The variation of orbit shape has been investigated, especially its role in population classification. However, previous studies that treated orbit shape as a linear metric or non-metric trait have not produced conclusive quantitative data to show whether orbit shape is an accurate reflection of population affinity. Thus, in this study in order to examine regional variation in the orbit shape of contemporary Asian, African, and European populations we use geometric morphometrics with a novel standardization technique. A standardized orbital plane was obtained and each specimen was photographed. The results from this study show that regional variation in orbit shape exists. The Asian orbital contour was generally tall, rounded, and its inferior contour was symmetrical. The European tended to be square and more inclined, with the African being shorter. Moreover, the orbit shape of some specimens from these three regions overlapped. The similarities between the Asian and European samples were much smaller than those between Africans and Asians, or Africans and Europeans. Additionally, intergroup variability was larger on the bones of the maxilla and zygoma which form the inferior contour of the orbit, compared with the frontal bone forming the superior contour. The most variable areas of the orbit concentrate on the internal aspect of the upper margin, on the contours near the frontomalare orbitale and zygomaxillare. The application of geometric morphometrics with the newly developed standardization protocol to examine orbit shape between individuals from different geographic areas, has demonstrated its use to measure quantitatively human orbit shape, variation, and population affinity.
Tail morphology in primates is important for interpreting functional adaptation and phylogeny. Tail length is probably the most remarkable trait. Establishing usable methods to predict the tail length of extinct primates is part of the basis for the reconstruction of primate evolution, particularly of hominoids. Previous studies revealed that sacral morphology often predicts tail length. However, most previous studies have only attempted this by using categories (short, long, etc.). A problem with those studies is that the range of short tail length is wide. Accordingly, this study aimed to quantitatively estimate tail length in catarrhines with intermediate tail lengths. Sacra and proximal caudal vertebrae (first to third) of 89 hybrid individuals between Japanese macaque (Macaca fuscata) and Formosan rock macaque (Macaca cyclopis) were measured. These hybrid macaques were phylogenetically controlled but varied greatly in their relative tail length (tail length/head and body length = 18.8–88.8%), and thus were an excellent sample to obtain general regression formulae to estimate catarrhine tail length. A total of 15 predicting models were devised and five formulae performed well. The utility of these formulae were confirmed by application to 15 species/subspecies of catarrhine taxa.
Most studies of dental microevolution have used the standard methodologies employed in dental anthropology: buccolingual/mesiodistal lengths and the frequencies of non-metric dental traits. In this work we use the occlusal polygon method which is based on a polygon created by linking the four molar cusp apices using digital analysis. This method has been used to identify different evolutionary trends in Neandertal and modern humans; our objective was to assess the existence of changes in the occlusal polygon area, and thus the general morphology of first upper molars, between two Portuguese samples from the Late Neolithic (4130 ± 90 BP) and the early 20th century. This method allows us to evaluate both tooth size and relative cusp position in the occlusal plane. Contrary to the accentuated tooth size reduction commonly found from the past 10000 years using buccolingual/mesiodistal measurements, no statistically significant change of the total occlusal area of the crown was observed between these samples. Nevertheless, we report an increase of 7.45% in the size of the occlusal polygon and hence 9.38% in its relative area, from 27.30% of the total crown area to 30.30% over this time span. This result implies that microevolutionary changes among Portuguese populations led to changes in the positions of the cusps relative to one another in the first upper molar, whereas the location of their apices have moved away from the centre of the crown to a more peripheral position. This apparent increasing trend contrasts with the one reported in studies of both Neandertals and modern humans.
Jebel Irhoud 1 represents an almost complete cranium from the North African late Middle Pleistocene. Despite the good preservation of most of its anatomical regions, its phylogenetic position is still uncertain, particularly its relationship to the emergence of the modern human lineage. The present paper supplies a basic morphometric description and comparison of the endocast of Jebel Irhoud 1. The endocast’s maximum width is large when compared with the hemispheric length, with values similar to those of Neandertals. Conversely, the frontal width is less pronounced, showing proportions compatible with modern and non-modern human taxa. The vertical proportions are similar to those displayed by Homo erectus, while the lateral proportions are comparable to Neandertals. Furthermore, the upper parietal areas show a certain parasagittal lateral bulging, as in European Neandertals. It remains to be established if this trait evolved independently in both the Neandertal and modern human lineages, or if it was already present in a common ancestor of these two groups. Given that Jebel Irhoud 1 in North Africa and Herto in East Africa have similar geological age, similar facial morphology, but different vault proportions, it seems likely that the origin of the modern human lineage may have predated the origin of many aspects of the modern human brain.
Leprogenic odontodysplasia (LO), also known as dens leprosus, consists of anomalous root development of the permanent upper incisors. This dental anomaly was first reported by Danielsen in 1968 among Danish juvenile skeletons from medieval leprosaria cemeteries. As yet, no clinical cases have been documented and the etiological and epidemiological significance of the condition are poorly understood. The aim of this study is to discuss a case of LO found amongst the skeletons from the St. Jørgen’s leprosarium cemetery (13th–16th/17th centuries), housed in the ADBOU (Anthropological Database of Odense University), Southern Denmark University. A juvenile individual presents a disarticulated maxillary right central incisor possessing a short root that shows a groove caused by marked constriction beginning approximately 1.5 mm above the neck. From this groove, the diameter decreases considerably until the apex. Atrophy of the anterior alveolar maxillary process, extending laterally from the central incisors to the canines, is also apparent. This individual exhibits additional rhinomaxillary lesions (e.g. absorption of the piriform margin including the anterior nasal spine) and foot changes (including phalangeal acro-osteolysis) compatible with a diagnosis of lepromatous leprosy. This case contributes to the debate about the significance of this rare condition, particularly in terms of its presence in Scandinavian skeletons from medieval leprosaria cemeteries. Possible interpretations are discussed, including the pathognomonic value of the specific lesion and whether it indicates early childhood onset of leprosy during the Middle Ages. The understanding of LO epidemiology and its relationship with leprosy will benefit from future clinical and skeletal studies.
Twelve metric variables of the humerus, radius, femur, and tibia were investigated in 11 male samples from northeastern and eastern Asian populations. Variations among regions and correlations between latitude and respective measurements and indices were calculated and a principal component analysis was conducted to elucidate human limb bone characteristics. Significant correlation and marginally significant correlation were found for the maximum subtrochanteric diameter (r = 0.662, P = 0.027) and the platymeric index (r = −0.583, P = 0.060) with latitude, respectively, suggesting that the femur of northern Asians had a wide and flat subtrochanteric shape. The second principal component of the principal component analysis shows that the northeastern samples with comparatively long shaft length and thin and flat shaft diameters were discriminated from the southern samples; the second principal component was significantly correlated with latitude (r = −0.743, P = 0.009). The estimated Fst value of 0.432–0.336 shows that the variation in limb bone measurements across regions is rather large, at approximately two or three times the low levels of interregional variation (0.078–0.180) in analyses of cranial and dental data. Limb bone morphology has been repeatedly proposed to be more strongly influenced by environmental and nutritional factors than cranial and dental traits, but this study is the first to confirm it on the basis of statistical analysis.
Entheseal changes (ECs) have been widely recorded using visual methods, but size and shape affect stress distribution which cannot be quantified visually. The aim of this paper is to present a simple method for quantifying size and shape by applying parameters to quantify shape and to highlight preliminary results indicating that this method provides useful data. Hypotheses tested were: common extensor origin size correlates with humerus size; ECs change the size and shape of entheses; surface area is increased in those entheses with bony proliferation. The common extensor origins of 43 male skeletons from medieval York were recorded. The entheses were recorded visually for any deviation from a smooth surface. The chord was measured using sliding calipers and the shape of the entheses recorded using a profile gauge and quantified using parameters (e.g. the standard deviation of the surface from a mean line) which assess the relationship of the surface to a flat surface. To test replicability, disarticulated humeri were also recorded (inter-observer error n = 9; intra-observer error n = 20) using the same methodology. Replicability for size and shape was good for intra-observer error but weaker for inter-observer error. There is variability in enthesis size and distal humeral condyle size; normal entheses are smaller than those with EC while their surface shape differs and is affected by the type of EC (proliferative or destructive); surface area in those entheses with proliferative ECs is increased. The use of these parameters for quantifying enthesis size and shape provides insights into enthesis variability which cannot be tested using visual methods alone. These parameters can be recorded using this two-dimensional method or can be measured on data collected with a laser scanner. Future research will test the relationship between surface size/shape and the effects of biological sex, age and occupation.
The present-day Sherpa are thought to descend from a small number of ancestors that settled in Nepal several centuries ago, coming from the Eastern Tibetan region of Kham. A generally accepted ethnographic theory involves the out-of-Kham migration of four proto-clans between the 15th and 16th centuries. Traditional Sherpa society is still divided into clans, called ru, which are patrilin-early transmitted. Ru therefore roughly correspond to the surnames of Western societies: males of the same ru are expected to share identical Y-chromosome haplotypes. However, multiple origins of ru and/or frequent gene flow of male lineages from neighbouring populations can complicate the genealogical structure. In the present work, 25 male Sherpas of the Solukhumbu district were typed for the 17 Y-chromosomal short tandem repeats included in the AmpFlSTR® Yfiler™ kit. Seventeen different haplotypes were found; 12 were unique. A phylogenetic tree was then drawn from the pairwise mutational distance matrix with a neighbour-joining algorithm. Branching reliability was also assessed through bootstrap analysis. Two macro-clusters of haplotypes were found, ascribable on the whole to two out of four of the presumed Tibetan proto-ru, the Thimmi and the Minyagpa. However, the Minyagpa macro-cluster was found to be bipartite in terms of haplogroups, being composed by two distinct haplotype clusters. Clustering of the contributors by birthplace was also performed, suggesting a differential ru spatial distribution between upper Khumbu and lower Solu. Khumbu seems predominantly populated by newer clans and putative descendants of the Thimmi proto-ru, whereas Solu is mostly inhabited by members of the Minyagpa proto-ru.