Climatic influence on the skeletal nasal aperture

Abstract Climate is thought to be one of the factors affecting the distribution of nasal form as represented by the breadth and height of the skeletal nasal aperture. A model of nasal function is developed to predict influences on the skeletal nasal dimensions by selection acting upon the external nasal passage and aperture. Cranial series from Alaska and Australia, each series representing a climatic continuum from warmer and moister conditions to cooler and drier conditions, verify the predictions. These data suggest conditions for testing hypotheses about human variation.     

Nasal shape,prognathism and adaptation in man

The association between nasal shape, prognathism and the shape of the maxillary dental arch has been examined within samples of Negro and European skulls. Prognathism tends to be accompanied by an increasingly broad and short nose. Particularly high correlations exist between nasal height and the length of the cranial base and between nasal breadth and the distance which separates the upper canine teeth. Regression analysis has yielded quantitative estimates of the effect on a given dimension of variation in one or more of the others. It seems probable that both nasal shape and the maxillary dental arch-prognathism complex may be subject to direct selection by environmental stress. The morphological association between these complexes suggests that a part of the interpopulation variation in prognathism may be a secondary effect of selection acting on the nose. Similarly, selection acting on the dental arch or maxilla could produce secondary changes in the nasal index (i.e. a non-adaptive component of nasal variation).     

Technical note: Comparability of Hrdlička's Catalog of crania data based on measurement landmark definitions

Archival sources of data are critical anthropological resources that inform inferences about human biology and evolutionary history. Craniometric data are one of the most widely available sources of information on human population history because craniometrics were critical in early 20th century debates about race and biological variation. As such, extensive databases of raw craniometric data were published at the same time that the field was working to standardize measurement protocol. Hrdli?ka published between 10 and 16 raw craniometric variables for over 8,000 individuals in a series of seven catalogs throughout his career. With a New World emphasis, Hrdli?ka's data complement those of Howells ( 1973 , 1989 ) and the two databases have been combined in the past. In this note we verify the consistency of Hrdli?ka's measurement protocol throughout the Catalog series and compare these definitions to those used by Howells. We conclude that 12 measurements are comparable throughout the Catalogs, with five of these equivalent to Howells' measurements: maximum cranial breadth (XCB), basion‐bregma height (BBH), maximum bizygomatic breadth (ZYB), nasal breadth (NLB), and breadth of the upper alveolar arch (MAB). Most of Hrdli?ka's measurements are not strictly comparable to those of Howells, thus limiting the utility of combined datasets for multivariate analysis. Four measurements are inconsistently defined by Hrdli?ka and we recommend not using these data: nasal height, orbit breadth, orbit height, and menton‐nasion height. This note promotes Hrdli?ka's tireless efforts at data collection and re‐emphasizes observer error as a legitimate concern in craniometry as the field shifts to morphometric digital data acquisition. Am J Phys Anthropol, 2011. © 2011 Wiley‐Liss, Inc.     

Physical characteristics of Chinese Hakka

Using standard and internationally validated methods,86 anthropologic characteristics were determined in 650 male(305 from urban areas and 345 from rural areas) and 704 female(331 from urban areas,373 from rural areas) Chinese Hakka adults living in Guangdong and Jiangxi.The data were used to calculate 24 anthropologic indices,which were analyzed statistically.The physical characteristics of Hakka subjects were analyzed and compared with reference ethnic data.There were four main findings of this study.First,a small proportion of Hakka adults had an eye fold on the upper eyelid,but a large proportion had a mongoloid fold.The eye slits were narrow in most adults,had a medium nasal root height and straight bridges,and most of the external angles were prominent.The nasal base was upturned in most men.The distributions of the three types of nasal base in women were similar.The proportions of subjects with middle and high alae nasi heights were high and similar.Males with a maximum nostril diameter were mostly classified as transverse and oblique,while many women were classified as transverse and had relatively wide alae nasi.The round lobe type was the most common.Upper lip skin height was mostly classified as medium.Lips were classified as thin.The hair was black,eyes were brown,and the skin was yellowish.Second,the head length was long in male Hakka.The minimum frontal breadth,face breadth,lip height,and interocular breadth were similar to those of North-Asian populations.Meanwhile,head breadth,morphological facial height,nose breadth,mouth breadth,and nose height were similar to those of South-Asian populations.Head length was long in female Hakka.The minimum frontal breadth,face breadth,lip height,and interocular breadth were similar to those of North-Asian populations.Head breadth,nose breadth,and mouth breadth were similar to those of South-Asian populations.Third,the stature of male and female Hakka in urban and rural areas was classified as medium.The proportions of male and female Hakka classified as mesocephaly(length-breadth index of the head),hypsicephalic type,metriocephalic type(breadth-height index of the head) mesorrhiny,long trunk,subbrachyskelic type,broad shoulder breadth,and narrow distance between iliac crests were higher than those of other types.Finally,principal component analyses showed that the physical characteristics of Hakka were between those of South-Asian and North-Asian ethnic populations,but were generally closer to those of North-Asian populations in China.     

Anthropometric studies in Brazilian Cayapo Indians

Results of 16 measurements and 7 indices obtained from 130 men and 156 women belonging to three populations of Brazilian Indians are reported. For both males and females the averages for stature and head breadth are in the middle of the distribution range of values observed in other South American tribes; those for head length and nasal height are relatively low but the averages for sitting height, calf circumference and minimum frontal breadth are high. As for the indices, in both sexes the cephalic and cephalofacial are medium, the Rohrer, jugomandibularis and facial low, and the nasal high when compared with other tribes. Morphological distances between the three Cayapo populations were estimated using Mahalanobis' D² statistic; they are smaller than those separating different tribes and are not the expected ones when the demographic variables of these groups and the geographic distances between them are considered. The amount of variability as expressed by the coefficient of variation and the prevailing pattern of sexual dimorphism are similar to those observed in other Indian populations.     

Geographic patterns of craniofacial variation in pre-Hispanic populations from the Southern Cone of South America

In this study we analyzed the relationships and patterns of spatial variation from morphological cranial variability of 17 population samples representing the ancient inhabitants of the central territory of Argentina (archaeologically known as "Sierras Centrales") and other pre-Hispanic populations from different ecological and geographic regions of the Southern Cone of South America (Argentina and Uruguay), based on the analysis of 10 craniofacial measurements. Results obtained from D2 distances can be interpreted as evidence of a similar biological history for the populations that inhabited the Sierras Centrales and the population of Santiago del Estero. Matrix correlation analysis demonstrated that craniometric variation is significantly influenced by geography, suggesting that populations that lived at lower geographical distance share more biological similarity. Global spatial autocorrelation analysis suggests a clinal pattern for the biological variation, although Moran's I estimates calculated for each variable demonstrate that only nasal height and breadth show this spatial pattern of variation. Results from spatial regression techniques show a significant effect of altitude modeling nasal shape, in agreement with previous studies suggesting that nasal morphology is strongly influenced by environment variables.     

Gene flow and variation in stature and craniofacial dimensions among indigenous populations of southern Mexico, Guatemala, and Honduras

Populations with histories of outbreeding tend to be taller even in the face of seemingly unchanged health and nutritional circumstances, while inbreeding generally results in a negative correlation between body dimensions and level of inbreeding. Populations that have experienced a positive secular trend in stature and maturation typically have histories of higher outbreeding rates in combination with improved nutritional, health, and economic conditions, suggesting a genetic-environment interaction. In general, Middle American Indians have not experienced a secular trend in stature, nor a substantial increase in their standard of living, but they have experienced varying degrees of admixture with Spanish and African populations since the Spanish Conquest. The relationship between estimated gene flow and variation in several anthropometric dimensions is thus considered in indigenous Mesoamerican populations. Available data on height, sitting height, craniofacial dimensions, and admixture rate of Indian populations from southern Mexico, Guatemala, and Honduras were assembled from the literature. The population mean data on 3,371 adults from 23 populations for males and 18 for females were analyzed by regression with anthropometry as the dependent variable, and log10 of admixture as the independent variable. Admixture was less than or equal to 28.9% in this study and is suggestive of a primarily traditional Indian cultural and economic base. The results suggest that populations with higher admixture tend to be taller, and that the increase in stature is due to greater subischial length in both sexes. A decrease in nasion-menton height, and an increase in nasal breadth, nasal height, and the nasal index is suggested for the dimensions of the craniofacial complex.(ABSTRACT TRUNCATED AT 250 WORDS)     

Influence of cranial deformation on facial morphology among prehistoric South Central Andean populations

Calculating biodistances among South American populations using cranial measurements is often hindered, as many available skeletal collections exhibit deformation. Acknowledging vault modifications, researchers have sought measurements in other regions which are unaffected by deformation. In the 1970s, a set of 10 "relatively" unaffected facial measurements was identified in Argentinean crania that later became the basis of numerous South American biodistance studies. These measurements include: minimum frontal breadth, bizygomatic breadth, orbit height, orbit breadth, palate breath, palate length, upper facial height, basion-prosthion length, nasal height, and nasal breadth. Palate length was excluded from the present analysis due to considerable measurement error. The suitability of these measurements in populations other than Argentineans has not been rigorously tested. Using a sample of 350 prehistoric crania from the Museo Arqueológico San Miguel de Azapa (MASMA, Arica, Chile), this project tested the hypothesis that these measurements are unaffected by either annular or tabular deformation. Results obtained from MANOVA analysis indicate this hypothesis cannot be fully supported. Among males, only 3 of the 9 measurements are unaffected by either form of deformation (palate breadth, basion-prosthion length, and nasal breadth), while analysis of females indicates that 4 of the 9 measurements remain unaltered (minimum frontal breadth, orbit breadth, basion-prosthion length, and nasal breadth). Additionally, analogous to the vault, facial measurements display patterns consistent with the deformation applied. Two implications can be drawn from this research: 1) previous studies using these measurements must be interpreted cautiously, and 2) researchers using these measurements must explicitly test their suitability in each population.     

Ecogeographic variation in human nasal passages

Theoretically, individuals whose ancestors evolved in cold and/or dry climates should have greater nasal mucosal surface area relative to air volume of the nasal passages than individuals whose ancestors evolved in warm, humid climates. A high surface-area-to-volume (SA/V) ratio allows relatively more air to come in contact with the mucosa and facilitates more efficient heat and moisture exchange during inspiration and expiration, which would be adaptive in a cold, dry environment. Conversely, a low SA/V ratio is not as efficient at recapturing heat and moisture during expiration and allows for better heat dissipation, which would be adaptive in a warm, humid environment. To test this hypothesis, cross-sectional measurements of the nasal passages that reflect surface area and volume were collected from a sample of CT scans of patients of European and African ancestry. Results indicate that individuals of European descent do have higher SA/V ratios than individuals of African descent, but only when decongested. Otherwise, the two groups show little difference. This pattern of variation may be due to selection for different SA/V configurations during times of physical exertion, which has been shown to elicit decongestion. Relationships between linear measurements of the skeletal nasal aperture and cavity and cross-sectional dimensions were also examined. Contrary to predictions, the nasal index, the ratio of nasal breadth to nasal height, is not strongly correlated with internal dimensions. However, differences between the nasal indices of the two groups are highly significant. These results may be indicative of different adaptive solutions to the same problem.     

Genetic variation in egg dimensions in natural populations of the Great Tit

Length and breadth of eggs were measured in ringed populations of the Great Tit. During a part of the study volume and weight were also measured, but this did not give additional information, viz. variation in specific weight of fresh eggs and deviations from calculated volume were within the limits of precision. Only in small eggs are length and breadth positively correlated.In two populations, a major part (60–80%) of the variation in the clutch means of egg length, egg breadth, shape index and egg volume is only found between clutches of different females. The absence of correlation between different female partners of one male and the similarity of female repeatability to heritability estimates based on daughter-mother regression lead to the conclusion that 60–80% of the variation in egg dimensions is genetic.The implications for a potential rapid response to selection resulting in a micro-evolutionary change are discussed.     

Anthropometric variation among the reddis of Southern Andhra Pradesh,India

Five select Reddi populations based on 750 males in the age range of 20 to 50 years have been studied for 15 anthropometric measurements and 10 indices. The Pokanati show higher mean value for a majority of the measurements. F-values are significant for all measurements except for bicristal breadth. All indices but nasal index show negligible variation. Mesocephalic heads predominate among Pokanati and dolicocephalic heads among the rest. the cluster analysis and principal coordinate analysis, as diagrammatically represented, show the extent of variation among the five Reddi populations.     

How Humans Differ from Other Animals in Their Levels of Morphological Variation

Animal species come in many shapes and sizes, as do the individuals and populations that make up each species. To us, humans might seem to show particularly high levels of morphological variation, but perhaps this perception is simply based on enhanced recognition of individual conspecifics relative to individual heterospecifics. We here more objectively ask how humans compare to other animals in terms of body size variation. We quantitatively compare levels of variation in body length (height) and mass within and among 99 human populations and 848 animal populations (210 species). We find that humans show low levels of within-population body height variation in comparison to body length variation in other animals. Humans do not, however, show distinctive levels of within-population body mass variation, nor of among-population body height or mass variation. These results are consistent with the idea that natural and sexual selection have reduced human height variation within populations, while maintaining it among populations. We therefore hypothesize that humans have evolved on a rugged adaptive landscape with strong selection for body height optima that differ among locations.     

Family resemblance for cranio-facial measurements in Velanti Brahmins from Andhra Pradesh, India

Maximum likelihood estimates of familial correlations are presented for 12 cranio-facial measurements taken on 399 nuclear families from Southern India. Marital resemblance is significantly different from zero for head circumference, head breadth, minimum frontal breadth, bizygomatic breadth, total facial height, and nasal height, but not for bigonial breadth, nose breadth, nose depth, or ear dimensions. All other familial correlations are significantly greater than zero except for the father-daughter correlation for nasal depth. Path analysis with a TAU transmission model with sex effects reveals that family resemblance for head circumference, head length, bigonial breadth, total facial height, and nasal height, but not for bigonial breadth, nose breadth, nose depth, or ear dimensions. All other familial correlations are significantly greater than zero except for the father-daughter correlation for nasal depth. Path analysis with a TAU transmission model with sex effects breadth, and sex effects in transmission were found for head breadth and nose dimensions. Sex effects in this sample may be due to the fact that different anthropometrists were used for male and female subjects.     

A TEST OF THE CONJECTURE THAT G‐MATRICES ARE MORE STABLE THAN B‐MATRICES

The G‐matrix occupies an important position in evolutionary biology both as a summary of the inheritance of quantitative traits and as an ingredient in predicting how those traits will respond to selection and drift. Consequently, the stability of G has an important bearing on the accuracy of predicted evolutionary trajectories. Furthermore, G should evolve in response to stable features of the adaptive landscape and their trajectories through time. Although the stability and evolution of G might be predicted from knowledge of selection in natural populations, most empirical comparisons of G‐matrices have been made in the absence of such a priori predictions. We present a theoretical argument that within‐sex G‐matrices should be more stable than between‐sex B‐matrices because they are more powerfully exposed to multivariate stabilizing selection. We tested this conjecture by comparing estimates of B‐ and within‐sex G‐matrices among three populations of the garter snake Thamnophis elegans. Matrix comparisons using Flury's hierarchical approach revealed that within‐sex G‐matrices had four principal components in common (full CPC), whereas B‐matrices had only a single principal component in common and eigenvalues that were more variable among populations. These results suggest that within‐sex G is more stable than B , as predicted by our theoretical argument.     

GENOTYPE-BY-ENVIRONMENT INTERACTIONS FOR FITNESS OF ERIGERON ANNUUS SHOW FINE-SCALE SELECTIVE HETEROGENEITY

The results of natural selection depend critically on whether variation in fitness is finegrained or coarse-grained with respect to dispersal, but little is known of the spatial scale of fitness variation in natural populations. For most evolutionary questions, environmental heterogeneity must be defined by reversals in the relative fitness of genotypes; absolute fitness may vary, but if genotypes respond in parallel then selection is uniform. Thus, measurements of genotype-by-environment (G × E) interactions for fitness are necessary to understand patterns of variation in natural selection.     

The paradox of a wide nasal aperture in cold-adapted Neandertals: a causal assessment

Neandertals have been characterized as possessing features indicative of cold-climate adaptation largely based on ecogeographical morphological patterning found in recent humans. Interestingly, one character that deviates from this pattern is a relatively wide nasal aperture. The ecogeographical patterning of the nasal aperture in recent humans would predict instead that Neandertals should exhibit reduced nasal breadth dimensions. To explain this apparent anomaly it has been argued that a reduction in Neandertal nasal breadth was not possible due to dentognathic constraints on their midfaces via large anterior palatal breadth dimensions, especially large intercanine distances. A complicating factor in understanding the relationship between anterior palate breadth and nasal breadth is that both measurements are also correlated with facial prognathism. It is, therefore, unknown to what degree the relationship between anterior palate breadth and nasal breadth in Neandertals is a function of the pleisiomorphic retention of a prognathic facial skeleton. We used path analysis to test for a causal relationship between intercanine breadth and nasal breadth taking into account the potential effect of facial projection and facial prognathism (i.e., basion-nasion length and basion-prosthion length) using a large sample of geographically diverse recent and fossil Homo. Additionally, we examined the ontogenetic relationship between nasal breadth and intercanine breadth using a longitudinal human growth series to determine whether these variables exhibit similar growth trajectories. The results of these analyses indicate a weaker association between intercanine breadth and nasal breadth than expected, and that more variation in nasal breadth can be explained through basion-prosthion length rather than anterior palatal breadth dimensions. Moreover, the ontogenetic development of anterior palate breadth does not correspond to the growth trajectory of the breadth of the nose. These results explain the apparent paradox of wide piriform apertures in generally cooler climate-adapted Neandertals without resorting to dentognathic constraints, and provide additional insight into both the adaptive and nonadaptive (i.e., neutral) basis for Neandertal facial evolution.     

The evolution of the phenotypic covariance matrix: evidence for selection and drift in Melanoplus

Phenotypic variation in trait means is a common observation for geographically separated populations. Such variation is typically retained under common garden conditions, indicating that there has been evolutionary change in the populations, as a result of selection and/or drift. Much less frequently studied is variation in the phenotypic covariance matrix (hereafter, P matrix), although this is an important component of evolutionary change. In this paper, we examine variation in the phenotypic means and P matrices in two species of grasshopper, Melanoplus sanguinipes and M. devastator. Using the P matrices estimated for 14 populations of M. sanguinipes and three populations of M. devastator we find that (1) significant differences between the sexes can be attributed to scaling effects; (2) there is no significant difference between the two species; (3) there are highly significant differences among populations that cannot be accounted for by scaling effects; (4) these differences are a consequence of statistically significant patterns of covariation with geographic and environmental factors, phenotypic variances and covariances increasing with increased temperature but decreasing with increased latitude and altitude. This covariation suggests that selection has been important in the evolution of the P matrix in these populations Finally, we find a significant positive correlation between the average difference between matrices and the genetic distance between the populations, indicating that drift has caused some of the variation in the P matrices.     

香港地区现代人头骨的研究：性别和地区类型的判别分析

本文报告了香港地区现代中国人头骨测量性状的性别差异情况和香港与太原的男性头骨的差异情况。在此基础上,使用判别分析的方法建立了各自的判别函数,正判率分别达到93.1％和85.3％。它们分别适用于华南头骨的性别鉴定和华南与华北男性头骨的区分。     

从野店人骨论山东三组新石器时代居民的种族类型

<正> 我国人类学家颜訚先生,在研究山东大汶口和西夏侯两组新石器时代人骨特征时,认为这两组居民的体质特征属同一类型,即蒙古大人种中的玻里尼西亚类型。为了弄清楚新石器时代山东地区居民体质的种族类型,作者研究了由山东省博物馆提供野店遗址的新石器时代人骨,并参考颜訚的有关资料,对这个问题作进一步的讨论。     

Morphological Clines and Weak Drift along an Urbanization Gradient in the Butterfly,Pieris rapae

Urban areas are increasing globally, providing opportunities for biodiversity researchers to study the process in which species become established in novel, highly disturbed habitats. This ecological process can be understood through analyses of morphological and genetic variation, which can shed light on patterns of neutral and adaptive evolution. Previous studies have shown that urban populations often diverge genetically from non-urban source populations. This could occur due to neutral genetic drift, but an alternative is that selection could lead to allele frequency changes in urban populations. The development of genome scan methods provides an opportunity to investigate these outcomes from samples of genetic variation taken along an urbanization gradient. Here we examine morphological variation in wing size and diversity at neutral amplified fragment length polymorphisms in the butterfly Pieris rapae L. (Lepidoptera, Pieridae) sampled from the center to the periphery of Marseille. We utilize established and novel environmental correlation approaches to scan genetic variation for evidence of selection. We find significant morphological differences in urban populations, as well as weak genetic structure and decreased genetic diversity in urban versus non-urban sites. However, environmental correlation tests provide little support for selection in our dataset. Our comparison of different methods and allele frequency clines suggests that loci identified as significant are false positives. Although there is some indication that selection may be acting on wing size in urban butterflies, genetic analyses suggest P. rapae are undergoing neutral drift.