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J. Anal. (1992) 180, pp. 387-393, with I figure Printed in Great Britain 387 A comparison of tooth structure in and early sapiens sapiens: a radiographic study

URI ZILBERMAN AND PATRICIA SMITH Department of Anatomy and Embryology, Dental School of Medicine, The Hebrew University-Hadassah Ein Karem, Jerusalem,

(Accepted 30 December 1991)

ABSTRACT Tooth components of 1st and 2nd erupted permanent molars were measured from standardised radiographs of Homo sapiens sapiens and Homo sapiens neanderthalensis. Enamel height was greater in Homo sapiens sapiens but pulp height and width and the height of the enamel to floor of the pulp chamber were greater in Homo sapiens neanderthalensis. Dentine height, crown width and enamel width showed similar results in the two groups. Unerupted first molars were measured to analyse the influence of function on tooth components and the results obtained were always within the range measured for the erupted teeth. Discriminant analysis between groups, using tooth components, showed accuracy of 93 % for identification of Homo sapiens sapiens and 94% for identification of Homo sapiens neanderthalensis. The results support the hypothesis of a distinct evolutionary line for the Neanderthals.

influence both tooth morphology and size. Growth of INTRODUCTION enamel is promoted by factors on the X and Y Teeth are the best preserved part of the skeleton and chromosomes (Alvesalo et al. 1985; Varrela et al. so play a major role in evolutionary studies. Age has 1988). The effect may occur through the regulation of no direct influence on teeth as it has on other parts of amelogenesis, with the X chromosome more effective the skeleton. Only attrition and dental disease in- in increasing metric enamel growth and the Y fluence the morphology of teeth and the results are chromosome in promoting general dental growth easily recognised. Due to attrition, enamel thickness is (Alvesalo et al. 1985, 1987). Interspecies differences reduced, dentine height increases (secondary and in enamel and pulp thickness were shown between tertiary dentine apposition) and pulp size decreases; africanus and Australopithecus thus the ratio of enamel height to dentine or pulp robustus permanent molars (Zilberman et al. 1991, height is changed (Ten Cate, 1985). The dental 1992). The results suggested that tooth size is phenotype expressed in tooth size and morphology influenced both by the outline of the tooth at the has been used to classify phylogenetically the re- dentinoenamel junction and by the thickness of lationship of the Neanderthals to Homo sapiens enamel. sapiens. Morphologically, the teeth show Thickness of enamel in modern was characteristic features such as taurodontism, large size measured by Shillinburg & Grace (1973). They used of lingual tubercles and Carabelli's trait (Gorjanovic- ground sections that intersect the cusp tips bucco- Kramberger, 1906; Keith, 1925; Kallay, 1963; Smith, lingually in upper molars and mesiodistally in lower 1989). molars. The same technique was used to determine Tooth components (enamel, dentine and pulp size) differences in enamel thickness in primates (Molnar & are determined genetically. The 'freezing' of the Gantt, 1977); differences in average enamel thickness dentinoenamel junction early in life and the rate and between primates and (Martin, 1985) and duration of enamel apposition (Ten Cate, 1985) differences in enamel structure between modern

Correspondence to Dr Uri Zilberman, Laboratory of Physical Anthropology, Department of Anatomy and Embryology, Dental School of Medicine, The Hebrew University-Hadassah Ein Karem, P.O. Box 1172, Jerusalem 91010, Israel.

26 ANA 180 388 U. Zilberman and Patricia Smith humans and early hominids (Grine & Martin, 1988). overlapping of buccal and lingual cusps were used. To The invasive technique used in these studies is not ensure lack of bias in taking the measurements, all applicable to the rare early hominid specimens. radiographs were coded so that their attribution was However, some measurements of enamel thickness in unknown to the individual at the time of measure- (Robinson, 1956) and Australopithecus ment. have been made using naturally fragmented teeth Seven measurements of tooth components were (Beynon & Wood, 1986). The 3rd method used for taken on each tooth using a digital calliper on a light measuring enamel thickness is radiography of the table (see Fig.) by the same person. Enamel height (1), teeth (Sperber, 1985; Zilberman et al. 1991). dentine height (2), pulp height (3), and enamel to floor Ground sections of teeth have also been used to measure dentine height (Shillinburg & Grace, 1973) Table 1. Number ofpermanent mandibular molars measured and dentine apposition rates (Molnar et al. 1981). The pulp chambers of early hominid teeth have been Tooth no. described and measured from radiographic images by Kallay (1963), Blumberg et al. (1971), Sperber (1986), Left MI Left M2 Right MI Right M2 Zilberman et al. (1991, 1992), and the radiographic Homo sapiens 22 13 20 11 image of the pulp ofmodern primary teeth has sapiens been compared with the anatomy of the pulp horns Homo sapiens 10 5 7 2 neanderthalensis (Puddhikarant & Rapp, 1983). Specimens studied. Early Homo sapiens: Isturits 1950-5, 1950-6, The present study, using a radiographic technique, 1950-7; Lachaud 5; Saint Germain la Riviere 1979-8 B-3, B-4, was designed to determine the significance of differ- B-5; Solutre 1956-49; Fontechevade 1957-53; Le Roc de Sers 75113; Le Placard 68098; Le Placard 4, 80628; Le Placard ences in tooth components of mandibular permanent 61397; Laugerie Basse 1,2; Les Roches 53143; Roc de ; molar teeth between Neanderthals and Homo sapiens La Pique; le Marin A III; Parpallo; Bruniquel Lafaye 24; sapiens and to compare the influence of function on Miesslingtal 22034; Bruniquel les Forges 537; Djebel Irhoud 3; thickness of tooth components. 1; Les Rois; La Genierre 3; Grotte des Enfants 6; 1; Qafzeh 2,4. N. Neanderthals: ; Ehringsdorf; Chateauneuf 2; La Chaise 14, 15; Roc de Marsal; Malarnaud; Le Petit Puymoyen; H 9; MATERIALS AND METHODS B,C,D,E; Vindija 76/232; Montgaudier. This study was based on 31 mandibles of Homo sapiens sapiens and 15 mandibles from Neanderthals. From the 2 sides of the mandibles a total of 90 mandibular 1st and 2nd molars were examined (Table 1). All mandibles were radiographed by the same person. The power and voltage were fixed at 10 mA and 65 kV, the only variable being the exposure time. The focus-film distance was 23 cm. The radiographs were taken by applying the film parallel to the major axes of the teeth. The X-rays were directed at right angles to an imaginary plane bisecting the vertical and mesiodistal axes of the teeth and the plane of the radiographic plate - the parallel film technique (Gron 1960; Wood et al. 1988). The amount of radiation exposure was consistent with obtaining the sharpest photographic image possible. In order to determine the reliability of the radio- graphic method, 10 radiographs of the same specimen were taken at different angles. It was found that deviations of more than 5° in the mesiodistal plane produced overlapping of adjacent teeth on the radiographic image. Deviation of more than 5° in the vertical plane caused marked separation of the buccal Fig. Measurements taken on each tooth. 1, Enamel height (EH); 2, dentine height (DH); 3, pulp height (PH); 1+2+3, enamel to and lingual cusps. Accordingly, only radiographs floor of pulp chamber (CH); 4, pulp width (PW); 5, enamel width without overlapping of adjacent teeth and with full (EW); 6, crown width (CW) mesiodistal length. Components ofpermanent mandibular molars 389 of pulp chamber (1 + 2 + 3), were measured parallel to dibular molars. Pulp height and enamel to floor of the long axis of the tooth, mesial to the central fossa, pulp chamber distance were larger in the Neanderthals on the same line. Maximum enamel width (5) was but enamel height was greater in Homo sapiens sapiens measured perpendicular to the long axis of the tooth and the differences between the 2 species were at the widest mesial enamel width and pulp width was statistically significant. Pulp width was greater in the measured at the maximal mesiodistal width per- Neanderthals, but the differences were not statistically pendicular to the long axis of the tooth. Crown width significant. Enamel width, dentine height and crown (6) (mesiodistal length) was measured at the level of width showed similar values for both groups. maximum convexity of the mesial and distal surfaces The results for erupted second mandibular molars and at right angles to the long axis of the tooth. are summarised in Table 3. All values, except for The range of variation found between measure- dentine height, showed the same trend as in the first ments taken on different accepted radiographs of the molars. Pulp height, pulp width, enamel to floor of same specimen was 2-5% and averaged 3.2%. All pulp chamber distance, and crown width were larger data were transferred to the computer and the 2 for the Neanderthal teeth and the differences were subsamples compared using statistical analyses taken statistically significant. Enamel height was greater in from the SPSS program (Nie et al. 1975). Homo sapiens sapiens teeth but the differences were not statistically significant and enamel width and dentine height showed similar results for both groups. RESULTS Correlations between measurements were examined The number of molars measured in the 2 taxonomic using Pearson's correlation coefficient (Table 4). The groups studied are shown in Table 1. Since in most results showed no correlation between enamel height, mandibles only molars of one side were present, all dentine height and pulp height. The main correlations homologous permanent molars were grouped together found were between enamel height and enamel width, in order to enlarge the sample for statistical purposes. pulp height and crown height, enamel width and Case analysis and tooth analysis (homologous teeth crown width, and pulp width and crown width. There grouped together) gave similar results statistically. All was a negative but low correlation between enamel teeth were compared using Student's 2-tailed t test height and dentine height. (Tables 2, 3). The P value used for statistical Ratios of tooth components were calculated. The significance was determined at 0.01. most significant differences between species were Table 2 shows the results for erupted first man- found using the ratio of enamel height to pulp height (Table 5). This ratio was 2 to 4 times greater in mandibular permanent molars of Homo sapiens Table 2. Descriptive statistics of erupted mandibular Ist molars

Variable Group n X (mm) S.D. P value Table 3. Descriptive statistics of erupted mandibular 2nd molars EH HSS 41 1.67 0.47 0.036 HSN 16 1.43 0.34 Variable Group n X (mm) S.D. P value EW HSS 40 1.25 0.26 0.568 HSN 16 1.21 0.27 EH HSS 23 2.00 0.41 0.122 HSN 7 1.72 0.36 DH HSS 41 3.27 0.63 0.382 HSN 16 3.09 0.63 EW HSS 23 1.31 0.24 0.562 HSN 7 1.27 0.15 PH HSS 37 1.24 0.78 0.0008 HSN 11 3.42 1.54 DH HSS 23 3.10 0.51 0.319 HSN 7 3.36 0.59 PW HSS 38 4.25 0.56 0.304 HSN 11 4.47 0.56 PH HSS 22 1.82 0.68 0.003 HSN 6 4.26 1.21 CH HSS 37 6.39 1.32 0.004 HSN 11 8.30 1.71 PW HSS 23 4.12 0.74 0.025 HSN 7 4.65 0.41 CW HSS 40 11.67 0.78 0.595 HSN 16 11.80 0.83 CH HSS 22 7.27 1.09 0.011 HSN 6 9.78 1.62 EH, enamel height; EW, enamel width; DH, dentine height; PH, CW HSS 23 11.41 0.54 0.012 pulp height; PW, pulp width; CH, enamel to floor ofpulp chamber; HSN 7 12.50 0.82 CW, crown width; HSS, Homo sapiens sapiens; HSN, Homo sapiens neanderthalensis. Abbreviations as in Table 2. 26-2 390 U. Zilberman and Patricia Smith

Table 4. Values for Pearson's correlation coefficient

First permanent mandibular molars Second permanent mandibular molars

EW DH PH PW CH CW EW DH PH PW CH CW

Homo sapiens sapiens EH 0.4031* -0.2199 0.2047 0.0797 0.3867 0.0719 0.4818* -0.1704 -0.0062 -0.0927 0.2785 0.2142 EW -0.1297 0.0988 0.0743 0.3582 0.3626* 0.1093 0.1408 0.1330 0.4516 0.3676 DH -0.1807 0.0450 0.3803 0.4850 -0.1061 0.1120 0.3779 0.0068 PH 0.0192 0.6853* 0.0161 0.0341 0.7753* 0.0836 PW 0.0519 0.4910* 0.1452 0.5617* CH 0.4199* 0.2106 Homo sapiens neanderthalensis EH 0.5718* -0.1469 0.3983 -0.3945 0.5631 0.1616 0.3345 -0.1620 0.6961 -0.6496 0.5838 -0.2579 EW 0.1798 0.2679 0.0320 0.4164 0.6580* 0.7743 0.7698 0.2945 0.8408 0.6569 DH 0.1192 0.1714 0.4184 0.4020 0.4176 0.6066 0.6040 0.8582 PH 0.1544 0.9188* 0.1437 -0.2672 0.9735* 0.1438 PW 0.1215 0.5207 -0.0938 0.8131 CH 0.3587 0.3622

Abbreviations as in Table 2. * P<0.01.

Table 5. Ratio ofenamel height (EH) to pulp height (PH) for Table 6. Descriptive statistics of the influence offunction on erupted mandibular permanent molars permanent first mandibular molars of Homo sapiens sapiens

Tooth group Variable Status n X (mm) S.D. Range

Left Ml Right Ml Left M2 EH Erupted 40 1.67 0.46 0.42-2.80 Unerupted 4 2.08 0.44 1.46-2.48 HSS HSN HSS HSN HSS HSN EW Erupted 40 1.25 0.26 0.60-1.82 Unerupted 5 1.72 0.21 1.37-1.93 n 20 6 14 4 15 5 Mean 1.98 0.50 1.67 0.50 1.15 0.45 DH Erupted 41 3.27 0.63 1.88-4.84 Unerupted 4 2.94 0.46 2.47-3.54 PH Erupted 37 1.24 0.78 0.25-3.27 For all teeth P < 0.001. 1 2.46 HSS, Homo sapiens sapiens; HSN, Homo sapiens neanderthalensis. Unerupted PW Erupted 38 4.25 0.56 2.82-5.39 Unerupted 1 4.33 CH Erupted 37 6.39 1.32 3.37-9.52 sapiens than in the Neanderthals. The ratios for right Unerupted 1 8.23 M2 were not given due to the small number of CW Erupted 40 11.67 0.78 10.28-14.78 Neanderthal teeth. The ratio of enamel width to Unerupted 5 11.96 0.78 10.95-12.67 crown width shows less striking differences but does demonstrate that differences in tooth size in the 2 Abbreviations as in Table 2. species reflect differences in the morphology of the pulp. Tables 6 and 7 deal with the question as to how dentine height. The differences were not statistically function and attrition influence the height and width significant and the results obtained for the unerupted of tooth components. Unerupted first mandibular teeth were always within the range measured for the molars were measured for both groups and the results erupted teeth. The results for the single unerupted compared with those of erupted first mandibular Neanderthal tooth showed the same pattern of molars. As expected, function caused decrease in differences as for the erupted teeth. enamel height, enamel width and crown width in both Discriminant analysis of variance was performed species. For the other components only teeth of Homo using several combinations of variables. The best sapiens sapiens were available for measurements. results were obtained using enamel height and width, Function caused decrease in pulp height, pulp width pulp height and width, and dentine height, using the and enamel to floor of pulp chamber, and increase in taxonomic categories given in Table 1. For all 1st and Components ofpermanent mandibular molars 391

Table 7. Descriptive statistics of the influence offunction on but that the overall radiographic image of the pulp is permanent Ist mandibular molars ofHomo sapiens neander- similar to its 3-dimensional anatomy (Barker et al. thalensis 1969, 1974). Variable Status n X (mm) Range This study has shown that there are marked differences between Neanderthals and Homo sapiens EH Erupted 16 1.43 0.86-1.97 sapiens in the height and width of the pulp chamber Not erupted 1 1.84 and in enamel height. The assumption that the thinner EW Erupted 16 1.21 0.70-1.58 enamel is not due to attrition is based on the methods Not erupted 1 1.49 and results of this study: the measurements of enamel CW Erupted 16 11.80 10.66-13.24 Not erupted 1 12.30 height were taken 1 mm mesial to the central fossa where attrition has minimal impact (Fig. 1) and values Abbreviations as in Table 2. for tooth components of unerupted teeth fell within the range of variation of the erupted teeth (Tables 6, 7). Finally, Pearson's correlation coefficients showed 2nd molars of Homo sapiens sapiens, 93 % were no statistically significant correlation between enamel grouped correctly (52 out of 56 teeth) and 94% of height and dentine height or pulp height (Table 4), Homo sapiens neanderthalensis molars were grouped and the inverse ratios of enamel height to pulp height correctly (16 out of 17 teeth). (Table 5) showed that the differences between species The misclassified teeth of Homo sapiens sapiens were not only due to attrition. The pulp chamber of were right MI and M2 of Qafzeh 2 with 66 and 95 % Neanderthals showed the expected taurodontism. The probability of belonging to Neanderthals, right Ml of thinner enamel found in them may be explained by Qafzeh 4 with 69 % probability of belonging to genetic or developmental factors. It may be the result Neanderthals, and left MI of with 62 % of slower enamel formation or earlier cessation of probability of belonging to Neanderthals. The only ameloblast activity. The teeth of Neanderthals de- misclassified Homo sapiens neanderthalensis tooth was veloped faster (Dean, 1985) and erupted earlier than right Ml of Vindija 76/232 with 96% probability of teeth of Homo sapiens sapiens (Legoux, 1965; Dean belonging to Homo sapiens sapiens. et al. 1986). This need for early eruption may have provided the trigger to stop enamel formation. The use of tooth components for discriminating DISCUSSION between Homo sapiens sapiens and Neanderthals Skeletal and morphological differences reported be- showed promising results. All of the misclassified tween the Neanderthals and Homo sapiens sapiens teeth are from specimens whose attribution is still indicate that the Neanderthals are a side branch in the questionable. Almost 93 % of all mandibular molars hominid evolutionary sequence (Smith & Arensburg, of Homo sapiens sapiens were correctly grouped. The 1977; Stringer et al. 1984; Stringer & Andrews, 1988; incorrectly classified cases were Qafzeh 2 and 4, Protsch, 1989; Smith, 1989; Stringer, 1989). The determined by Trinkaus (1984) as an 'early ana- major distinctive metric features of Neanderthal teeth tomically modern human sample' and by Arensburg are the large buccolingual diameters of the incisors, (1991), as 'Neanderthaloid', and Jebel Irhoud de- the ratio of 2nd molar to 1st molar root length, and scribed by Brauer (1984) as 'Neandertaloid Homo taurodontism. These are plesiomorphic traits. How- sapiens'. Of the Neanderthal mandibular molars all ever, the marked accentuation of certain features such except one were correctly classified. The only in- as lingual tubercles and taurodontism appears to be correctly classified case was Vindija 76/232 which characteristic of the Neanderthal permanent dentition 'apparently represents a more gracile variant of the (Smith, 1989). The basis of taurodontism appears to Neanderthals, one which is more similar to ana- be a delay in fusion of the interradicular processes tomically modern humans' (Brauer, 1984) and was (Keith, 1913). Kallay (1963) described the taurodont classified as Homo sapiens sapiens by F. H. Smith pulps of the Neanderthals as shown in radiographs (1984), Stringer et al. (1984) and Stringer (1989). and Blumberg et al. (1971) measured them in a The discriminant analysis using various tooth biometric study. In comparing the radiographic image component measurements may help in classifying of the pulp with its anatomy it was shown that the single tooth or mandibular fragments containing outlines of the lingual horns were contained within the teeth. The characteristic morphological traits of the buccal pulpal images (Puddhikarant & Rapp, 1983), Neanderthal dentition (Patte, 1959; Smith & Arens- 392 U. Zilberman and Patricia Smith burg, 1977; Smith & Tillier, 1989), together with the KEITH A (1913) Problems relating to the teeth of the earlier forms analysis of tooth components, suggest that there are of prehistoric man. Proceedings of the Royal Society of Medicine (Odontological Section) 6, 103-124. major differences in dental development between KEITH A (1925) The Antiquity of Man. London. William and Neanderthals and Homo sapiens sapiens. The differ- Norgate. ences found in this study support the hypothesis that LEGOUX P (1965) D6termination de l'age dentaire de l'enfant Neanderthalien du Roc-Marsal. Revue Francais d'Odonto- the Neanderthals are an evolutionary side branch Stomatologie 10, 1-24. (Trinkaus, 1983; Stringer et al. 1984; F. H. Smith, MARTIN L (1985) Significance of enamel thickness in hominoid 1984; P. Smith, 1989: Stringer, 1989). evolution. 314, 260-263. MOLNAR S, GANTT DG (1977) Functional implications of primate enamel thickness. Americal Journal of Physical Anthropology 46, 447-454. ACKNOWLEDGEMENTS MOLNAR S, PRZYBECK TR, GANTT DG, ELIZONDO RS, WILKERSON, We would like to thank Professor Mark Skinner for JE (1981) Dentine apposition rates as markers ofprimate growth. American Journal of Physical Anthropology 55, 443-453. making the radiographs available to us for study. NIE NH, HULL CH, JENKINS JG, STEINBRENNER K, BENT DH (1975) Statistical Package for the Social Sciences. New York: McGraw Hill. REFERENCES PATTE E (1959) La dentition des Neanderthaliens. Annales de Palkontologie 45, 223-235. ALVESALO L, TAMMISALO E, HOKOLA P (1985) Enamel thickness in PROTSCH R (1989) Some facts supporting an immigration theory of 47, xyy males permanent teeth. Annals of Human Biology 12, anatomically modern man into Europe rather than the theory of 421-427. morphological transition from H. S. neanderthalensis to H. S. ALVESALO L, TAMMISALO E, THERMAN E (1987) 47, XXX females sapiens. In L'Homme de Neanderthal, vol 7. L'extinction (ed. B. sex chromosomes and tooth crown structure. Human 77, Vandermeersch), pp. 109-110. Liege: Etudes et Recherches 345-348. Archeologigues de l'Universit6 de Liege. ARENSBURG B (1991) From Sapiens to Neanderthals: rethinking the PUDDHIKARANT P, RAPP R (1983) Radiographic anatomy of pulpal Middle East. American Journal ofPhysical Anthropology (suppl.) chambers of primary molars. Pediatric Dentistry 5 25-29. 12, 44. ROBINSON JT (1956) The dentition of the Australopithecinae. BARKER BC, LOCKETT BC, PARSON KC (1969) The demonstration Memoirs of the Transvaal Museum of Pretoria 9 1-179. of root canal anatomy. Australian Dental Journal 14, 37-41. SHILLINBURG HT, GRACE CS (1973) Thickness of enamel and BARKER BC, PARSON KC, MILLS PR, WILLIAMS GL (1974) Anatomy dentine. Journal ofSouth California Dental Association 41, 33-52. of root canals. III. Permanent mandibular molars. Australian SMITH FH (1984) hominids from Upper of Dental Journal 19, 408-413. Central Europe and the origin of modern Europeans. In The BEYNON AD, WOOD BA (1986) Variations in enamel thickness and Origin of Modern Humans (ed. F. H. Smith & F. Spencer), pp. structure in East African hominids. American Journal ofPhysical 137-209. New York: Alan Liss. Anthropology 70, 177-193. SMITH P (1989) Dental evidence for phylogenetic relationships of BLUMBERG JE, HYLANDER WL, GOEPP RA (1971) Taurodontism: a middle hominids. In L'Homme de Neanderthal, vol. 7. biometric study. American Journal of Physical Anthropology 34, L'extinction (ed. B. Vandermeersch), pp. 111-120. Liege Etudes 243-256. et Recherches Arch6ologiques de l'Universite de Liege. BRAUER G (1984) A craniological approach to the origin of SMITH P, ARENSBURG B (1977) The infant from Kebara. anatomically modern Homo sapiens in and implications In Eretz Israel, vol. 13 (ed. B. Arensburg & 0. Bar-Yosef), pp. for the appearance of modern humans. The Origin of Modern 164-176. Jerusalem: Israel Exploration Society. Humans: A World Survey ofthe Fossil Evidence (ed. F. H. Smith SMITH P, TILLIER AM (1989) Additional infant remains from the & F. Spencer), pp. 327-410. New York: Alan Liss. Mousterian strata at , (Israel). In Investigations in DEAN MC (1985) Variation in the developing tooth core angle in the South Levantine Prehistory (ed. 0. Bar-Yosef & B. Vander- permanent mandibular teeth of modern man and certain fossil meersch), pp. 323-335. Oxford: BAR. hominids. American Journal of Physical Anthropology 68, SPERBER GH (1985) Comparative primate dental enamel thickness: 233-238. a radiological study. In Hominid Evolution.- Past, Present and DEAN MC, STRINGER CB, BROMAGE TG (1986) Age at death of the Future (ed. P. V. Tobias), pp. 443-454. New York: Alan Liss. Neanderthal child from Devil's Tower, Gibraltar and the SPERBER GH (1986) Paleodontology: radiographic revelation of implications for studies of general growth and development in the Australopithecinae. In Variation, Culture and Evolution in Neanderthals. American Journal of Physical Anthropology 70, African Populations (ed. R. Singer & J. K. Lundy, pp. 195-207. 301-309. Johannesburg: Witwatersrand University Press. GORJANOVIC-KRAMBERGER K (1906) Der Kiluviale Mensch von STRINGER CB (1989) The evolution of Homo sapiens: an exam- Krapina in Kroatia. Ein Beitrag zur Palaoanthropologie. ination of patterns in fossil hominid data. In L'Homme de Wiesbaden: Kridels. Neanderthal, vol. 7. L'extinction (ed. B. Vandermeersch), pp. GRINE FE, MARTIN LB (1988) Enamel thickness and development 121-127. Etudes et Recherches Archeologiques de l'Universite in Australopithecus and Paranthropus. In Evolutionary History de Liege. of the 'Robust' (ed. F. E. Grine), pp. 3-43. STRINGER CB, ANDREWS P (1988) Genetic and fossil evidence for New York: Aldine de Gruyter. the origin of modern humans. Science 239, 1263-1268. GRON P (1960) A geometrical evaluation of image size in dental STRINGER, CB, HUBLIN JJ, VANDERMEERSCH B (1984) The origin of radiography. Journal of Dental Research 39, 289-301. anatomically modern humans in Western Europe. In The Origins KALLAY J (1963) A radiographic study of the Neanderthal teeth of Modern Humans: A World Survey of the Fossil Evidence (ed. from Krapina, . In Symposia of the Society for the Study F. H. Smith & F. Spencer), pp. 51-135. New York: Alan Liss. of Hfuman Biology, vol. 5. Dental Anthropology (ed. D. R. TEN CATE (1985) Oral Histology. Development, Structure and Brothwell), pp. 75-86. New York: Pergamon. Function., pp. 177, 212. St Louis: Mosby. Components ofpermanent mandibular molars 393

TRINKAUS E (1983) The Shanidar Neanderthals. New York: dental morphology of Plio-Pleistocene hominids. IV. Mandibular Academic Press. post canine-root morphology. Journal ofAnatomy 156, 107-139. TRINKAUS E (1984) Western Asia. In The Origin of Modern ZILBERMAN U, SMITH P, SPERBER GH (L991) Components of Humans: A World Survey ofthe Fossil Evidence (ed. F. H. Smith teeth. A radiographic study. & F. Spencer), pp. 251-293. New York: Alan Liss. 5, 515-529. VARRELA L, TowNsEND G, ALvESALo L (1988) Tooth crown size in ZILBERMAN U, SKINNER M, SMITH P (1992) Tooth components of human females with 45,X/46,XX chromosomes. Archives ofOral mandibular deciduous molars ofHomo sapiens sapiens and Homo Biology 33, 291-294. sapiens neanderthalensis: a radiographic study. American Journal WooD BA, ABBoTT SA, UY FERSHAUT H (1988) Analysis of the of Physical Anthropology 87, 245-254.