Relationships between the frontal sinus and climatic conditions: a skeletal approach to cold adaptation

Previous studies in physical anthropology, using superficial facial features, show that the relationship between human facial morphology and climate is not clear. An alternate approach to the problem is the investigation of the deeper facio-anatomical structures (i.e., cranial sinuses and/or foramina) in relation to climatic variables. The present investigation statistically analyses the relationship between climatic conditions (wind chill equivalent temperatures and absolute humidities) and the occurrence and size of frontal sinuses in 153 Eskimo crania. Conditional results from tests of significance of differences and correlation suggest a relationship between low wind chill equivalent temperatures and small frontal sinus surface areas. These results are interpreted in light of cranial sinus function and environmental physiology.     

The Caribou Eskimo: General and specific disease

Reported here are two forms of skeletal pathology identified in an inclusive sample of Caribou Eskimo skeletons. Harris Lines, nonspecific indicators of stress, show marked periodicity in approximately one-half of the observable adults. This pattern is interpreted as the result of a recurrent, annual stress cycle, perhaps attributable to late winter famine. A second form of pathological change comprises resorptive lesions primarily localized in the spinal column and infrequently found on articular surfaces of the appendicular skeleton. Differential diagnosis is developed utilizing attributes of lesion form, lesion distribution, and epidemiology. Emphasis is placed upon deriving objective models which reflect disease in the absence of modern medical intervention. Major forms of pathology known to produce vertebral lesions are included. The model which best fits the Caribou Eskimo data is that of tuberculosis.     

Infanticide and fertility among Eskimos: A computer simulation

Until recently, certain Eskimo groups were reported to practice female infanticide in the belief that the time spent suckling a girl would delay the mother's next opportunity to bear a son, males being preferred to females because of their future role as providers in a hunting economy. From sex ratios in census data, rates of female infanticide of up to 66% for some groups have been inferred, leading some ethnographers to conclude that these groups were headed for extinction. Eskimo beliefs regarding the effects of infanticide on fertility, however, are in accord with the results of research on the relation of fertility and lactation: The cessation of lactation following infanticide would significantly shortern the expected interval until the next birth. Given this fact and available field data regarding the parameters of Eskimo population growth, the present computer simulation indicates that Eskimo populations could sustain a rate of 30% female infanticide and still survive. Higher reported rates are explained as the combined result of female infanticide plus the tendency of ethnographers to overestimate to overestimate the ages of juvenile females relative to juvenile males.     

Changes among wild House mice (Mus musculus) bred for ten generations in a cold environment, and their evolutionary implications

Wild House mice, Mus musculus , bred at 23°C (controls) changed little in reproductive performance over ten generations. Similar mice bred at 3°C (Eskimo) became more fertile and heavier. Eskimo body fat also rose. Control adrenal weights declined; Eskimo adrenal weights were heavier than those of controls, but only during the first four generations. The Eskimo phenotype after ten generations was a combined result of a direct response to cold, parental effects and genetical changes in the Eskimo population. Maternal effects were probably especially important. In such conditions, the minimum unit of selection that it is useful to consider is the female and her litter.     

Cephalometric analysis of the craniofacial region of the northern Foxe Basin Eskimo

Past investigations of the Eskimo have indicated that there are marked morphological differences in the craniofacial skeleton of this relatively isolated ethnic group compared to other ethnic and racial groups. This study, using cephalometric radiography, attempted to characterize the craniofacial phenotype of the Eskimo living in the northern Foxe Basin, Northwest Territories, Canada. Age changes were examined on a cross-sectional basis with comparisons being made with a Winnipeg Caucasian group. This investigation indicates that the Igloolik Eskimo has a phenotype, established early in life, and is distinct from the Winnipeg group. The overall size of the Eskimo craniofacial complex was significantly larger at three years of age and remained larger through the ages studied. Development of the craniofacial region, however, was fairly similar in rate and direction for both populations. The greatest differences between the Eskimo and Caucasian groups were found in the linear measurements assessing cranial width, facial width, mandibular length, facial height, protrusion of the incisors, chin point development, and nasal morphology. Differences between the two groups in the morphological relationships of the component structures include the angular relationships of the maxilla and nasal bones to the anterior cranial base, the gonial angle of the mandible, and the angle of facial convexity.     

Interaction of genotype and parental environment in the adaptation of wild House mice Mus musculus to cold

Wild House mice, Mus musculus, were bred in two laboratory environments, one warm (controls) and one cold (Eskimo). At the seventh generation, mice of both stocks were cross-fostered at birth in both environments. In the warm environment, differences in both genotype and nest environment influenced growth: (1) Eskimo reared by Eskimo females were the heaviest of the four classes of fostered young; and (2) control foster parentage retarded growth. There was, however, no good evidence of differences in the reproductive performance of the four classes of fostered mice. In the cold environment, the effects of both genetical differences and of fostering were greater. Both the superior growth of Eskimo reared by Eskimo and the retarding effect of control foster parentage were more marked. Moreover, adult males with control foster parents had less fat than had those with Eskimo foster parents. Reproductive performance was also affected: (1) the young of the pairs with Eskimo genotype were heavier than the young of control pairs; (2) the litters of mice with Eskimo foster parents were larger than those of mice with control foster parents, and their young were heavier. Differences among the young of fostered mice represent a grandmother effect. Evidently, selection in a cold environment had led, not only to adaptive genetical changes in the ability to respond directly to cold, but also to changes in parental performance; and the latter enhanced the fitness, in the cold environment, of their offspring and grandoffspring.     

mtDNA variation among Greenland Eskimos: the edge of the Beringian expansion

The Eskimo-Aleut language phylum is distributed from coastal Siberia across Alaska and Canada to Greenland and is well distinguished from the neighboring Na Dene languages. Genetically, however, the distinction between Na Dene and Eskimo-Aleut speakers is less clear. In order to improve the genetic characterization of Eskimos in general and Greenlanders in particular, we have sequenced hypervariable segment I (HVS-I) of the mitochondrial DNA (mtDNA) control region and typed relevant RFLP sites in the mtDNA of 82 Eskimos from Greenland. A comparison of our data with published sequences demonstrates major mtDNA types shared between Na Dene and Eskimo, indicating a common Beringian history within the Holocene. We further confirm the presence of an Eskimo-specific mtDNA subgroup characterized by nucleotide position 16265G within mtDNA group A2. This subgroup is found in all Eskimo groups analyzed so far and is estimated to have originated <3,000 years ago. A founder analysis of all Eskimo and Chukchi A2 types indicates that the Siberian and Greenland ancestral mtDNA pools separated around the time when the Neo-Eskimo culture emerged. The Greenland mtDNA types are a subset of the Alaskan mtDNA variation: they lack the groups D2 and D3 found in Siberia and Alaska and are exclusively A2 but at the same time lack the A2 root type. The data are in agreement with the view that the present Greenland Eskimos essentially descend from Alaskan Neo-Eskimos. European mtDNA types are absent in our Eskimo sample.     

Size and number of the hypoglossal nerve foramina in the avian skull and their potential neuroanatomical significance

The cranial openings of nervus hypoglossus, the 12th cranial nerve, are for the first time studied across a broad range of higher avian taxa. This nerve plays an important role in the innervation of the syrinx and exits the skull through a variable number of foramina. Most previous authors described 2–3 foramina nervi hypoglossi (FNH) for neornithine birds, but the number, size, and arrangement of FNH is actually more variable than what is apparent from the literature. In the case of three foramina, there is usually a pair of caudal foramina and a rostral one, but even in closely related taxa, a great variability of the FNH pattern may exist. Many taxa of Neognathae exhibit a quadruple of symmetrically arranged FNH, in others four foramina are strung together in a line. A few taxa show more than four FNH, although in these cases the additional foramina are very small. Of particular interest is the occurrence of a very large caudal FNH in Trochilidae and many species of Passeriformes. This large foramen is suggestive of a correlation with the highly developed vocal capabilities of these birds and may transmit fibers from the tracheosyringeal portion of nucleus nervi hypoglossi, in which case it would be an osteological correlate of vocal capabilities. However, targeted neuroanatomical studies are required to determine how individual hypoglossal foramina relate to hypoglossal roots and their branches, and which of them receive fibers supplying axial, lingual, and syringeal muscles.     

国人颈椎横突孔的形态观察与测量

本文作者用精密度为0.02毫米的游标卡尺对东北地区出土的100副成套颈椎,1200个颈椎横突孔的诸径进行了测量,得到了一系列数据,并对颈椎横突孔的形状(将它分为五型)及一些特异颈椎进行了观察,根据这些材料探讨了横突孔与椎动脉的关系。     

BOOK REVIEWS

Book reviewed in this article:
AMERICA: Inugsuk, a Mediaeval Eskimo Settlement in Upernivik District, West Greenland. T herkel M athiassen .
Ancient Eskimo Settlements in the Kangâmiut Area. T herkel M athiassen .     

Atrial septation: II. Formation of the foramina secunda in the chick

Chick hearts were prepared for light microscopy and transmission electron microscopy by conventional methods, the purpose being to investigate the developing foramina secunda in the atrial septum. As the growing septum approaches and fuses with the endocardial cushions, small perforations (foramina secunda) are formed in the middorsal portion of the septum. During Days 5 and 6 the number and size of these foramina increase significantly. Formation of foramina creates thin cords of endocardium-covered tissue. Two varieties of endocardial cells are associated with the atrial septum during this period. The endocardial cells on the surface of the septum, some distance from the foramina secunda, are flattened and possess long, attenuated processes. Conversely, the endocardium in the rough portion of the septum near the foramina is characterized by the presence of numerous rounded cells which project notably into the atrial chambers. These rounded endocardial cells resemble phagocytic cells and possess thin cytoplasmic processes which extend into the septal core, gradually separating the cells of the core, resulting in an isolation of a portion of septal tissue. Once a transseptal communication is established the cytoplasmic processes separate, creating a new foramen secundum. The rounded endocardial cells are also responsible for maintaining the integrity of the endocardium-covered septum throughout the remodeling process. The origin of the rounded cells is unknown at this time. The most likely sources are differentiation from existing endocardial cells or circulating phagocytes.     

Skull anatomy of the Oligocene toothed mysticete Aetioceus weltoni (Mammalia; Cetacea): implications for mysticete evolution and functional anatomy

Toothed mysticetes of the family Aetiocetidae from Oligocene rocks of the North Pacific play a key role in interpretations of cetacean evolution because they are transitional in grade between dorudontine archaeocetes and edentulous mysticetes. The holotype skull of Aetiocetus weltoni from the late Oligocene (28–24 Ma) of Oregon, USA, has been further prepared, revealing additional morphological features of the basicranium, rostrum and dentary that have important implications for mysticete evolution and functional anatomy. The palate of Aetiocetus weltoni preserves diminutive lateral palatal foramina and associated delicate sulci which appear to be homologous with the prominent palatal foramina and sulci that occur along the lateral portion of the palate in extant mysticetes. In modern baleen whales these foramina allow passage of branches of the superior alveolar artery, which supplies blood to the epithelia of the developing baleen racks. As homologous structures, the lateral palatal foramina of A. weltoni suggest that baleen was present in this Oligocene toothed mysticete. Cladistic analysis of 46 cranial and dental characters supports monophyly of the Aetiocetidae, with toothed mysticetes Janjucetus and Mammalodon positioned as successive sister taxa. Morawanacetus is the earliest diverging aetiocetid with Chonecetus as sister taxon to Aetiocetus species. © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society, 2008, 154 , 308–352.     

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.     

Vertebral arch defects in the lumbar vertebrae of pre-historic American Eskimos. A study of skeletons in the American Museum of Natural History,chieely from Point Hope,Alaska

The incidence of lumbar vertebral arch defects was studied in 295 Eskimo skeletons now in the American Museum of Natural History, New York, which were obtained from adjacent burial grounds at Point Hope, Alaska. One burial ground containing 47 skeletons was used by the Ipiutak at about the start of the Christian era. The other burial ground was used by the Tigara a thousand years later and contained 248 skeletons. The lesion is a separation of the vertebral arch from the vertebral body. It usually involves the fifth lumbar vertebra but may involve others and more than one. The present incidence in the United States is about 7%. Among the Tigara the incidence was 45% and more than twice that of the Ipiutak, 21%. The youngest case was in a child of five and the deformity was uncommon before adult life. The incidence and extent of the lesion increased with age suggesting an hereditary weakness as an etiological factor. No other etiological factor could be determined although several were considered. The clinical disability could not be determined but it seemed to have no effect on longevity.     

Kaposi's sarcoma in an Eskimo

An Eskimo who had been treated for a nasopharyngeal carcinoma was subsequently found to have a rapidly progressive form of Kaposi''s sarcoma confirmed at biopsy. No objective response was obtained by irradiation treatment of isolated nodules. However, vinblastine sulfate arrested the progression of the disease. Because this neoplasm is most prevalent in tropical climates its presentation in an Eskimo is believed sufficiently unusual to warrant this report.     

Does postcranial palaeoneurology provide insight into pterosaur behaviour and lifestyle? New data from the azhdarchoid Vectidraco and the ornithocheirids Coloborhynchus and Anhanguera

The postcranial palaeoneurology of fossil reptiles is understudied, and those studies that exist focus predominantly on crocodyliforms and dinosaurs. The intervertebral foramina of the spine house nerves that exit to innervate surrounding tissues and the extremities. In the heavily fused (and typically distorted or poorly preserved) pterosaurian sacrum, intervertebral foramina can be difficult to observe and are rarely identified. The Early Cretaceous azhdarchoid Vectidraco from the Isle of Wight, UK, exhibits large, paired foramina on each sacral vertebra, originally identified as pneumatic foramina. Micro‐computed tomography imaging reveals these communicate with the neural canal and are intervertebral foramina for sacral nerves. The sacral vertebrae of Vectidraco are fused, and intervertebral foramina occur dorsolaterally on the centra. We identified these structures in other pterosaur sacra, including those of the ornithocheiroids Anhanguera and Coloborhynchus. The sizes of the sacral and notarial neural canals are compared and considered within interpretations of palaeoecology and locomotion, following previous studies. The relatively large sacral neural canal of Vectidraco implies a sacral enlargement for innervation of the legs and lumbosacral plexus. When compared with Anhanguera, this supports indications that azhdarchoids were more hindlimb‐proficient than ornithocheiroids. Neural canal size in the Coloborhynchus notarium suggests that ornithocheirids spent less time on the ground, their brachial enlargement and small sacral region indicating enhanced innervation of the wings and poor innervation of the sacrum and legs. This is the first study focusing on pterosaur postcranial palaeoneurology; more studies on other taxa are needed to reveal patterns across Pterosauria as a whole.     

The Aboriginal Eskimo Diet in Modern Perspective

The aboriginal diet of the Arctic Eskimo, which consisted mainly of land and sea mammals and fish, is analyzed with respect to its capacity to provide the nutrients now regarded as essential for nutritional health. It is concluded that, despite its remarkably restricted composition, the native diet is capable of furnishing all the essential nutritional elements when prepared and consumed according to traditional customs. However, its low carbohydrate and high protein content necessitated major metabolic adaptations in energy and nitrogen metabolism. Erosion of the traditional diet culture and life style has been accompanied by a decline in nutritional status. [Eskimo, diet, nutrition]     

The St. Lawrence Island Eskimos: genetic variation and genetic distance

The Eskimos of St. Lawrence Island have been typed for genetic variation at 44 discrete genetic loci. Three private polymorphisms, at the 2,3-diphosphoglycerate mutase, peptidase B, and purine nucleoside phosphorylase loci, have been observed, which may be useful in future studies of genetic relationships between Eskimos and other circumpolar populations. Genetic distance analysis reveals a close relationship between the St. Lawrence Island Eskimos and other Eskimo populations and that the Eskimo populations form a distinct cluster from Amerindian populations. The St. Lawrence Island Eskimos appear to be more similar to Asiatic Eskimos than to other groups. Caucasian admixture in this population is estimated to be between 2 and 7%.     

Pneumonia in Indian and Eskimo Infants and Children: Part I. A Clinical Study

Ninety-seven Indian and Eskimo infants and children who suffered 112 episodes of pneumonia were the subjects of a prospective study carried out at the Charles Camsell Hospital, Edmonton, Alberta, from August 1963 until August 1964. Investigation included viral studies and an evaluation 10 days after admission. The patients were divided into four diagnostic categories and a comparison was made between cases of bacterial and viral origin. The frequency of right-sided disease, particularly of the upper lobe and/or dependent segment involvement, is described. An evaluation of physical signs is attempted. The problem of recurrent pneumonia and the differential diagnosis of tuberculosis in Indian and Eskimo children with pneumonia is discussed.     

Msx2 and Twist cooperatively control the development of the neural crest-derived skeletogenic mesenchyme of the murine skull vault

The flat bones of the vertebrate skull vault develop from two migratory mesenchymal cell populations, the cranial neural crest and paraxial mesoderm. At the onset of skull vault development, these mesenchymal cells emigrate from their sites of origin to positions between the ectoderm and the developing cerebral hemispheres. There they combine, proliferate and differentiate along an osteogenic pathway. Anomalies in skull vault development are relatively common in humans. One such anomaly is familial calvarial foramina, persistent unossified areas within the skull vault. Mutations in MSX2 and TWIST are known to cause calvarial foramina in humans. Little is known of the cellular and developmental processes underlying this defect. Neither is it known whether MSX2 and TWIST function in the same or distinct pathways. We trace the origin of the calvarial foramen defect in Msx2 mutant mice to a group of skeletogenic mesenchyme cells that compose the frontal bone rudiment. We show that this cell population is reduced not because of apoptosis or deficient migration of neural crest-derived precursor cells, but because of defects in its differentiation and proliferation. We demonstrate, in addition, that heterozygous loss of Twist function causes a foramen in the skull vault similar to that caused by loss of Msx2 function. Both the quantity and proliferation of the frontal bone skeletogenic mesenchyme are reduced in Msx2-Twist double mutants compared with individual mutants. Thus Msx2 and Twist cooperate in the control of the differentiation and proliferation of skeletogenic mesenchyme. Molecular epistasis analysis suggests that Msx2 and Twist do not act in tandem to control osteoblast differentiation, but function at the same epistatic level.