Dentition of Bedouin in Israel. II. Morphology

Plaster casts of the dentition of 137 Bedouin, mostly members of the Abu Rabiya tribe in the Negev desert, were subjected to odontometric and morphologic analysis. They show a marked sexual dimorphism, very strongly developed maxillary and mandibular first molars and much reduced second molars. They exhibit the characteristics of middle-eastern populations with a rather weak expression of the shovel trait, upper premolars with relatively short BL diameters, a high prevalence of Carabelli's complex on the first maxillary molar and virtually complete absence of the protostylid. In general, the Bedouin have larger teeth than three other ethnic groups living in Israel whose dentitions have been recently investigated. Further similarities and differences are discussed.     

Morphologic characteristics of the Alaskan Eskimo dentition. II. Carabelli's cusp

A study of coastal and inland Alaskan Eskimos revealed that a faintly developed Carabelli's cusp was present in 42.7%. No sex difference in the occurrence of Carabelli's cusp was evident and no family showed any difference in the distribution of the frequencies when each family was compared to the rest of the population. A general tendency toward a higher prevalence of Carabelli's cusp in the coastal Eskimos may be due to more admixture with white people along the coast. Alaskan Eskimos have a significantly higher frequency of Carabelli's cusp than do Aleuts. Statistical evaluation revealed that in the Alaskan Eskimo dentition the formation of Carabelli's cusp is independent of the size of the molars and the suppression of the third molars.     

Some dental traits of Diaguitas Indian skulls

Dental characteristics were studied on 60 skulls that belong to a population of Diaguitas Indians of approximately the Tenth Century. Mesiodistal crown diameters of permanent teeth were as follows: central incisors (8.77 mm), lateral incisors (7.23 mm), canines (8.40 mm), first maxillary molars (10.77 mm), second maxillary molars (10.71 mm), first mandibular molars (11.13 mm), and second mandibular molars (10.17 mm). Also determined was the frequency of shovel shaped incisors (80.30%), groove and cusp patterns of mandibular molars (Y5 73.40%), groove and cusp patterns of maxillary molars (H4 87.25%), and mesiopalatal version of maxillary incisors (66.20%). No skull showed Carabelli's cusp. The findings were compared with those for different populations past and living. The results suggest that the affiliation of the population analyzed was mongoloid.     

Genetic structure of a population of Valparaiso. II. Distribution of two dental traits with anthropological importance

The frequency of Carabelli's cusp (27.24%) and shovel-shaped incisors (45.72%) were determined in a sample of students from the city of Valparaíso. These values are intermediate between those found in Caucasian and Mongolian populations. A sexual dimorphism was observed for shovel-shaped incisors; the relation of this trait to a socio-economic index and occlusal type is indicated. Carabelli's cusp is found to vary with the number of foreign ancestors of an individual and his or her ABO blood group and color vision. There is also evidence that Carabelli's cusp serves better as an ethnic marker in a mixed population such as ours than does shovel-shaped incisors. This is thought to be due to the less complicated genetic basis of the former. It is also shown that the two traits are independent in their expression.     

Complex segregation analysis of Carabelli's trait in a melanesian population

A complex segregation analysis was performed on Carabelli's trait on the upper first molar utilizing 358 nuclear families from the Solomon Islands of Bougainville and Malaita. Simultaneous estiamtion of three sources of variation by the method of maximum likelihood demonstrates a significant effect of shared sibling environment which accounts for over 19% of the variance in liability for the trait. In addition, a statistically significant major gene influence is discussed and suggestions for quantifying individual liability levels for this and other dental traits are outlined.     

Incidence of Carabelli's trait in Kenyan Africans and Asians

Examination for incidence of Carabelli's trait was done on 1267 Africans and 781 Asian school children, 298 dental plaster casts and 248 skulls of Africans. The African sample is composed of 80% Bantu, 20% Nilote, and Nilo-Hamitic people. When observed intraorally, the trait is present in 31–35% of Africans and 26–27% of Asians. In the dental casts and skull sample of Africans, the trait is present as pit in 23–28%, groove in 20%, and as tubercle and cusp in 22%. The total trait frequency in Africans is 68%.     

Dental morphology of Jews from Yemen and Cochin

60 dental plaster casts of Jewish adolescents, half of them children of immigrants from Yemen and half of them from Cochin (India), were investigated as to tooth measurements and morphologic traits. Each group was composed of an equal number of males and females. Cochini showed a sex specific dimorphism in tooth size, a relatively larger bucco-lingual diameter of upper and lower first premolars, lower frequency of Carabelli's tuberculum and in males larger tooth measurements than their Yemenite counterparts. The variability of ²I² was significantly higher in females than in males, and in Yemenite girls than in Cochini. The molar patterns were similar in both groups with regard to number and development of cusps and occlusal form of the mandibular molars.     

Sexual dimorphism in human cranial trait scores: Effects of population,age, and body size

Sex estimation from the skull is commonly performed by physical and forensic anthropologists using a five‐trait scoring system developed by Walker. Despite the popularity of this method, validation studies evaluating its accuracy across a variety of samples are lacking. Furthermore, it remains unclear what other intrinsic or extrinsic variables are related to the expression of these traits. In this study, cranial trait scores and postcranial measurements were collected from four diverse population groups (U.S. Whites, U.S. Blacks, medieval Nubians, and Arikara Native Americans) following Walker's protocols (total n = 499). Univariate and multivariate analyses were utilized to evaluate the accuracy of these traits in sex estimation, and to test for the effects of population, age, and body size on trait expressions. Results revealed significant effects of population on all trait scores. Sample‐specific correct sex classification rates ranged from 74% to 94%, with an overall accuracy of 85% for the pooled sample. Classification performance varied among the traits (best for glabella and mastoid scores and worst for nuchal scores). Furthermore, correlations between traits were weak or nonsignificant, suggesting that different factors may influence individual traits. Some traits displayed correlations with age and/or postcranial size that were significant but weak, and within‐population analyses did not reveal any consistent relationships between these traits across all groups. These results indicate that neither age nor body size plays a large role in trait expression, and thus does not need to be incorporated into sex estimation methods. Am J Phys Anthropol 154:259–269, 2014. © 2014 Wiley Periodicals, Inc.     

Discrete dental trait asymmetry in Mexican and Belizean groups

Discrete dental trait asymmetry was scored on four Mexican Indian and two Afro-Belizean groups. The Mexican populations show significantly higher mean asymmetry than the two populations from Belize even though the Belizean groups have larger teeth. Point biserial coefficients of correlation between asymmetry of discrete traits and tooth size is low and in most cases not significant. This study indicates that populational and ethnic differences exist in the asymmetry of discrete traits, suggesting that these traits may be used to investigate the etiology of dental asymmetry, and the relative roles of genetics and environment.     

Carabelli's trait and tooth size of human maxillary first molars

Carabelli's trait is a morphological feature that can occur on the protocone of human maxillary molars. This study tests the hypothesis that Carabelli's trait is correlated statistically with the dimensions of the crown's four principal cusps or whether, as a cingular feature, the trait truly accretes onto an otherwise unaffected crown. Computer-assisted image analysis was used to measure the 6 intercusp distances and 12 angular relationships among cusp tips on the permanent first molar of 300 young adult American whites. Carabelli's complex was scored using an 8-grade ordinal scheme. Crown size was quantified in three ways, namely as 1) maximum mesiodistal and buccolingual diameters, 2) the 6 intercusp distances, and 3) the 12 angular cusp arrangements. There was no sex difference in the morphological expression of Carabelli's trait in this sample. Overall crown size and intercusp distances were significantly and progressively larger in molars with larger Carabelli's trait expressions. There are graded size responses between crown size (mesiodistal and buccolingual diameters), sizes of the four principal cusps, and morphological stage of Carabelli's complex, though the statistical relationships are appreciably stronger in males than females. Carabelli's trait occurs preferentially in larger molars. In contrast, angular (shape) relationships among cusp tips are not discernibly affected by trait size in either sex. There is the situation, then, that Carabelli's trait is developmentally correlated with crown size, but with no apparent alteration of cusp arrangements, suggesting that the increases are isometric across the occlusal table. Why the association is much weaker in females remains speculative, but these data provide yet another line of evidence that, within a population, tooth size is associated in a positive fashion with crown complexity.     

Dental caries in nineteenth century Upper Canada

This study examines the presence of dental caries in a large sample of adult skeletons from the 19th century cemetery of St. Thomas' Anglican Church in Belleville, Ontario. The cemetery was used from 1821 to 1874. Caries prevalence and frequencies of diseased and missing teeth were calculated both by observing summary statistics of individual rates and by the total sample of teeth. Postmortem tooth loss is low in this sample and antemortem tooth loss is highest in first mandibular molars, all other molars and then premolars. Age at death, but not sex, was found to be significantly related to the overall Caries Rate while both age and sex were significantly associated with the Diseased-Missing Index. The increase in diseased and missing teeth in older individuals is expected while the sex difference is not explained by simple dietary factors. When compared to reports on British and American samples, caries and antemortem tooth loss in the St. Thomas' sample is most similar to a pre-1850 British group and higher than American samples. Although there is undoubtedly a complex of factors contributing to caries prevalence in this sample, more data are required from large historic samples, particularly from the American northeast and late 19th century Britain, to have a clearer understanding of the influence of diet, cultural, and environmental factors affecting caries rates in historic populations. Am J Phys Anthropol 104:71–87, 1997. © 1997 Wiley-Liss, Inc.     

Qualitative population divergence in proximate determination of a sexually selected trait in the collared flycatcher

We examined proximate determination of sexually selected forehead patch size in a Central‐European population of Ficedula albicollis, the collared flycatcher, using a 9‐year database, and compared our results with those obtained in other populations of the same and the sister species. Between‐individual variation of forehead patch size was large, its repeatability larger than, and heritability similar to the Swedish population. Unlike in the other populations, the trait proved unaffected by body condition, and only very slightly influenced by age. There was no relationship between forehead patch size and breeding lifespan, and a marginal negative association with survivorship in adult males. Our results suggest that additive genetic variance of the trait in this population is large, but genes act independently of body condition, and there is no viability indicator value of the trait. This is the first report of a qualitative intraspecific difference in proximate determination of a sexually selected trait.     

Dimensional characteristics of the Filipino dentition

This study concerns odontometric analysis of the Tagalog Filipinos in Manila, Philippines. Mesiodistal and buccolingual dimensions of the permanent dentition, a total of 56 variables, were studied in 100 males and 152 females. Results showed that their absolute tooth size was small. Relative tooth size, however, seemed to reflect their Southeast Asian Mongoloid origin. From univariate analysis, considerable male-female differences were shown in most of the variables studied. When correlation effects among the teeth were held constant through multivariate analysis, male-female distance was found to be small and substantial overlapping of the two multivariate distributions was evident. Only four variables could be shown by stepwise discriminant analysis to contribute significantly to the distance. Even the mandibular canine, as the strongest discriminator, could only account for 16.4% of the total multivariate distance. These contrasting findings for sex dimorphism in a set of teeth taken singly and taken jointly indicate that there are factors other than the teeth themselves that are expected to play important roles in determining overall male-female size differences in the set of teeth, and that these differences may not be as clear-cut as univariate analysis suggests.     

Morphological features of Jat dentition

Observations on morphological characters of milk and permanent teeth, based on 648 pairs of dental casts of 356 male and 292 female Jat children of Haryana (India) are reported. Deciduous teeth show high frequencies of bilateral winging of maxillary central incisor, Carabelli's cusp of maxillary second molar, and deflecting wrinkle of mandibular second molar. Reduction of maxillary molar cusps is more marked in males than in females. Y pattern is very common in deciduous molars. Permanent teeth have high frequencies of grooved cingulum of incisors, cingular nodule of lateral incisors and canines, and distal accessary ridge of canines. Low frequencies of Carabelli's cusp and winging are also common. The tendency towards faintly developed shovelling in milk incisors occurs more often than in the permanent teeth.     

湖北长阳青铜时代人类乳齿特征的研究

对在湖北长阳县深潭湾崖葬墓出土的青铜时代人类乳齿形态特征的观察研究显示在人类恒齿出现的大多数具有种族识别价值的形态特征在乳齿有相等程度的表现,其中部分特征的出现率和表现程度高于恒齿。与其他地区人群相比,长阳青铜时代人类乳齿特征在总体上与东北亚人类具有的“中国型牙齿”特征接近。同时,在个别牙齿特征上呈现出南亚蒙古人种的特点。作者对产生这种现象的原因进行了分析。本文还就长阳青铜时代人类乳齿测量数据的表现特点进行了探讨。     

Sexual dimorphism in modern human permanent teeth

On average, males possess larger tooth crowns than females in contemporary human populations, although the degree of dimorphism varies within different populations. In previous studies, different amounts of either enamel or dentine were implicated as the cause of this dimorphism. In this study, we attempt to determine the nature of sexual dimorphism in the crowns of permanent modern human teeth and to determine if two contrasting tooth types (permanent third molars and canines) show identical patterns of dimorphism in enamel and dentine distribution. We estimated the relative contributions of both enamel and dentine to total crown size, from buccolingual sections of teeth. Our sample consisted of a total of 144 mandibular permanent third molars and 25 permanent mandibular canines of known sex. We show that sexual dimorphism is likely due, in part, to the presence of relatively more dentine in the crowns of male teeth. However, whatever the underlying cause, dimorphism in both tooth root and tooth crown size should produce measurable dimorphism in tooth weight, though this has not been previously explored. Therefore, we provide some preliminary data that indicate the usefulness of wet tooth weight as a measure of sexual dimorphism. Both male permanent third molars and canines are significantly heavier than those of females. The weight dimorphism reported here for both classes of teeth may prove a useful finding for future forensic studies. In particular, weights of canines may be more useful as a means of sexing modern human skeletal material than linear or area measurements of teeth.     

Meek mothers with powerful daughters: effects of novel host environments and small trait differences on parasitoid competition

Outcomes of competition may depend both on subtle differences in traits relevant to fitness and on how those traits are expressed in the context of the environment. Environmental effects on traits impacting population dynamics are often overlooked in studies of parasitic wasp (parasitoid) competition. Lineages of the parasitoid Diachasma alloeum (Hymenoptera: Braconidae) differ in relative ovipositor length (a trait affecting the proportion of hosts available for parasitism). Since the size of natal hosts affects the overall body size of many adult parasitoids, outcomes of competition between D. alloeum lineages should be influenced by both their natal host's size and their inherited ovipositor:body size ratios. Previous genetic work showed the unexpected result that the apparently inferior competitor (the lineage with smaller ovipositors in its ancestral environment) has successfully colonized a new host. We present body size measurements and a phenomological model of competition showing that relative ovipositor sizes of the two lineages predict success of the apparently inferior wasp lineage in the new host. We present several variants of the model, including simulations: 1) wherein competitors have either ancestral trait values or trait values acquired in the novel environment; 2) that allow varying rates of constant immigration from the inferior competitor's source population; and 3) with stochastic immigration from both lineages' source populations. We show that ancestral trait differences and changes in environmentally mediated traits interact to affect outcomes of competition. Apparently inferior female parasitoids (‘meek mothers’) attacking a host in a novel environment can produce highly successful daughters if those daughters inherit large ovipositor:body size ratios and grow to a larger size in the new environment. Predictive models of parasitoid competition that consider effects of environmentally mediated trait changes may be particularly important for biocontrol programs wherein parasitoids are introduced into new environments or used to control novel hosts.     

Tooth size and morphology in a recent Australian Aboriginal population from Broadbeach,South East Queensland

Odontometric and morphologic observations were made of the dentition of skeletal remains of Australian aborigines from Boradbeach, S.E. Queensland. Tooth size, especially of the molars, was found to be significantly larger than that reported for other recent Aboriginal populations. Tooth morphology also differed, with a higher frequency of five cusped second molars, and a lower frequency of shoveling and Carabelli's cusp than previously reported as typical of Australian aborigines.