International Journal of Osteoarchaeology Int J Osteoarchaeol (2016) Published online in Wiley Online Library (wileyonlinelibrarycom) DOI 101002oa2537

SHORT REPORT

Stable Isotopes and Oral Tori in Greenlandic Norse and Inuit M BAUMANNa N LYNNERUPa AND G R SCOTTb a Laboratory of Biological Anthropology Department of Forensic Medicine University of Copenhagen Copenhagen Denmark b Department of AnthropologyMS 0096 University of Nevada Reno Reno NV USA

ABSTRACT Palatine (PT) and mandibular torus (MT) have long been of interest to dental researchers and anthropologists but their aetiology remains unresolved Some combination of genetic and environmental factors influences their expression but the relative role of each remains contentious Previous research has shown that the Greenlandic Norse exhibit exceptionally high frequencies and pronounced expressions of PT and MT In this regard they are significantly different from genetically related medieval Scandinavian populations so envi-ronmental factors have to be considered An earlier study that estimated stable carbon and nitrogen isotope compositions for a Greenlandic Norse sample makes it possible to compare directly PT and MT expression with the relative degree of marine protein intake For comparative purposes parallel observations were made on a Greenlandic Inuit sample Some researchers suggest the intake of marine resources could impact bone development including torus expression but our analysis found no significant correlation between PT or MT expression and δ13C and δ15N values in the Norse In the Inuit PT expression also showed no relationship to stable isotope compositions MT size in the Inuit did however show a significant inverse relationship with δ13C and δ15N values As MT size goes up stable isotope compositions go down Compared with contempo-rary European populations the Greenlandic Norse show very positive isotope compositions but the Inuit with their high protein-high fat diet show significantly higher δ13C and δ15N values than the Norse It is unclear how this relates to the contrasting findings for MT size and stable isotope values Copyright copy 2016 John Wiley amp Sons Ltd

Key words Greenland mandibular torus palatine torus stable isotopes

Introduction

Palatine and mandibular torus (MT) are nonmetric traits of the oral cavity (Haugen 1992 Pedersen amp Alexandersen 2008) Although oral tori and exostoses can be manifested on the lingual or buccal aspects of both jaws most researchers focus on palatine and MT Palatine torus (PT) is an intraoral protuberance that typically starts on the paired palatine bones and extends towards and sometimes reaches the incisive fo-ramen It often takes the form of an ellipse where it ex-pands from its inception to a midpoint on the palate and then contracts towards its termination As with other tori the size of a PT can range from small to large In contrast to PT which is centred on the hard

Correspondence to G Richard Scott Department of AnthropologyMS 0096 University of Nevada Reno Reno NV 89557 USA e-mail grscottunredu

Copyright copy 2016 John Wiley amp Sons Ltd

palate MT is expressed on the lingual aspect of the left and right sides of the lower jaw inferior to the canine and premolars but sometimes extending as far back as the second molar MT is often lobate in form In some instances it is divided into two segments a smaller an-terior segment and a larger posterior lobe (Hooton 1918 Haugen 1992 Antoniades et al 1998 Jainkittivong et al 2007)

The aetiology of palatine and mandibular tori has long been contentious Some researchers emphasise the im-portance of genetics in torus expression while others feel their development reflects environmental especially functional factors Today most agree tori are a manifes-tation of multi-factorial causes reflecting both genetic and environmental inputs on presence and degree of ex-pression (Woo 1950 Haugen 1992 Eggen 1993 Antoniades et al 1998 Pechenkina amp Benfer 2002 Al Quran amp Al-Dwairi 2006 Ihunwo amp Phukubye 2006 Jainkittivong et al 2007 Sawair et al 2009)

Received 20 January 2016 Revised 22 April 2016 Accepted 6 May 2016

M Baumann et al

Figure 1 Palatine torus expression on graded scale from 0 (absence) to 4 (pronounced) grade 1 expression begins on paired palatine bones but ex-tends only about a third of the way to the incisive foramen Grades 2ndash4 show increasingly larger manifestations of palatine torus While grade 4 is large some examples in the Greenlandic Norse are more substantial

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

Figure 2 Mandibular torus expression on graded scale from 0 (absence) to 4 (pronounced) For purposes of illustration grade 1 involves a slight and visible expression of the trait In some cases grade 1 cannot be photographed but is evident by palpation Grade 2 is multi-lobate but this is not a requirement for this grade size is the key determinant

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Studies have shown extensive interpopulation varia-tion in PT and MT frequencies with particularly high frequencies recorded for north Asian (Pechenkina amp Benfer 2002 Al Quran amp Al-Dwairi 2006 Jainkittivong et al 2007) Lapp (Schreiner 1935 Skrzat et al 2003) and Inuit populations (Hooton 1918 Woo 1950 Oschinsky 1964 Al Quran amp Al-Dwairi 2006 Jainkittivong et al 2007) This geo-graphical pattern led several investigators to refer to tori as lsquoMongolian traitsrsquo (Hooton 1918 Eroglu amp Erdal 2008 Garcia-Garcia et al 2010) Despite this characterisation oral tori have been found in high fre-quencies among some European and European-derived populations (Hooton 1918 Axelsson amp Hedegaard 1985 Eggen et al 1991 Halffman et al 1992 Scott et al 1992 Eggen amp Natvig 1994 Chohayeb amp Volpe 2001)

Eggen (1993) discussed possible factors influencing PT and MT in a contemporary Norwegian population A marine diet was singled out as a possible contributing factor to torus development More specifically Eggen et al (1991) hypothesised that PT was positively corre-lated with a diet rich in saltwater fish possibly because of their high content of polyunsaturated fatty acids of the omega-3 family and vitamin D which could trigger excessive bone formation

The Greenlandic Norse exhibit an extreme degree of both PT and MT (Sellevold 1980 Halffman et al 1992 Scott et al 1992) This Scandinavian population settled in Greenland ca AD 985 and established them-selves primarily in two regions on the west coast sepa-rated by about 350 km referred to as the Eastern and Western Settlements The Western Settlement was abandoned around 1350 while the Eastern Settlement lasted into the 15th century (Arneborg et al 2012) They make up a unique study population as they shared genes with contemporary Scandinavian popula-tions but were subjected to a radically different subarc-tic environment making it reasonable to suggest that environmental factors were involved in the extreme de-velopment of oral tori (Halffman et al 1992) Their re-mains have been analysed by numerous researchers who found the prevalence of PT and MT much higher than in other medieval Scandinavian populations Not only were tori in extremely high frequency they also exhibited some of the largest expressions ever observed (Mellquist amp Sandberg 1939 Fischer-Moslashller 1942 Pedersen 1949 Sellevold 1980 Halffman et al 1992 Scott et al 1992) Different explanations for this have been proposed Halffman et al (1992) discuss a combination of increased masticatory stress and chronic undernutrition as possible causes of PT forma-tion Sellevold (1980) argued against masticatory stress

as a cause for MT and proposed that genetic factors played a major role Recently a comprehensive isotopic analysis of the

Norse Greenland diet was conducted (Nelson et al 2012) The analysis of stable nitrogen and carbon iso-topes of 80 human skeletons showed a change in the Norse diet through time As environmental conditions worsened for domestic animals there was increased re-liance on marine resources During the latter period of occupation the Greenlanders had one of the most ma-rine focused diets recorded for a medieval Northern European populations almost on par with the Inuit well known for their high-protein high-fat diet The isotopic data from this study make it possible to inves-tigate the previously mentioned hypotheses regarding a possible correlation between a diet mainly based on marine protein and the frequency and degree of PT and MT expression

For comparative purposes this approach was ex-tended to a sample of Inuit skeletons associated with the Greenlandic Thule Culture People bearing the Thule culture arrived in Greenland approximately 1100 AD (Lynnerup 1998) As sea-mammal hunters adapted to an Arctic climate the Inuit were almost en-tirely dependent on marine resources (Arneborg et al 2012)

Materials

A total of 88 skulls were analysed for this study 47 Greenlandic Norse and 41 Inuit All remains are housed at the Laboratory of Biological Anthropology Section of Forensic Pathology University of Copenhagen Denmark In an earlier study Nelson et al (2012) mea-sured the stable carbon (δ13C) and nitrogen (δ15N) values of bone collagen from these individuals Sample sizes in the tables vary as some individuals could not be scored for either PT or MT To be included in the sam-ple a palate or mandible intact enough for scoring at least one of the two different types of torus was required

Methods

Given the diversity of the torus expression and the nonmetric character of these traits several scoring sys-tems have been developed (Haugen 1992 Halffman et al 1992 Antoniades et al 1998 Pechenkina amp Benfer 2002 Skrzat et al 2003) Because of irregular surfaces and inconsistent landmarks metric measure-ments of tori are difficult (but for PT refer to Halffman

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

et al 1992) Most researchers utilise a ranked classifica-tion that begins with absence and includes variable degrees of trait presence

In our study each individual was scored for PT and MT based on size and morphology As some skulls had fragmented mandibles and maxillary bones there were instances where only one type of tori or just one side of a mandible or palate could be scored Both MT and PT are predominantly bilateral traits (Woo 1950 Haugen 1992 Skrzat et al 2003 Garcia-Garcia et al 2010) If one side of a palate or mandible could be assessed for torus expression the skull was included in the study When a bony protuberance along either the intermaxillary suture of the hard palate or on the inside of the mandible could be observed andor pal-pated it was scored as positive Initially morphological characteristics were taken into account but for purposes of analysis focus is exclusively on torus size Five cate-gories were used to rank torus size (Hooton 1918 Eroglu amp Erdal 2008) PT and MT were scored in the same way (0) no torus (1) small torus (2) medium to-rus (3) large torus and (4) extreme torus (Figures 1 and 2) Scoring by visual inspection was undertaken by a single trained observer Data on stable isotopes (δ13C and δ15N) were made available from an earlier study (Nelson et al 2012)

To determine if there is a relationship between stable isotope compositions and torus expression two statistical procedures were followed First product-moment correla-tions were computed among the four variables (PT MT δ13C and δ15N) in the two samples Second ANOVA Model I was utilised to determine if mean isotope compo-sitions differed significantly by degree of expression

Results

The class frequency distributions for PT and MT in the Greenlandic Norse and Inuit are shown in Table 1 There is no significant sex difference for either torus in the two samples The Norse have a slightly higher frequency of PT than the Inuit (905 vs 0757) and the mean trait score is slightly larger (148 vs 122) However the sample differences are not statistically significant For MT the situation is reversed The Inuit have a higher frequency (0846 vs 0675) and higher mean trait score (1490 vs 1000) and the difference is statistically significant

To put stable isotope compositions in perspective Table 2 provides the summary statistics for male and fe-male Norse and Inuit individuals along with totals Again there are no significant differences between men and women For both δ13C and δ15N there is a significant difference in isotope compositions between the Norse and Inuit Although the Norse show more positive values for both isotopes compared with con-temporary European populations (cf Scott amp Poulson 2012) they do not exhibit the high level of protein de-pendency shown by the Inuit

Table 3 shows a correlation matrix between the two tori and two isotopes for the Norse and Inuit First there is no significant correlation between the expres-sion of palatine and MT in either sample For the Norse all correlations between isotope compositions and torus expressions are small and nonsignificant For the Inuit this situation holds for PT but there is a sig-nificant inverse relationship between MT expression and both δ13C and δ15N values The two significant

Table 1 Class frequency distributions for palatine and mandibular tori in Greenlandic Norse and Inuit

Grade Total trait Mean X2 X2

Oral torus Sample Sex n 0 1 2 3 4 frequency trait score sex sample

Norse Male 23 0043 0522 0261 0174 0000 0957 Female 15 0200 0333 0400 0000 0067 0800 004 Unknown 4 0000 0750 0250 0000 0000 1000 (p gt 005) Total 42 0095 0476 0310 0095 0024 0905 148

Palatine 0088 (p gt 005) torus

Inuit Male 26 0192 0462 0269 0077 0000 0808 Female 11 0364 0273 0182 0182 0000 0636 0006 Total 37 0243 0405 0243 0108 0000 0757 122 (p gt 005)

Norse Male 24 0333 0583 0041 0000 0041 0667 Female 11 0272 0182 0182 0091 0000 0728 0149 Unknown 5 0400 0400 0000 0200 0000 0800 (p gt 005) Total 40 0325 0450 0150 0050 0025 0675 1000

Mandibular 6717 (p lt 001) torus

Inuit Male 30 0200 0333 0300 0167 0000 0800 Female 9 0000 0444 0444 0111 0000 1000 0207 Total 39 0154 0359 0333 0154 0000 0846 1490 (p gt 005)

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Table 2 Stable carbon and nitrogen isotope compositions in Norse and Inuit men and women

δ13C δ15N Sample Sex n mean SD P mean SD P

Norse Male 23 1622 0958 059 1548 1367 082 Female 15 1605 0902 1537 1486 Total 38 1616 0928 1544 1400

Inuit Male 25 1386 1196 033 1945 1491 017 Female 11 1432 1288 1873 1365 Total 36 1400 1225 1923 1474

Between samples Diff 216 lt001 379 lt001

Table 3 Correlations between palatine and mandibular tori and carbon and nitrogen isotopes in Norse and Inuit

Greenlandic Inuit (n = 32)

Palatine torus Mandibular torus δ13C δ15N

Greenlandic Norse (n = 37)

Palatine torus Mandibular torus

δ13C δ15N

x 0179 0122 0163

Bold faced

0179 x

0144 0155

significant at 005 level

0214 0554

x 0758

0188 0516 0682 x

negative correlations are almost identical (0544 four grades of expression Individuals scored as grade 0516) For both samples the two isotopes show high 0 have the highest positive δ13C and δ15N values and significant correlations with one another (0758 and there is a linear shift to less positive compositions 0682) moving from grade 0 to grade 3+ When mean isotope compositions associated with

specific torus grades are compared (Table 4) there is no significant difference in δ13C and δ15N values for Discussion PT in either the Norse or Inuit This is also true for MT expression in the Norse However corroborating The impetus for this study was to investigate the hypoth-the correlation coefficients in Table 3 MT shows sig- esis that elements of a marine diet as estimated by δ13C nificantly different mean compositions between the and δ15N values could trigger the hyper-development of

Table 4 ANOVA Model I comparisons for mean isotope compositions by grade of torus expression

Grade

Sample Oral torus Isotope 0 1 2 3+ P

δ13C Mean 1595 1648 1582 1594 0348 Norse

δ15N Mean 1565 1491 1594 1618 0128 n 4 17 13 5

Palatine torus δ13C Mean 1374 1389 1446 1395 0653

Inuit δ15N Mean 1948 1930 1868 1968 0518

n 9 14 9 4 δ13C Mean 1581 1626 1603 0525

Norse δ15N Mean 1582 155 1559 0855

n 14 17 9 Mandibular torus

δ13C Mean 1293 1392 1438 1524 lt0001 Inuit

δ15N Mean 204 1934 1852 1796 0020 n 6 14 13 5

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

palatine and MT in the Greenlandic Norse For compar-ative purposes an Inuit sample from the Thule culture was studied for the same set of variables For the Norse we found no statistical correlation between the expres-sion of either torus and stable isotope values At first glance this might indicate that a marine diet does not play a role in torus development Surprisingly however the Inuit sample does show a significant inverse correla-tion between MT expression and isotope compositions More positive isotopes are associated with low grades of MT expression with absence phenotypes showing the heaviest δ13C and δ15N values If a more systemic di-etary mechanism was involved we would expect this to be expressed in both PT and MT However we know that Inuit made heavy use of their jaws for skin prepara-tion and that Inuit dental abrasion is more pronounced than for the Norse Perhaps the greater mechanical load-ing because of this activity could influence torus forma-tion in the mandible which would experience more bending forces Analyses of other arctic skeletal assem-blages may shed light on whether or not this is a consis-tent finding

An arctic diet consisting mostly of saltwater fish and marine animals may not be the primary reason why the Greenlandic Norse developed palatine and MT to such an exaggerated degree compared with medieval Scandinavians in Europe It should be reiterated that medieval Icelanders another Scandinavian group that lived in a comparable subarctic environment also showed unusually pronounced torus expressions (Hooton 1918 Scott et al 1992) A strong dependence on marine resources in conjunction with the rigors of a subarctic environment may still be implicated in Norse oral tori variation

References

Al Quran FA Al-Dwairi ZN 2006 Torus palatinus and torus mandibularis in edentulous patients Journal of Contemporary Dental Practice 7 112ndash119 PM16685302

Antoniades DZ Belazi M Papanayiotou P 1998 Concur-rence of torus palatinus with palatal and buccal exostoses Case report and review of the literature Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 85 552ndash557 DOI101016S1079-2104(98)90290-6

Arneborg J Lynnerup N Heinemeier J 2012 Human diet and subsistence patterns in Norse Greenland AD c 980ndashAD c 1450 archaeological interpretations Journal of the North Atlantic 3 119ndash133

Axelsson G Hedegaard B 1985 Torus palatinus in Icelandic school children American Journal of Physical Anthropology 67 105ndash112 DOI101002ajpa1330670205

Chohayeb AA Volpe AR 2001 Occurrence of torus palatinus and mandibularis among women of different ethnic groups American Journal of Dentistry 14 278ndash28 PM11803989

Eggen S 1993 Torus mandibularis and torus palatinus in Norway A study on factors influencing their variation PhD Dissertation Eget forlag

Eggen S Natvig B 1994 Concurrence of torus mandibularis and torus palatinus Scandinavian Journal of Dental Research 102 60ndash63 DOI101111j1600-07221994tb01154x

Eggen S Natvig B Gasemyr J 1991 Variation in torus mandibularis prevalence in Norway A statistical analysis using logistic regression Community Dentistry and Oral Epidemiology 19 32ndash35 DOI101111j1600-07221994 tb01153x

Eroglu S Erdal YS 2008 Why did the frequency of palatine torus increase in the ancient Anatolian populations Homo 59 365ndash382 DOI101016jjchb200806005

Fischer-Moslashller K 1942 The mediaeval Norse settlements in Greenland Anthropological investigations Meddelelser om Groslashnland 89 lndash82

Garcia-Garcia AS Martinez-Gonzalez JM Gomez-Font R Soto-Rivadeneira A Oviedo-Roldan L 2010 Current sta-tus of the torus palatinus and torus mandibularis Medicina Oral Patologiacutea Oral y Cirugiacutea Bucal 15(2) e353ndashe360 DOI104317medoral15e353

Halffman CM Scott GR Pedersen PO 1992 Palatine torus in the Greenlandic Norse American Journal of Physical Anthropology 88 145ndash161 DOI101002 ajpa1330880204

Haugen LK 1992 Palatine and mandibular tori A morpho-logic study in the current Norwegian population Acta Odontologica Scandinavica 50 65ndash77 PM1604967

Hooton EA 1918 On certain eskimoid characters in Icelan-dic skulls American Journal of Physical Anthropology 1 53ndash78

Ihunwo AO Phukubye P 2006 The frequency and anatomical features of torus mandibularis in a Black South African popula-tion Homo 57 253ndash262 DOI101016jjchb200603004

Jainkittivong A Apinhasmit W Swasdison S 2007 Preva-lence and clinical characteristics of oral tori in 1520 Chulalongkorn University Dental School patients Surgical and Radiologic Anatomy 29 125ndash131 PM17340055

Lynnerup N 1998 The Greenland Norse - A Biological-Anthropological Study Vol 24 The Commission for Sci-entific Research in Greenland Copenhagen

Mellquist C Sandberg T 1939 Odontological studies of about 1400 mediaeval skulls from Halland and Scania in Sweden and from the Norse colony in Greenland and a contribution to the knowledge of their anthropology Odontologisk Tidskrift 38 lndash83

Nelson DE Heinemeier J Lynnerup N Sveinbjoumlrnsdoacutettir AacuteE Arneborg J 2012 An isotopic analysis of the diet of the Greenland Norse Journal of the North Atlantic 3 93ndash118

Oschinsky L 1964 The Most Ancient Eskimos The Cana-dian Research Centre for Anthropology University of Ottawa Ottawa

Pechenkina EA Benfer RA Jr 2002 The role of occlusal stress and gingival infection in the formation of exostoses

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

Figure 2 Mandibular torus expression on graded scale from 0 (absence) to 4 (pronounced) For purposes of illustration grade 1 involves a slight and visible expression of the trait In some cases grade 1 cannot be photographed but is evident by palpation Grade 2 is multi-lobate but this is not a requirement for this grade size is the key determinant

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Studies have shown extensive interpopulation varia-tion in PT and MT frequencies with particularly high frequencies recorded for north Asian (Pechenkina amp Benfer 2002 Al Quran amp Al-Dwairi 2006 Jainkittivong et al 2007) Lapp (Schreiner 1935 Skrzat et al 2003) and Inuit populations (Hooton 1918 Woo 1950 Oschinsky 1964 Al Quran amp Al-Dwairi 2006 Jainkittivong et al 2007) This geo-graphical pattern led several investigators to refer to tori as lsquoMongolian traitsrsquo (Hooton 1918 Eroglu amp Erdal 2008 Garcia-Garcia et al 2010) Despite this characterisation oral tori have been found in high fre-quencies among some European and European-derived populations (Hooton 1918 Axelsson amp Hedegaard 1985 Eggen et al 1991 Halffman et al 1992 Scott et al 1992 Eggen amp Natvig 1994 Chohayeb amp Volpe 2001)

Eggen (1993) discussed possible factors influencing PT and MT in a contemporary Norwegian population A marine diet was singled out as a possible contributing factor to torus development More specifically Eggen et al (1991) hypothesised that PT was positively corre-lated with a diet rich in saltwater fish possibly because of their high content of polyunsaturated fatty acids of the omega-3 family and vitamin D which could trigger excessive bone formation

The Greenlandic Norse exhibit an extreme degree of both PT and MT (Sellevold 1980 Halffman et al 1992 Scott et al 1992) This Scandinavian population settled in Greenland ca AD 985 and established them-selves primarily in two regions on the west coast sepa-rated by about 350 km referred to as the Eastern and Western Settlements The Western Settlement was abandoned around 1350 while the Eastern Settlement lasted into the 15th century (Arneborg et al 2012) They make up a unique study population as they shared genes with contemporary Scandinavian popula-tions but were subjected to a radically different subarc-tic environment making it reasonable to suggest that environmental factors were involved in the extreme de-velopment of oral tori (Halffman et al 1992) Their re-mains have been analysed by numerous researchers who found the prevalence of PT and MT much higher than in other medieval Scandinavian populations Not only were tori in extremely high frequency they also exhibited some of the largest expressions ever observed (Mellquist amp Sandberg 1939 Fischer-Moslashller 1942 Pedersen 1949 Sellevold 1980 Halffman et al 1992 Scott et al 1992) Different explanations for this have been proposed Halffman et al (1992) discuss a combination of increased masticatory stress and chronic undernutrition as possible causes of PT forma-tion Sellevold (1980) argued against masticatory stress

as a cause for MT and proposed that genetic factors played a major role Recently a comprehensive isotopic analysis of the

Norse Greenland diet was conducted (Nelson et al 2012) The analysis of stable nitrogen and carbon iso-topes of 80 human skeletons showed a change in the Norse diet through time As environmental conditions worsened for domestic animals there was increased re-liance on marine resources During the latter period of occupation the Greenlanders had one of the most ma-rine focused diets recorded for a medieval Northern European populations almost on par with the Inuit well known for their high-protein high-fat diet The isotopic data from this study make it possible to inves-tigate the previously mentioned hypotheses regarding a possible correlation between a diet mainly based on marine protein and the frequency and degree of PT and MT expression

For comparative purposes this approach was ex-tended to a sample of Inuit skeletons associated with the Greenlandic Thule Culture People bearing the Thule culture arrived in Greenland approximately 1100 AD (Lynnerup 1998) As sea-mammal hunters adapted to an Arctic climate the Inuit were almost en-tirely dependent on marine resources (Arneborg et al 2012)

Materials

A total of 88 skulls were analysed for this study 47 Greenlandic Norse and 41 Inuit All remains are housed at the Laboratory of Biological Anthropology Section of Forensic Pathology University of Copenhagen Denmark In an earlier study Nelson et al (2012) mea-sured the stable carbon (δ13C) and nitrogen (δ15N) values of bone collagen from these individuals Sample sizes in the tables vary as some individuals could not be scored for either PT or MT To be included in the sam-ple a palate or mandible intact enough for scoring at least one of the two different types of torus was required

Methods

Given the diversity of the torus expression and the nonmetric character of these traits several scoring sys-tems have been developed (Haugen 1992 Halffman et al 1992 Antoniades et al 1998 Pechenkina amp Benfer 2002 Skrzat et al 2003) Because of irregular surfaces and inconsistent landmarks metric measure-ments of tori are difficult (but for PT refer to Halffman

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

et al 1992) Most researchers utilise a ranked classifica-tion that begins with absence and includes variable degrees of trait presence

In our study each individual was scored for PT and MT based on size and morphology As some skulls had fragmented mandibles and maxillary bones there were instances where only one type of tori or just one side of a mandible or palate could be scored Both MT and PT are predominantly bilateral traits (Woo 1950 Haugen 1992 Skrzat et al 2003 Garcia-Garcia et al 2010) If one side of a palate or mandible could be assessed for torus expression the skull was included in the study When a bony protuberance along either the intermaxillary suture of the hard palate or on the inside of the mandible could be observed andor pal-pated it was scored as positive Initially morphological characteristics were taken into account but for purposes of analysis focus is exclusively on torus size Five cate-gories were used to rank torus size (Hooton 1918 Eroglu amp Erdal 2008) PT and MT were scored in the same way (0) no torus (1) small torus (2) medium to-rus (3) large torus and (4) extreme torus (Figures 1 and 2) Scoring by visual inspection was undertaken by a single trained observer Data on stable isotopes (δ13C and δ15N) were made available from an earlier study (Nelson et al 2012)

To determine if there is a relationship between stable isotope compositions and torus expression two statistical procedures were followed First product-moment correla-tions were computed among the four variables (PT MT δ13C and δ15N) in the two samples Second ANOVA Model I was utilised to determine if mean isotope compo-sitions differed significantly by degree of expression

Results

The class frequency distributions for PT and MT in the Greenlandic Norse and Inuit are shown in Table 1 There is no significant sex difference for either torus in the two samples The Norse have a slightly higher frequency of PT than the Inuit (905 vs 0757) and the mean trait score is slightly larger (148 vs 122) However the sample differences are not statistically significant For MT the situation is reversed The Inuit have a higher frequency (0846 vs 0675) and higher mean trait score (1490 vs 1000) and the difference is statistically significant

To put stable isotope compositions in perspective Table 2 provides the summary statistics for male and fe-male Norse and Inuit individuals along with totals Again there are no significant differences between men and women For both δ13C and δ15N there is a significant difference in isotope compositions between the Norse and Inuit Although the Norse show more positive values for both isotopes compared with con-temporary European populations (cf Scott amp Poulson 2012) they do not exhibit the high level of protein de-pendency shown by the Inuit

Table 3 shows a correlation matrix between the two tori and two isotopes for the Norse and Inuit First there is no significant correlation between the expres-sion of palatine and MT in either sample For the Norse all correlations between isotope compositions and torus expressions are small and nonsignificant For the Inuit this situation holds for PT but there is a sig-nificant inverse relationship between MT expression and both δ13C and δ15N values The two significant

Table 1 Class frequency distributions for palatine and mandibular tori in Greenlandic Norse and Inuit

Grade Total trait Mean X2 X2

Oral torus Sample Sex n 0 1 2 3 4 frequency trait score sex sample

Norse Male 23 0043 0522 0261 0174 0000 0957 Female 15 0200 0333 0400 0000 0067 0800 004 Unknown 4 0000 0750 0250 0000 0000 1000 (p gt 005) Total 42 0095 0476 0310 0095 0024 0905 148

Palatine 0088 (p gt 005) torus

Inuit Male 26 0192 0462 0269 0077 0000 0808 Female 11 0364 0273 0182 0182 0000 0636 0006 Total 37 0243 0405 0243 0108 0000 0757 122 (p gt 005)

Norse Male 24 0333 0583 0041 0000 0041 0667 Female 11 0272 0182 0182 0091 0000 0728 0149 Unknown 5 0400 0400 0000 0200 0000 0800 (p gt 005) Total 40 0325 0450 0150 0050 0025 0675 1000

Mandibular 6717 (p lt 001) torus

Inuit Male 30 0200 0333 0300 0167 0000 0800 Female 9 0000 0444 0444 0111 0000 1000 0207 Total 39 0154 0359 0333 0154 0000 0846 1490 (p gt 005)

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Table 2 Stable carbon and nitrogen isotope compositions in Norse and Inuit men and women

δ13C δ15N Sample Sex n mean SD P mean SD P

Norse Male 23 1622 0958 059 1548 1367 082 Female 15 1605 0902 1537 1486 Total 38 1616 0928 1544 1400

Inuit Male 25 1386 1196 033 1945 1491 017 Female 11 1432 1288 1873 1365 Total 36 1400 1225 1923 1474

Between samples Diff 216 lt001 379 lt001

Table 3 Correlations between palatine and mandibular tori and carbon and nitrogen isotopes in Norse and Inuit

Greenlandic Inuit (n = 32)

Palatine torus Mandibular torus δ13C δ15N

Greenlandic Norse (n = 37)

Palatine torus Mandibular torus

δ13C δ15N

x 0179 0122 0163

Bold faced

0179 x

0144 0155

significant at 005 level

0214 0554

x 0758

0188 0516 0682 x

negative correlations are almost identical (0544 four grades of expression Individuals scored as grade 0516) For both samples the two isotopes show high 0 have the highest positive δ13C and δ15N values and significant correlations with one another (0758 and there is a linear shift to less positive compositions 0682) moving from grade 0 to grade 3+ When mean isotope compositions associated with

specific torus grades are compared (Table 4) there is no significant difference in δ13C and δ15N values for Discussion PT in either the Norse or Inuit This is also true for MT expression in the Norse However corroborating The impetus for this study was to investigate the hypoth-the correlation coefficients in Table 3 MT shows sig- esis that elements of a marine diet as estimated by δ13C nificantly different mean compositions between the and δ15N values could trigger the hyper-development of

Table 4 ANOVA Model I comparisons for mean isotope compositions by grade of torus expression

Grade

Sample Oral torus Isotope 0 1 2 3+ P

δ13C Mean 1595 1648 1582 1594 0348 Norse

δ15N Mean 1565 1491 1594 1618 0128 n 4 17 13 5

Palatine torus δ13C Mean 1374 1389 1446 1395 0653

Inuit δ15N Mean 1948 1930 1868 1968 0518

n 9 14 9 4 δ13C Mean 1581 1626 1603 0525

Norse δ15N Mean 1582 155 1559 0855

n 14 17 9 Mandibular torus

δ13C Mean 1293 1392 1438 1524 lt0001 Inuit

δ15N Mean 204 1934 1852 1796 0020 n 6 14 13 5

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

palatine and MT in the Greenlandic Norse For compar-ative purposes an Inuit sample from the Thule culture was studied for the same set of variables For the Norse we found no statistical correlation between the expres-sion of either torus and stable isotope values At first glance this might indicate that a marine diet does not play a role in torus development Surprisingly however the Inuit sample does show a significant inverse correla-tion between MT expression and isotope compositions More positive isotopes are associated with low grades of MT expression with absence phenotypes showing the heaviest δ13C and δ15N values If a more systemic di-etary mechanism was involved we would expect this to be expressed in both PT and MT However we know that Inuit made heavy use of their jaws for skin prepara-tion and that Inuit dental abrasion is more pronounced than for the Norse Perhaps the greater mechanical load-ing because of this activity could influence torus forma-tion in the mandible which would experience more bending forces Analyses of other arctic skeletal assem-blages may shed light on whether or not this is a consis-tent finding

An arctic diet consisting mostly of saltwater fish and marine animals may not be the primary reason why the Greenlandic Norse developed palatine and MT to such an exaggerated degree compared with medieval Scandinavians in Europe It should be reiterated that medieval Icelanders another Scandinavian group that lived in a comparable subarctic environment also showed unusually pronounced torus expressions (Hooton 1918 Scott et al 1992) A strong dependence on marine resources in conjunction with the rigors of a subarctic environment may still be implicated in Norse oral tori variation

References

Al Quran FA Al-Dwairi ZN 2006 Torus palatinus and torus mandibularis in edentulous patients Journal of Contemporary Dental Practice 7 112ndash119 PM16685302

Antoniades DZ Belazi M Papanayiotou P 1998 Concur-rence of torus palatinus with palatal and buccal exostoses Case report and review of the literature Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 85 552ndash557 DOI101016S1079-2104(98)90290-6

Arneborg J Lynnerup N Heinemeier J 2012 Human diet and subsistence patterns in Norse Greenland AD c 980ndashAD c 1450 archaeological interpretations Journal of the North Atlantic 3 119ndash133

Axelsson G Hedegaard B 1985 Torus palatinus in Icelandic school children American Journal of Physical Anthropology 67 105ndash112 DOI101002ajpa1330670205

Chohayeb AA Volpe AR 2001 Occurrence of torus palatinus and mandibularis among women of different ethnic groups American Journal of Dentistry 14 278ndash28 PM11803989

Eggen S 1993 Torus mandibularis and torus palatinus in Norway A study on factors influencing their variation PhD Dissertation Eget forlag

Eggen S Natvig B 1994 Concurrence of torus mandibularis and torus palatinus Scandinavian Journal of Dental Research 102 60ndash63 DOI101111j1600-07221994tb01154x

Eggen S Natvig B Gasemyr J 1991 Variation in torus mandibularis prevalence in Norway A statistical analysis using logistic regression Community Dentistry and Oral Epidemiology 19 32ndash35 DOI101111j1600-07221994 tb01153x

Eroglu S Erdal YS 2008 Why did the frequency of palatine torus increase in the ancient Anatolian populations Homo 59 365ndash382 DOI101016jjchb200806005

Fischer-Moslashller K 1942 The mediaeval Norse settlements in Greenland Anthropological investigations Meddelelser om Groslashnland 89 lndash82

Garcia-Garcia AS Martinez-Gonzalez JM Gomez-Font R Soto-Rivadeneira A Oviedo-Roldan L 2010 Current sta-tus of the torus palatinus and torus mandibularis Medicina Oral Patologiacutea Oral y Cirugiacutea Bucal 15(2) e353ndashe360 DOI104317medoral15e353

Halffman CM Scott GR Pedersen PO 1992 Palatine torus in the Greenlandic Norse American Journal of Physical Anthropology 88 145ndash161 DOI101002 ajpa1330880204

Haugen LK 1992 Palatine and mandibular tori A morpho-logic study in the current Norwegian population Acta Odontologica Scandinavica 50 65ndash77 PM1604967

Hooton EA 1918 On certain eskimoid characters in Icelan-dic skulls American Journal of Physical Anthropology 1 53ndash78

Ihunwo AO Phukubye P 2006 The frequency and anatomical features of torus mandibularis in a Black South African popula-tion Homo 57 253ndash262 DOI101016jjchb200603004

Jainkittivong A Apinhasmit W Swasdison S 2007 Preva-lence and clinical characteristics of oral tori in 1520 Chulalongkorn University Dental School patients Surgical and Radiologic Anatomy 29 125ndash131 PM17340055

Lynnerup N 1998 The Greenland Norse - A Biological-Anthropological Study Vol 24 The Commission for Sci-entific Research in Greenland Copenhagen

Mellquist C Sandberg T 1939 Odontological studies of about 1400 mediaeval skulls from Halland and Scania in Sweden and from the Norse colony in Greenland and a contribution to the knowledge of their anthropology Odontologisk Tidskrift 38 lndash83

Nelson DE Heinemeier J Lynnerup N Sveinbjoumlrnsdoacutettir AacuteE Arneborg J 2012 An isotopic analysis of the diet of the Greenland Norse Journal of the North Atlantic 3 93ndash118

Oschinsky L 1964 The Most Ancient Eskimos The Cana-dian Research Centre for Anthropology University of Ottawa Ottawa

Pechenkina EA Benfer RA Jr 2002 The role of occlusal stress and gingival infection in the formation of exostoses

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Studies have shown extensive interpopulation varia-tion in PT and MT frequencies with particularly high frequencies recorded for north Asian (Pechenkina amp Benfer 2002 Al Quran amp Al-Dwairi 2006 Jainkittivong et al 2007) Lapp (Schreiner 1935 Skrzat et al 2003) and Inuit populations (Hooton 1918 Woo 1950 Oschinsky 1964 Al Quran amp Al-Dwairi 2006 Jainkittivong et al 2007) This geo-graphical pattern led several investigators to refer to tori as lsquoMongolian traitsrsquo (Hooton 1918 Eroglu amp Erdal 2008 Garcia-Garcia et al 2010) Despite this characterisation oral tori have been found in high fre-quencies among some European and European-derived populations (Hooton 1918 Axelsson amp Hedegaard 1985 Eggen et al 1991 Halffman et al 1992 Scott et al 1992 Eggen amp Natvig 1994 Chohayeb amp Volpe 2001)

Eggen (1993) discussed possible factors influencing PT and MT in a contemporary Norwegian population A marine diet was singled out as a possible contributing factor to torus development More specifically Eggen et al (1991) hypothesised that PT was positively corre-lated with a diet rich in saltwater fish possibly because of their high content of polyunsaturated fatty acids of the omega-3 family and vitamin D which could trigger excessive bone formation

The Greenlandic Norse exhibit an extreme degree of both PT and MT (Sellevold 1980 Halffman et al 1992 Scott et al 1992) This Scandinavian population settled in Greenland ca AD 985 and established them-selves primarily in two regions on the west coast sepa-rated by about 350 km referred to as the Eastern and Western Settlements The Western Settlement was abandoned around 1350 while the Eastern Settlement lasted into the 15th century (Arneborg et al 2012) They make up a unique study population as they shared genes with contemporary Scandinavian popula-tions but were subjected to a radically different subarc-tic environment making it reasonable to suggest that environmental factors were involved in the extreme de-velopment of oral tori (Halffman et al 1992) Their re-mains have been analysed by numerous researchers who found the prevalence of PT and MT much higher than in other medieval Scandinavian populations Not only were tori in extremely high frequency they also exhibited some of the largest expressions ever observed (Mellquist amp Sandberg 1939 Fischer-Moslashller 1942 Pedersen 1949 Sellevold 1980 Halffman et al 1992 Scott et al 1992) Different explanations for this have been proposed Halffman et al (1992) discuss a combination of increased masticatory stress and chronic undernutrition as possible causes of PT forma-tion Sellevold (1980) argued against masticatory stress

as a cause for MT and proposed that genetic factors played a major role Recently a comprehensive isotopic analysis of the

Norse Greenland diet was conducted (Nelson et al 2012) The analysis of stable nitrogen and carbon iso-topes of 80 human skeletons showed a change in the Norse diet through time As environmental conditions worsened for domestic animals there was increased re-liance on marine resources During the latter period of occupation the Greenlanders had one of the most ma-rine focused diets recorded for a medieval Northern European populations almost on par with the Inuit well known for their high-protein high-fat diet The isotopic data from this study make it possible to inves-tigate the previously mentioned hypotheses regarding a possible correlation between a diet mainly based on marine protein and the frequency and degree of PT and MT expression

For comparative purposes this approach was ex-tended to a sample of Inuit skeletons associated with the Greenlandic Thule Culture People bearing the Thule culture arrived in Greenland approximately 1100 AD (Lynnerup 1998) As sea-mammal hunters adapted to an Arctic climate the Inuit were almost en-tirely dependent on marine resources (Arneborg et al 2012)

Materials

A total of 88 skulls were analysed for this study 47 Greenlandic Norse and 41 Inuit All remains are housed at the Laboratory of Biological Anthropology Section of Forensic Pathology University of Copenhagen Denmark In an earlier study Nelson et al (2012) mea-sured the stable carbon (δ13C) and nitrogen (δ15N) values of bone collagen from these individuals Sample sizes in the tables vary as some individuals could not be scored for either PT or MT To be included in the sam-ple a palate or mandible intact enough for scoring at least one of the two different types of torus was required

Methods

Given the diversity of the torus expression and the nonmetric character of these traits several scoring sys-tems have been developed (Haugen 1992 Halffman et al 1992 Antoniades et al 1998 Pechenkina amp Benfer 2002 Skrzat et al 2003) Because of irregular surfaces and inconsistent landmarks metric measure-ments of tori are difficult (but for PT refer to Halffman

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

et al 1992) Most researchers utilise a ranked classifica-tion that begins with absence and includes variable degrees of trait presence

In our study each individual was scored for PT and MT based on size and morphology As some skulls had fragmented mandibles and maxillary bones there were instances where only one type of tori or just one side of a mandible or palate could be scored Both MT and PT are predominantly bilateral traits (Woo 1950 Haugen 1992 Skrzat et al 2003 Garcia-Garcia et al 2010) If one side of a palate or mandible could be assessed for torus expression the skull was included in the study When a bony protuberance along either the intermaxillary suture of the hard palate or on the inside of the mandible could be observed andor pal-pated it was scored as positive Initially morphological characteristics were taken into account but for purposes of analysis focus is exclusively on torus size Five cate-gories were used to rank torus size (Hooton 1918 Eroglu amp Erdal 2008) PT and MT were scored in the same way (0) no torus (1) small torus (2) medium to-rus (3) large torus and (4) extreme torus (Figures 1 and 2) Scoring by visual inspection was undertaken by a single trained observer Data on stable isotopes (δ13C and δ15N) were made available from an earlier study (Nelson et al 2012)

To determine if there is a relationship between stable isotope compositions and torus expression two statistical procedures were followed First product-moment correla-tions were computed among the four variables (PT MT δ13C and δ15N) in the two samples Second ANOVA Model I was utilised to determine if mean isotope compo-sitions differed significantly by degree of expression

Results

The class frequency distributions for PT and MT in the Greenlandic Norse and Inuit are shown in Table 1 There is no significant sex difference for either torus in the two samples The Norse have a slightly higher frequency of PT than the Inuit (905 vs 0757) and the mean trait score is slightly larger (148 vs 122) However the sample differences are not statistically significant For MT the situation is reversed The Inuit have a higher frequency (0846 vs 0675) and higher mean trait score (1490 vs 1000) and the difference is statistically significant

To put stable isotope compositions in perspective Table 2 provides the summary statistics for male and fe-male Norse and Inuit individuals along with totals Again there are no significant differences between men and women For both δ13C and δ15N there is a significant difference in isotope compositions between the Norse and Inuit Although the Norse show more positive values for both isotopes compared with con-temporary European populations (cf Scott amp Poulson 2012) they do not exhibit the high level of protein de-pendency shown by the Inuit

Table 3 shows a correlation matrix between the two tori and two isotopes for the Norse and Inuit First there is no significant correlation between the expres-sion of palatine and MT in either sample For the Norse all correlations between isotope compositions and torus expressions are small and nonsignificant For the Inuit this situation holds for PT but there is a sig-nificant inverse relationship between MT expression and both δ13C and δ15N values The two significant

Table 1 Class frequency distributions for palatine and mandibular tori in Greenlandic Norse and Inuit

Grade Total trait Mean X2 X2

Oral torus Sample Sex n 0 1 2 3 4 frequency trait score sex sample

Norse Male 23 0043 0522 0261 0174 0000 0957 Female 15 0200 0333 0400 0000 0067 0800 004 Unknown 4 0000 0750 0250 0000 0000 1000 (p gt 005) Total 42 0095 0476 0310 0095 0024 0905 148

Palatine 0088 (p gt 005) torus

Inuit Male 26 0192 0462 0269 0077 0000 0808 Female 11 0364 0273 0182 0182 0000 0636 0006 Total 37 0243 0405 0243 0108 0000 0757 122 (p gt 005)

Norse Male 24 0333 0583 0041 0000 0041 0667 Female 11 0272 0182 0182 0091 0000 0728 0149 Unknown 5 0400 0400 0000 0200 0000 0800 (p gt 005) Total 40 0325 0450 0150 0050 0025 0675 1000

Mandibular 6717 (p lt 001) torus

Inuit Male 30 0200 0333 0300 0167 0000 0800 Female 9 0000 0444 0444 0111 0000 1000 0207 Total 39 0154 0359 0333 0154 0000 0846 1490 (p gt 005)

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Table 2 Stable carbon and nitrogen isotope compositions in Norse and Inuit men and women

δ13C δ15N Sample Sex n mean SD P mean SD P

Norse Male 23 1622 0958 059 1548 1367 082 Female 15 1605 0902 1537 1486 Total 38 1616 0928 1544 1400

Inuit Male 25 1386 1196 033 1945 1491 017 Female 11 1432 1288 1873 1365 Total 36 1400 1225 1923 1474

Between samples Diff 216 lt001 379 lt001

Table 3 Correlations between palatine and mandibular tori and carbon and nitrogen isotopes in Norse and Inuit

Greenlandic Inuit (n = 32)

Palatine torus Mandibular torus δ13C δ15N

Greenlandic Norse (n = 37)

Palatine torus Mandibular torus

δ13C δ15N

x 0179 0122 0163

Bold faced

0179 x

0144 0155

significant at 005 level

0214 0554

x 0758

0188 0516 0682 x

negative correlations are almost identical (0544 four grades of expression Individuals scored as grade 0516) For both samples the two isotopes show high 0 have the highest positive δ13C and δ15N values and significant correlations with one another (0758 and there is a linear shift to less positive compositions 0682) moving from grade 0 to grade 3+ When mean isotope compositions associated with

specific torus grades are compared (Table 4) there is no significant difference in δ13C and δ15N values for Discussion PT in either the Norse or Inuit This is also true for MT expression in the Norse However corroborating The impetus for this study was to investigate the hypoth-the correlation coefficients in Table 3 MT shows sig- esis that elements of a marine diet as estimated by δ13C nificantly different mean compositions between the and δ15N values could trigger the hyper-development of

Table 4 ANOVA Model I comparisons for mean isotope compositions by grade of torus expression

Grade

Sample Oral torus Isotope 0 1 2 3+ P

δ13C Mean 1595 1648 1582 1594 0348 Norse

δ15N Mean 1565 1491 1594 1618 0128 n 4 17 13 5

Palatine torus δ13C Mean 1374 1389 1446 1395 0653

Inuit δ15N Mean 1948 1930 1868 1968 0518

n 9 14 9 4 δ13C Mean 1581 1626 1603 0525

Norse δ15N Mean 1582 155 1559 0855

n 14 17 9 Mandibular torus

δ13C Mean 1293 1392 1438 1524 lt0001 Inuit

δ15N Mean 204 1934 1852 1796 0020 n 6 14 13 5

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

palatine and MT in the Greenlandic Norse For compar-ative purposes an Inuit sample from the Thule culture was studied for the same set of variables For the Norse we found no statistical correlation between the expres-sion of either torus and stable isotope values At first glance this might indicate that a marine diet does not play a role in torus development Surprisingly however the Inuit sample does show a significant inverse correla-tion between MT expression and isotope compositions More positive isotopes are associated with low grades of MT expression with absence phenotypes showing the heaviest δ13C and δ15N values If a more systemic di-etary mechanism was involved we would expect this to be expressed in both PT and MT However we know that Inuit made heavy use of their jaws for skin prepara-tion and that Inuit dental abrasion is more pronounced than for the Norse Perhaps the greater mechanical load-ing because of this activity could influence torus forma-tion in the mandible which would experience more bending forces Analyses of other arctic skeletal assem-blages may shed light on whether or not this is a consis-tent finding

An arctic diet consisting mostly of saltwater fish and marine animals may not be the primary reason why the Greenlandic Norse developed palatine and MT to such an exaggerated degree compared with medieval Scandinavians in Europe It should be reiterated that medieval Icelanders another Scandinavian group that lived in a comparable subarctic environment also showed unusually pronounced torus expressions (Hooton 1918 Scott et al 1992) A strong dependence on marine resources in conjunction with the rigors of a subarctic environment may still be implicated in Norse oral tori variation

References

Al Quran FA Al-Dwairi ZN 2006 Torus palatinus and torus mandibularis in edentulous patients Journal of Contemporary Dental Practice 7 112ndash119 PM16685302

Antoniades DZ Belazi M Papanayiotou P 1998 Concur-rence of torus palatinus with palatal and buccal exostoses Case report and review of the literature Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 85 552ndash557 DOI101016S1079-2104(98)90290-6

Arneborg J Lynnerup N Heinemeier J 2012 Human diet and subsistence patterns in Norse Greenland AD c 980ndashAD c 1450 archaeological interpretations Journal of the North Atlantic 3 119ndash133

Axelsson G Hedegaard B 1985 Torus palatinus in Icelandic school children American Journal of Physical Anthropology 67 105ndash112 DOI101002ajpa1330670205

Chohayeb AA Volpe AR 2001 Occurrence of torus palatinus and mandibularis among women of different ethnic groups American Journal of Dentistry 14 278ndash28 PM11803989

Eggen S 1993 Torus mandibularis and torus palatinus in Norway A study on factors influencing their variation PhD Dissertation Eget forlag

Eggen S Natvig B 1994 Concurrence of torus mandibularis and torus palatinus Scandinavian Journal of Dental Research 102 60ndash63 DOI101111j1600-07221994tb01154x

Eggen S Natvig B Gasemyr J 1991 Variation in torus mandibularis prevalence in Norway A statistical analysis using logistic regression Community Dentistry and Oral Epidemiology 19 32ndash35 DOI101111j1600-07221994 tb01153x

Eroglu S Erdal YS 2008 Why did the frequency of palatine torus increase in the ancient Anatolian populations Homo 59 365ndash382 DOI101016jjchb200806005

Fischer-Moslashller K 1942 The mediaeval Norse settlements in Greenland Anthropological investigations Meddelelser om Groslashnland 89 lndash82

Garcia-Garcia AS Martinez-Gonzalez JM Gomez-Font R Soto-Rivadeneira A Oviedo-Roldan L 2010 Current sta-tus of the torus palatinus and torus mandibularis Medicina Oral Patologiacutea Oral y Cirugiacutea Bucal 15(2) e353ndashe360 DOI104317medoral15e353

Halffman CM Scott GR Pedersen PO 1992 Palatine torus in the Greenlandic Norse American Journal of Physical Anthropology 88 145ndash161 DOI101002 ajpa1330880204

Haugen LK 1992 Palatine and mandibular tori A morpho-logic study in the current Norwegian population Acta Odontologica Scandinavica 50 65ndash77 PM1604967

Hooton EA 1918 On certain eskimoid characters in Icelan-dic skulls American Journal of Physical Anthropology 1 53ndash78

Ihunwo AO Phukubye P 2006 The frequency and anatomical features of torus mandibularis in a Black South African popula-tion Homo 57 253ndash262 DOI101016jjchb200603004

Jainkittivong A Apinhasmit W Swasdison S 2007 Preva-lence and clinical characteristics of oral tori in 1520 Chulalongkorn University Dental School patients Surgical and Radiologic Anatomy 29 125ndash131 PM17340055

Lynnerup N 1998 The Greenland Norse - A Biological-Anthropological Study Vol 24 The Commission for Sci-entific Research in Greenland Copenhagen

Mellquist C Sandberg T 1939 Odontological studies of about 1400 mediaeval skulls from Halland and Scania in Sweden and from the Norse colony in Greenland and a contribution to the knowledge of their anthropology Odontologisk Tidskrift 38 lndash83

Nelson DE Heinemeier J Lynnerup N Sveinbjoumlrnsdoacutettir AacuteE Arneborg J 2012 An isotopic analysis of the diet of the Greenland Norse Journal of the North Atlantic 3 93ndash118

Oschinsky L 1964 The Most Ancient Eskimos The Cana-dian Research Centre for Anthropology University of Ottawa Ottawa

Pechenkina EA Benfer RA Jr 2002 The role of occlusal stress and gingival infection in the formation of exostoses

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

et al 1992) Most researchers utilise a ranked classifica-tion that begins with absence and includes variable degrees of trait presence

In our study each individual was scored for PT and MT based on size and morphology As some skulls had fragmented mandibles and maxillary bones there were instances where only one type of tori or just one side of a mandible or palate could be scored Both MT and PT are predominantly bilateral traits (Woo 1950 Haugen 1992 Skrzat et al 2003 Garcia-Garcia et al 2010) If one side of a palate or mandible could be assessed for torus expression the skull was included in the study When a bony protuberance along either the intermaxillary suture of the hard palate or on the inside of the mandible could be observed andor pal-pated it was scored as positive Initially morphological characteristics were taken into account but for purposes of analysis focus is exclusively on torus size Five cate-gories were used to rank torus size (Hooton 1918 Eroglu amp Erdal 2008) PT and MT were scored in the same way (0) no torus (1) small torus (2) medium to-rus (3) large torus and (4) extreme torus (Figures 1 and 2) Scoring by visual inspection was undertaken by a single trained observer Data on stable isotopes (δ13C and δ15N) were made available from an earlier study (Nelson et al 2012)

To determine if there is a relationship between stable isotope compositions and torus expression two statistical procedures were followed First product-moment correla-tions were computed among the four variables (PT MT δ13C and δ15N) in the two samples Second ANOVA Model I was utilised to determine if mean isotope compo-sitions differed significantly by degree of expression

Results

The class frequency distributions for PT and MT in the Greenlandic Norse and Inuit are shown in Table 1 There is no significant sex difference for either torus in the two samples The Norse have a slightly higher frequency of PT than the Inuit (905 vs 0757) and the mean trait score is slightly larger (148 vs 122) However the sample differences are not statistically significant For MT the situation is reversed The Inuit have a higher frequency (0846 vs 0675) and higher mean trait score (1490 vs 1000) and the difference is statistically significant

To put stable isotope compositions in perspective Table 2 provides the summary statistics for male and fe-male Norse and Inuit individuals along with totals Again there are no significant differences between men and women For both δ13C and δ15N there is a significant difference in isotope compositions between the Norse and Inuit Although the Norse show more positive values for both isotopes compared with con-temporary European populations (cf Scott amp Poulson 2012) they do not exhibit the high level of protein de-pendency shown by the Inuit

Table 3 shows a correlation matrix between the two tori and two isotopes for the Norse and Inuit First there is no significant correlation between the expres-sion of palatine and MT in either sample For the Norse all correlations between isotope compositions and torus expressions are small and nonsignificant For the Inuit this situation holds for PT but there is a sig-nificant inverse relationship between MT expression and both δ13C and δ15N values The two significant

Table 1 Class frequency distributions for palatine and mandibular tori in Greenlandic Norse and Inuit

Grade Total trait Mean X2 X2

Oral torus Sample Sex n 0 1 2 3 4 frequency trait score sex sample

Norse Male 23 0043 0522 0261 0174 0000 0957 Female 15 0200 0333 0400 0000 0067 0800 004 Unknown 4 0000 0750 0250 0000 0000 1000 (p gt 005) Total 42 0095 0476 0310 0095 0024 0905 148

Palatine 0088 (p gt 005) torus

Inuit Male 26 0192 0462 0269 0077 0000 0808 Female 11 0364 0273 0182 0182 0000 0636 0006 Total 37 0243 0405 0243 0108 0000 0757 122 (p gt 005)

Norse Male 24 0333 0583 0041 0000 0041 0667 Female 11 0272 0182 0182 0091 0000 0728 0149 Unknown 5 0400 0400 0000 0200 0000 0800 (p gt 005) Total 40 0325 0450 0150 0050 0025 0675 1000

Mandibular 6717 (p lt 001) torus

Inuit Male 30 0200 0333 0300 0167 0000 0800 Female 9 0000 0444 0444 0111 0000 1000 0207 Total 39 0154 0359 0333 0154 0000 0846 1490 (p gt 005)

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Table 2 Stable carbon and nitrogen isotope compositions in Norse and Inuit men and women

δ13C δ15N Sample Sex n mean SD P mean SD P

Norse Male 23 1622 0958 059 1548 1367 082 Female 15 1605 0902 1537 1486 Total 38 1616 0928 1544 1400

Inuit Male 25 1386 1196 033 1945 1491 017 Female 11 1432 1288 1873 1365 Total 36 1400 1225 1923 1474

Between samples Diff 216 lt001 379 lt001

Table 3 Correlations between palatine and mandibular tori and carbon and nitrogen isotopes in Norse and Inuit

Greenlandic Inuit (n = 32)

Palatine torus Mandibular torus δ13C δ15N

Greenlandic Norse (n = 37)

Palatine torus Mandibular torus

δ13C δ15N

x 0179 0122 0163

Bold faced

0179 x

0144 0155

significant at 005 level

0214 0554

x 0758

0188 0516 0682 x

negative correlations are almost identical (0544 four grades of expression Individuals scored as grade 0516) For both samples the two isotopes show high 0 have the highest positive δ13C and δ15N values and significant correlations with one another (0758 and there is a linear shift to less positive compositions 0682) moving from grade 0 to grade 3+ When mean isotope compositions associated with

specific torus grades are compared (Table 4) there is no significant difference in δ13C and δ15N values for Discussion PT in either the Norse or Inuit This is also true for MT expression in the Norse However corroborating The impetus for this study was to investigate the hypoth-the correlation coefficients in Table 3 MT shows sig- esis that elements of a marine diet as estimated by δ13C nificantly different mean compositions between the and δ15N values could trigger the hyper-development of

Table 4 ANOVA Model I comparisons for mean isotope compositions by grade of torus expression

Grade

Sample Oral torus Isotope 0 1 2 3+ P

δ13C Mean 1595 1648 1582 1594 0348 Norse

δ15N Mean 1565 1491 1594 1618 0128 n 4 17 13 5

Palatine torus δ13C Mean 1374 1389 1446 1395 0653

Inuit δ15N Mean 1948 1930 1868 1968 0518

n 9 14 9 4 δ13C Mean 1581 1626 1603 0525

Norse δ15N Mean 1582 155 1559 0855

n 14 17 9 Mandibular torus

δ13C Mean 1293 1392 1438 1524 lt0001 Inuit

δ15N Mean 204 1934 1852 1796 0020 n 6 14 13 5

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

palatine and MT in the Greenlandic Norse For compar-ative purposes an Inuit sample from the Thule culture was studied for the same set of variables For the Norse we found no statistical correlation between the expres-sion of either torus and stable isotope values At first glance this might indicate that a marine diet does not play a role in torus development Surprisingly however the Inuit sample does show a significant inverse correla-tion between MT expression and isotope compositions More positive isotopes are associated with low grades of MT expression with absence phenotypes showing the heaviest δ13C and δ15N values If a more systemic di-etary mechanism was involved we would expect this to be expressed in both PT and MT However we know that Inuit made heavy use of their jaws for skin prepara-tion and that Inuit dental abrasion is more pronounced than for the Norse Perhaps the greater mechanical load-ing because of this activity could influence torus forma-tion in the mandible which would experience more bending forces Analyses of other arctic skeletal assem-blages may shed light on whether or not this is a consis-tent finding

An arctic diet consisting mostly of saltwater fish and marine animals may not be the primary reason why the Greenlandic Norse developed palatine and MT to such an exaggerated degree compared with medieval Scandinavians in Europe It should be reiterated that medieval Icelanders another Scandinavian group that lived in a comparable subarctic environment also showed unusually pronounced torus expressions (Hooton 1918 Scott et al 1992) A strong dependence on marine resources in conjunction with the rigors of a subarctic environment may still be implicated in Norse oral tori variation

References

Al Quran FA Al-Dwairi ZN 2006 Torus palatinus and torus mandibularis in edentulous patients Journal of Contemporary Dental Practice 7 112ndash119 PM16685302

Antoniades DZ Belazi M Papanayiotou P 1998 Concur-rence of torus palatinus with palatal and buccal exostoses Case report and review of the literature Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 85 552ndash557 DOI101016S1079-2104(98)90290-6

Arneborg J Lynnerup N Heinemeier J 2012 Human diet and subsistence patterns in Norse Greenland AD c 980ndashAD c 1450 archaeological interpretations Journal of the North Atlantic 3 119ndash133

Axelsson G Hedegaard B 1985 Torus palatinus in Icelandic school children American Journal of Physical Anthropology 67 105ndash112 DOI101002ajpa1330670205

Chohayeb AA Volpe AR 2001 Occurrence of torus palatinus and mandibularis among women of different ethnic groups American Journal of Dentistry 14 278ndash28 PM11803989

Eggen S 1993 Torus mandibularis and torus palatinus in Norway A study on factors influencing their variation PhD Dissertation Eget forlag

Eggen S Natvig B 1994 Concurrence of torus mandibularis and torus palatinus Scandinavian Journal of Dental Research 102 60ndash63 DOI101111j1600-07221994tb01154x

Eggen S Natvig B Gasemyr J 1991 Variation in torus mandibularis prevalence in Norway A statistical analysis using logistic regression Community Dentistry and Oral Epidemiology 19 32ndash35 DOI101111j1600-07221994 tb01153x

Eroglu S Erdal YS 2008 Why did the frequency of palatine torus increase in the ancient Anatolian populations Homo 59 365ndash382 DOI101016jjchb200806005

Fischer-Moslashller K 1942 The mediaeval Norse settlements in Greenland Anthropological investigations Meddelelser om Groslashnland 89 lndash82

Garcia-Garcia AS Martinez-Gonzalez JM Gomez-Font R Soto-Rivadeneira A Oviedo-Roldan L 2010 Current sta-tus of the torus palatinus and torus mandibularis Medicina Oral Patologiacutea Oral y Cirugiacutea Bucal 15(2) e353ndashe360 DOI104317medoral15e353

Halffman CM Scott GR Pedersen PO 1992 Palatine torus in the Greenlandic Norse American Journal of Physical Anthropology 88 145ndash161 DOI101002 ajpa1330880204

Haugen LK 1992 Palatine and mandibular tori A morpho-logic study in the current Norwegian population Acta Odontologica Scandinavica 50 65ndash77 PM1604967

Hooton EA 1918 On certain eskimoid characters in Icelan-dic skulls American Journal of Physical Anthropology 1 53ndash78

Ihunwo AO Phukubye P 2006 The frequency and anatomical features of torus mandibularis in a Black South African popula-tion Homo 57 253ndash262 DOI101016jjchb200603004

Jainkittivong A Apinhasmit W Swasdison S 2007 Preva-lence and clinical characteristics of oral tori in 1520 Chulalongkorn University Dental School patients Surgical and Radiologic Anatomy 29 125ndash131 PM17340055

Lynnerup N 1998 The Greenland Norse - A Biological-Anthropological Study Vol 24 The Commission for Sci-entific Research in Greenland Copenhagen

Mellquist C Sandberg T 1939 Odontological studies of about 1400 mediaeval skulls from Halland and Scania in Sweden and from the Norse colony in Greenland and a contribution to the knowledge of their anthropology Odontologisk Tidskrift 38 lndash83

Nelson DE Heinemeier J Lynnerup N Sveinbjoumlrnsdoacutettir AacuteE Arneborg J 2012 An isotopic analysis of the diet of the Greenland Norse Journal of the North Atlantic 3 93ndash118

Oschinsky L 1964 The Most Ancient Eskimos The Cana-dian Research Centre for Anthropology University of Ottawa Ottawa

Pechenkina EA Benfer RA Jr 2002 The role of occlusal stress and gingival infection in the formation of exostoses

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

Table 2 Stable carbon and nitrogen isotope compositions in Norse and Inuit men and women

δ13C δ15N Sample Sex n mean SD P mean SD P

Norse Male 23 1622 0958 059 1548 1367 082 Female 15 1605 0902 1537 1486 Total 38 1616 0928 1544 1400

Inuit Male 25 1386 1196 033 1945 1491 017 Female 11 1432 1288 1873 1365 Total 36 1400 1225 1923 1474

Between samples Diff 216 lt001 379 lt001

Table 3 Correlations between palatine and mandibular tori and carbon and nitrogen isotopes in Norse and Inuit

Greenlandic Inuit (n = 32)

Palatine torus Mandibular torus δ13C δ15N

Greenlandic Norse (n = 37)

Palatine torus Mandibular torus

δ13C δ15N

x 0179 0122 0163

Bold faced

0179 x

0144 0155

significant at 005 level

0214 0554

x 0758

0188 0516 0682 x

negative correlations are almost identical (0544 four grades of expression Individuals scored as grade 0516) For both samples the two isotopes show high 0 have the highest positive δ13C and δ15N values and significant correlations with one another (0758 and there is a linear shift to less positive compositions 0682) moving from grade 0 to grade 3+ When mean isotope compositions associated with

specific torus grades are compared (Table 4) there is no significant difference in δ13C and δ15N values for Discussion PT in either the Norse or Inuit This is also true for MT expression in the Norse However corroborating The impetus for this study was to investigate the hypoth-the correlation coefficients in Table 3 MT shows sig- esis that elements of a marine diet as estimated by δ13C nificantly different mean compositions between the and δ15N values could trigger the hyper-development of

Table 4 ANOVA Model I comparisons for mean isotope compositions by grade of torus expression

Grade

Sample Oral torus Isotope 0 1 2 3+ P

δ13C Mean 1595 1648 1582 1594 0348 Norse

δ15N Mean 1565 1491 1594 1618 0128 n 4 17 13 5

Palatine torus δ13C Mean 1374 1389 1446 1395 0653

Inuit δ15N Mean 1948 1930 1868 1968 0518

n 9 14 9 4 δ13C Mean 1581 1626 1603 0525

Norse δ15N Mean 1582 155 1559 0855

n 14 17 9 Mandibular torus

δ13C Mean 1293 1392 1438 1524 lt0001 Inuit

δ15N Mean 204 1934 1852 1796 0020 n 6 14 13 5

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

palatine and MT in the Greenlandic Norse For compar-ative purposes an Inuit sample from the Thule culture was studied for the same set of variables For the Norse we found no statistical correlation between the expres-sion of either torus and stable isotope values At first glance this might indicate that a marine diet does not play a role in torus development Surprisingly however the Inuit sample does show a significant inverse correla-tion between MT expression and isotope compositions More positive isotopes are associated with low grades of MT expression with absence phenotypes showing the heaviest δ13C and δ15N values If a more systemic di-etary mechanism was involved we would expect this to be expressed in both PT and MT However we know that Inuit made heavy use of their jaws for skin prepara-tion and that Inuit dental abrasion is more pronounced than for the Norse Perhaps the greater mechanical load-ing because of this activity could influence torus forma-tion in the mandible which would experience more bending forces Analyses of other arctic skeletal assem-blages may shed light on whether or not this is a consis-tent finding

An arctic diet consisting mostly of saltwater fish and marine animals may not be the primary reason why the Greenlandic Norse developed palatine and MT to such an exaggerated degree compared with medieval Scandinavians in Europe It should be reiterated that medieval Icelanders another Scandinavian group that lived in a comparable subarctic environment also showed unusually pronounced torus expressions (Hooton 1918 Scott et al 1992) A strong dependence on marine resources in conjunction with the rigors of a subarctic environment may still be implicated in Norse oral tori variation

References

Al Quran FA Al-Dwairi ZN 2006 Torus palatinus and torus mandibularis in edentulous patients Journal of Contemporary Dental Practice 7 112ndash119 PM16685302

Antoniades DZ Belazi M Papanayiotou P 1998 Concur-rence of torus palatinus with palatal and buccal exostoses Case report and review of the literature Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 85 552ndash557 DOI101016S1079-2104(98)90290-6

Arneborg J Lynnerup N Heinemeier J 2012 Human diet and subsistence patterns in Norse Greenland AD c 980ndashAD c 1450 archaeological interpretations Journal of the North Atlantic 3 119ndash133

Axelsson G Hedegaard B 1985 Torus palatinus in Icelandic school children American Journal of Physical Anthropology 67 105ndash112 DOI101002ajpa1330670205

Chohayeb AA Volpe AR 2001 Occurrence of torus palatinus and mandibularis among women of different ethnic groups American Journal of Dentistry 14 278ndash28 PM11803989

Eggen S 1993 Torus mandibularis and torus palatinus in Norway A study on factors influencing their variation PhD Dissertation Eget forlag

Eggen S Natvig B 1994 Concurrence of torus mandibularis and torus palatinus Scandinavian Journal of Dental Research 102 60ndash63 DOI101111j1600-07221994tb01154x

Eggen S Natvig B Gasemyr J 1991 Variation in torus mandibularis prevalence in Norway A statistical analysis using logistic regression Community Dentistry and Oral Epidemiology 19 32ndash35 DOI101111j1600-07221994 tb01153x

Eroglu S Erdal YS 2008 Why did the frequency of palatine torus increase in the ancient Anatolian populations Homo 59 365ndash382 DOI101016jjchb200806005

Fischer-Moslashller K 1942 The mediaeval Norse settlements in Greenland Anthropological investigations Meddelelser om Groslashnland 89 lndash82

Garcia-Garcia AS Martinez-Gonzalez JM Gomez-Font R Soto-Rivadeneira A Oviedo-Roldan L 2010 Current sta-tus of the torus palatinus and torus mandibularis Medicina Oral Patologiacutea Oral y Cirugiacutea Bucal 15(2) e353ndashe360 DOI104317medoral15e353

Halffman CM Scott GR Pedersen PO 1992 Palatine torus in the Greenlandic Norse American Journal of Physical Anthropology 88 145ndash161 DOI101002 ajpa1330880204

Haugen LK 1992 Palatine and mandibular tori A morpho-logic study in the current Norwegian population Acta Odontologica Scandinavica 50 65ndash77 PM1604967

Hooton EA 1918 On certain eskimoid characters in Icelan-dic skulls American Journal of Physical Anthropology 1 53ndash78

Ihunwo AO Phukubye P 2006 The frequency and anatomical features of torus mandibularis in a Black South African popula-tion Homo 57 253ndash262 DOI101016jjchb200603004

Jainkittivong A Apinhasmit W Swasdison S 2007 Preva-lence and clinical characteristics of oral tori in 1520 Chulalongkorn University Dental School patients Surgical and Radiologic Anatomy 29 125ndash131 PM17340055

Lynnerup N 1998 The Greenland Norse - A Biological-Anthropological Study Vol 24 The Commission for Sci-entific Research in Greenland Copenhagen

Mellquist C Sandberg T 1939 Odontological studies of about 1400 mediaeval skulls from Halland and Scania in Sweden and from the Norse colony in Greenland and a contribution to the knowledge of their anthropology Odontologisk Tidskrift 38 lndash83

Nelson DE Heinemeier J Lynnerup N Sveinbjoumlrnsdoacutettir AacuteE Arneborg J 2012 An isotopic analysis of the diet of the Greenland Norse Journal of the North Atlantic 3 93ndash118

Oschinsky L 1964 The Most Ancient Eskimos The Cana-dian Research Centre for Anthropology University of Ottawa Ottawa

Pechenkina EA Benfer RA Jr 2002 The role of occlusal stress and gingival infection in the formation of exostoses

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

Oral Tori and Stable Isotopes in Greenlanders

palatine and MT in the Greenlandic Norse For compar-ative purposes an Inuit sample from the Thule culture was studied for the same set of variables For the Norse we found no statistical correlation between the expres-sion of either torus and stable isotope values At first glance this might indicate that a marine diet does not play a role in torus development Surprisingly however the Inuit sample does show a significant inverse correla-tion between MT expression and isotope compositions More positive isotopes are associated with low grades of MT expression with absence phenotypes showing the heaviest δ13C and δ15N values If a more systemic di-etary mechanism was involved we would expect this to be expressed in both PT and MT However we know that Inuit made heavy use of their jaws for skin prepara-tion and that Inuit dental abrasion is more pronounced than for the Norse Perhaps the greater mechanical load-ing because of this activity could influence torus forma-tion in the mandible which would experience more bending forces Analyses of other arctic skeletal assem-blages may shed light on whether or not this is a consis-tent finding

An arctic diet consisting mostly of saltwater fish and marine animals may not be the primary reason why the Greenlandic Norse developed palatine and MT to such an exaggerated degree compared with medieval Scandinavians in Europe It should be reiterated that medieval Icelanders another Scandinavian group that lived in a comparable subarctic environment also showed unusually pronounced torus expressions (Hooton 1918 Scott et al 1992) A strong dependence on marine resources in conjunction with the rigors of a subarctic environment may still be implicated in Norse oral tori variation

References

Al Quran FA Al-Dwairi ZN 2006 Torus palatinus and torus mandibularis in edentulous patients Journal of Contemporary Dental Practice 7 112ndash119 PM16685302

Antoniades DZ Belazi M Papanayiotou P 1998 Concur-rence of torus palatinus with palatal and buccal exostoses Case report and review of the literature Oral Surgery Oral Medicine Oral Pathology Oral Radiology and Endodontics 85 552ndash557 DOI101016S1079-2104(98)90290-6

Arneborg J Lynnerup N Heinemeier J 2012 Human diet and subsistence patterns in Norse Greenland AD c 980ndashAD c 1450 archaeological interpretations Journal of the North Atlantic 3 119ndash133

Axelsson G Hedegaard B 1985 Torus palatinus in Icelandic school children American Journal of Physical Anthropology 67 105ndash112 DOI101002ajpa1330670205

Chohayeb AA Volpe AR 2001 Occurrence of torus palatinus and mandibularis among women of different ethnic groups American Journal of Dentistry 14 278ndash28 PM11803989

Eggen S 1993 Torus mandibularis and torus palatinus in Norway A study on factors influencing their variation PhD Dissertation Eget forlag

Eggen S Natvig B 1994 Concurrence of torus mandibularis and torus palatinus Scandinavian Journal of Dental Research 102 60ndash63 DOI101111j1600-07221994tb01154x

Eggen S Natvig B Gasemyr J 1991 Variation in torus mandibularis prevalence in Norway A statistical analysis using logistic regression Community Dentistry and Oral Epidemiology 19 32ndash35 DOI101111j1600-07221994 tb01153x

Eroglu S Erdal YS 2008 Why did the frequency of palatine torus increase in the ancient Anatolian populations Homo 59 365ndash382 DOI101016jjchb200806005

Fischer-Moslashller K 1942 The mediaeval Norse settlements in Greenland Anthropological investigations Meddelelser om Groslashnland 89 lndash82

Garcia-Garcia AS Martinez-Gonzalez JM Gomez-Font R Soto-Rivadeneira A Oviedo-Roldan L 2010 Current sta-tus of the torus palatinus and torus mandibularis Medicina Oral Patologiacutea Oral y Cirugiacutea Bucal 15(2) e353ndashe360 DOI104317medoral15e353

Halffman CM Scott GR Pedersen PO 1992 Palatine torus in the Greenlandic Norse American Journal of Physical Anthropology 88 145ndash161 DOI101002 ajpa1330880204

Haugen LK 1992 Palatine and mandibular tori A morpho-logic study in the current Norwegian population Acta Odontologica Scandinavica 50 65ndash77 PM1604967

Hooton EA 1918 On certain eskimoid characters in Icelan-dic skulls American Journal of Physical Anthropology 1 53ndash78

Ihunwo AO Phukubye P 2006 The frequency and anatomical features of torus mandibularis in a Black South African popula-tion Homo 57 253ndash262 DOI101016jjchb200603004

Jainkittivong A Apinhasmit W Swasdison S 2007 Preva-lence and clinical characteristics of oral tori in 1520 Chulalongkorn University Dental School patients Surgical and Radiologic Anatomy 29 125ndash131 PM17340055

Lynnerup N 1998 The Greenland Norse - A Biological-Anthropological Study Vol 24 The Commission for Sci-entific Research in Greenland Copenhagen

Mellquist C Sandberg T 1939 Odontological studies of about 1400 mediaeval skulls from Halland and Scania in Sweden and from the Norse colony in Greenland and a contribution to the knowledge of their anthropology Odontologisk Tidskrift 38 lndash83

Nelson DE Heinemeier J Lynnerup N Sveinbjoumlrnsdoacutettir AacuteE Arneborg J 2012 An isotopic analysis of the diet of the Greenland Norse Journal of the North Atlantic 3 93ndash118

Oschinsky L 1964 The Most Ancient Eskimos The Cana-dian Research Centre for Anthropology University of Ottawa Ottawa

Pechenkina EA Benfer RA Jr 2002 The role of occlusal stress and gingival infection in the formation of exostoses

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)

M Baumann et al

on mandible and maxilla from Neolithic China Homo 53 112ndash130 DOI1010780018-442X-00040

Pedersen PO 1949 The East Greenland Eskimo Dentition Meddelelser om Groslashnland Copenhagen Denmark 142(3) 1ndash256

Petersen HC Alexandersen V 2008 Non-metriske traeligk In Biologisk Antropologi og human osteologi N Lynnerup P Bennike E Iregren (eds) Munksgaard Copenhagen Denmark 111ndash115

Sawair FA Shayyab MH Al-Rababah MA Saku T 2009 Prevalence and clinical characteristics of tori and jaw exos-toses in a teaching hospital in Jordan Saudi Medical Journal 30 1557ndash1562 DOI 0018-442X025302ndash112

Schreiner KE 1935 Zur Osteologie der Lappen H Aschehoug amp Co Oslo

Scott GR Halffman CM Pedersen PO 1992 Dental conditions of medievel Norsemen in the North Atlantic

Acta Archaeologica 62 183ndash207 DOI101002 ajpa1330880204

Scott GR Poulson SR 2012 Stable carbon and nitrogen iso-topes of dental calculus A potentially new non-destructive proxy for paleodietary analysis Journal of Ar-chaeological Science 39 1388ndash1393 DOI101016j jas201109029

Sellevold BJ 1980 Mandibular torus morphology American Journal of Physical Anthropology 53 569ndash572 DOI101002ajpa1330530411

Skrzat J Holiat D Walocha J 2003 The morphological ap-pearance of the palatine torus in the Cracovian skulls (XV-XVIII century) Folia Morphologica (Warsz) 62 183ndash186 PM14507044

Woo J-K 1950 Torus palatinus American Journal of Physical Anthropology 8 81ndash112 DOI101002ajpa1330080114

Copyright copy 2016 John Wiley amp Sons Ltd Int J Osteoarchaeol (2016)