ANNALS OF ANATOMY Osteometric study of metapodial bones in sheep (Ovis aries, L. 1758) Claude Guintard and Michai~l Lallemand Ecole Nationale V6t6rinaire de Nantes, Laboratoire d'Anatomie Comparde, route de Gachet, BP 4 07 06, F-44307 Nantes cedex 03, France Summary. This study, based on a sample of 215 individuals, gives detailed insight into Sheep metapodial bone main features: their variability and correlations between their various parts. This data allowed us to reveal the most relevant measurements for study of metapodial bones in sheep (GL, Bp, Dp, SD, DD, Bd, and Dd), as well as references used to split up the main population. Those references give a great help in placing any sample in relation to the breeds described in this work. The main purpose of this tool is to compare unknown populations, such as fossil ones, to present sheep breeds, in order to increase our knowledge of domesticated Sheep History, from its origins to the present day. Key words: Sheep - Metapodials - Osteometry - History - Variability Introduction: Short summary of a long (European) history Time and location of domestication of Ovis aries Linnaeus, 1758 are still debated. Many authors (Delort 1984; Mason 1984; Gautier 1990; Bernis 2001) speak of a "classical" date, which would have been around the 8th millennium BC, but it seems this date should be reconsidered (Muzzolini, undated) and the 6 th millennium BC is probably a better approximation. More than the date, the location of sheep domestication is a far greater subject of debate: according to an "academic" model (Lauvergne 1979; Delort 1984; Ryder 1984; Aillaud 1986; Quemener 1997), the sheep was domesticated in a single place, in the Near-East and scattered from there to Africa and Correspondence to: C. Guintard E-mail: guintard@vet-nantes.fr Ann Anat (2003) 185:573-583 © Urban & Fischer Verlag http:llwww.urbanfischerdeljoumalslannanat Europe. Lauvergne (1979) has even proposed a centrifugal diffusion model with 2 successive waves starting from the Near East. On the other hand, the hypothesis of a multifocal origin is commonly mentioned, though not developed (Aillaud 1986; Gautier 1990; Quemener 1997). As to Muzzolini (undated), the hypothesis of an African origin should not be quickly excluded as it has always been by many authors, since several arguments suggest an incompatibility between the "academic" model and archaeological discoveries in northern Africa: archaeological site dating does not match with a centrifugal diffusion model, since farther sites containing sheep bones from northern Africa are more recent than those found close to the Nile valley. The size of African sheep does not match with this model either, since those animals were taller than they should have been if they had already been domesticated (Muzzolini, undated). To sum up this debate, we should say that the answer to the difficult question of domestication probably lies in several theories, such as natural migration, diffusion of already domesticated animals, and native origin. Further evolution of sheep populations is quite difficult to describe, since we have little information about them before the end of the 18th century. Size is the best parameter to deal with, on account of its use in many publications (Audoin-Rouzeau 1997; Audoin-Rouzeau 1991; Lepetz 1997; Columeau 1996; Vila 2002), the simplicity of its extrapolation from metapodial bone measurement, and the availability of large samples of values (Lepetz 1997). In the Middle-Ages, we can distinguish 3 periods of development: a first period of increase in size under Roman influence with a peak size at the end of the 1st century, then a second period during which size is stationary, and finally a third period of decrease in size, starting in the 4th--5th century. At the end of this last period, animals are shorter than at the beginning of the first one. As we can see, size evolution during the MiddleAges is closely related to the apogee and the waning in0940-9602/03/185/6-573 $15.00/0 f l u e n c e of t h e R o m a n E m p i r e ( L e p e t z 1997). T h e " r e v o l u t i o n " of M o d e r n T i m e s t h a t f o l l o w e d is r e l a t e d to an inc r e a s e in size, w h i c h is q u i t e similar to t h e o n e s e e n in t h e first p e r i o d o f t h e M i d d l e - A g e s . H o w e v e r , t h e e x t e n t of t h e p h e n o m e n o n is m u c h g r e a t e r , w i t h t h r e e i m p o r t a n t i n f l u e n c e s in F r a n c e : F l a n d r i a n s h e e p at t h e b e g i n n i n g of t h e 18 ta c e n t u r y ( A u d o i n - R o u z e a u 1997), M e r i n o s h e e p at t h e e n d of t h e 18 ta c e n t u r y ( A u d o i n - R o u z e a u 1997), a n d British b r e e d s in t h e 19 ta c e n t u r y ( A u d o i n - R o u z e a u 1997; Q u e m e n e r 1997). T h e v a r i o u s b r e e d s o f s h e e p in o u r c o u n t r y s i d e ( m o r e t h a n 50 b r e e d s in F r a n c e [ B a b o 2000]) result f r o m this history, a n d size e v o l u t i o n is a p a r t o f it. A s a c o n s e q u e n c e , o u r topic, m e t a p o d i a l b o n e study, w h i c h is a w a y to d e s c r i b e t h e a n i m a l p h e n o t y p e , has a significant r o l e to p l a y in t h e u n d e r s t a n d i n g of s h e e p history. Zooarchaeologists know the importance of parameters such as height, w e i g h t , sex a n d age, w h e n d e s c r i b i n g an a n i m a l p o p u l a t i o n a n d c o m p a r i n g it to others. T h e m a i n p r o b l e m is t h a t this i n f o r m a t i o n c a n n o t b e f o u n d w i t h sufficient p r e c i s i o n in texts. K n o w i n g this, m e t a p o d i a l b o n e s t u d y o n a r t i o d a c t y l species c a n b e a g r e a t h e l p since t h e y are u s u a l l y w e l l c o n s e r v e d in a r c h a e o l o g i c a l e x c a v a t i o n s ( B e r t e a u x a n d G u i n t a r d 1995; G u i n t a r d 1996), a n d t h e i r m e a s u r e m e n t allows for r e c o v e r y o f s o m e p a r a m e t e r s w e n e e d to c h a r a c t e r i z e a p o p u l a t i o n , in p a r t i c u l a r an a n i m a l size e v a l u a t i o n ( A u d o i n - R o u z e a u 1991; D a u z a t 2000; R o s s e t et al. 2002; V i l a 2002). H o w e v e r , w e a r e l a c k i n g d a t a for c o m p a r i s o n w i t h z o o a r c h a e o l o g i c a l m a t e r i a l . This l a c k of i n f o r m a t i o n is alr e a d y o b v i o u s d e a l i n g w i t h Bos taurus L i n n a e u s , 1758 ( B e r t e a u x a n d G u i n t a r d 1995; G u i n t a r d 1996), a n d e v e n m o r e p r o n o u n c e d for Ovis aries L i n n a e u s , 1758 ( A u d o i n R o u z e a u 1991; D a v i s 1996), t h e species this s t u d y is c o n c e r n e d with. O u r p u r p o s e was t h e r e f o r e to a c h i e v e a statistical study o n a 215 adult s h e e p sample, t a k e n f r o m a w i d e r a n g e of p r e s e n t b r e e d s and r e p r e s e n t i n g d i f f e r e n t m o r p h o l o g i c a l types, f r o m the small B r e t o n D w a r f ( U s h a n t ) to the big Valais Blacknose. T h e results we o b t a i n e d should be u s e d as a " b a s e l i n e " to c o m p a r e groups and to stress their differences, which should be helpful for a b e t t e r u n d e r s t a n d i n g of s h e e p p o p u l a t i o n m o r p h o l o g i c a l e v o l u t i o n (Davis 1996). Materials and methods A total of 215 adult individuals make up the study population: 44 males, 139 females, and 32 individuals of unknown sex. We collected 556 metapodials: 362 metacarpi and 194 metatarsi; only 72 individuals were "complete": most of the time we were not able to recover 4 metapodials from each animal. Since one of our main goals was to describe the variability of metapodials in sheep, they come from 34 different categories (Table 1): some of them correspond to well-known and numerous breeds - such as Texel or Vend6en - and some others correspond to local and limited populations - such as Belle-Ile or Breton Dwarf. These categories cover a wide range of variability, as wide as it was possible for us to obtain. Slaughterhouses (Le Vigeant, Poitiers, and Challans - France), Veterinary faculties (Nantes - France, Toulouse France, and Madrid - Spain), and Museums (Geneva Museum of Natural History - Switzerland) were our main sources of metapodials. Those which needed to be cleaned up (all of them, except those coming from Toulouse and Geneva) were gathered at Nantes National Veterinary School (France). A total of 17 linear measurements were defined for both metacarpi and metatarsi (Fig. 1), according to von den Driesch (1976) and Davis (1996), except for Be (greatest width of metaphysis, see Fig. 1) and De (greatest depth of metaphysis, see Fig. 1) which were used exclusively in this study; they give a three-dimensional "vision" of each bone: diaphysis, epiphysis, and metaphysis are described thanks to length, width, and depth measures. Figure i shows only metacarpus since measurements are equivalent on metatarsus. Also, two ratios were calculated: d/GL, Table 1. Breeds and local populations constitutive of the study population. Number of males (M), number of females (F), number of individuals of unknown sex (Ind). Breeds put in alphabetical order (in French). Breed M F Ind Breed M Belle-Ile West Swiss White Swiss Black-Brown Mountain Charmoise Charolaise Crete French alpine Grisons (Biindner Oberland) Jacob Karakul Karaman Koroni Landais Landes de Bretagne Manchega Manech M6rinos de Rambouillet 2 4 6 2 1 1 2 1 1 17 1 1 1 1 3 1 4 2 1 1 - ] 1 ] 1 - Valais Blacknose Nilotic Breton Dwarf (Ushant) Palma de Mallorca Romanov Rouge de l'Ouest (Western red) Roux de Bagnes Skudde (Kosse) Somali Desert Sudanese St-Aubin Suffolk Tarasconnais Texel Vend6en Crossbreed with Vend6en Zackel 2 2 3 1 1 4 1 8 2 - 574 F 3 1 2 2 2 1 2 11 5 10 ] 61 4 1 Ind 1 18 9 - a) GL = Greatest length Bp = Width of proximal end Dp = Depth of proximal end d = Mid-shaft width of diaphysis e = Mid-shaft depth of diaphysis SD : Smallest width of diaphysis DD = Smallest depth of diaphysis Bd = Width of distal end Dd = Depth of distal end Be = Greatest width of metaphysis De = Greatest depth of metaphysis DIM = Antero-posterior diameter of the internal trochlea of the medial condyle DEM = Antero-posterior diameter of the external trochlea of the medial condyle DIL = Antero-posterior diameter of the internal trochiea of the lateral condyle DEL = Antero-posterior diameter of the external trochlea of the lateral condyle WCM = Medio-lateral width of the medial condyle WCL = Medio-lateral width of the lateral condyle. b) GL )I c) GL d> I Fig. 1. Description of metapodial characteristics measured, a: Dorsal view of right metacarpus, b: Medial view of right metacarpus. e: Proximal view of right metacarpus, d: Distal view of right metacarpus. according to Guintard (1996), and SD/GL, according to Boessneck et al. (1964), which characterize gracility in metapodials. Measures were made to the nearest 0.1 mm with an electronic calliper rule. When bones were spoiled, some measurements were not taken to avoid distortion of the results. When metacarpi or metatarsi were available on both sides, a mean was calculated for each parameter in order to avoid taking some individuals into account twice. We performed Kolmogorov-Smiruov one sample test of goodness of fit (Lilliefors 1967) on each variable, assuming they had a continuous distribution, to test for the homogeneity of the population. We described variability in our sample using coefficients of variation (CV), which is dimensionless and allows a comparison of variability of large and small organs (Yablokov 1974). Relationships between variables were characterized using Pearson's coefficients of correlation (r) and agglomerative hierarchical clustering (since results were similar using both single or "nearest neighbour" and average linkage method, we have chosen to present only those obtained with this last method). This last tool, the result of which is a "tree-diagram", was used to split our variables' sample in some groups of well-correlated variables; information which was useful in our attempt to discover the rules governing relationships between each part of metapodials. Finally, we used graphic representations of B p = f ( G L ) and SD/ GL = f(GL) to determine limit values which should be used to separate sheep morphological types. The SYSTAT (Wilkinson 1989) and EXCEL2000 programs were used for all data analyses. Results The o b s e r v e d distributions of d a t a were significantly different from n o r m a l i t y (5% t h r e s h o l d of t o l e r a n c e ) for every variable, which was quite predictable, taking account of the s a m p l e nature: it is an artificial p o p u l a t i o n c r e a t e d for the p u r p o s e of this study, a gathering of individuals coming from different b r e e d s and origins. 575 The sorting of m e a s u r e m e n t s by decreasing value of CV (Tables 2 and 3) highlights the most and least variable parts of m e t a p o d i a l bones in sheep, since we tried to collect as m a n y different b r e e d s as we could within this species. The m a i n results are quite similar on b o t h m e t a carpus and metatarsus: the diaphysis medio-lateral axis records the maximal variability, since d and SD CVs are always on top of the sorting. This result is similar to the one o b t a i n e d when combining males, females, and individuals of u n k n o w n sex in one single sample: d and S D values of C V are respectively 17.36 and 16.77 for metacarpus, and 15.37 and 14.45 for metatarsus (Lallem a n d 2002). O n the o t h e r hand, the dorso-palmar (or plantar) axis records' the minimal variability, because such m e a s u r e m e n t s as D d , D I M , or D I L are always at the bott o m of the sorting, which is also n o t i c e d dealing with a s e x - c o m b i n e d s a m p l e ( L a l l e m a n d 2002). O n e last thing, which is obvious when describing Table 2 and 3, is that the external trochlea of each condyle (DEM and DEL) is always more variable than the internal trochlea (DIM and DIL). Difference in n a t u r a l selection pressure is one possible explanation: the internal t r o c h l e a of each condyle p r o b a b l y has a m a j o r functional role in the articulation with the first phalanx, and should be subjected to a greater selection pressure than the external trochlea, which should b e m o r e variable without interfering with the function of the articulation. E x c e p t S D / G L , d/GL, and especially G L , which are p o o r l y c o r r e l a t e d to o t h e r variables and r e c o r d mr[values lower than 0.55 for b o t h m e t a c a r p u s and metatarsus, every o t h e r variable is highly c o r r e l a t e d to others; the first quartile of ire distribution is 0.65 for correlation matrices defined for m e t a c a r p u s and metatarsus. B o x - p l o t diagrams (Figs. 2 and 3) obviously show an asymmetric distribution of [r[ values in relation to all measurements, d / G L and S D / G L ; in b o t h Figs. 2 a n d 3, the b o x is close Table 2. Variation of sheep metacarpal bones in males and females. Number of individuals examined (n), mean value of each measurement (/~), standard deviation (SD), minimum-maximumrange (Min-Max), and coefficient of variation (CV). Variables listed in CV's descending magnitude. All values in mm, CV in %. Males d SD e DD Bp Dp WCL Be DEL WCM DEM Bd DIM DIL GL De Dd Females n /~ SD Min Max CV 43 42 41 43 43 43 43 38 40 43 40 42 40 40 44 38 41 18.0 17.4 12.1 11.3 28.9 20.6 13.5 32.4 12.2 14.0 13.0 30.6 16.1 16.1 133.0 16.4 19.2 3.5 3.3 1.8 1.6 4.0 2.7 1.8 4.2 1.6 1.8 1.6 3.7 1.9 1.9 15.4 1.8 1.9 9.6 9.6 6.8 6.7 17.0 12.8 8.5 20.9 7.5 9.0 8.2 20.9 10.3 10.3 88.8 11.0 12.8 24.8 23.4 17.7 15.3 34.6 24.6 16.6 41.8 14.7 17.1 15.8 36.9 19.1 18.9 166.0 19.3 22.4 19.61 18.85 15.24 14.32 13.76 13.32 13.09 12.98 12.75 12.69 12.32 11.96 11.75 11.74 11.58 11.24 9.97 d SD Bp GL e DD Be Dp WCM DEL De DEM WCL Bd Dd DIL DIM n /~ SD Min Max CV 135 136 136 136 129 132 130 132 130 125 130 125 130 132 128 125 125 16.7 16.1 27.7 128.9 11.7 10.6 30.0 19.9 13.4 11.8 15.3 12.6 12.9 29.0 18.4 15.6 15.6 2.5 2.3 3.0 12.3 1.1 1.0 2.7 1.7 1.1 1.0 1.3 1.0 1.0 2.3 1.4 1.1 1.1 9.0 8.9 15.9 89.0 9.0 8.4 23.5 15.5 10.9 9.4 12.4 10.2 10.7 23.8 13.9 12.8 12.8 21.5 20.8 37.1 163.5 15.6 13.7 37.5 23.4 16.4 14.3 19.6 15.2 15.5 34.2 21.4 18.2 18.0 15.04 14.52 10.79 9.56 9.55 9.37 9.07 8.56 8.42 8.32 8.21 8.14 8.04 7.97 7.73 7.36 7.18 Table 3. Variation of sheep metatarsal bones in males and females. Number of individuals examined (n), mean value of each measurement (/~), standard deviation (SD), minimum-maximumrange (Min-Max), and coefficient of variation (CV). Variables listed in CV's descending magnitude. All values in mm, CV in %. Males d SD DEM e DEL DD Bp Dp DIL GL WCL DIM De Be WCM Bd Dd Females n # SD Min Max CV 18 18 16 17 16 17 18 17 16 18 17 16 17 18 17 18 17 14.1 13.7 11.6 12.6 10.9 11.6 23.7 23.0 15.0 143.7 11.6 15.1 16.5 28.3 12.8 27.9 18.4 2.6 2.4 1.9 2.1 1.8 1.9 3.6 3.5 2.2 20.9 1.7 2.2 2.4 4.0 1.8 3.8 2.4 8.5 8.4 7.7 7.4 7.4 7.2 15.3 11.5 10.0 96.4 7.9 10.3 10.9 19.1 8.7 18.6 12.5 18.1 17.7 14.8 15.3 13.9 14.3 28.5 28.3 18.0 176.9 14.4 17.8 19.3 34.4 15.8 33.7 21.7 18.54 17.68 16.83 16.64 16.30 16.14 15.30 15.16 14.82 14.55 14.47 14.45 14.39 14.23 14.23 13.71 12.91 d SD e GL DEL DEM DD Dp WCM WCL Bp Be Dd De Bd DIL DIM to the diagram right edge, which m e a n s close to high Irl values. It stresses a m a j o r feature of m e t a p o d i a l b o n e s in sheep: they display a great h o m o g e n e i t y in their proportion, a h a r m o n y in their constitution, and since G L is the most poorly correlated to other measurements, most of the difference b e t w e e n breeds will be assessed regarding the longitudinal axis, and to be more precise, appreciated in terms of gracility. I n order to reveal a pattern of correlation b e t w e e n different parts of the bones, agglomerative hierarchical clustering was used. Figs. 4 a n d 5 show that the main factor n /~ SD Min Max CV 85 85 84 85 79 79 84 84 85 85 85 84 84 84 84 79 79 13.9 13.5 12.9 139.6 10.8 11.4 11.5 23.1 12.9 11.7 23.6 27.6 18.0 15.8 27.6 15.0 15.1 1.9 1.7 1.5 14.5 1.1 1.2 1.2 2.3 1.3 1.2 2.3 2.6 1.7 1.4 2.5 1.3 1.2 10.2 9.9 10.1 113.6 8.8 9.2 8.8 18.2 10.1 9.3 12.4 22.8 14.0 12.3 21.8 12.3 12.3 17.9 17.2 19.4 170.0 13.8 15.0 14.4 28.1 17.3 15.4 28.6 34.6 21.6 20.1 32.5 18.0 17.7 13.73 12.66 11.49 10.41 10.20 10.20 10.18 10.04 9.9 9.96 9.95 9.52 9.44 9.17 8.95 8.50 8.25 ruling correlations b e t w e e n variables is the axis along which they were taken: in Fig. 4, such depth measurem e n t s as Dd, DIM, DIL, D E M , and D E L are grouped together, a n d leaving aside Dp, such width m e a s u r e m e n t s as SD, d, Be, Bd, Bp, W C M , and W C L are also grouped together. Fig. 5 provides us with the same kind of results, since there are obviously two groups of variables: on top of the tree-diagram lies a first group of depth measurements, and below this one, a second group of width measurements. A second factor ruling correlations b e t w e e n variables is proximity of the m e a s u r e m e n t s on the bone: 576 Pearson's coefficient DISTANCES of correlation 1.000 0.000 GL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DD + . . . . . e SD I t 0.0 I 0.i 1 0.2 I 0.3 I 0.4 I 0.5 I 0.6 I 0.7 0.8 1 0.9 d 1.0 Be Fig. 2. Box-plot diagram showing the distribution of [r[ values, concerning every couple of variables defined to characterize the metacarpus, including d/GL and SD/GL. Each vertical line of the box represents a quartile of the distribution. From left to right: first quartile, median, and third quartile. Bd WCL -- ii E I +__ Bp n +__ +-- ] -II +-I I I I + ....... I' I ,~ ++ --El ÷--I - + l :DZL 1 Pearson's coefficient of correlation i I .... WCM [~;l **~**. : ...... Dp 1 EE~ i 1 1 i +__ i222" De I t 0.0 0.i I 0.2 I 0.3 I 0.4 I I 0.5 0.6 I 0.7 I 0.8 I I 0.9 1.0 Fig. 3. Box-plot diagram showing the distribution of [r[ values, concerning every couple of variables defined to characterize the metatarsus, including d/GL and SD/GL. Each vertical line of the box represents a quartile of the distribution. From left to right: first quartile, median, and third quartile. the closer two measurements are defined (they are taken along the same axis and on some near parts of the bone), the closer they are correlated to each other (see for example d and SD, D E M and DEL, D I M and DIL, WCM and W C L on Figs. 4 and 5). This study of variability and correlation allows us to select the most representative measurements of metapodial bones from our seventeen measurement sample. Our purpose is to define a small group of measurements, easy and quick to obtain, which will describe the metapodial bone osteometric characteristics as well as possible. To achieve this goal we used our previous results, especially those concerning correlations. Since axis is the main factor ruling correlations, we must have at least one measurement taken along each one, in order to get a threedimensional "view" of the bone. GL must be selected, since it is the only length measurement, essential to assess bone gracility. Bp and Dp are quite far in the tree-diagrams, and excluding one of them would mean losing much information about the bone proximal end. We can also rule two measurements out of those concerning the diaphysis: the couples d/SD and e/DD are strongly correlated, specially the first one (r = 0.99 for d/SD, and r = 0.87 for e/DD concerning metacarpus, and r = 0.99 for d/SD, and r = 0.90 for e/DD concerning metatarsus), so we can keep only SD and DD, since they are easier to get (mid-shaft position is unnecessary to get them). Measurements taken along the same axis on distal end are also strongly correlated (along each axis, r concerning each couple of distal end's measurements is always superior to 0.95), so, using the same reasoning, we should keep only Fig. 4. Agglomerative hierarchical clustering (tree-diagram) concerning the seventeen metacarpus measurements, using average linkage method. B Width measurements (+ Dp) Ilnl•ll -" -" Depth measurements one measurement describing each axis: since Bd and Dd are easier to get, they must be selected. To sum up these results, we can say that metapodial bones are easily and adequately described using 7 measurements: GL, Bp, Dp, SD, DD, Bd, and Dd. This measurement sample was not defined at random, but using osteometric characteristics of metapodial bones in sheep; therefore it should be used to harmonize studies, and to be sure to get a good understanding of these characteristics. Now that we have a good knowledge of our metapodial bone sample, our last goal will be to separate the main population into different morphological types, on the basis of their osteometric characteristics. The achievement of this task would allow us to compare any sample to our modern breed sample, and to assess its morphological type in comparison to this last one. Since similar measurements are strongly correlated between metacarpus and metatarsus, all 17 measurements show r values lying between 0.88 and 0.97 (Lallemand 2002), we decide to deal only with metacarpus when trying to separate different morphological groups from each other. We also had to select the most suitable variables out of those we defined, and G L seems to be essential: since it is the variable which is the most poorly correlated to others, it will have the best discriminating power compared with measurements taken along different axes, and will be used as reference. Bp will be used as a "size" parameter, as it is when studying cattle (Bos Taurus Linnaeus, 1758); it allows for separation of "heavy" from "light" individuals (Audoin-Rouzeau 1983; Noddle 1984; Guintard 1996). 577 DISTANCES 0.000 ............................................... GL 1.000 7---- i :Dd : : , l + .... DIL ! IDIMI | i : DELi : : 1 DEM I .... : ! +- II [ I + ....... .... +-- I +---] +T +-- ..... I +---i +-- I d + ....... ........ II +-i I II +-- Dp . . . . . . . . . . . . . . . . I + . . . . . . . . . . . . . . . . . . . . . . . . . . Fig. 5. Agglomerative hierarchical clustering (tree-diagram) conceming the seventeen metatarsus measurements, using average linkage method. ~ I l l l I • We can divide Figs. 6 and 7 into 4 areas, each way across two limit values of Bp and GL, which are 27 mm and 135 mm in females, and 30 mm and 145 mm in males, respectively. The upper-left area is quasi-exclusively occupied by breeds specialized in meat production: Charolaise, Rouge de l'Ouest, Suffolk, Vend6en, Texel. The morphological type corresponding to these well-built animals is "small" and "heavy". As for the upper-right area, it is occupied by Swiss breeds, such as Valais Blacknose and Roux de Bagnes, and dairy breeds, such as Manchega and Tarasconnais, which are made up of "heavy" and "tall" animals; their morphological type is thinner than the one defined by the upper-left area. Breeds that best represent the lower-left area are prolific (Romanov and Belle-Ile), wool-producing (Rambouillet and Karakul) or rustic (Breton Dwarf and Landes de Bretagne for example), and most of the time poorly selected; the corresponding morphological type is "small" and "light", Breton Dwarf being an extreme, about one may speak of dwarfism. Finally, the lower-right area gathers "tall" and "light" breeds together; Landais and Sudanese (North Riverine Wooled and Nilotic) sheep, which best represent this type, are actually best defined as "slim" and "walking" breeds. Width measurements (+ Dp) i 35 i 26 I •. "- Depth measurements •_l.. I 30 ~ "~ Thus, our first tool will be a scatter diagram representing Bp = f(GL): G L will separate "small" from "tall" individuals, and Bp "heavy" from "light" ones, as we already mentioned. As we noticed before, most of the difference between breeds is appreciated in term of gracility; so, using a "gracility" parameter seems to be suitable to achieve our purpose. Guintard (1996, 1998) defined SD/ G L as such a parameter since it is used to assess skeleton slenderness. Therefore, our second tool will be a scatter diagram representing SD/GL = f(GL), SD/GL being used to separate "fat" from "slender" individuals. Figs. 6, 7, 8, and 9 provide us with scatter diagrams gathering together each breed and local population mentioned in our study. The characteristics of each breed (dairy production, rusticity, etc.) were determined according to Porter (2002). Each dot is labelled using a number whose definition is given below: 1. Belle-Ile; 2. West Swiss White; 3. Swiss Black-Brown Mountain; 4. Charmoise; 5. Charolaise; 6. French Alpine; 7. Grisons (Btindner Oberland); 8. Karakul; 9. Karaman; 10. Landais; 11. Landes de Bretagne; 12. Manchega; 13. Manech; 14. Rambouillet (Mdrinos de Rambouillet); 15. Valais Blacknose; 16. Nilotic (Sudanese population); 17. Breton Dwarf (Ushant); 18. Romanov; 19. Rouge de l'Ouest (Western Red); 20. Roux de Bagnes; 21. Skudde (Kosse); 22. Somali; 23. Desert Sudanese (North Riverine Wooled); 24. Suffolk; 25. Tarasconnais; 26. Texel; 27. Vendden; 28. Crossbreed with Vend6en; 29. Zackel. /'~4 27ram 2V'3 /9.__ 1S 90 100 110 . 120 GL " . 130 (ram) "~9 .t~ I I 140 150 | 160 Fig. 6. Scatter diagram of Bp = f(GL) in metacarpals, in females in our study. • females, (n° = breed) 35 27 ~i 30 mn 30 19 I A '~9 A / i / -A15 S 23 It ~"25 17 < s~n , 159o loo i 11o 12o I I I I ~3o 14o 150 160 170 G L (ram) Fig. 7. Scatter diagram of Bp = f(GL) in metacarpals, in males in our study. /k males, (n° = breed) 578 0,15 . . . . ,-1 24 27 ' i 0,13 o,12 '. / 90 13° .18 0,11 lle • ~ml/7 8• • 12 0/ 1o" 6 / 0,09 ta.U. 0,0790 I I I 100 110 120 130 GL (ram) 140 " 150 160 Fig. 8. Scatter diagram of SD/GL = f(GL) in metacarpals, in females in our study. • females, (n° = breed) 0,18 0,16 ~] 4 m \ 0,14 0,13 r~ 17 / 1 0,12 Z ~ 1, A ~ 9- IL~ A& 15 13 s since they are taller with a similar weight). Among all breeds constitutive of the lower-left area, rustic ones are probably the most typical, as in Figs. 6 and 7 (Karaman, Somali, Landes de Bretagne, which is nearly extinct, and Breton Dwarf, for example); their morphological type is "small" and "slender". Finally, dairy breeds and above all "walking" breeds (Landais and Sudanese sheep) are characteristic of the lower-right area. Sudanese sheep should even be considered as an extreme in this "tall" and "slender" type. One should probably see an adaptation to desert climate in this feature, which can be an argument in favour of the domestic sheep multifocal origin hypothesis: it would have probably been easier for early shepherd to domesticate local animals, which were already adapted to such a rigorous climate. It is very likely that their being tall and slender depends rather on their ability to survive in the desert than on man's will to select this kind of animal. Yet, one should be careful when dealing with the difficult question of domestication in sheep: we give only an argument in favour of an African domestication centre existence; osteometry should be compared to historical data if we want to get the truth on domestic sheep origins, without being misleading. From now on we have a basis to compare any sheep population to a defined and well-known modern breed sample, and to extrapolate the average morphological type of its individuals from their metapodial bone osteometric study. 0,10 0,08 90 a t i 100 110 120 i i 130 140 GL ( m m ) 23 I 150 160 170 Fig. 9. Scatter diagram of SD/GL=f(GL) in metacarpals, in males in our study. /k males, (n° = breed) Figs. 8 and 9 can also be divided up into 4 areas, but instead of separating "light" from "heavy" breeds, we can distinguish "fat" from "slender" breeds thanks to these figures. Limit values of G L are the same as those defined in Figs. 6 and 7: respectively 135 mm and 145 mm for females and males; limit values of SD/GL are 0.12 and 0.13 for females and males respectively. As in Figs. 6 and 7, breeds specialized in meat production are typical of the upper-left area, since it is quasi-exclusively occupied by these breeds (Charmoise, Charolaise, Rouge de l'Ouest, Suffolk, Vend6en, Texel); the corresponding morphological type is "small" and "fat-set". The upper-right area is quite "deserted": only one breed (Roux de Bagnes) is located there, on Fig. 8, which would mean either this kind of breed is poorly represented in our sample, or this kind of morphological type, "tall" and "thick", is uncommon among sheep. It also means that dairy breeds, although they are as "heavy" as breeds specialized in meat production (see Figs. 6 and 7), are nonetheless more "slender" than those last breeds, since they move to the diagram lower part in Figs. 8 and 9 (which seems quite logical, Discussion One should notice that our variables' CVs are quite high (see Tables 2 and 3), far beyond most biological variables' CVs, which lie between 3 and 6 (Simpson et al. 1960), and far beyond most CV values given in other studies: all CVs given by Haak (1965), Clutton-Brock et al. (1990), and Davis (1996) are lower than 6, and among all the others, 10 is the highest value we could find (Drewes 1924). Sampling is obviously the reason why we observe such differences: in other studies (Haak 1965; CluttonBrock et al. 1990; Davis 1996), sheep come from close origins (the same farm or a single flock), contrary to our animals, which come from many breeds, many farms, and many origins. This observation is similar to the one made by Guintard (1996, 1998) in his cattle metapodial bone studies: variability is rather dependent on sampling than on morphological type, and certain observed variabilities can only be explained by population mixing (Guintard 1998). Concerning metapodial bone variability in sheep, 10 seems to be CV's limit-value when dealing with onesex samples: all CV's values higher than 10 come from our sample, where many breeds were mixed. Such results should be helpful when trying to find out whether a sample is constituted of several populations or not. We can also notice that in every study, SD is always one of the most variable measurements, and often the 579 most variable measurement. What is true dealing with the species seems to be true at breed-level: the diaphysis our purpose has been to define a basis which would allow us to compare any sample to a reference. medio-lateral axis reveals the maximal variability. One of our main purposes has been to define a basis which would allow us to assess the morphological type of any sample, in comparison with our own population. Thus, we have collected Bp, GL, and SD values from many modern and well-known breed samples, and used them to draw scatter diagrams, which are going to help us in testing our basis discriminating power. Figs. 10, 11, 12, and 13 show Bp = f ( G L ) and SD/GL = f ( G L ) in females and males of modern breeds. Each dot is labelled using a number whose definition is given below, along with the number of males (M) and females (F) in each sample. 30. Clun Forest, M = 5, F = 8 (Chaix 1999); 31. Heidschnucke, M = 2, F = 100 (Haak 1965); 32. Herdwick, F = 1 (Chaix 1999); 33. Icelandic, F = 1 (Chaix 1999); 34. Llanwehog, F = 1 (Chaix 1999); 35 Manx Loaghtan, F = 2 (Chaix 1999); 36. Merinolandschaf, M = 8, F = 7 1 (Haak 1965); 37. Norfolk Horn, M -- 1 (Chaix 1999); 38. Portland, F = 1 (Chaix 1999); 39. Shetland, F = 26 (Davis 1996); 40. Soay, M = 8, F = 8 (Clutton-Brock et al 1990); 41. Southdown, F = 1 (Chaix 1999); 42. Speckled-face, F = 2 (Chaix 1999); 43. Teeswater, M = 1 (Chaix 1999); 44. Welsh Mountain, F = 2 (Chaix 1999); 45. Welsh Speckled Face, F = 1 (Chaix 1999); 46. Wensleydale, F = 1 (Chaix 1999). It can be seen in Figs. 10, 11, 12 and 13 that our sample encompasses most of sheep metapodial bone variability range, and that our limit values have a satisfactory discriminating power. Fig. 11 upper-left area is occupied by Norfolk Horn (nearly extinct since 1973 [Porter 2002]), which is the only breed specialized in meat production, and Clun Forest, which has mixed attributes (meat and wool production). Since females belonging to this breed are in Fig. 10 lower-left area, the upper-left area seems to be really specific of breeds specialized in meat production. Merinolandschaf (meat and wool production) and Wensleydale (meat and dairy production) perfectly fit the specific morphological type of Fig. 10 upper-right area: "tall" and "heavy". Most breeds listed above have mixed attributes (meat and wool production) and are located in the lower-left area of Figs. 10 and 11. Since those mixed attributes reveal a form of rusticity, it is not surprising to find them here; they correspond to the "small" and "light" morphological type we defined in our study. As to Figs. 12 and 13, the main difference between modern breeds and our sample is the position of certain breeds possessing mixed attributes: Clun Forest, Llanwenog, Herdwick, Southdown, Speckleface, Teeswater and Welsh Speckleface are "small" and "light" (lower-left area of Figs. 10 and 11), but they are also "fat-set" (upper-left area of Figs. 12 and 13). Although Belle-Ile is the only breed in our study to have such characteristics, it seems possible to find some "small" and "light" breeds which have "heavy" metapodials, which was not really obvious dealing with our own sample. Our limit-values are really interesting, since they allowed us to highlight such a difference between our sample and other breeds. Actually, 35 i t , D , D 46 ,7 30 27 mm 2s / 4! • u / ~2 ~42D 4 4 Cl 31 35 Cl -" 20 tall 15 90 100 110 120 GL 130 , i 140 150 160 (ram) Fig. 10. Scatter diagram of Bp = f(GL) in metacarpals, in females of modern breeds. • variability in our study, [] other modern breeds, (n ° = breed) 3s 37 , 30 m m / • 30 30 q[ 15 small i 90 100 I ! 110 120 130 tall | | i 140 150 160 170 (mm) GL Fig. 11. Scatter diagram of Bp = f(GL) in metacarpals, in males of modern breeds. /~ variability in our study, [] other modern breeds, (n° = breed) 580 0,17 J i 41 0,15 ! ,-1 0 0,13 [] ' 12 / i / ~ ' 0,11 -f 44 -- 46 n 34 no 3so o 3s m [] 40 0,09 - 0,07 , 90 , 100 , 110 ~ 120 & i 130 GL I 140 l l 1 150 160 (mm) Fig. 12. Scatter diagram of SD/GL = f(GL) in metacarpals, in females of modem breeds• • variability in our study, [] other modern breeds, (n ° = breed) 0,18 t , , ' [ I I I A" heavy 30 m m 0,16 27 i g~ 0,12 0,13 / 43 L ~ 51 °: • -" 4% 48 50 47 49 + • " 12 % , 0,0~ 90 • ~ 100 I I 110 120 m,ll g sle~der I I t I 130 140 150 160 5 I 170 110 I 'I 25 1 ]I 20 , 1:3 96 . . . . . . . . . . . . . . . . . . . . . . . . 0,10 OI 1I thick | 30 I mm light 0,14 35 120 7'~¢~48 4 9 small I 130 o Bp (re_m) O SDtGL 15 - . . . . . . . . . . II 51 dtlll111 ~M II T" ,.¢ I ! 140 & 10 (%) ~.~ tall I 150 5 160 GL (ram) GL (ram) Fig. 13. Scatter diagram of SD/GL = f(GL) in metacarpals, in males of modern breeds. /k variability in our study, • other modern breeds, (n° = breed) Therefore, our dividing of B p = f ( G L ) and SD/ G L = f(GL) into different areas according to morphological type is not artificial: modern breeds are mostly located in the area corresponding to their presumed morphological type. It is also useful to appreciate differences between any sample and our own sample, as we did concerning modern breed gracility. Now that we have checked the validity of our reference, we will use it to assess the morphological type of fossil populations. Fig. 14 shows the distribution of Bp = f ( G L ) and SD/ G L = f(GL) (SD/GL expressed in %) from 5 fossil populations labelled as follows: 47. Site of Feddersen Wierde (northern Germany), I--Vth century A.C., 152 metacarpi (Reichstein 1991). 48. Site of Manching (Bavaria), 150-15 B.C., 60 metacarpi (Boessneck et al. 1971). 49. Site of Eketorp II (Sweden), IV-VI th century A.C., 12 metacarpi (Anonymous 1976). 50. Site of Eketorp III (Sweden), X-XIII th century A.C., 55 metacarpi (Anonymous 1976). 51. Site of Tac-Gorsium (Pannonia, Hungary), II-III th century A. C., 75 metacarpi (B6k0nyi 1984). This last figure is noteworthy, since its features are in accordance with sheep size evolution. The metacarpi coming from Manching, which is contemporary with the beginning of sheep increase in size, and those coming from Eketorp II, which is contemporary to sheep decrease in size, have close G L values. Their positions indicate that their morphological type was "small", "light", and "slender" in comparison to modern breeds. They are situated in the lower-left area defined by the axes concerning males and females, so we don't need to know the populations' sex-ratios to assess their morphological type. The metacarpi coming from Eketorp III, which is contemporary to the end of sheep decrease in size during the Middle-Ages, are smaller than those of Eketorp II, which is closer to the beginning of decrease in size. The metacarpi coming from the Roman city of Pannonia are taller than every other. This site is contemporary to the Roman Fig. 14. Scatter diagram of Bp = f(GL) and SD/GL = f(GL) in metacarpals, in fossil populations. (n° = name of the archaeological site), - - female axis, . . . . male axis Empire's apogee, when sheep reached their maximal height. Assuming this sample is situated in the lower-right area (there were probably some females in the sample, which shifts the plot to the left), the corresponding morphological type is "tall", "light", and "slender", close to the French breed Landais. The metacarpi coming from Feddersen Wierde are contemporary to the last ones, but they are closer to the other sites in Fig. 14. The lack of Roman influence in this region, situated in the north of Germany, is one possible explanation of such different morphological types, dealing with contemporary animals. So, graphic representations of B p - - f ( G L ) and SD/ G L = f(GL) combined with our limit values, which require easy to determine measurements, give a good estimation of sheep population morphological types, and can be used to get a better understanding of sheep morphological evolution, just as we did using five fossil populations. Finally, we decided to calculate (DEM/Dd) * 100 values for every breed in our sample. This metapodial index was used by Hillson (1999) to separate sheep from goat. Such an index can be valuable for zooarchaeologists, since metapodials coming from sheep and goat are often mixed when excavations are carried out. Indeed, this index allows a differentiation between sheep and goat, since 'the most lateral and medial elements (trochlear condyles) of the distal articulation are more notched-in relative to the verticilli of the articulation in goat than they are in sheep' (Hillson 1999). ( D E M / D d ) * 100 maximum values are 63% and 62.5% respectively for metacarpal and metatarsal bones in goat (Hillson 1999), and (DEM/Dd)* 100 minimum values are respectively 60.6% and 59% for metacarpal and metatarsal bones in sheep (Hillson 1999). Metapodial index values from our sample are displayed in Table 4. Leaving aside Koroni breed (only one individual with spoiled metapodials), every value is superior to 64% concerning metacarpus, which means that the minimum value for sheep is superior to the maximum value for goat. As to metatarsus, our minimum value is 58.8%, very close to the one mentioned by Hillson (1999). The 581 Table 4. Variation of metapodial index (DEM/Dd) in %, concerning breeds represented in our sample. Breed Belle-Ile West Swiss White Swiss Black-Brown Mountain Charmoise Charolaise Crete French alpine Grisons (Btindner Oberland) Karakul Karaman Koroni Landais Landes de Bretagne Manchega Manech M6rinos de Rambonillet Valais Blacknose Nilotic Breton Dwarf (Ushant) Palma de Mallorca Romanov Rouge de l'Ouest (Western red) Roux de Bagnes Desert Sudanese St-Aubin Suffolk Tarasconnais Texel Vend6en Crossbreed with Vend6en Nevertheless, differences exist; they allow us to separate various morphological types. Revealing those types, using metacarpal bone osteometric features, was a crucial stage in our attempt to define a basis, which will be a valuable tool for zooarchaeologists: the required measurements are easy to get and allow for assessment of every population morphological type. The ultimate goal of this tool is to gain a better understanding of sheep history, osteology being a part of it, among other disciplines. The "intra-species" variability study we have just achieved should be extended, if we should say so, at the "intra-breed" level. It would be interesting to know if rules which govern variability and correlations inside the species are also true at breed-level. If it were so, we would be able to assess every sheep morphological type, using the same kind of tools we used in this study. Metapodial Index (in %) Metacarpus Metatarsus 69.5 68.9 65.7 68.3 68.5 69.2 66.7 66.3 67.7 67.4 58.0 68.1 67.9 66.3 68.0 64.0 70.8 67.6 65.3 72.0 66.3 69.3 68.3 68.8 67.6 66.2 67.8 68.1 69.1 67.9 59.8 58.9 60.8 63.3 63.0 58.8 64.0 63.0 62.3 57.4 63.3 62.5 61.4 60.8 67.2 63.8 60.6 64.0 59.7 References 63.7 64.5 64.7 69.8 63.0 62.5 61.6 metapodial index should be useful in setting sheep apart from goat, since its values seem really different between these two species, dealing with metacarpus. 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