ORIENTALIA LOVANIENSIA ANALECTA ————— 273 —————

PUBLICATIONS DE LA MISSION ARCHÉOLOGIQUE SUISSE À KERMA 1

NUBIAN ARCHAEOLOGY IN THE XXIST CENTURY

Proceedings of the Thirteenth International Conference for Nubian Studies, Neuchâtel, 1st-6th September 2014

edited by

MATTHIEU HONEGGER

PEETERS LEUVEN – PARIS – BRISTOL, CT 2018

BIOLOGICAL AFFINITY OF THE MESOLITHIC AND POPULATIONS FROM EL-BARGA, : THE DENTAL REMAINS

Anne-Sophie Benoiston, Priscilla Bayle and Isabelle Crevecoeur

Abstract Introduction

In the Valley, the Late Pleistocene and early The Early Holocene site of El-Barga, in the Kerma Holocene were marked by major climatic changes. In region, was discovered in 2001 by the Swiss archaeo- addition, this period witnessed the emergence of new logical mission in Sudan and has been excavated over subsistence strategies with the introduction of pastoral- the last decade. Two occupations were identified based ism and progressive sedentism behaviors. However, on archaeological and radiometric grounds: a Meso- because of the scarcity of human remains dated from lithic assemblage (~ 7,800 – 6,900 BCE) and an Early this transitional period, the effects of these changes on Neolithic cemetery (~ 6,000 – 5,500 BCE). This loca- human population processes in the Nile Valley remain tion is of the utmost importance in the Nubian Nile poorly understood. Valley because this is the only location that documents with a substantial number of -preserved individuals At the end of the Late Pleistocene and until the the transitional period leading to the onset of the Neo- beginning of the Holocene (> 8,500 BCE), geological lithic. Separated by only a millennium, the study of evidence indicates that the climate in the Nile Valley these two populations has the potential to enrich our was hyper-arid (Butzer 1980). All archaeological sites understanding of the population processes in the Nile documented for the Late Palaeolithic were restricted to Valley during this period of cultural transition. the floodplain in the Egyptian portion of the Nile Valley and in , and only a few sites yielded complete The comparative morphometrical analyses of the human remains (Jebel Sahaba Site 117 and Tushka, and dental remains show strong biological affinities between Wadi Kubbaniya; Wendorf 1968; Wendorf and Schild the Mesolithic sample from El-Barga and the Nubian 1986). Epipalaeolithic populations from Jebel Sahaba. These During the ninth millennium, the climate became characteristics significantly differentiate the Mesolithic more humid with the arrival of the monsoonal rains in and Early Neolithic samples at El-Braga. These pheno- 8,500 BCE. The Sahara became a habitable region, and typic data were supplemented by the study of microto- few archaeological sites have been discovered in the mographic acquisitions (µ-CT) of the dental tissue pro- vicinity of the Nile Valley (Nicoll 2004; Kuper and portions of a sample of incisors and molars from both Kröpelin 2006). This advent of wetter conditions lasted assemblages. The results highlight variations in size until the end of the sixth millennium (~ 5,300 BCE) and conformation of these inner structures that support when the monsoonal rains retreated and the Egyptian the hypothesis of a biological differentiation between Sahara became desiccated. After five thousand years the two El-Barga populations; it is unlikely that these BCE, moister climatic conditions generally waned in differences could be related to dietary changes on such Sudan and Southern , and the Nile Valley was a short timescale and at the onset of pastoralism. again a refuge zone for human occupation in Northeast Without excluding the possibility of a certain level Africa (Nicoll 2004; Kuper and Kröpelin 2006). of continuity, the anthropological study of the El-Barga Parallel to these climatic changes, the beginning of assemblage suggests a complex history of population the Holocene was characterized by the progressive processes in the Nile Valley during this crucial period, introduction of herding activities within the human although poorly documented, of the beginning of the populations of this region. Whether the spread of Holocene. pastoralism in Africa was the result of diffusion and 806 a.-s. benoiston, p. bayle & i. crevecoeur adoption of that practice by hunter-gatherer groups These cranio-dental differences may be interpreted (independently or from the other continents) or related in two different manners. to a certain level of population replacement remains debatable, as is the earliest African evidence - For some authors, the differences in craniofacial (Wendorf and Schild 1998; Kuper and Riemer 2013; morphology are related to progressive adaptation to Stock and Gifford-Gonzales 2013). The first changes in subsistence activities: the morpho- uncontroversial occurrences of cattle functional hypothesis (Greene et al. 1967; Carlson in eastern Sahara and the Nubian Nile Valley, with and Van Gerven 1977; Galland et al. 2016). a possible diffusion from Southwest Asia, are - For other authors, the differences, for example, in documented for the seventh millennium (~ 6,500- non-metric trait variation, are genetically related 5,500 BCE; Kuper and Riemer 2013; Stock and and support a replacement of population in the Nile Gifford-Gonzales 2013); however, only in the Valley (Irish 2000; 2005). second half of the Holocene were the North- However, the absence of early Holocene samples in populations involved in fully fledged pastoralism these studies regarding hypotheses of continuity com- (Kuper and Kröpelin 2006). pared with replacement of populations in the Nile Val- The scarcity of human remains discovered in sites ley limits the interpretation because the transitional dated to the early Holocene period limits our under- period, between the Late Pleistocene and the mid-Hol- standing of population processes in the Nile Valley dur- ocene, is not documented. ing this transitional period. The majority of the well- dated sites is located in Lower Nubia and in Central Sudan and relates to recent excavations; if a certain Interest of the El-Barga archaeological Site diversity is depicted regarding the funerary practices, In this framework, the archaeological site of El- little is known regarding their biological affinities. In Barga, near Kerma, represents a rare opportunity to Lower Nubia, the oldest Holocene sites containing understand population processes in the Nile Valley dur- human remains are Wadi El-Arab (~ 9e millennium; ing this transitional period of climatic and cultural Honegger 2011, 2012) and El-Barga (7,800 – 5,500 changes. The El-Barga human skeletal collection BCE; Honegger 2004, 2006). The sites from Central includes 149 individuals from the Mesolithic and Early Sudan are slightly younger (Jebel Sabaloka, 7,335 – Neolithic period. Its chronological position and the 7,078 BCE, Suková and Varadzin 2012; Shabona, 6,585 large number of human remains discovered render this – 5,800 BCE, Clark 1989). Only the earliest phase of collection unique in the Nile Valley. Al Khiday 2 (> 7,040 – 6,250 BCE, Usai et al. 2010) is possibly contemporaneous, and preliminary bio- The El-Barga site was excavated between 2001 and archaeological comparisons suggest some level of con- 2007 by the Swiss Archaeological Mission in Kerma tinuity between the Mesolithic and Neolithic remains under the supervision of M. Honegger (2006). Two in this region (Irish 2012). occupations were identified, a Mesolithic settlement with habitat structures and burials that delivered a min- These results are contrary to the craniometric and imum number of 44 individuals and an Early Neolithic dental study results on the hypothetical relation between cemetery containing 105 individuals (Crevecoeur the Late Pleistocene groups from Nubia, namely Jebel 2012). The two occupations are located in the same Sahaba and , and the Late Neolithic popula- area, and several C14 dates on shells and eggshells tions discovered later in the Egyptian and Nubian por- directly associated with the human remains have tions of the Nile Valley (Irish 2005). Indeed, the Late allowed fixing their chronology (Honegger 2004). The Pleistocene individuals are characterized by a more Mesolithic assemblage, situated at the top of the hill, robust cranial (powerful masticatory apparatus) and has been dated to 7,800 – 6,900 BCE, and the early infra-cranial morphology and a higher average stature Neolithic cemetery is dated to 6,000 – 5,500 BCE, (~1m 67) and lower limb structural conformation that which corresponds to the earliest Neolithic occupation suggest an active and mobile lifestyle (Shackelford in Nubia (Salvatori and Usaï 2008). If these two occu- 2007). In addition, these individuals appear to exhibit pations are separated by less than a millennium, pre- a higher phenotypic variation than do the more recent liminary insights into the funerary practices and mor- Holocene populations (Crevecoeur et al. 2009). phometric comparisons have suggested some biological affinity of the mesolithic and neolithic populations 807

MNI UI1 UI2 UC UP1 UP2 UM1 UM2 LI1 LI2 LC LP1 LP2 LM1 LM2 Total JS_117 24 33 36 39 33 37 46 50 26 33 45 36 38 47 48 547 EBK_MESO 23 28 34 36 40 44 42 42 35 38 45 35 40 41 45 545 EBK_NEO 58 84 67 70 60 72 104 69 70 66 76 63 69 97 79 1046 KDK1 23 24 27 26 33 39 38 44 28 38 44 43 49 51 51 535 Total 128 169 164 171 166 192 230 205 159 175 210 177 196 236 223 2673

Table 1. Composition of the sample for the crown dimension comparison. MNI=minimum number of individuals; U=upper; I=incisor; C=canine; P=premolar; M=molar; L=lower; JS_117= Jebel Sahaba, Site 117; KDK1= Kadruka, site 1

differences in the two El-Barga groups (Crevecoeur El-Barga Mesolithic and Neolithic samples to assess 2012). their biological affinities and address the hypotheses of The Neolithic cemetery is distinct from the Meso- the continuity or replacement of populations in the Nile lithic period by the wealth of funerary offerings, Valley at the onset of pastoralism. whereas only a few bivalves, fish remains or fragments of ostrich eggshells are associated with Mesolithic bur- Material and Methods ials (Honegger 2006 and 2011). The analysis of the funerary practices highlighted some differences in Crown external Dimensions selection of the buried individuals between the two periods: there is a deficiency of immature individuals We compared the dental crown diameters of the per- for the Mesolithic whereas the Neolithic corpus com- manent teeth from El-Barga based on the measure- prises a majority of women (Crevecoeur 2012). Based ments defined by Martin (M.81, M.81[1] and I.74; on morphology, the Mesolithic skeletons are quite Bräuer 1988), with two chronologically and geograph- robust whereas the Neolithic individuals can be char- ically close additional samples: the Late Pleistocene acterized as more slender. The morphology of the man- population from Jebel Sahaba (JS_117) and the Neo- dible and the non-metric dental variation also differen- lithic sample of Kadruka 1 (KDK_1) (Table 1). tiate the two populations (Crevecoeur 2012). Jebel Sahaba (Site 117), dated to at least 11,600 These preliminary observations led us to conduct a years old (Antoine et al. 2013; Zazzo 2014), is the ear- more thorough investigation of the dental remains from liest cemetery in the Nile Valley. Excavated by Wen- the Mesolithic and Neolithic populations of El-Barga. dorf in the 1960s (Wendorf 1968), it is the largest col- The interest in dental remains in paleoanthropology lection of human remains preceding the Mesolithic relies on their strong genetic component and limited group from El-Barga. Sixty-one individuals were remodelling over time that have allowed evaluating the buried in this funerary complex and are well known for biological relations between populations, phylogenetic showing, in nearly half of the cases, traces of inter- relations between species and evolutionary trends personnal violence (Wendorf and Schild 2004). (Scott and Turner 1988; Jernvall and Jung 2000). Nota- The cemetery of Kadruka 1, located a few kilo- bly, enamel thickness and dental tissue proportion var- meters south of Kerma, was excavated by J. Reinold iation have proved useful in providing insights into during the 1980s. Ninety-six burials were attributed to biological affinities, even at the population level (e.g. the Neolithic period and dated to the second half of the Hlusko 2015). fifth millennium (Reinold 2000). The spatial organiza- Here we use external and internal dental morpho- tion of the burials, their repartition regarding the age metric properties to enhance the characterization of the at death and the gender of the deceased, and the

Table 2. Composition of the El-Barga sample for dental MNI Ldc Ldm2 UI1 UM1 Total tissue proportion analysis. MNI=minimum number of EBK_MESO 8 3 3 4 5 15 individuals; L=lower; d=deciduous; U=upper; I=incisor; EBK_NEO 22 13 13 12 13 51 C=canine; P=premolar; M=molar. (right) Total 30 16 16 16 18 66 808 a.-s. benoiston, p. bayle & i. crevecoeur

CROWN DIAMETERS JS_117 EBK_NEO KDK_1 JS_117 KDK_1 UI1_MD EBK_MESO = = = EBK_NEO = > UI1_VL EBK_MESO < = = EBK_NEO < = UI2_MD EBK_MESO = > = EBK_NEO < = UI2_VL EBK_MESO < > = EBK_NEO < = UC_MD EBK_MESO = > > EBK_NEO < = UC_VL EBK_MESO < = = EBK_NEO < = UP1_MD EBK_MESO = > = EBK_NEO < = UP1_VL EBK_MESO = > > EBK_NEO < = UP2_MD EBK_MESO = = = EBK_NEO = = UP2_VL EBK_MESO = > > EBK_NEO < = UM1_MD EBK_MESO = = = EBK_NEO = = UM1_VL EBK_MESO = > > EBK_NEO < = UM2_MD EBK_MESO = > = EBK_NEO < < UM2_VL EBK_MESO = > = EBK_NEO < < UM3_MD EBK_MESO > > = EBK_NEO = < UM3_VL EBK_MESO = > = EBK_NEO < < LI1_MD EBK_MESO < = > EBK_NEO < = LI1_VL EBK_MESO < = < EBK_NEO < < LI2_MD EBK_MESO = = = EBK_NEO = = LI2_VL EBK_MESO < = < EBK_NEO < < LC_MD EBK_MESO = = > EBK_NEO < = LC_VL EBK_MESO < = < EBK_NEO < < LP1_MD EBK_MESO = > > EBK_NEO < = LP1_VL EBK_MESO < > > EBK_NEO < = LP2_MD EBK_MESO = = < EBK_NEO = < LP2_VL EBK_MESO = > = EBK_NEO < < LM1_MD EBK_MESO = > = EBK_NEO < = LM1_VL EBK_MESO = > > EBK_NEO < < LM2_MD EBK_MESO = > > EBK_NEO < < LM2_VL EBK_MESO = > > EBK_NEO < < LM3_MD EBK_MESO = = < EBK_NEO < < LM3_VL EBK_MESO = > = EBK_NEO < < CROWN SHAPE INDEX JS_117 EBK_NEO KDK_1 JS_117 KDK_1 UI1_IND EBK_MESO = = < EBK_NEO < < UI2_IND EBK_MESO < = = EBK_NEO < = UC_IND EBK_MESO < = < EBK_NEO = = UP1_IND EBK_MESO = = > EBK_NEO = = UP2_IND EBK_MESO = > > EBK_NEO < = UM1_IND EBK_MESO = = > EBK_NEO < = UM2_IND EBK_MESO = = = EBK_NEO = > UM3_IND EBK_MESO < = = EBK_NEO < = LI1_IND EBK_MESO = = < EBK_NEO = < LI2_IND EBK_MESO < = < EBK_NEO < < LC_IND EBK_MESO < = < EBK_NEO < < LP1_IND EBK_MESO < = = EBK_NEO < = LP2_IND EBK_MESO = > > EBK_NEO < = LM1_IND EBK_MESO = > = EBK_NEO = = LM2_IND EBK_MESO = > > EBK_NEO < = LM3_IND EBK_MESO = = > EBK_NEO < >

Table 3. Results of the Student’s t-test for the comparison of the dental crown measurment means and indices of EBK_ MESO and EBK_NEO with the other groups. biological affinity of the mesolithic and neolithic populations 809 associated archaeological material suggest a certain JS_117 EBK_MESO EBK_NEO KDK_1 form of hierarchy among the individuals whose expres- JS_117 - 0.5190 0.0006 0.0004 sion is exceptional for this period (Reinold 2000). EBK_MESO 0.5190 - 0.0001 0.0004 Notably, the chronological gap between KDK 1 and the EBK_NEO 0.0006 0.0001 - 0.0645 early Neolithic assemblage from El-Barga is nearly KDK_1 0.0004 0.0004 0.0645 - identical to the gap separating the two El-Barga samples. All of the external crown dimensions from El-Barga Table 4. Results of the MANOVA test on the crown shape and the comparative groups were taken by IC on the indices (I.74) of upper and lower second premolars and original material. The metric variables were tested for molars. Bold=significant statistical differences. normality by the Shapiro-Wilk test, the variance of the groups was evaluated for equivalence using the F-Sne- decor method and the significance between the mean tion and more balanced (with significantly higher and differences was tested using Student’s t-test. Differ- lower means) when compared with the Kadruka 1 sam- ences are considered significant with a p<0.05. ple. Conversely, the Neolithic sample from El-Barga exhibits a significant reduction in dental crown size for Dental Tissue Proportions the majority of the dimensions when compared to the Jebel Sahaba sample, primarily for the posterior teeth We also investigated the inner structures of the den- in relation to the Kadruka 1 population. tal remains using microtomographic acquisitions (µCT) The results from the crown shape index indicate that of a sample of moderately worn permanent and decidu- the posterior teeth of the El-Barga Mesolithic sample ous teeth (Table 2). have a significant relative vestibulo-lingual develop- Teeth were scanned on SkyScan 1076 X-ray equip- ment compared with the El-Barga Neolithic group and ment of the Montpeller RIO Imaging platform accord- the Kadruka 1 sample, whereas the anterior teeth pre- ing to the following parameters: 100 kV voltage of 100 sent the reverse morphology at a significant level in kV, 100 µA current and a projection each 0.2° of rota- relation to the Jebel Sahaba and Kadruka 1 populations. tion. We used Nrecon v.1.6.6 (Skyscan) to reconstruct Finally, the El-Barga Neolithic sample exhibits a clear the final volumes with an isotropic voxel size of 17.92 µm. tendency to a relative reduction of the vestibulo-lingual The reconstructed 16 bits TIFF images were semi- diameter for the majority of the teeth compared with automatically segmented using threshold values deter- Jebel Sahaba and for the anterior teeth compared with mined following the half-maximum height methods Kadruka 1. (Coleman and Colbert 2007). Three-dimensional dental tissue proportions were computed following the proto- We used the crown shape index (I.74) of the upper cols defined by Kono (2004), Tafforeau (2004) and and lower second premolars and molars for multivari- Olejniczak (2006) using Avizo 7 (VSG). ate analysis of variance (MANOVA) to test for statisti- The Mann-Whitney U test was used to compare the cal significance of mean differences. The selection of results for the permanent teeth. Differences were con- the I.74 and the teeth for this multivariate test is related sidered significant with a p<0.05. to the lowest degree of correlation of these variables within arcade. As illustrated in Table 4, the mean dif- ferences are not statistically significant between the Results Mesolithic sample of El-Barga and the Jebel Sahaba Crown external Dimensions population or between the Neolithic sample of El-Barga and the Kadruka 1 population; the intra-site comparison The results of the dental crown morphometric com- of both El-Barga samples shows significant differences. parisons are presented in Table 3, in which the mean of both El-Barga groups are compared with one another Dental Tissue Proportions and with Jebel Sahaba and Kadruka 1. The El-Barga Mesolithic individuals are on average The sample size of the El-Barga Mesolithic decidu- characterized by significantly higher crown dimensions ous teeth is too small to be submitted to statistical than the El-Barga Neolithic sample. The situation is analysis. When compared to the El-Barga Neolithic reversed when compared with the Jebel Sahaba popula- means, the dental tissue proportions of the Mesolithic 810 a.-s. benoiston, p. bayle & i. crevecoeur

AET is significantly higher in the Mesolithic group than in the Neolithic group (AET_MESO=0.94 mm; AET_NEO=0.81 mm; Table 5), but the difference in RET (RET_MESO=17.61; RET_NEO=15.09) is near the threshold of statistical significance (p=0.0786). Figure 2 maps the repartition of the enamel in the crown area (the thicker figures in red) and shows how the Mesolithic upper central incisors possess, on aver- Figure 1. Boxplots of the means and ranges of variation of age, a significantly higher enamel thickness than the the average (AET) and relative enamel thickness (RET) of Neolithic group’s, notably on the buccal surface of the the upper first incisors (UI1s) from the Mesolithic (MESO) tooth. This result indicates a difference in conformation and Neolithic (NEO) samples of El-Barga. for the dental tissue that is independent of the size of the tooth. Notably, the upper first molars (UM1s) exhibit dif- ferent patterns of distinction in the Mesolithic and the UNIT MEAN COMPARISON Neolithic samples of El-Barga. Although significant differences are present for all volumes and the enamel- Volume of the crown (CVOL) mm3 EBK_MESO = EBK_NEO dentine junction area (Table 6), the average and relative Volume of the enamel mm3 EBK_MESO = EBK_NEO enamel thicknesses are similar in the two groups (EVOL) (Figure 3). Volume of the coronal mm3 EBK_MESO = EBK_NEO dentine & pulp (DPVOL) Even more striking is that the volumes and area dif- Surface area of the enamel- ferences between the Mesolithic and the Neolithic sam- mm2 EBK_MESO = EBK_NEO dentine junction (EDJ) ples are not consistent with the external data; the El- Average enamel thickness Barga Mesolithic upper first molars showed significant mm EBK_MESO > EBK_NEO (AET) lower absolute dental tissue dimensions than did the Relative enamel thickness - EBK_MESO = EBK_NEO Neolithic sample. Therefore, the question was how the (RET) Mesolithic sample, characterized by significantly higher Percentage of coronal % EBK_MESO = EBK_NEO dentine & pulp (%DP) vestibulo-lingual diameter, presented significantly smaller crown tissue values than the Neolithic group Table 5. Results of the Mann-Withney test for the comparison but comparable average and relative enamel thickness of the means of the UI1s dental tissue proportions between ratios. The reason was that the height of the crown of EBK_MESO and EBK_NEO. Significant mean differences the upper first molars was significantly higher in the (p<0.05) are indicated by an arrow. Neolithic population than in the Mesolithic (Table 6). This parameter explains why although larger in occlusal view, the Mesolithic upper first molars have smaller dental tissue values but similar average and relative enamel thicknesses to the Neolithic sample. These lower deciduous canines and second molars are results suggest real crown morphology differences included in the variation range of this population, with rather than size differences. Figure 4 presents the repar- a position more in the upper portion of the Neolithic tition of the enamel thickness of the upper first molar variation for the deciduous canine absolute values. crown for both groups. The maximum thickness is The results for the permanent upper central incisors observed on the lingual cusps and is similar between (UI1s) and the upper first molars (UM1) have been sta- the Mesolithic (2.09mm) and the Neolithic (2.08mm). tistically compared with both El-Barga samples. Regarding the UI1s, the Mesolithic sample exhibits Discussion and Conclusion higher values of crown, enamel and dentine volumes than the Neolithic sample. These tendencies are illus- The results of the external coronal diameter com- trated in Figure 1, which presents the mean and varia- parisons have shown that the Neolithic population of tion range of the El-Barga sample regarding the aver- El-Barga is characterized by smaller crown dimensions age (AET) and relative enamel thickness (RET). than the Mesolithic population. Regarding the perma- biological affinity of the mesolithic and neolithic populations 811

Figure 2. Cartographic representation of the enamel thickness variation for the Mesolithic upper first incisors (EBK_T121) and the Neolithic UI1 (EBK_T18). The teeth are represented from left to right in occlusal (O), medial (M), distal (D), vestibular (V) and lingual (L) views. Both incisors reflect the average values of their groups.

nent teeth, the reduction is visible on both the anterior agno 1986; Brace et al. 1987; Y’Ednyak 1989; Pinhasi and posterior teeth and the upper and lower teeth, with and Meiklejohn 2011). Calcagno (1986) showed a sig- the exception of the anterior lower teeth. In addition, nificant reduction in crown size (over 6%) between the there is a significant difference between the results for Mesolithic individuals from Wadi Halfa (10,000 – the vestibulo-lingual and mesio-distal diameters. 7,000 BCE) and a sample of Agriculturalists (3,300 – Indeed, the size reduction in the Neolithic sample is 11,00 BCE) from Nubia. Calcagno also noted that the more frequently related to the vestibulo-lingual diam- vestibulo-lingual diameter showed a greater reduction eters than in the El-Barga Mesolithic sample. Crown than the mesio-distal diameter in these populations shape differences between the two El-Braga groups are (Calcagno 1986). The same trend is present in El- significant for the posterior teeth and primarily observed Barga, given that the reductions observed on the dental on the mandible. One explanation could be the higher remains are more significant along the vestibulo-lingual frequency of a fifth cusp on the Mesolithic lower axis. Notably, the vestibulo-lingual diameter is less molars compared with the Neolithic molars (Crevecoeur influenced by environment and is more genetically con- 2012). Finally, the multivariate crown shape compari- trolled than the mesio-distal diameter (Potter and Nance son emphasizes differences in affinities between the 1976; Potter et al. 1976). two El-Barga samples, with the Mesolithic group being The comparative enamel thickness and dental tissue closer to the Late Pleistocene Jebel Sahaba population proportions study indicated that the anterior and poste- and the Neolithic group more similar to the Later Neo- rior teeth exhibit different trends with regard to enamel lithic population of Kadruka 1. thickness variation. Although the absolute volumes of Post-Pleistocene dental reduction, based on external the crown, the enamel, the crown dentine and pulp, and measurements, has been observed locally and region- the area of the enamel-dentine junction are comparable ally (e.g., Brace and Mahler 1971; Frayer 1977; Calc- between the two populations for the UI1s, these vari- 812 a.-s. benoiston, p. bayle & i. crevecoeur

In summary, the upper first incisors have outer (ves- tibulo-lingual and mesio-distal diameters) and absolute dental tissue dimensions that are comparable in the El- Barga Mesolithic and Neolithic groups but show sig- nificant differences in the average enamel thickness, reflecting different conformations in the arrangement of the dental tissues. Conversely, the absolute volumes of the different dental tissues of the upper first molars Figure 3. Boxplots of the means and ranges of variation of increase in the El-Barga Neolithic population although the average (AET) and relative (RET) enamel thickness of the external occlusal crown dimensions exhibit a reduc- the upper first molars (UM1) from the Mesolithic (MESO) tion in the vestibulo-lingual diameter compared with and Neolithic (NEO) samples of El-Barga. the Mesolithic sample. These conflicting results are explained by a significant change in the height of the crown in the two groups. UNIT MEAN COMPARISON The results of the analysis of the dental tissue pro- Volume of the crown (CVOL) mm3 EBK_MESO < EBK_NEO portions of the El-Braga dental remains reveal more complex changes than the changes observed on the Volume of the enamel (EVOL) mm3 EBK_MESO < EBK_NEO basis of external dimensions and support significant differences in dental conformation in the two groups Volume of the coronal dentine mm3 EBK_MESO < EBK_NEO & pulp (DPVOL) for the anterior and posterior dentition. Surface area of the enamel- The El-Barga assemblage belongs to a period that is mm2 EBK_MESO < EBK_NEO dentine junction (EDJ) believed to have witnessed the emergence of pastoral- Average enamel thickness mm EBK_MESO = EBK_NEO ism. Several studies have suggested that behavioral and (AET) dietary changes contributed to the changes in dental Relative enamel thickness - EBK_MESO = EBK_NEO morphology observed in Late Pleistocene and post (RET) Percentage of coronal dentine mid-Holocene populations from the Nile Valley (Greene % EBK_MESO = EBK_NEO & pulp (%DP) et al. 1967; Carlson and Van Gerven 1977; Calcagno 1986). The first occurrences of animal domestication Height of the crown mm EBK_MESO < EBK_NEO are controversial in Northeast Africa because the attri- bution of archaeofaunal remains dating from the middle Table 6. Results of the Mann-Withney test for the comparison of the ninth millennium to domestic cattle remains of the means of the UM1s dental tissue proportions between debatable (Gautier 2007; Marshall and Hildebrand EBK_MESO and EBK_NEO. Significant mean differences (p<0.05) are indicated by an arrow. 2002; Stock and Gifford-Gonzales 2013). Cattle remains were discovered discretely in economic con- texts based on hunting and fishing during the Early Neolithic (6,500 – 5,000 BCE) (Chaix 2011; Stock and ables (with the exception of the volume of the coronal Gifford-Gonzales 2013); however, it is only by the end dentine and pulp) are significantly higher for the UM1s of the sixth millennium that evidence establishes the in the Neolithic sample. development of fully fledged pastoralism in Nubia However, the Mesolithic UI1s possesses a signifi- (Kuper and Kröpelin 2006). The archaeozoological cantly higher average enamel thickness and high rela- study of the El-Barga collection revealed the presence tive enamel thickness, close to the significant threshold of fish and shellfish remains (Linseele 2012), suggest- when compared with the Neolithic group. These differ- ing that the diet of the population at El-Barga was ences are clearly illustrated by the representation of the based primarily on Nilotic resources, leaving little evi- thickness cartography in which the maximal thickness dence of a radical change in lifestyle or diet between is visible on the vestibular face. Conversely, the UM1s the Mesolithic and the Neolithic assemblages. average and relative enamel thickness does not show a The dental morphological and metrical differences significant difference between the two El-Barga popu- between the two El Barga groups are all the more nota- lations, and the enamel distribution pattern is similar ble because the two populations are chronologically between the two populations. close, lived in the same territory and because the biological affinity of the mesolithic and neolithic populations 813

Figure 4. Cartographic representation of the enamel thickness variation for the Mesolithic upper first molars (EBK_T140b) and the Neolithic UM1 (EBK_T115). The teeth are represented from left to right in occlusal (O), medial (M), distal (D), vestibular (V) and lingual (L) views. Both molars reflect the average values of their group.

archaeological evidence does not suggest a drastic analysis of the entire cranio-facial complex and the change in lifestyle between the two occupations. enamel-dentine junction conformation. Assuming a biological continuity between the El-Barga Mesolithic and Neolithic groups, we are left with the Acknowledgments difficult explanation of dental conformation changes that occurred over a short period of time (less than a We are grateful to Prof. M. Honegger who entrusted millennium) without environmental constraints or the study of the El-Barga anthropological collection to behavioral changes being clearly identified. IC. We thank the curators and researchers who allowed Therefore, if a certain level of continuity cannot and IC to examine the comparative original collections in should not be ruled out between these two human occu- their care: D. Antoine (), J. Reinold pations, the scenario involving a replacement of popu- (SFDAS), M. Besse (Université de Genève), and R. lation to explain these differences in biological affini- Lebrun from the MRI platform in Montpellier, who ties between the Mesolithic and the Neolithic groups facilitated the µ-CT acquisitions of the El-Barga dental should be acknowledged. material. This study was supported in part by the DHP This hypothesis of population replacement must be Project (Diversité biologique et culturelle de l’Homme addressed in more depth because the El-Barga assem- de la fin de la Préhistoire à la Protohistoire) and funded blage is the only substantial collection of human by the Université de Bordeaux and the LabEx LaS- remains from the beginning of the Holocene in Nubia. cArBx (LASCARBX-AAP1-2011), by the “BIG DRY” The El-Barga material fills a chronological gap of con- project (Ruptures et continuité dans le peuplement de siderable interest in the debate over population pro- l’Afrique à la fin du Pléistocène: paléoanthropologie, cesses in the Nile Valley at the onset of pastoralism. paléoenvironnement et archéologies comparées du Rift This investigation of the dental remains characteristics et du Nil dans leur cadre continental), and by the will be strengthened by comparative morphometric Agence Nationale de la Recherche (ANR-14-CE31). 814 a.-s. benoiston, p. bayle & i. crevecoeur

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