeration of the proportion of domestic specimens? At Selevac, Legge did not divide the metrics in advance into wild and domestic ranges; this only occurred once a scatter plot revealed bimodality of the data set (Legge 1990). The same can also be said for the Arene Candide data, which Rowley-Conwy (1997) did not initially divide into wild and domestic, and thus a considerable range of variation can be seen in many dimensions in Figures 2.2-2.1. In other cases, the identification of the wild and domestic groups within the Sus assemblage was made using a suite of several different dimensions from various elements, for example in Clutton-Brock’s analysis of Yvonard IV (1990). A specimen identified as either wild or domestic using this method may appear in the overlap zone for another dimension, which may not have been

included in the analysis.

In an ideal world, there are a number of means by which the reliability of a wild/domestic identification can be increased. Firstly, sample size: when the number of individuals drops below 1 0, the sample is not likely to give a good representation of the range of variation within the original population. A second useful approach is to label the specimens as Sus scrofa rather than to attempt separation into wild and domestic categories early in the analysis. In this way, the measurement variability can be fully explored in a manner that is as objective as possible, and the data are presented in a form which is of greatest use to others wishing to re-evaluate them at a later date. The third point is that it is good practice to compare metrics from sites within the same

geographical area. In section 2.1 the range of diversity amongst extant Sus scrofa in Europe was described using Groves’ (1981) assessment of the subspecies. Even if the concept of subspecies is rejected, the fact remains that wild boar populations from different parts of Eurasia vary greatly in colour, body size, facial profile and molar morphology. This would, for example, make it inappropriate to compare an early domestic pig from Scandinavia with a wild boar from Central Europe. If local domestication was practised, the early domesticates might be expected to vary in size according to location in the same way their wild progenitors did. Equally if the model is accepted that there was an initial Near Eastern domestication of Sus, which was followed by transport of livestock, the resultant domestic animals would be expected to adapt to their local environment. This can be seen in many other domestic species. For example, horses are believed to have evolved in steppe environments (Clutton-Brock 1992) and to have been quite sturdy in build. In desert regions, they evolved into the slight, gracile Arab horse. The relatively gracile wild ass {Equus africanus), on the other hand, was a resident of arid areas, but once exported to colder wetter environments became bigger and more robust (Clutton-Brock 1992). Returning to pigs, if newly imported stock was crossed with local wild boar, as has been suggested for Europe, the process of body-size change in response to local environment would be accelerated.

Identification o f populations from metric data

Some measurements are better discriminators between wild and domestic specimens than others, which relates to the observation that some measurements are more variable within groups than others. A number of factors influence variation in measurements within a population. For example, some dimensions are affected by sexual dimorphism. This is a problem when elements cannot be sexed easily. For Sus scrofa, an adult maxilla or mandible can be identified as male or female by examining the canines.

However, if the anterior part of the jaw is missing - as is often the case in archaeological material - the cheek teeth would be measured without knowledge of the specimens’ sex. If an archaeological sample of jaws was measured and bimodality of size resulted, this need not be evidence that two separate populations contributed to the sample, but could reflect the presence of both sexes.

Age is also an important factor. In skeletal data, a distinction should always be made between fused and unfused elements, since unfused elements are likely to undergo significant size increase. Even a fused element, however, can change in size due to remodelling (Legge and Rowley-Conwy 1988). Teeth are often used to attribute age (or wear ranges) to specimens because dental eruption sequences tend to be more consistent. Once erupted the teeth wear down, and occlusal wear stages have been used to establish relative age sequences within assemblages (e.g. Payne 1973, Grant 1982). Dental wear is likely to be less consistent between populations (and hence assemblages), due to the variations which will affect wear (including diet, soil types, husbandry). If dental measurements are used for exploring the contribution of breeding populations to the sample, tooth wear can have a significant effect on measurement variability. With

increased age, teeth lose not only height but also length, so that dental dimensions should really be compared within age groups or wear stages (see Chapters Four, Six and

Seven).

Before metrics can be used to examine possible wild and domestic groups within a sample, any variation that is due to sex or age needs to be identified and accounted for or excluded. In an ideal situation, those dimensions which are least affected by age or sex should be selected. Thus the range of variation between individuals within the population under study can be established.

This approach was outlined by Payne and Bull (1988) in an examination of a sample of modem wild boar from Turkey in order to establish the range and nature of variation within a biological population. Their study revealed that wild boar forelimb measurements tend to increase with age, and also exhibited a high degree of sexual dimorphism. Hind limb measurements showed an increase with age, and moderate sexual dimorphism. Tooth lengths decreased with age, but were not dimorphic; tooth widths were stable with age and not dimorphic. Thus it appears that the post-canine teeth are a good source of data, but that tooth lengths which decrease with age may be less useful than tooth widths.