Craniometric Data Research Articles

Understanding race and human variation: Why forensic anthropologists are good at identifying race

American forensicanthropologists uncritically accepted the biological race concept from classic physical anthropology and applied it to methods of human identification. Why and how the biological race concept might work in forensic anthropology was contemplated by Sauer (Soc Sci Med 34 1992 107-111), who hypothesized that American forensic anthropologists are good at what they do because of a concordance between social race and skeletal morphology in American whites and blacks. However, Sauer also stressed that this concordance did not validate the classic biological race concept of physical anthropology that there are a relatively small number of discrete types of human beings. Results from Howells (Papers of the Peabody Museum of Archaeology and Ethnology 67 1973 1-259; Papers of the Peabody Museum of Archaeology and Ethnology 79 1989 1-189; Papers of the Peabody Museum of Archaeology and Ethnology 82 1995 1-108) and others using craniometric and molecular data show strong geographic patterning of human variation despite overlap in their distributions. However, Williams et al. (Curr Anthropol 46 2005 340-346) concluded that skeletal morphology cannot be used to accurately classify individuals. Williams et al. cited additional support from Lewontin (Evol Biol 6 1972 381-398), who analyzed classic genetic markers. In this study, multivariate analyses of craniometric data support Sauer's hypothesis that there are morphological differences between American whites and blacks. We also confirm significant geographic patterning in human variation but also find differences among groups within continents. As a result, if biological races are defined by uniqueness, then there are a very large number of biological races that can be defined, contradicting the classic biological race concept of physical anthropology. Further, our results show that humans can be accurately classified into geographic origin using craniometrics even though there is overlap among groups.

Estimating the probability that the sample mean is within a desired fraction of the standard deviation of the true mean

The use of small sample sizes in human and primate evolutionary research is commonplace. Estimating how well small samples represent the underlying population, however, is not commonplace. Because the accuracy of determinations of taxonomy, phylogeny, and evolutionary process are dependant upon how well the study sample represents the population of interest, characterizing the uncertainty, or potential error, associated with analyses of small sample sizes is essential. We present a method for estimating the probability that the sample mean is within a desired fraction of the standard deviation of the true mean using small ( n < 10) or very small ( n ≤ 5) sample sizes. This method can be used by researchers to determine post hoc the probability that their sample is a meaningful approximation of the population parameter. We tested the method using a large craniometric data set commonly used by researchers in the field. Given our results, we suggest that sample estimates of the population mean can be reasonable and meaningful even when based on small, and perhaps even very small, sample sizes.

Foramen magnum angle and its effect on visual field in two Apodemus murids

Abstract In rodents, an adaptation for biting off hard materials, accompanied by extension of the masseter origin anterior to the orbit, might interfere with vision in the anteroventral direction. In arboreal rodents, the anatomy must be modified somewhat to allow for the clear anteroventral vision necessary to safely descend from, or move about on trees. In the present study, we tested this hypothesis by comparing the craniometric data between two Apodemus murids, semiarboreal A. argenteus and terrestrial A. speciosus. Based on the correlation between the index of relative encephalization (IRE; cube root of the brain case volume divided by the basicranial length) and the angle of the foramen magnum, the head in A. argenteus is situated so that the snout is more depressed than in A. speciosus, which has the same IRE value. The head posture of A. argenteus does not seem to be due to the relative brain size, but rather to a semiarboreal adaptation that ensures clear anteroventral vision by lowering the ante...

Craniometric evidence for South African Later Stone Age herders and hunter–gatherers being a single biological population

Later Stone Age (LSA) hunter–gatherers and herders co-existed in South Africa during the last 2000 years. In spite of being the focus of intensive research over the years, the biological status and origins of the herders are still unclear. Did they represent a genetically distinct immigrant population who remained separate from the indigenous hunter–gatherers, or where they indigenous hunter–gatherers who took up herding after contact with herders, probably in northern Botswana? Here, this issue is investigated using craniometric data collected on a large sample of individually dated human crania from coastal LSA context. Mahalanobis distances ( D), calculated from the raw metric data, show that there was a small increase in inter-individual craniofacial variation after the introduction of herding at ca. 2000 BP. Here it is argued that this small increase in variation is neither consistent with a large-scale immigration of genetically distinct herders into South Africa, or the long-term co-existence of two genetically distinct populations. Two alternative explanations fit the data better: (1) herding entered South Africa via the small-scale immigration of genetically distinct herders; and (2) local hunter–gatherer populations adopted herding after coming in contact with herders in northern Botswana. While small-scale immigration would not have had a major influence on the local gene pool, it would have increased variation to some extent as immigrants mixed with local populations. If small-scale external gene flow was not a factor in the introduction of herding, secular issues related to the introduction of herding could explain the increased variation in post-2000 BP populations.

Age, sex and body mass index in relation to calvarial diploe thickness and craniometric data on MRI

It might be critical to determine sex, body mass and age of the individual from skull in forensic medicine and anthropology. Our purpose in this study was to evaluate whether a relationship existed between the diploeic bone thickness measured from glabella, bregma, lambda, opisthocranion, and euryon regions and sex, age and body mass index of the individual. Glabella–opisthocranion, vertex–basion, euryon–euryon, basion–opisthion length were also determined for the same purpose. The anthropological landmarks were determined on sagittal and axial T1-weighted sequences and measurements were obtained on a workstation by two radiologists. A total of 107 subjects (F/M:59/48; mean age: 45.05 ± 15.28, age range: 21–81) were included in the study. The mean body mass index was 25.51 ± 4.44 [17.50–41]. There was a statistically significant linear correlation between age and diploe thickness from glabella, bregma, lambda, opisthocranion, right and left euryon. There was sexual dimorphism in all craniometric data including the distance between glabella–opisthocranion, vertex–basion, euryon–euryon, basion–opisthion, and calvarial volume. There was a statistically significant linear correlation between body mass index and basion–opisthion length. The diploe thicknesses from certain points of the calvarium are statistically related to each other. A standard cerebral MRI examination would be sufficient to obtain anthropological landmarks and craniometric data. According to this study, it might be possible to identify age, sex and body mass index of the individual from diploeic thickness and craniometric data.

Variability of the Upper Palaeolithic skulls from Předmostí near Přerov (Czech Republic): Craniometric comparison with recent human standards

One of the largest skeletal series of the Upper Palaeolithic period from Předmostí was destroyed during the Second World War, but the study of this material continues up to the present. The discovery of Matiegka's original photographic documentation on glass plates [Velemínská et al., 2004. The use of recently re-discovered glass plate photo-documentation of those human fossil finds from Předmostí u Přerova destroyed during World War II. J. Nat. Mus. Nat. Hist. Ser. 173, 129–132] gives an opportunity to perform a new and detailed craniometric analysis of five adult skulls in their lateral projection. The craniometric data were analysed using specialised Craniometrics software, and the analysis included morphological and dimensional comparisons with current Central European norms. The aim of the study was not only to monitor the skull shape as a whole, but predominantly, to evaluate the size and shape of various parts of the splanchnocranium. The Upper Palaeolithic skulls are significantly longer, and male skulls are also higher than the current norms. The crania of anatomically modern humans are characterised by two general structural features: mid-lower facial retraction and neurocranial globularity. The height of the face of the Palaeolithic skulls corresponds to that of the current Central European population. The face has a markedly longer mandibular body (3–4 SD), while female mandibular rami are shorter. The skulls are further characterised by a smaller gonial angle, the increased steepness of the mandibular ramus, and the greater angle of the chin. These changes in the size and shape associated with anterior rotation of the face produce a strong protrusion of both jaws, but the sagittal inter-maxillary relationships remain unchanged. The observed facial morphology is similar to the Czech Upper Palaeolithic skulls from Dolní Věstonice. This study confirms the main diachronic changes between skulls of Upper Palaeolithic and present-day human populations.

Brief Communication: Human cranial variation fits iterative founder effect model with African origin

Recent studies comparing craniometric and neutral genetic affinity matrices have concluded that, on average, human cranial variation fits a model of neutral expectation. While human craniometric and genetic data fit a model of isolation by geographic distance, it is not yet clear whether this is due to geographically mediated gene flow or human dispersal events. Recently, human genetic data have been shown to fit an iterative founder effect model of dispersal with an African origin, in line with the out-of-Africa replacement model for modern human origins, and Manica et al. (Nature 448 (2007) 346-349) have demonstrated that human craniometric data also fit this model. However, in contrast with the neutral model of cranial evolution suggested by previous studies, Manica et al. (2007) made the a priori assumption that cranial form has been subject to climatically driven natural selection and therefore correct for climate prior to conducting their analyses. Here we employ a modified theoretical and methodological approach to test whether human cranial variability fits the iterative founder effect model. In contrast with Manica et al. (2007) we employ size-adjusted craniometric variables, since climatic factors such as temperature have been shown to correlate with aspects of cranial size. Despite these differences, we obtain similar results to those of Manica et al. (2007), with up to 26% of global within-population craniometric variation being explained by geographic distance from sub-Saharan Africa. Comparative analyses using non-African origins do not yield significant results. The implications of these results are discussed in the light of the modern human origins debate.

Biogeochemical and craniometric investigation of dietary ecology, niche separation, and taxonomy of Plio‐Pleistocene cercopithecoids from the Makapansgat Limeworks

Three sympatric fossil cercopithecoid genera (Cercopithecoides, Parapapio, and Theropithecus) occur in Members 3 and 4 at the Makapansgat Limeworks hominin locality, South Africa, and their presence in a single ecosystem suggest a certain degree of ecological and/or dietary differentiation between taxa. Here, we explore the extent of dietary niche separation amongst these taxa using stable isotope (13C/12C, 18O/16O) and trace-element (Sr, Ba, Ca) analyses of fossil tooth enamel. In particular we searched for evidence of subtle niche separation between the more closely related, morphologically similar taxa of the genus Parapapio, as uncertainties exist around their taxonomy and taxonomic identification. Given these uncertainties, craniometric analyses were also performed to ground the dietary interpretations in a morphological context. The results found no clear taxonomic signal in the craniometric data for the Parapapio sample, and further indicate that this sample was no more variable morphologically than a single, geographically circumscribed, extant chacma baboon sample. In contrast, two overlapping dietary ecologies were found within this same Makapansgat Parapapio sample. Additionally, two widely differing dietary ecologies were found within the Cercopithecoides williamsi sample, while results for Theropithecus darti indicate a predominantly C4 diet. Hence, although biogeochemical dietary indicators point towards distinct dietary ecologies within and between fossil genera at Makapansgat, within the genus Parapapio disjunctions exist between the dietary categories and the taxonomic assignment of specimens.

Craniofacial variation and population continuity during the South African Holocene

We assess craniometric variation in 153 individually dated human crania from South Africa with the aim of investigating genetic continuity/discontinuity during the Holocene. Evidence from the archaeological record is used to pinpoint likely episodes of genetic discontinuity. Craniometric data are then used to assess the likelihood of genetic change having occurred. Two periods of possible genetic discontinuity are identified: i) c. 4,000 BP, when an increase in overall population size, shifts in site organization and diet, and reduced mobility, were accompanied by reductions in stature; ii) c. 2,000 BP, when the herding of domesticates and the use of pottery vessels were introduced into the region. Results indicate that there was a decrease in cranial size and concomitant size-related changes in craniofacial shape between c.4,000 BP and 3,000 BP. This was followed almost immediately by a recovery in craniofacial size and a return to pre-4,000 BP craniofacial shape at c. 3,000 BP. This recovery continued gradually, extending into the herder period without any major shifts in morphology at 2,000 BP. It is suggested that the fluctuations in craniofacial size/shape were related to changes in environmental factors. Results obtained are consistent with long term continuity in South African Later Stone Age populations during the Holocene.

Evolutionary Relationships Among Prehistoric Human Populations: An Evaluation of Relatedeness Patterns Based on Facial Morphometric Data Using Molecular Data

The study of evolutionary relationships among human populations is fundamental to inferring processes that determine their structure and history. Among the different data types used to infer such relationships, molecular data, particularly nuclear and mitochondrial DNA, are preferred because of their high heritability and the low probability of changes during development. However, although the reliability of relatedness patterns based on other traits is discussed, except in unusual circumstances most prehistoric populations remain within the domain of morphological study. Therefore the primary goal of this study is to test the reliability of relatedness patterns constructed on the basis of craniometric data on a regional scale. In particular, we analyze samples from populations belonging to the Chaco, Pampa, and Patagonia regions of South America for which craniometric and molecular data are available. We compare a strongly supported relatedness pattern based on molecular data with the results obtained through landmark-based and semilandmark-based facial data. The matrices based on Euclidean distance for morphometric data and DA distances for molecular data were used to perform principal coordinates analyses and to obtain reticulograms. Finally, a principal components analysis of all individuals was performed with morphometric data. The results indicate that ordination analyses yield slightly different results depending on the morphometric data used. However, the reticulograms obtained with both landmark-based and semilandmark-based data allow the separation of the Chubut samples from the Chaco samples, with the Pampa sample in between the others; this pattern is congruent with molecular-based analyses. As a consequence, our results indicate that facial morphometric data allow the inference of the structure and history of the prehistoric populations for the studied region.

The status of Otomys orestes dollmani Heller, 1912 (Muridae: Otomyinae), a rodent described from the Mathews Range, central Kenya

Morphological and morphometric comparisons of Otomys orestes dollmani, known only from Mount Gargues in the Mathews Range, central Kenya, indicate that the taxon is a valid species distinct from other African forms under which it has been previously synonymized (O. irroratus, O. orestes, O. tropicalis). Based also on these comparisons, the morphological recognition and distribution of O. orestes (including thomasi Osgood) are further clarified in relation to O. tropicalis (including elgonis Wroughton) in Kenyan mountains and O. typus proper in Ethiopian highlands; another taxon relegated to junior synonymy within O. typus, O. uzungwensis Lawrence and Loveridge from south-central Tanzania, is resurrected to species. Certain traditional characters used in Otomys taxonomy, in particular molar lamination, demonstrate conservative patterns of variation that complement spatial structure derived from morphometric analyses of craniometric data and that vindicate their continued utility in delimiting species. We argue that uncritical emphasis of polytypic species, applied following the biological species concept during the latter 1900s, has led to chronic underestimation of species diversity of Otomys confined to the Afromontane Biotic Region in eastern Africa, in particular those populations that inhabit afroalpine environments.

Differences between sliding semi‐landmark methods in geometric morphometrics, with an application to human craniofacial and dental variation

Over the last decade, geometric morphometric methods have been applied increasingly to the study of human form. When too few landmarks are available, outlines can be digitized as series of discrete points. The individual points must be slid along a tangential direction so as to remove tangential variation, because contours should be homologous from subject to subject whereas their individual points need not. This variation can be removed by minimizing either bending energy (BE) or Procrustes distance (D) with respect to a mean reference form. Because these two criteria make different assumptions, it becomes necessary to study how these differences modify the results obtained. We performed bootstrapped-based Goodall's F-test, Foote's measurement, principal component (PC) and discriminant function analyses on human molars and craniometric data to compare the results obtained by the two criteria. Results show that: (1) F-scores and P-values were similar for both criteria; (2) results of Foote's measurement show that both criteria yield different estimates of within- and between-sample variation; (3) there is low correlation between the first PC axes obtained by D and BE; (4) the percentage of correct classification is similar for BE and D, but the ordination of groups along discriminant scores differs between them. The differences between criteria can alter the results when morphological variation in the sample is small, as in the analysis of modern human populations.

Late Chachapoya population structure prior to Inka conquest

Archaeological and ethnohistorical documents suggest that the Chachapoya region was inhabited by a number of distinct sociopolitical groups that only united in the face of their common enemy, the Inka. The purpose of this research is to quantify the amount of internal genetic differentiation and levels of extraregional gene flow during the Late Chachapoya period, in order to obtain a better understanding of the genetic relationship between these presumed ethnic groups. Craniometric data were collected from three Late Chachapoya samples (Laguna Huayabamba, Kuelap, and Laguna de los Cóndores), in order to understand the genetic relationships between the groups and facilitate our understanding of Late Chachapoya population structure. Genetic differentiation among these series ranged from 0.047 (heritability = 1.0) to 0.090 (heritability = 0.55). The Relethford-Blangero residuals indicate that the Laguna Huayabamba and Laguna de los Cóndores populations were receiving greater than average external gene flow, while Kuelap was receiving less than average external gene flow. The correspondence between biological and archaeological data in the investigation of prehistoric ethnic identity is discussed.

East–West cranial differentiation in pre-Columbian human populations of South America

South Amerindians are frequently thought of as a rather biologically homogeneous megapopulation. However, when native South Americans are assessed by information coming from DNA variability analysis, they resolve into two, major distinct entities of Eastern and Western zones. The purpose of this study is to investigate if the same dual pattern emerges from craniometric data. We approached this question by means of functional craniometric variables. We found strong evidence that Westerners and Easterners constitute two distinct and independent microevolutionary universes when cranial morphology is assessed. The existence of a third universe, Northwest, cannot be completely ruled out, but needs further investigation. We also discovered that Westerners and Easterners present similar degrees of internal variation, contrary to the findings of geneticists and molecular biologists. Palaeoamericans seem to be more similar to Easterners than to Westerners and North-Westerners. Our results suggest that this East–West cranial differentiation is more probably the result of differential rates of genetic drift and gene flow acting on each side of the Cordillera. However, different intensities of gene flow between Palaeoamericans and Amerindians in the highlands and in the lowlands cannot be completely dismissed as a possible explanation for the differentiation found.

Systematics of African lowland rainforest Praomys (Rodentia, Muridae) based on molecular and craniometrical data

Representatives of the genus Praomys occur throughout the African intertropical zone. It is unclear how many species this genus contains, nor do we know the exact distribution ranges and phylogenetic relationships of these taxa. Using molecular (16S rRNA gene sequencing) and morphological (multivariate craniometry) analyses we clarify the taxonomy and phylogenetic relationships among the Praomys occurring in Africa's lowland tropical rainforests. We studied most species known from this area, based on specimens collected in seven countries (Guinea, Ivory Coast, Cameroon, Central African Republic, Gabon, Congo Republic and Democratic Republic of Congo). In our study, Praomys appears to be monophyletic. Our results identify two species complexes: the jacksoni complex includes at least two species (P. jacksoni and P. mutoni) and the tullbergi complex contains at least four species (P. tullbergi, P. rostratus, P. misonnei, P. petteri). Although the 16S rRNA gene appears insufficient to resolve the phylogenetic relationships among all the members of the tullbergi species complex, it is suitable for the identification of most of the studied species, and its use has allowed us to redefine the geographical limits of several species. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 539–553.

Comparison of skull measurements and sexual dimorphism between the Minorcan pine marten ( Martes martes minoricensis) and the Iberian pine marten ( M. m. martes): A case of insularity

The sub-species Martes martes minoricensis was described using craniometric data being larger in size than populations living on the European continent ( M. m. martes). A new sample of 39 animals (22 males and 17 females) of this sub-species from Minorca was pooled by sex and age, and 26 craniometric variables were analysed and compared with 104 Iberian pine martens (73 males and 31 females). Age was determined through readings of the cementum layers of the teeth, enabling distinctions to be made between adult and young animals. Further data is shown regarding the characterisation of the sub-species in terms of these measurements and its sexual dimorphism for these variables. The values obtained enable us to identify the larger size of the Minorcan individuals, both males and females, in relation to those from the mainland, there being a development in the longitudinal characters of the facial bones. With regard to sexual dimorphism, the differences are similar to those found on the continent, males being on average 10.6% larger than females. However, we also found notable differences at the level of the facial bones. Some hypotheses regarding this segregation between the sexes and the larger size of individuals in relation to continental populations are discussed.

Metric dental variation of major human populations

Mesiodistal and buccolingual crown diameters of all teeth recorded in 72 major human population groups and seven geographic groups were analyzed. The results obtained are fivefold. First, the largest teeth are found among Australians, followed by Melanesians, Micronesians, sub-Saharan Africans, and Native Americans. Philippine Negritos, Jomon/Ainu, and Western Eurasians have small teeth, while East/Southeast Asians and Polynesians are intermediate in overall tooth size. Second, in terms of odontometric shape factors, world extremes are Europeans, aboriginal New World populations, and to a lesser extent, Australians. Third, East/Southeast Asians share similar dental features with sub-Saharan Africans, and fall in the center of the phenetic space occupied by a wide array of samples. Fourth, the patterning of dental variation among major geographic populations is more or less consistent with those obtained from genetic and craniometric data. Fifth, once differences in population size between sub-Saharan Africa, Europe, South/West Asia, Australia, and Far East, and genetic drift are taken into consideration, the pattern of sub-Saharan African distinctiveness becomes more or less comparable to that based on genetic and craniometric data. As such, worldwide patterning of odontometric variation provides an additional avenue in the ongoing investigation of the origin(s) of anatomically modern humans.

A Regional Biological Approach to the Spread of Farming in Europe

This article examines the potential contribution of archaeological human skeletal material, in particular craniometric data, to interpretations of the nature of the transition to farming in Europe. The material is discussed particularly in relation to recent debates about demographic variables and processes and modern genetic frequency patterns. It is suggested that biological morphometrics enables the comparison of ancient populations on a regional basis. Analysis of the material suggests that there was considerable morphological heterogeneity among the earliest farmers of the Levant belonging to the PrePottery Neolithic but that similar variability is generally not seen among the earliest mainland agriculturalists of southeastern Europe. We propose that this may be explained by the existence of a genetic bottleneck among Anatolian populations and that it supports models of the largely exogenous origin of many early Neolithic populations in this region. Regional comparisons further demonstrate a biologic...

Boas and beyond: migration and craniometric variation.

Migration is expected to affect craniometric variation in three ways: 1) movement into a different environment leading to developmental plasticity; 2) movement into a different environment followed by in situ adaptation through natural selection; and 3) changes in among-group differentiation and genetic distance through the action of gene flow. The relative influence of these three factors has been argued in the literature, most recently in a series of articles debating the statistical and biological significance of Boas's immigration studies as they relate to cranial plasticity. The Boas debate is discussed within the broader context of debate over genetic and environmental influences on craniometric variation. Additional examples are provided from an ongoing study of global craniometric variation. Although developmental plasticity and climatic adaptation have had an impact on craniometric variation, these factors tend not to erase, or even obscure greatly, underlying patterns of population structure and history that fit a neutral model of quantitative variation. Thus, craniometric data can be used to explore questions of gene flow and genetic affinity.

Morphometrical relationships between South‐east Asian deer (Cervidae, tribe Cervini): evolutionary and biogeographic implications

AbstractTwo hundred and fourteen skulls of Asian deer species (Cervini) were measured and the resulting craniometric data analysed using multivariate statistics. Our results suggest that elements of skull shape as determined by morphometrics can be used as phylogenetic characters and depict phylogenetic relationships among Cervini deer species that is not far removed from the picture given by molecular studies and other characters. Morphometrics‐based phylogeny was used in combination with other phylogenies and palaeoenvironmental reconstructions to investigate factors that may have influenced evolutionary changes. Our data indicate the need for a revision of the genus and subgenus level taxonomy of the Cervini.