|Year : 2019 | Volume
| Issue : 4 | Page : 233-238
Race determination based on nonmetric teeth morphological traits
Siritta Kalistu1, Nagabhushana Doggalli1, Karthikeya Patil2, Sushma Rudraswamy3
1 Department of Forensic Odontology, JSS Dental College and Hospital, JSS Academy of Higher Education and Research, Mysore, Karnataka, India
2 Department of Oral Medicine and Radiology, JSS Dental College and Hospital, JSS Academy of Higher Education and Research, Mysore, Karnataka, India
3 Department of Public Health Dentistry, JSS Dental College and Hospital, JSS Academy of Higher Education and Research, Mysore, Karnataka, India
|Date of Submission||14-Oct-2019|
|Date of Acceptance||24-Oct-2019|
|Date of Web Publication||22-Jan-2020|
Dr. Nagabhushana Doggalli
Department of Forensic Odontology, JSS Dental College and Hospital, JSS Academy of Higher Education and Research, Mysore - 570 015, Karnataka
The relationship between dental morphological traits and ancestry has received the utmost amount of attention from dental anthropologists and forensic odontologists. Caucasoid, Mongoloids, and Negroid are the chief racial groups of the world. The dentition of each race has been reported to be unique to its race and has been employed to determine ancestry. Unfortunately, over the years, the concept of race has been fading away due to hybridization between races worldwide. Hence, one cannot solely rely on dental morphological traits to assign a race to an unknown. Nevertheless, even though dental morphological traits have been blended among the three races, there are still those traits that are dominant in one or the other ethnic group.
Keywords: Caucasoid, Mongoloid, morphological traits, Negroids, racial identification
|How to cite this article:|
Kalistu S, Doggalli N, Patil K, Rudraswamy S. Race determination based on nonmetric teeth morphological traits. SRM J Res Dent Sci 2019;10:233-8
|How to cite this URL:|
Kalistu S, Doggalli N, Patil K, Rudraswamy S. Race determination based on nonmetric teeth morphological traits. SRM J Res Dent Sci [serial online] 2019 [cited 2020 Feb 25];10:233-8. Available from: http://www.srmjrds.in/text.asp?2019/10/4/233/276369
| Introduction|| |
Physical anthropologists, human biologists, and geneticists share the same idea that generally all humanity living today belong to the species, Homo sapiens. Anthropologists point out that nature and different environmental factors in which a certain population find themselves influences the ethnical patterns of that population and enables it to become accustomed in a particular environment and permits the multiplication and continued existence of that particular population. The segregation of human being into groups referred to as “races” is a result of different environmental impacts of their surroundings. Not only does the environmental factors segregate people into races, but also leads to erraticism within a specific race. Blumenfeld alluded two authors for the definition of race. Shipman et al. (1985) defined race as “a morphologically identifiable subset of a species.” Dyer,(1974:1) defined the word “race” as one that describes populations, and not individuals, and it suggests that a population, or group of populations, is amply diverse from all others in the species to be separately noticeable.
The main Caucasoids, Mongoloids, and Negroids are the main racial groups of the world. The people that originated from European countries are referred to as Caucasoids. The people that originate from Asian countries belong to the race Mongoloid, including Native and Latin Americans. Negroids are people that hail from African countries. However, modern trends in physical anthropology have revised these words to be more exact. Caucasoids and Negroids are at the moment denoted as whites and blacks, respectively, whereas Mongoloids are at present divided into binary groups: Asians and Southwest Mongoloids. Nevertheless, nowadays, there exist numerous different human groups due to more people traveling around the world, exposure to media and intermarriages. As a result, pure race no longer exist as such. However, even though unblemished races are no longer existent, forensic anthropologist, forensic odontologists, and geneticist should be well equipped to identify an unrecognizable body by race, as the concept of race persist to be used.
Establishing the biological race (ancestry) of skeletal remains is an important part of forensic identification. Race, along with sex, stature, and age, is one of the four principal factors used when determining the biological identity of an individual in a forensic context. The lack of documentation often employed to aid in the process of recognizing skeletal dental remnants of an individual poses a challenge for investigators to establish the origin of the owner of the remains discovered. Discriminant function analysis of craniometrical traits is commonly the favored method for ethnic analysis in forensic cases, but, requires that the skulls are well-preserved. In cases where the skull is fractured, dental traits would be a more helpful tool to establish the ethnicity of an individual in lieu.
Several studies have demonstrated the likelihood of using the dissimilarities in the appearance of dental morphological characteristics among various cultural groups to establish their race. Scott and Turner used a qualitative approach based on a number of nonmetric dental traits for identifying the race of isolated human remains. This tactic is in general trustworthy if these traits are employed as a set in lieu of isolated variables. Further methodologies to predict heritage are more quantitative, using multivariate statistics, such as logistic regression to equate dissimilarities in metric and nonmetric dental traits among European Americans and African Americans. Using a sample of 40 people, Edgar effectively assigned an origin to each individual, either European American or African American with an accuracy of 90%. This was achieved by utilizing eight nonmetric dental morphologies. Furthermore, various studies claim that there is notable differences between metric and nonmetric dental traits among the subadult teeth of various tribal groups.,,,
This article aims to review the various morphological traits of cranium and teeth often used to establish ancestry. For simplicity, the author opts to use the three major races, namely, Mongoloids, Caucosoids, and Negroids.
| Morphological/anatomical Variation in the Skull and Dentition|| |
Several studies have been carried out to describe the cranium of different races over the past years. By employing the skull-based categorization, anthropologists described the cranium of each racial group.
- Caucasoid is branded by a tall dolichocephalic skull, receded zygomas, large brow ridge, and projecting-narrow nasal apertures as described by Alsoleihat
- Alsoleihat categorized people of the Negroid race as having a short dolichocephalic skull, receded zygomas, and wide nasal apertures
- Lastly, Alsoleihat distinguished the people belonging to the race Mongoloid by their medium brachycephalic skull, projecting zygomas, small brow ridge, and small nasal apertures.1
In the same manner, Durbar used 585 crania from eight (Egypt, Nigeria, Palestine, India, Burma, North America, and South America) diverse areas and compared 30 variations which pointed out some of the anthropological and anatomical features used for racial identification [Table 1]. Durbar results are similar to those of previous studies that indicated that Caucasian (or whites) are devoid of the extension of the lower jaw known as the prognathism, plus, they present a minimal projection of the alveolar ridge. Their facial aspects are normally reduced, with a tower-shaped nasal bones and tear-shaped nasal cavity. The palate is triangular, and the skull has a sloping eye orbital formation with prominent forehead and cranium.
|Table 1: Racial Variation of different skulls from Egypt, Nigeria, Palestine, India, Burma, North and South America by Umme Salma Durbar (2014)|
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The cranium of a Negroid is described as lengthy, narrow in breadth, and has a lower height. Blacks or Negroids have a broad skull and round nasal cavity and lack a nasal sill. The palate is rectangular and poses a prominent facial projection in the area of the jaw and mouth. The orbit is squarish or rectangular in shape. The skull being long anterior-posteriorly, it is said to be dolichocephalic, with a flat sagittal contour and a smooth-edged occipital shape. Blacks possess a jawbone with lower, wider, and more vertical ramus, with a bigger corpal and longer dental arch [Table 2].
|Table 2: Essential craniofacial trait variations commonly used for racial identification by Blumenfeld (2000)|
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Mongoloids, or what is referred to as Asians have skulls that are long in length, broad in breadth and have a medium height, considered to be between the high Caucasoid skull and the low Negroid skull. The occipital shape is angular, and the nuchal muscle markings are reasonable prominent. The malar bones (zygomatic bones) retreats in the Caucasoid skull which can make the skull appear somewhat pointed [Table 2].,
Blumenfeld reviewed several unlike morphological distinctions in the cranium and dentition that occur among dissimilar racial groups and summarized the findings in the [Table 2] below.
| Dentition|| |
Dental anthropologists and forensic odontologists discovered that there exists a link between dental morphological traits and ancestry. As a result, dentition received enormous amount of attention from forensic experts. The human dentition is said to be genetically governed and is minimally affected by environmental factors, hence, exhibit little modification over many generations. Therefore, teeth are used widely for determining biological affiliation and genetic relationships between human populations.
Several studies pointed out traits that have the most different frequencies in the samples of different races and analyzed them through quantitative methods such as logistic regression and Bayesian probability analysis to determine the chance of their cooccurrence in the general populations of different races. These probabilities have then been organized in tables according to the presence and absence of those traits. This kind of table permits forensic practitioners to hastily compare dentition from a single individual of unknown origin to a databank of trait observations with ease. These probability tables are a new presentation of traits used for the determination of racial affiliation. However, Scott and Turner's rather used a qualitative approach to determine the race of human remains based on non-measurable dental forms that are commonly or rarely associated with various racial groups. Nonetheless, the author cautions that the method is more dependable when these nonmeasurable dental forms are employed as a set in lieu of isolated variables.
| Caucasoid|| |
Maxillary teeth protruding over the mandibular teeth are commonly observed in this particular race., Carabelli's trait, seemingly first described in 1842 by Von Carabelli may be the most studied of all dental morphological variables. The upper first permanent molars and the upper second primary molars host the extra cusp on the mesiolingual aspects. The Cusp of Carabelli does not just manifest itself as a cusp but may appear in the form of a pit, furrow or even as a trivial protuberance. Several studies report this feature commonly occurring in “White's” teeth with an incidence of 35%–50% and are seldom observed among Blacks and Asian teeth. The presence of the cusp has prompt researchers to come up with different theories that might shed light on its existence. As per Dahlberg, attributable to transformative diminished in the length (mesiodistal width) of the upper molars, the Cusp of Carabelli's developed to make up for that decrease, extending the occlusal surface of the molars on the buccolingual viewpoint. Another study argues that the existence of Carabelli's trait may be due to resistance of the first molar to excessive biomechanical stresses. The frontal teeth of Caucasoids are described as “chisel-shaped” and are commonly reduced with smoother lingual surface. The arch of Caucasoid is normally narrow “v” shaped and renders little space for the teeth to develop properly. Hence, crowding of teeth is a distinguishable feature used to identify individuals of the above-mentioned race. In addition, overbites with the upper jaw teeth protruding over the lower jaw teeth are commonly observed in this particular race. Furthermore, Scott and Turner report that this race is characterized by low frequencies of cusps 6 and 7, protostylids and deflective wringles.
| Mongoloid|| |
This race has racial discriminating features that are better appreciated in the permanent teeth rather than the primary teeth. Edge-to-edge bite was seen in Mongoloid dentitions when the lower jaw and upper jaw are shut. Unlike the Caucasoid dentition, Mongoloids do not present an overbite. The incisor teeth normally will occlude edge-to-edge resulting in occlusal wear on the incisors. Blumenfeld quotes Ubelaker (1989), who opined that Mongoloids have the largest teeth in size as compared with those of the other ethnic groups (Negroids and Caucasoids). Bailit, as cited by John et al., revealed that the Lateral Incisors are seen large in Asian ancestry comparative to the adjacent incisors. This was verified amongst the Japanese, Where, 19% of the central incisors in male were bigger than the lateral incisors. On the contrary, the values for American Whites and Norwegian were 33% and 24%, respectively. Shoveling, observed on the lingual surface of the centrals is described as the most outstanding diagnostic feature in the Mongoloid dentition. Complement of the minimal edges melded with a raised cingulaum produce a profound lingual fossa, and when the edges blurs toward the incisal edge, it brings about a “shovel” or “scoop” shape. Shoveling is reported to be observed in Mongoloids with an incidence of 90%. The “double-shovel shaped” incisor in Mongoloid are formed by lingual marginal ridges. According to John et al., when the Caribelli's cusp is present, then shoveling of central maxillary incisors would be absent in most cases. Owing to this, shoveling Inferable from this, scooping and Carabelli's qualities have been considered as distinguishing markers of Chinese (Mongoloids) and Whites. Mongoloids bicuspids may display a tubercle on the buccal cusp and the tooth is commonly referred to as Leong's premolar or Oriental premolar. Mongoloid's first and third molars are bigger than the second molars. This contradicts the general trend of progressive reduction in tooth size towards the back. The molar roots are more regularly fused, shorter, and less splayed. Several studies have assessed the occlusal morphology of the permanent mandibular first and second molars, and results indicate that there is a constant occurrence of 5 cusps pattern with Y grooves in the first mandibular molars and 4 cusps pattern with + grooves., Dholia et al. have evaluated the occlusal morphology of the lower first and second molars of Gujarati inhabitants, India. In agreement with previous studies,, analysis indicate that 5 cusp with Y groove pattern was seen in about 47% of the mandibular first molars and 4 cusp and + groove pattern in 88.5% for second molar in Gujarati population. Therefore, the author concluded that the dissimilarity in degree of expression and occurrence of teeth traits in unlike populations varies and that this may be of great assistance in forensic identification. There may likewise be the nearness of protostylid cusp which is on the buccal surfaces of the mesiobuccal cusps of the lower perpetual molars and lower second essential molar. When all is said in done, Mongoloids have an explanatory curve with enormous incisors, canines, little premolars, and huge molars behind them. This is underlined guideline speaking particularly in the lower curve for recognizing a person as a Mongoloid.
| Negroids|| |
The people of African origin have smaller teeth compared to other races, with spacing in between. Furthermore, Negroids often tend to have excessive teeth. The mandibular first premolar has two distinct cusps, even it can be with three cusps. Not at all like with the Mongoloids and Caucosoids, cusp of Carabelli and scoop molded incisor is seldom found in this race. In contrast to the Mongoloids that often do not poses the third molar, Negroids always have the third molars and are less likely to be impacted. Considering the mandibular molars, Shara Bailey's results indicate that the first molar of Sub Saharan African had seven cusps in most cases and second molar of the San people had Y grooves in high frequencies. Blumenfeld cited EI-Najjar and McWilliams (1978) and stated that the Negroid palate is rectangular in shape, or pointed and narrow. Similarly, Benjamin (2000) studied the shape and size of maxillary arches of American Blacks and Whites in an attempt to point out the racial differences. The study revealed that arch size is notably larger in American blacks than whites, and arch form is squarer and less tapered in blacks in the canine-premolar region. Moreover, the first permanent lower molar in the Blacks dentition often displays the “Y5” cusp pattern. Shara (2000) carried out a study to assess 18 traits of ten populations representing the three major racial groups (Negroids, Caucasoids, and Mongoloid). The Mean Measure of Divergence analysis was used to find out how diverged the 18 traits are in the ten populations, including San and Sub Saharan Africans. The multivariate analysis indicated that the populations indeed differ in their dentition morphologies, with the Sub Saharan Africans showing a low-frequency occurrence of the shoveling and double shoveling of maxillary central incisors. Additionally, results also suggest that there is a connection between the recent Northern Africans and Europeans (Neandertals). This clearly indicates the existence of inter-racial relationship, which is not astonishing, considering the short distance between Europe and Northern Africa. This led to the evolution of the unique traits of each race giving birth to intermediate traits. Similarly, Scott and Turner (1997) opined that dentally, North Africans bear a resemblance to Europeans and Western Asians to some extent. Furthermore, Shara (2000) states that even though the shoveling and double shoveling of central incisor is a marker for Mongoloids, it is also observed in the sub-Saharan Africans in a much lower frequency.2 This findings correlate with other studies that emphasized that despite the fact that shoveling commonly indicates Mongoloid, it may occur in other races as well.,,, A mesial ridge is reported to appear in high frequencies in the Sub Saharan Africans canines [Table 3]. This trait was also reported by Turner et al., as prominent in the Bushman of Africa and named it the “Bushman canine.” To evade topographical designators, Turner et al., referred to the Bushman canine as the mesial ridge.
|Table 3: Table compiled from Scott and Turner (1997), Joel Irish (1998) and Shara E. Bailey (2000) results and tables|
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The author has tabulated [Table 3] the traits that are often used for race identification worldwide using results from Scott and Turner Irish and Bailey. If the trait is definite to be observed in a certain race, it is said to occur in high frequency for that race. If the trait is seen on average for a certain race, then it occurs with moderate frequency, and if it is observed below average, it is said to occur in low frequency.
| Conclusion|| |
Human dentition has the greatest strength and rigidity as compared to other mineralized body structures hence withstand environmental stress during and after life. The indestructability of teeth makes teeth an essential instrument in the process of establishing the identity of the unknown. Legacy of hereditary material without a doubt has a colossal influence in the advancement of dental physical appearance, allowing the teeth to be a tool for forensic odontologist, aiding in the process of race identification. However, racial affinity based on the teeth features is indeed not a laid-back issue as blending between races in diverse (multicultural) populations has instigated the downfall of the unique racial dental features. Having said that, it is clear that assigning a race to an individual based on dental features is highly a strenuous process. Therefore, caution must be exercised by the forensic odontologist when finishing up the racial character of a person.
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[Table 1], [Table 2], [Table 3]