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.     

Morphologic characteristics of the Alaskan Eskimo dentition. III. Number of cusps on the upper permanent molars

A study of 35 coastal and 64 inland Alaskan Eskimos revealed a reduction in the number of cusps from the first to the third maxillary molar. While 97% of the first molars had four cusps, only 39.6% of the second molars and 15.2% of the third molars had that number. The reduction occurs through elimination of the hypocone. No statistically significant sex difference in the trend towards reduction in the cusp numbers was found. In the inland female group the occurrence of four cusps in the maxillary second molar was statistically higher than in the coastal female group. This may be due to a more pronounced racial admixture of white people along the coast. A similar difference, although not statistically significant, was found in the corresponding male groups. Alaskan Eskimos have a tendency towards a lower frequency of four cusps on all three maxillary molars than Aleuts. Only the second molar exhibited a statistically significant difference in this respect. A statistical evaluation revealed that in the Alaskan Eskimo maxillary first and third molars the reduction of cusps is independent of the size and form of the molars and of the suppression of the third molar. For the second molar, however, the groups with four well-developed cusps showed significantly larger buccolingual diameter.     

A population study of the jugular foramen bridging of the human cranium

The author previously proposed a simple standard for diagnosing the jugular foramen bridging in man. The incidence of this bridging trait was investigated according to that standard in nine cranial series of East Indians, Micronesians, Japanese, Ainu, Mongols, Aleuts, Alaskan Eskimos, Canadian Eskimos, and Ontario Iroquois. No sex difference in incidence of the trait was recognized. Side difference in trait incidence was also slight but was statistically significant in the combined series of all the population samples examined. The bridging trait occurred more frequently on the right side than on the left side. Occurrences of the bridging trait were definitely associated between sides. Incidence of the trait was less in East Indians, Ontario Iroquois, and Micronesians, but greater in Alaskan Eskimos and Canadian Eskimos, the incidences in Japanese, Ainu, Aleuts, and Mongols being intermediate. The differences in trait incidence among the nine population samples were considered to reflect the differences in genetic compositions of these specific populations.     

Morphologic characteristics of the Alaskan Eskimo dentition: IV. Cusp number and groove patterns of mandibular molars

Data on the permanent dentition of 63 coastal and 33 inland Alaskan Eskimos are presented. The number of cusps and groove pattern of the mandibular molars were recorded. Agenesis of the mandibular third molars was classified and the mesiodistal and buccolingual crown diameter was measured on the first and the second mandibular molars. The predominant pattern of the lower first molars was Y5, while for the second molar the dominating patterns were +5 and +4. In the lower third molar, +5 was found in the majority of cases. For M1 and M2, men showed a stronger tendency toward a conservative pattern than did women. In the case of M2, the inland population exhibited a more conservative trait than did the coastal population. No connection was seen between the groove pattern and agenesis of M3, however, a reduction in the mesiodistal crown diameter for the second molars was seen when the number of cusps is reduced from 5 to 4.     

Genetic variation in the Aleuts of the Pribilof Islands and the Eskimos of Kodiak Island

A sample of Aleuts residing in the Pribilof Islands of St. Paul (N = 163) and St. George (N = 62) and Eskimo residents of Kodiak Island (N = 294) have been typed for genetic variation at 31 discrete genetic markers. Of these, 16 were polymorphic and 15 were monomorphic. Several private polymorphisms previously reported in Eskimo or Alaskan Amerindian populations were absent in both the Aleuts and Kodiak Island Eskimos. Genetic distance analysis shows considerable genetic differentiation between Aleuts and Kodiak Island Eskimos.     

Anthropometric variation among Bering Sea natives

Recent research indicates that anthropometrics can be used to study microevolutionary forces acting on humans. We examine the use of morphological traits in reconstructing the population history of Aleuts and Eskimos of the Bering Sea. From 1979 to 1981, W. S. Laughlin measured a sample of St. Lawrence Island Eskimos and Pribilof Island Aleuts. These samples included adult participants from St. George and St. Paul in the Pribilof Islands and from Gambell and Savoonga on St. Lawrence Island. The Relethford-Blangero method was used to examine the phylogenetic relationship between Aleuts and Eskimos. Anthropometric measurements for Native North Americans (measured by Boas and a team of trained anthropometrists in 1890-1904) and Native Mesoamericans (compiled from the literature for 1898-1952) were used for comparison. A principal components analysis of means for measurements and a neighbor-joining tree were constructed using Euclidean distances. All these tests revealed the same strong relationship among the focus populations. The R matrix from the Relethford-Blangero method clusters Aleuts and Eskimos separately and accounts for 97.3% of the variation in the data. Phenotypic variation within the population is minimal and therefore minimum F(ST) values are low. Genetic distances were compared to a Euclidean distance matrix of anthropometric measurements using a Mantel test and gave a high but not significant correlation. Our results provide evidence of a close phylogenetic relationship between Aleut and Eskimo populations in the Bering Sea. However, it is apparent that history has affected the relationship among the populations. Despite previous findings of higher European admixture in Gambell (based on blood group markers) than in Savoonga, Savoonga has greater within-group variation in anthropometric measurements. Anthropometrics reveal a close relationship between Gambell and St. Paul as a result of European admixture. The St. George population was the most divergent of the populations, indicating that it diverged from the Eskimos and St. Paul because of the compounding effects of genetic drift and limited European gene flow. These findings are in agreement with previous anthropometric and genetic studies of the Aleut and Eskimo populations and support the utility of anthropometrics in inferring population history and structure.     

Skeletal evidence of health and disease in pre-contact Alaskan Eskimos and Aleuts

There have been relatively few paleopathological studies of arctic populations to date, compared to other regions of North America. Studies aimed at elucidating patterns of health and disease in arctic peoples prior to contact and assessing inter- and intraregional differences in disease patterns have been particularly few. In the present study, five pre-contact skeletal samples (N = 193), representing 4 Eskimo populations from northern coastal Alaska and 1 Aleut population from the eastern Aleutian Islands, were examined macroscopically for the following indicators of health status: cribra orbitalia, porotic hyperostosis, trauma, infection, dental caries, abscesses, antemortem tooth loss, periodontal disease, and dental attrition. In addition, archeological and epidemiological data were used to help reconstruct the health of these populations. The goals of the analysis were 2-fold: 1) to assess the pre-contact health of North Alaskan Eskimos and Aleuts in order to provide a baseline comparison for the post-contact health of these groups, and 2) to determine if any differences in disease patterns exist between the Eskimos and Aleuts that might be related to differences in their physical environment, subsistence patterns, and cultural practices. The analysis revealed that both groups suffered from a variety of health problems prior to contact, including iron deficiency anemia, trauma, infection, and various forms of dental pathology. Statistical comparisons of the 2 groups revealed that Eskimos and Aleuts had different patterns of health and disease prior to contact. Most notably, the Aleuts had a significantly higher frequency of cranial trauma and infracranial infection than the Eskimos, while the latter had a significantly higher frequency of enamel hypoplasia. An examination of the physical and cultural environment of the 2 groups reveals several possible explanations for these differences, including warfare, subsistence pursuits, and housing practices. The documentation of these differences indicates that variability in pre-contact disease patterns can be identified between hunter-gatherer populations living in similar environments and exhibiting similar general lifestyles. Am J Phys Anthropol 107:51–70, 1998. © 1998 Wiley-Liss, Inc.     

The morphological basis of the underbite trait in langurs (P. melalophus and T. cristatus) with an analysis of adaptive and evolutionary implications

Underbites or mandibular incisor protrusions are widely prevalent among Coloboid monkeys. The morphological basis of the trait is explored in two langur species differing with respect to its incidence. P. melalophus, characterized by a high occurrence of underbites, has mandibular incisors which are significantly wider than those of T. cristatus, the more “normative” occlusal group. No other statistically significant incisor metric differences are noted. Comparisons of convexgent traits in the Colobinae, Alouattinae, and Ruminantia support the contention that underbites are a herbivorous adaptation. The zoogeographic distribution of the trait in langurs is discussed in the context of evolutionary dynamics.     

Origins of Aleuts and the genetic structure of populations of the archipelago: molecular and archaeological perspectives

We summarize the results of a field and laboratory research program (1999-2006) in the Aleutian Islands on the origins of the inhabitants of the archipelago and the genetic structure of these populations. The Aleuts show closest genetic affinity to the contemporary Siberian Eskimos and Chukchi of Chukotka and differ significantly from the populations of Kamchatka (the terminus of the archipelago) and Alaskan Eskimos. Our findings support the hypothesis that the ancestors of the Aleuts crossed Beringia and expanded westerly into the islands approximately 9,000 years ago. The Monmonier algorithm indicates genetic discontinuity between contemporary Kamchatkan populations and western Aleut populations, suggesting that island hopping from Kamchatka into the western Aleutian Islands was highly unlikely. The primary determinant of the distribution of genes throughout the archipelago is geography. The most intimate relationship exists between the genetics (based on mtDNA sequences and intermatch/mismatch distances) and geographic distances (measured in kilometers). However, the Y-chromosome haplogroup frequencies are not significantly correlated with the geography of the Aleutian Islands. The underlying patterns of precontact genetic structure based on Y-chromosome markers of the Aleut populations is obscured because of the gene flow from Russian male colonizers and Scandinavian and English fishermen. We consider alternative theories about the peopling of the Americas from Siberia. In addition, we attempt a synthesis between archaeological and genetic data for the Aleutian Islands.     

Dental chipping in Aleuts, Eskimos and Indians

Analysis of dentitions belonging to 324 prehistoric and protohistoric Aleuts, Eskimos and northern Indians, all of whom were regularly meat-eaters, reveals a significant difference between Eskimos and Aleut-Indians for a little known type of tooth wear. This wear is characterized by severe crushing and/or flaking of the crown surface of one or more teeth (termed “pressure-chipping”). It occurs chiefly in dentitions of high arctic Eskimos of Alaska, Canada, and Greenland, and significantly less often in the teeth of Kodiak Island Eskimos, Aleuts and northern Indians. Sex differences do not exist but pressure-chipping occurs significantly more often in adult (21–x years) than in non-adult (0–20 years) Eskimos. The exact mechanism(s) responsible for pressure-chipping is unknown, although ethnographic accounts of Eskimo eating habits suggest that crushing of hard substances such as bone was involved. The severity of this wear could have contributed to the selection for, or preservation of, large and complex crowns in high arctic Eskimos. Pressure-chipping is offered as evidence favoring the view that tooth size (longevity) may have had in the past some adaptive value.     

Genetic history of Aleuts of the Komandor islands from results of analyzing variability of class II HLA genes

Variability of the HLA class II genes (alleles of the DRB1, DQA1, and DQB1 loci) was investigated in a sample of Aleuts of the Commanders (n = 31), whose ancestors inhabited the Commander Islands for many thousand years. Among 19 haplotypes revealed in Aleuts of the Commanders, at most eight were inherited from the native inhabitants of the Commander Islands. Five of these haplotypes (DRB1*0401-DQA1*0301-DQB1*0301, DRB1*1401-DQA1*0101-DQB1*0503, DRB1*0802-DQA1*0401-DQB1*0402, DRB1*1101-DQA1*0501-DQB1*0301, and DRB1*1201-DQA1*0501-DQB1*0301) were typical of Beringian Mongoloids, i.e., Coastal Chukchi and Koryaks, as well as Siberian and Alaskan Eskimos. Genetic contribution of the immigrants to the genetic pool of proper Aleuts constituted about 52%. Phylogenetic analysis based on Transberingian distribution of the DRB1 allele frequencies favored the hypothesis on the common origin of Paleo-Aleuts, Paleo-Eskimos, and the Indians from the northwestern North America, whose direct ancestors survived in Beringian/southwestern Alaskan coastal refugia during the late Ice Age.     

Long bone growth in western Eskimo and Aleut skeletons

The pattern of long bone growth in Eskimo and Aleut juvenile skeletons reflects that in living Eskimos and Aleuts. There is a pre-adolescent growth spurt which is particularly intense in females. After age 14 male long bones supercede those of females in length. The characteristic Eskimo and Aleut adult body proportion is established early in childhood. Eskimos and Aleuts have shorter bones than whites at all ages. The difference in length of the forearm and lower leg in comparison with whites appears to increase especially at adolescence.     

Mitochondrial DNA variation and the origins of the Aleuts

The mitochondrial DNA (mtDNA) variation in 179 Aleuts from five different islands (Atka, Unalaska, Umnak, St. Paul, and St. George) and Anchorage was analyzed to better understand the origins of Aleuts and their role in the peopling of the Americas. Mitochondrial DNA samples were characterized using polymerase chain reaction amplification, restriction fragment length polymorphism analysis, and direct sequencing of the first hypervariable segment (HVS-I) of the control region. This study showed that Aleut mtDNAs belonged to two of the four haplogroups (A and D) common among Native Americans. Haplogroup D occurred at a very high frequency in Aleuts, and this, along with their unique HVS-I sequences, distinguished them from Eskimos, Athapaskan Indians, and other northern Amerindian populations. While sharing several control region sequences (CIR11, CHU14, CIR60, and CIR61) with other circumarctic populations, Aleuts lacked haplogroup A mtDNAs having the 16265G mutation that are specific to Eskimo populations. R-matrix and median network analyses indicated that Aleuts were closest genetically to Chukotkan (Chukchi and Siberian Eskimos) rather than to Native American or Kamchatkan populations (Koryaks and Itel'men). Dating of the Beringian branch of haplogroup A (16192T) suggested that populations ancestral to the Aleuts, Eskimos, and Athapaskan Indians emerged approximately 13,120 years ago, while Aleut-specific A and D sublineages were dated at 6539 +/- 3511 and 6035 +/- 2885 years, respectively. Our findings support the archaeologically based hypothesis that ancestral Aleuts crossed the Bering Land Bridge or Beringian platform and entered the Aleutian Islands from the east, rather than island hopping from Kamchatka into the western Aleutians. Furthermore, the Aleut migration most likely represents a separate event from those responsible for peopling the remainder of the Americas, meaning that the New World was colonized through multiple migrations.     

Analysis of mitochondrial DNA diversity in the aleuts of the commander islands and its implications for the genetic history of beringia

The Aleuts are aboriginal inhabitants of the Aleutian archipelago, including Bering and Copper (Medny) Islands of the Commanders, and seem to be the survivors of the inhabitants of the southern belt of the Bering Land Bridge that connected Chukotka/Kamchatka and Alaska during the end of the Ice Age. Thirty mtDNA samples collected in the Commanders, as well as seven mtDNA samples from Sireniki Eskimos in Chukotka who belong to the Beringian-specific subhaplogroup D2, were studied through complete sequencing. This analysis has provided evidence that all 37 of these mtDNAs are closely related, since they share the founding haplotype for subhaplogroup D2. We also demonstrated that, unlike the Eskimos and Na-Dene, the Aleuts of the Commanders were founded by a single lineage of haplogroup D2, which had acquired the novel transversion mutation 8910A. The phylogeny of haplogroup D complete sequences showed that (1) the D2 root sequence type originated among the latest inhabitants of Beringia and (2) the Aleut 8910A sublineage of D2 is a part of larger radiation of rooted D2, which gave rise to D2a (Na-Dene), D2b (Aleut), and D2c (Eskimo) sublineages. The geographic specificity and remarkable intrinsic diversity of D2 lineages support the refugial hypothesis, which assumes that the founding population of Eskimo-Aleut originated in Beringan/southwestern Alaskan refugia during the early postglacial period, rather than having reached the shores of Alaska as the result of recent wave of migration from interior Siberia.     

The depth of the lingual fossa in permanent incisors of Norwegians. I. Method of measurement, statistical distribution and sex dimorphism

The depth of the incisor lingual fossa in permanent extracted incisors and plaster casts of Norwegians was examined. It was shown that plaster casts are well suited for measurements of lingual fossa depth, and that the measurements can be performed with great accuracy. Skewness values showed the symmetry of the distribution to decrease with decreasing mean lingual fossa depth. Kurtosis was found small in maxillary incisors, in mandibular outside the limits for normal theory. The distribution of the depth of the lingual fossa cannot generally be described as normal. No sex differences were found. The inheritance of this trait in Norwegians is probably not sex linked.     

Variation in the convexity of the human maxillary incisor labial surface

Labial surface convexity of the maxillary central incisors (ILC) is classified with a new five grade ranked scale. More than 2,000 individuals representing 20 worldwide populations were studied. Principle findings are 1) sexual dimorphism is not significant, 2) antimere asymmetry is moderate, 3) labial convexity is negatively associated (r = ?0.48) with labial surface double-shovelling, and 4) significant differences occur between several populations. Convexity is most marked in African and Asiatic Indian populations, particularly Bushmen. Europeans have intermediate degrees of convexity, and American Indians the least; Eskimos have the highest amount of convexity among Native Americans. Pacific Islanders are intermediate; Melanesians show the strongest expression of incisor labial convexity in the Pacific.     

Genetic History of Aleuts of the Commander Islands as Revealed by the Analysis of the HLA Class II Gene Variability

Variability of the HLA class II genes (alleles of the DRB1, DQA1, and DQB1 loci) was investigated in a sample of Aleuts of the Commanders (n = 31), whose ancestors inhabited the Commander Islands for many thousand years. Among 19 haplotypes revealed in the Aleuts of the Commanders, at most eight were inherited from the native inhabitants of the Commander Islands. Five of these haplotypes (DRB1*0401-DQA1*0301-DQB1*0301, DRB1*1401-DQA1*0101-DQB1*0503, DRB1*0802-DQA1*0401-DQB1*0402, DRB1*1101-DQA1*0501-DQB1*0301, and DRB1*1201-DQA1*0501-DQB1*0301) were typical of Beringian Mongoloids, i.e., Coastal Chukchi and Koryaks, as well as Siberian and Alaskan Eskimos. Genetic contribution of the immigrants to the genetic pool of the proper Aleuts constituted about 52%. Phylogenetic analysis based on Transberingian distribution of the DRB1 allele frequencies favored the hypothesis on the common origin of the Paleo-Aleuts, Paleo-Eskimos, and the Indians from the northwestern North America, whose direct ancestors survived in Beringian/southwestern Alaskan coastal refugia during the late Ice Age.     

The genetic structure of populations of Chuckotka Peninsula Eskimos and Chuckchi based on study of 13 loci of serum and erythrocyte proteins and enzymes

The Eskimos and Chuckchi of the Chuckotka Peninsula were studied at 13 loci of serum and erythrocyte proteins and enzymes by electrophoresis. Six loci-including albumin, transferrin, carbonic anhydrase I and II, monoamine oxidase, and superoxide dismutase-were monomorphic in the studied populations. The mean frequencies of alleles in nine polymorphic loci of Chuckotka Eskimos and Chuckchi, Eskimos of Alaska, Canada, and Greenland, some Mongoloid populations of Siberia, American Indians, and Lapps of circumpolar areas of Western Europe were obtained. The genetic distances between these populations were calculated. The Eskimos of Chuckotka were closest to the Alaskan Eskimos. The relative heterozygosity of Chuckotka Eskimos was calculated and was the highest in Chuckchi. The average heterozygosity in Eskimo populations increased in the following order, from least to greatest: Chuckotka Eskimos, St. Lawrence Island Eskimos, Alaskan Eskimos, Greenland Eskimos, and Canadian Eskimos. The average heterozygosity of the Chuckchi was similar to that of Western Hemisphere Eskimos.     

Macaca fuscata develops thin enamel on lingual sides of lower incisors

Among the cercopithecids, papionins were believed to have unique lower incisors without enamel on the lingual surfaces based on analyses by light microscopy. We examined unerupted lower permanent incisors ofMacaca fuscata with scanning electron microscopy and found a lingual thin enamel layer. This seems to be the case for all papionins. Thus, all cercopithecines can be regarded to share this trait which distinguishes cercopithecines from colobines who have substantial enamel layer on the lingual sides of lower incisors. Further study will support this hypothesis. This trait produces self-sharpening chisel-like edges on lower incisors. And the adaptive significance of this chisel-like edged incisor could be understood for scraping and cutting to prepare foods for consumption.     

The impact of digging on the evolution of the rodent mandible

There are two main (but not mutually exclusive) methods by which subterranean rodents construct burrows: chisel-tooth digging, where large incisors are used to dig through soil; and scratch digging, where forelimbs and claws are used to dig instead of incisors. A previous study by the authors showed that upper incisors of chisel-tooth diggers were better adapted to dig but the overall cranial morphology within the rodent sample was not significantly different. This study analyzed the lower incisors and mandibles of the specimens used in the previous study to show the impact of chisel-tooth digging on the rodent mandible. We compared lower incisors and mandibular shape of chisel-tooth digging rodents with nonchisel-tooth digging rodents to see if there were morphological differences between the two groups. The shape of incisors was quantified using incisor radius of curvature and second moment of area (SMA). Mandibular shape was quantified using landmark based geometric morphometrics. We found that lower incisor shape was strongly influenced by digging group using a Generalized Phylogenetic ancova (analysis of covariance). A phylogenetic Procrustes anova (analysis of variance) showed that mandibular shape of chisel-tooth digging rodents was also significantly different from nonchisel-tooth digging rodents. The phylogenetic signal of incisor radius of curvature was weak, whereas that of incisor SMA and mandibular shape was significant. This is despite the analyses revealing significant differences in the shape of both mandibles and incisors between digging groups. In conclusion, we showed that although the mandible and incisor of rodents are influenced by function, there is also a degree of phylogenetic affinity that shapes the rodent mandibular apparatus.