Pima Indians as a model to study the genetics of NIDDM.

More than half the Pima Indians over 35 years of age have non-insulin dependent diabetes mellitus (NIDDM). They have been the focus of prospective epidemiologic and metabolic studies for over two decades and the data collected during these studies are now proving invaluable in efforts to find genetic markers for NIDDM in humans. The Pima Indian model of this disease affords two major advantages. The population is genetically homogeneous compared to Caucasian populations, and therefore the causes of NIDDM are less heterogeneous, simplifying genetic linkage studies. Equally important, based on results from metabolic studies, two pre-diabetic phenotypes have been identified in the Pimas: insulin resistance and a low metabolic rate. Use of these phenotypes in genetic linkage analyses should greatly improve chances of finding genetic markers for NIDDM since these phenotypes may be more closely related to the putative abnormal gene products, and actual disease genes, than is the hyperglycemia of the fully developed phenotype of NIDDM.     

Obesity in Pima Indians: Large increases among post-World War II birth cohorts

Several studies have shown secular increases in obesity during the past 35 years, and others have reported increases in dietary fat consumption during the same period. Here we report a dramatic increase in obesity among Pima Indians born after World War II that appears to be associated with increased exposure to Western customs and diet following 1945. We examined the body mass index (BMI = weight in kilograms/height² in meters) of 1,128 male and 1,372 female Pima Indians aged 15–65 years who were born between 1901 and 1964 and were examined between 1965 and 1990. We found large increases in BMI among Pima Indian men and women in post-World War II birth cohorts (1945 and later). The parallel changes in body mass index, dietary fat, and exposure to Western culture following World War II suggest that culturally mediated changes in diet and level of physical activity associated with modern industrialized society may have led to the large increases in obesity in the Pima Indians and to smaller parallel changes observed worldwide in westernized countries. © 1993 Wiley-Liss, Inc.     

Patterns of dental wear in the Lengua Indians of Paraguay

Wear patterns were examined on dental casts of 202 living Lengua Indians from the Chaco area of Paraguay. Consideration was given to the development of the molar helicoidal plane, age-related changes in occlusal attrition, coalescence of dentine exposures, interproximal attrition, and erupted crown height. This study lends support to Osborn's theory of the helicoidal plane development by showing that attrition enhances rather than modifies posteruption molar occlusal planes. The rate of interproximal attrition was found to slow down with the eruption and functional initiation of the third molars. Sinuous and cavo-convex interproximal contact areas that are generated with age, however, appeared to be less abrasion resistant than straight surfaces, hence leading to an increase in interproximal attrition rates with advanced age. Maximum crown height reduction occurred between the ages of 20 and 40 years in central incisors, canines, and first molars. Kruskal-Wallis tests and log linera models failed to demonstrate significant sexually dimorphic or antimeric differences in wear patterns of Lengua teeth.     

Formation of the permanent dentition in Arikara Indians: timing differences that affect dental age assessments

This report concerns one problem encountered with application of American white dental formation standards to age assessment of sub-adults of archaeological context. Dental ages for eight mandibular permanent teeth and maxillary central and lateral incisors of Arikara Indian immature skeletons were determined according to degree of crown or root mineralization. Ages assigned to the various teeth of the same individual were compared. They showed similarities as well as patterned differences. First premolar, second premolar, and mandibular incisor ages closely approximated one another. In relation to this complex, dental ages for maxillary incisors and mandibular second molars were older by 0.5 to 1.1 years. Developmental ages assigned to individuals on the basis of third molars showed relative advancement by more than 2 years. The systematic occurrence of these observations reflects more than just individual variability; it shows the presence of population differences in tooth-formation timing. Timing differences complicate assessment of dental ages needed for growth or demographic studies.     

The dentition of the Queckchi Indians. Anthropological aspects

The incidence of nine minor dental traits, in 540 Queckchi Indians from Guatemala is reported. A combination of frequencies of neither Caucasoid nor Mongoloid groups was observed. The apparently Caucasoid elements of their tooth morphology might well be the result of admixture with Spanish genes during the conquest.     

The dentition of the Lengua Indians of Paraguay

The crown morphology of 202 dental casts from living Lengua Indians is described and compared with other Amerind, Melanesian, and Caucasoid samples. The Lengua dentition shows a high Mongoloid component with little effects of possible European admixture, thus supporting the theory that despite early Franciscan and Jesuit attempts at missionization, much of the Paraguayan Chaco has remained genetically and culturally relatively intact well into the present century. A finding of note was the apparent sexual dimorphism of the Carabelli cusp, which questions earlier assumptions that no correction for sex need be made in population studies when dealing with this trait. Since mandibular canines show proportionately less wear in the canine distal accessory ridge area than maxillary canines, the value of the incidence of this trait in population and microevolutionary studies is questioned.     

Diabetes mellitus in the Pima Indians: genetic and evolutionary considerations

Non-insulin-dependent diabetes mellitus is a common disease in the Pima Indians. It is familial and strongly related to obesity. Neel (1962) suggested that the introduction of a steady food supply to people who have evolved a "thrifty genotype" leads to obesity, insulin resistance, and diabetes. Our findings in the Pimas of differences in insulin sensitivity in different metabolic pathways suggest that the thrifty genotype involves the ability of insulin to maintain fat stores despite resistance to glucose disposal. The recent increase in diabetes incidence following the availability of an abundant food supply suggests that the ability to store energy efficiently during cycles of feast and famine may now lead to obesity, insulin resistance, and diabetes.     

Changing occlusal variation in Pima Amerinds

Occlusal variables and arch measurements have been recorded on 341 Pima Amerinds pertaining to two samples, one of older individuals raised on traditional diets, the other of younger individuals raised on refined commercial foods that are typical of modern urbanized people. Permanent dental occlusion is significantly more variable from defined ideals in the younger sample, despite their fewer deformities resulting from progressive aging. The youths had relatively narrower palates, correlating with a general trend among industrialized populations and also among experimental animals fed soft diets. Relative rate of deciduous tooth loss and replacement did not correlate with any occlusal variable.     

Biological differentiation at predynastic Naqada,Egypt: An analysis of dental morphological traits

Cemetery T at Naqada has been postulated as being the interment site of a predynastic royal or ruling elite due to its small, localized area and the richness of its burial goods. In order to examine possible biological differentiation between the individuals buried in Cemetery T and those buried in other, possibly lower status cemeteries at Naqada, nonmetric dental morphological data were analyzed using the Mean Measure of Divergence statistic. Results indicate that Cemetery T shows some biological distinction from both Cemetery B and the Great Cemetery. The size of the difference supports the archaeological interpretation that Cemetery T represents a ruling or elite segment (or lineage) of the local population at Naqada, rather than a ruling or elite immigrant population. Given the problem of small samples, however, this interpretation is tentative. © 1994 Wiley-Liss, Inc.     

Genetic structure of a tribal population, the Yanomama Indians. XIII. Dental microdifferentiation.

Data are presented on the frequency of the following eight dental traits in 635 Yanomama and 65 Makiritare Indians: upper central incisor rotation or winging, shoveling of maxillary incisors, maxillary molar hypocone reduction, Carabelli's trait, mandibular molar cusp number, mandibular molar cusp pattern rotation of second lower premolar, and pattern of second lower premolar cusps. Yanomama dentition is unusual in the high frequency of six cusps on the mandibular molars. There is marked dental microdifferentiation between villages; significant agreement was observed between a matrix of pairwise "dental distances" based on six morphological traits and corresponding matrices based on 11 genetic systems and on geographic location.     

Intra- and interobserver concordance in classifying dental morphology

A sample of 50 Kodiak Island Eskimo dental casts were observed, using standard reference plaques, three times by one observer and once by a second observer, for 47 graded and discrete morphological characters of the dentition and jaws. Although the frequency of both intra- and interobserver scoring differences between observation sessions are relatively high for some characters, statistical analysis reveals that differences are largely random in direction and cancel out. Most dental morphological variants can be observed in a ranked fashion with adequate within- and between-observer reliability. However, four traits present both within- and between-observer difficulties: the tuberculum dentale, the canine distal accessory ridge, marginal accessory cusps of the upper first premolar, and the anterior fovea on the lower first molar.     

The Aymara of Western Bolivia. II. Maxillofacial and dental arch variation

Maxillofacial and dental arch dimensions of the Bolivian Aymara population are age and sex dependent. Interpopulational comparisons reveal these dimensions to differ from those seen in Aleuts, Australian aborigines, and Swedes, but to be similar to those of the indigenous Taiwanese. Finally, these dimensions are not the same in Aymara of unmixed ancestry, and Mestizos residing in the same villages.     

Intra and intertribal genetic variation within a linguistic group: The Ge-speaking Indians of Brazil

A total of 562 individuals living in four villages of two Brazilian Indian tribes (Cayapo and Krahó) was studied in relation to blood groups ABO, MNSs, P, Rh, Lewis, Duffy, Kidd and Diego; haptoglobin, Gc, acid phosphatase and phosphoglucomutase types. These results were compared with those obtained previously among the Xavante, and the inhabitants of three other Cayapo villages, all of whom speak Ge languages; the ranges in gene frequencies observed in a representative series of South American Indians from all over the continent were also compiled. The Ge Indians are characterized by low frequencies ofR^z, medium frequencies ofR¹,R², R⁰, orr,Jk^a andPGM¹₁, and high frequencies ofGc² andACP^A when compared with other South American tribes. Genetic distance analyses based on six loci indicate that the intratribal variability observed among Cayapo is of the same order of magnitude as those obtained among the Xavante and Krahó, being much less pronounced than those observed among the Yanomama and Makiritare. The intertribal differences within this linguistic group are much less pronounced than those encountered among tribes that speak more differentiated languages.     

The cranial morphology of the Botocudo Indians,Brazil

The Botocudo Indians were hunter‐gatherer groups that occupied the East‐Central regions of Brazil decimated during the colonial period in the country. During the 19th century, craniometric studies suggested that the Botocudo resembled more the Paleoamerican population of Lagoa Santa than typical Native Americans groups. These results suggest that the Botocudo Indians might represent a population that retained the biological characteristics of early groups of the continent, remaining largely isolated from groups that gave origin to the modern Native South American variation. Moreover, recently, some of the Botocudo remains have been shown to have mitochondrial and autosomal DNA lineages currently found in Polynesian populations. Here, we explore the morphological affinities of Botocudo skulls within a worldwide context. Distinct multivariate analyses based on 32 craniometric variables show that 1) the two individuals with Polynesian DNA sequences have morphological characteristics that fall within the Polynesian and Botocudo variation, making their assignation as Native American specimens problematic, and 2) there are high morphological affinities between Botocudo, Early Americans, and the Polynesian series of Easter Island, which support the early observations that the Botocudo can be seen as retaining the Paleoamerican morphology, particularly when the neurocranium is considered. Although these results do not elucidate the origin of the Polynesian DNA lineages among the Botocudo, they support the hypothesis that the Botocudo represent a case of late survival of ancient Paleoamerican populations, retaining the morphological characteristics of ancestral Late Pleistocene populations from Asia. Am J Phys Anthropol 157:202–216, 2015. © 2015 Wiley Periodicals, Inc.     

Functional relationships between dental attrition and the helicoidal plane

Several quantitative techniques were used to describe and analyze the development of the helicoidal curve of the dentition in a pre-contact sample of 326 native Indians from British Columbia. Results were compared with studies of occlusal patterns in other populations, and anatomical-functional features of the helicoidal pattern were abstracted and generalized. The features that define the helicoidal pattern were found to develop with attrition. The pattern itself, and the complex which produces it, probably have been selected for because they produce an occlusion with an efficient cutting edge and a total complex that provides maximum resistance to the masticatory forces. Studies focusing on the developmental nature of occlusal patterns in early hominid populations would be beneficial in developing a model of the evolution of the helicoidal pattern in modern man.     

Allometric analysis of dental variation in a human population

There exists an extensive literature that deals with interspecific allometry, eg, brain size-body size relationships among species. Yet comparatively little attention has been paid to intraspecific or static adult allometry. An intraspecfic allometric analysis was conducted on the complete permanent dentition of a prehistoric American Indian population (N = 156). Mesiodistal and buccolingual measurements were logarithmically transformed and regressed on log transformations of femur length, an estimate of body size. When measurements of antimeric teeth were introduced together into common regressions on femur length, 20 of the 32 slopes were significantly different from zero. Thirty-one of the slopes ranged between zero and one and clustered between 0.2 and 0.4. Hence, negative allometry describes the tooth size-body size association, ie, taller individuals in general possess absolutely but not relatively larger teeth than shorter individuals. In addition, no significant sex differences for the regression slopes were observed. Though significantly correlated, tooth size and body size variables are too weakly associated to permit accurate predictons from regression equations. Evolutionary implications of intraspecfic dental allometry are discussed.     

A dynamic nonlinear optimization study of Mountain Pima subsistence technology

A dynamic nonlinear optimization analysis of subsistence patterns of the Mountain Pima of Chihuahua, Mexico, included requirements for adequate amounts of calories, calcium, vitamin A, vitamin C, and balanced protein. Two methods of incorporating nonenergy nutritional needs into a time minimization program were compared. The first was a constraint model with sharp boundaries between adequacy and fatality. The second involved multiplying the total work time by a series of nutrient indexing factors. Each factor was calculated as a function of the ratio between the recommended and actual rates of intake for all months and nutrients considered. Oxalate composition of some resources and seasonal variation in resource availability were taken into account. Two sets of data were analyzed, one for a year of adequate rainfall, the other for a year of severe drought. The predictions of the indexing model agreed more closely with observed intake patterns than did the predictions of the constraint model.     

The ruminant dental grooming apparatus

Correlations between dental morphology and dietary preferences in ruminants explain the similarities but not the differences in relative incisor width encountered within the group. Observations on African browsing antelope have revealed extensive use of the lateral anterior dental elements for grooming purposes using a distinctive upward sweeping movement of the head. Inspection of these dental elements (I₂, I₃₎ and C) reveals a comb-like array remarkably similar to the prosimian tooth-comb. An hypothesis is presented to explain differences in incisor morphology based on the use of the teeth for purposes other than eating. The alternative biological role has implications for the use of dental characteristics in the determination of the feeding ecology of living and extinct ruminants.     

The deflecting wrinkle on the teeth of Icelanders and the Mongoloid dental complex

Three local populations from Northeast Iceland are surveyed for the occurrence of the deflecting wrinkle of the metaconid on second deciduous and first permanent lower molars. The trait occurs more frequently on dm2 than on M1, and no sexual dimorphism is found, as expected. However, the frequencies are clearly within those predicted by the Mongoloid dental complex for Mongoloid populations. It is therefore suggested that the inclusion of the deflecting wrinkle in the Mongoloid dental complex be re-evaluated, and the racial diagnostic value of the trait taken with reservation.