American journal of physical anthropology最新文献

One hundred and four skeletons of adult individuals representing Neolithic populations of the Brześć Kujawski group of the Lengyel Culture (Kuyavia, central Poland, 4600-4000 BC) were analyzed with regard to evidence of nonalimentary tooth use, periapical lesions and antemortem tooth loss (AMTL). Instances of nonalimentary behaviors were found in 47.1% of females and 27.5% of males. Females were primarily characterized by occlusal grooves on the incisors and canines, most probably resulting from yarn production or weaving. The most frequent defect in males was severe tooth wear extending from the incisors to first molars, caused by some hard-to-identify nonalimentary activities. Occlusal grooves were also found in males, but their morphology indicates processing of some coarser material. The occupational nature of the tooth defects has been confirmed by archaeological data. The only two burials with grave goods indicative of craft specialization at the sites studied contain the remains of individuals with marks of nonalimentary tooth use. Moreover, the sites provide unequivocal evidence of weaving and basketry production in the form of loom weights and imprints of cloth and mats. Periapical lesions have been found in 40.4% of males and 35.6% of females, and AMTL in 32.1% of males and 36.7% of females. Individuals with evidence of nonalimentary tooth wear are characterized both by a higher incidence of these lesions in general, and by their more frequent location in the anterior part of the alveolar arch.

Tamarins of the genus Saguinus, subfamily Callitrichinae, represent one of the most diverse primate radiations. So far, about 35 taxa have been described, but detailed information about their taxonomy and phylogeny is still lacking. To further elucidate the phylogenetic relationships and the biogeographic history within the genus, and to contribute to a more reliable classification of its taxa, we sequenced the complete mitochondrial cytochrome b gene and the hypervariable region I of the D-loop. Therefore, we mainly used fecal samples from wild tamarins collected during two expeditions to the Peruvian Amazon, an area of high tamarin diversity. Our data suggest that the numerous taxa of the S. nigricollis species group are derived from a common ancestor that separated from the other representatives of the genus ~10 mya. Most taxa of the S. nigricollis group form monophyletic clusters, which mainly originated in a single rapid radiation ~2.9 mya. S. fuscicollis and S. nigricollis appear as polyphyletic taxa, but we could identify various clusters, which are mainly consistent with differences in coat coloration. We could confirm most of the existing taxa as distinct entities and suggest species status for fuscicollis, illigeri, lagonotus, leucogenys, nigricollis, nigrifrons, tripartitus, and weddelli. Our genetic data do not support a separate status for melanoleucus and graellsi, but due to differences in fur coloration, we give them subspecies status. The species group most likely originated in western Amazonia and diversified during the decline of the Acre wetland and the formation of the Amazonian river system.

To examine morphological interrelationships between canine size and mandibular corpus shape, inter-sex comparisons were made in the hamadryas baboon and the Japanese monkey, known to display extreme and moderate canine dimorphism, respectively. Results of adult comparisons showed that all mandibular dimensions were significantly larger in the males than in the females in both species. In the hamadryas baboon, the males also exhibited a higher ratio of anterior to posterior corpus height than the females. This sex difference in corpus shape was not significant in the Japanese monkey, indicating lack of involvement of canine dimorphism. Analysis of mandibular growth patterns in the hamadryas baboon demonstrated that significant sexual size difference did not occur before incisor eruption, and that the anteriorly high corpus of the adult male mandible was associated with a rapidly increasing symphyseal height after incisor eruption. It was also shown that the female canine started to erupt shortly after incisor eruption, while the forming male canine continued to stay near the mandibular base and developed further in size until eruption. The relative positions of the incisors kept shifting upwards even after eruption in the males, while they hardly changed in the females. It is therefore suggested that the prolonged development and size increase of the male canine is accompanied by further enlargement of the symphysis, resulting in the higher anterior corpus of the adult males compared to the adult females. The results thus indicate the importance of understanding the spatial relationships of the developing teeth in interpreting mandibular morphology.

The modern human mandibular symphysis differs from those of all other primates in being vertically orientated and possessing a chin, but the functional significance of this unique morphology is not well understood. Some hypotheses propose that it is an adaptation to specific loads occurring during masticatory function. This study uses finite element analysis to examine these symphyseal loads in a model of a modern human mandible. By modifying the symphyseal cross-sectional form, the mechanical significance of the presence of the chin and symphyseal orientation is tested, and modern human and Neanderthal symphyseal cross-sections are compared with regard to their ability to withstand different loads. The results show that changes in symphyseal form have profound effects on the strains. The presence of a chin leads to lower symphyseal strains overall, whereas a vertical orientation of the symphysis results in higher strains under wishboning, but not under vertical bending in the coronal plane and dorsoventral shear. Compared to Neanderthals, the modern human symphysis shows higher strains during dorsoventral shear and wishboning, but is as effective as the Neanderthal symphysis in resisting vertical bending in the coronal plane and the loads resulting from simulated incision and unilateral molar biting. In general, the results of this study corroborate prior hypotheses about the mechanical effects of the human chin and vertical symphyseal orientation and support the idea that the relative importance of wishboning and vertical bending in the coronal plane might have played a role in the evolution of modern human symphyseal morphology.

Understanding the costs and regulation of reproduction in primates requires understanding the separate but linked effects of energy availability and total energy expenditure (TEE). We compared variation in TEE and energy intake (EI) between two periods, early lactation and after the resumption of sexual cycling, for eight females from two groups of normally reproducing colony-living baboons (Papio h. anubis). Total energy expenditure was assessed using the doubly labeled water method. TEE was correlated with maternal mass both during early lactation and after the resumption of cycling. TEE after the resumption of cycling was positively related to infant growth rates; mothers with rapidly growing infants had higher energy expenditure. TEE was however unrelated to maternal rank and only weakly associated with reproductive parameters such as delay to conception. EI in early lactation was related to infant mass and interbirth intervals, but unrelated to infant growth or reproductive parameters once cycling had resumed. Energy availability (EA; the difference between intake and expenditure) differed significantly between subordinate and dominant females during early lactation, was highly variable among individuals as a function of body composition, and is suggested to follow a nonlinear relationship as a complex function of social status, lactation stage, infant growth, and female fertility. Thus, as a consequence of reduced energy availability, subordinate females in this captive context may experience reproductive delays even though the total energy expenditure after the return of cycling was similar between high and low ranking females.

The autapomorphic status of the Neanderthal suprainiac fossa was recently confirmed. This was a result of a detailed analysis of the internal bone composition in the area of the suprainiac depression on Neanderthal and Homo sapiens specimens. However, while anatomical differences between Neanderthal suprainiac fossa and the depression in the inion region of the occipital bone of fossil and recent Homo sapiens have been discussed in detail, the etiology of these structures has not been resolved. In this article, the hypothesis that the Homo sapiens non-supranuchal fossa and the Neanderthal suprainiac fossa both formed to maintain the optimal shape of the occipital plane (to minimize strain on the posterior cranial vault) is tested. First, the variation in the expression of the fossa above inion in the crania of recent Homo sapiens from European, African, and Australian samples was examined, and the degree of structural similarity between these depressions and the Neanderthal suprainiac fossa was assessed. Next, the relationship between the shape of the occipital squama in the midsagittal plane and two particular features (the degree of the occipital torus development and the occurrence of a depression in the inion region that is not the supranuchal fossa) were analyzed. Based on the results, it is suggested that the Homo sapiens non-supranuchal fossa and Neanderthal suprainiac fossa are convergent traits.

The peopling of Comoro Archipelago is defined by successive waves of migration from three main areas: the East African Coast (Bantu-speaking populations), the Persia and Arabian Peninsula, and Southeast Asia (especially Indonesia). It follows an apparent classic trihybrid admixture model. To better understand the Comorian population admixture dynamics, we analyzed the contributions of these three historical parental components to its genetic pool. To enhance accuracy and reliability, we used both classical and molecular markers. Samples consist of published data: blood group frequencies, 14 KIR genes, 19 mitochondrial DNA SNPs (to highlight female migrations), 14 Y chromosome SNPs (male migrations). We revealed distinct admixture patterns for autosomal and uniparental markers. KIR gene frequencies had never been used to estimate admixture rates, this being a first assessment of their informative power in admixture studies. To avoid major methodological and statistical bias, we determined admixture coefficients through nine well-tried estimators and their associated software programs (ADMIX95, ADMIX, admix 2.0, LEA, LEADMIX, and Mistura). Results from mtDNA and Y chromosome markers point to an important sex-bias in the admixture event. The original Bantu gene pool received a predominant male-mediated contribution from the Arabian Peninsula and Persia, and a female-mediated contribution from Southeast Asia. Admixture rates estimated from autosomal KIR gene markers point also to an unexpected elevated Austronesian contribution.

The Sima de las Palomas, southeastern Spain, has yielded a series of Neandertal postcranial remains, including immature and mature isolated elements and the fragmentary partial skeleton of a young adult (Palomas 92). The remains largely conform to the general late archaic/Neandertal morphological pattern in terms of humeral diaphyseal shape, pectoralis major tuberosity size and pillar thickness, ulnar coronoid process height, manual middle phalangeal epiphyseal breadth, manual distal phalangeal tuberosity shape and breadth, femoral diaphyseal shape, and probably body proportions. Palomas 92 contrasts with the Neandertals in having variably gracile hand remains, a more sellar trapezial metacarpal 1 facet, more anteroposteriorly expanded mid-proximal femoral diaphysis, and less robust pedal proximal phalanges. The Palomas Neandertals contrast with more northern European Neandertals particularly in various reflections of overall body size.