American journal of physical anthropology最新文献

This study attempts to fill a persistent gap in the literature by documenting the timing of epiphyseal union at the vertebral end of the ribs in a sample of modern Portuguese skeletons. The skeletal remains of 53 females and 45 males, between the ages of 11 and 30, were taken from the Lisbon documented skeletal collection. Individuals in the sample have been previously described as being representative of a middle-to-low socioeconomic segment of the early 20th century Lisbon population. Three anatomical locations were examined for epiphyseal union: the head, the articular tubercle and the nonarticular tubercle. The first epiphysis to show partial union is that of the nonarticular tubercle (females, 11-19 years; males, 11-19 years), followed by the epiphysis of the articular tubercle (females, 11-20 years; males, 16-20 years), and finally by the head epiphysis (females, 15-24 years; males, 16-22 years), which can still show incomplete epiphyseal closure at 25 and 24 years for females and males, respectively. A trend for earlier female maturation was observed, but the statistical tests only confirmed this result for some ribs and age groups. No directional asymmetry was found, but a significant fluctuating asymmetry was observed in all three epiphyses. A preliminary analysis showed that the asymmetric group of individuals in the study sample includes all the rural-to-urban migrants, relative to the symmetric group.

A novel technique for the removal of metal ions inhibiting DNA extraction and PCR of archaeological bone extracts is presented using size exclusion chromatography. Two case studies, involving copper inhibition, demonstrate the effective removal of metal ion inhibition. Light microscopy, SEM, elemental analysis, and genetic analysis were used to demonstrate the effective removal of metal ions from samples that previously exhibited molecular inhibition. This research identifies that copper can cause inhibition of DNA polymerase during DNA amplification. The use of size exclusion chromatography as an additional purification step before DNA amplification from degraded bone samples successfully removes metal ions and other inhibitors, for the analysis of archaeological bone. The biochemistry of inhibition is explored through chemical and enzymatic extraction methodology on archaeological material. We demonstrate a simple purification technique that provides a high yield of purified DNA (>95%) that can be used to address most types of inhibition commonly associated with the analysis of degraded archaeological and forensic samples. We present a new opportunity for the molecular analysis of archaeological samples preserved in the presence of metal ions, such as copper, which have previously yielded no DNA results.

We report here self-suckling in four wild female Barbary macaques (Macaca sylvanus), living in two troops (i.e. "Flat face" and "Large" troop) in the middle-Atlas Mountains, Morocco. The four females lost their infants due to predation or for unknown causes. Self-suckling was observed before and after the infants died in the four females living in the "Flat face" troop. When the infants were still alive, self-suckling was of short duration and it was probably a method to improve milk flow when the infant switched from one nipple to the other. After the infants died, self-suckling lasted significantly longer and the females were apparently drinking their own milk. Self-suckling was never observed among the four lactating females in the "Large" troop (including one monkey who lost her infant) and it could thus represent a cultural difference. Moreover, self-suckling after the death of an infant may be explained by the energetic and immunological benefits that a monkey may gain from drinking their own milk. Finally, self-suckling may have a stress-releasing effect on the mothers who have lost their infants.

Previous research has demonstrated that species and subspecies of extant chimpanzees and bonobos can be distinguished on the basis of the shape of their molar crowns. Thus, there is potential for fossil taxa, particularly fossil hominins, to be distinguished at similar taxonomic levels using molar crown morphology. Unfortunately, due to occlusal attrition, the original crown morphology is often absent in fossil teeth, and this has limited the amount of shape information used to discriminate hominin molars. The enamel-dentine junction (EDJ) of molar teeth preserves considerable shape information, particularly in regard to the original shape of the crown, and remains present through the early stages of attrition. In this study, we investigate whether the shape of the EDJ of lower first and second molars can distinguish species and subspecies of extant Pan. Micro-computed tomography was employed to non-destructively image the EDJ, and geometric morphometric analytical methods were used to compare EDJ shape among samples of Pan paniscus (N = 17), Pan troglodytes troglodytes (N = 13), and Pan troglodytes verus (N = 18). Discriminant analysis indicates that EDJ morphology distinguishes among extant Pan species and subspecies with a high degree of reliability. The morphological differences in EDJ shape among the taxa are subtle and relate to the relative height and position of the dentine horns, the height of the dentine crown, and the shape of the crown base, but their existence supports the inclusion of EDJ shape (particularly those aspects of shape in the vertical dimension) in the systematic analysis of fossil hominin lower molars.

Recent studies have demonstrated that the shape of the human temporal bone is particularly strongly correlated with neutral genetic expectation, when compared against other cranial regions, such as the vault, face, and basicranium. In turn, this has led to suggestions that the temporal bone is particularly reliable in analyses of primate phylogeny and human population history. While several reasons have been suggested to explain the temporal bone's strong fit with neutral expectation, the temporal bone has never systematically been compared against other individual cranial bones defined using the same biological criteria. Therefore, it is currently unknown whether the shapes of all cranial bones possess reliable information regarding neutral genetic evolution, or whether the temporal bone is unique in this respect. This study tests the hypothesis that the human temporal bone is more congruent with neutral expectation than six other individual cranial bones by correlating population affinity matrices generated using neutral genetic and 3D craniometric data. The results demonstrate that while the temporal bone shows the absolute strongest correlation with neutral genetic data compared with all other bones, it is not statistically differentiated from the sphenoid, frontal, and parietal bones in this regard. Potential reasons for the temporal bone's consistently strong fit with neutral expectation, such as its overall anatomical complexity and/or its contribution to the architecture of the basicranium, are examined. The results suggest that future phylogenetic and taxonomic studies would benefit from considering the shape of the entire cranium minus those regions that deviate most from neutrality.

The growth, development, and maintenance of bone are influenced by genetic and environmental variables. Understanding variability in bone microstructure among primates may help illuminate the factors influencing the number and size of secondary osteons. The purpose of this study is to assess the bone microstructure in 8 humeral and 12 femoral sections of 12 juvenile chimpanzees, aged 2-15.3 years, and one adult chimp. Secondary osteons were counted and measured for 16 fields per section. Results indicate that the femur exhibits a mean osteon population density (OPD) of 4.46 +/- 2.34/mm(2), mean Haversian canal area of 0.0016 +/- 0.0007 mm(2), and mean osteon area of 0.033 +/- 0.006 mm(2). The humerus has a mean OPD of 4.72 +/- 1.57/mm(2), mean Haversian canal area of 0.0013 +/- 0.0003 mm(2), and mean osteon area of 0.033 +/- 0.005 mm(2). Differences are not significant between the humerus and femur, possibly indicating similar mechanical demands during locomotion. Osteon population density exhibits a moderate correlation with age (r = 0.498) in the femur of the juvenile chimps, but the adult chimp has an OPD of 10.28/mm(2), suggesting that osteons likely accumulate with age. Females exhibit higher osteon densities in the periosteal envelope compared to males in the humerus, indicating more remodeling during periosteal expansion. Overall similarities between chimpanzees and humans as well as previously published data on Late Pleistocene hominids (Abbott et al.: Am J Phys Anthropol 99 1996 585-601) suggest that bone microstructure has been stable throughout human evolution.

The Egyptian Western Desert lies on an important geographic intersection between Africa and Asia. Genetic diversity of this region has been shaped, in part, by climatic changes in the Late Pleistocene and Holocene epochs marked by oscillating humid and arid periods. We present here a whole genome analysis of mitochondrial DNA (mtDNA) and high-resolution molecular analysis of nonrecombining Y-chromosomal (NRY) gene pools of a demographically small but autochthonous population from the Egyptian Western Desert oasis el-Hayez. Notwithstanding signs of expected genetic drift, we still found clear genetic evidence of a strong Near Eastern input that can be dated into the Neolithic. This is revealed by high frequencies and high internal variability of several mtDNA lineages from haplogroup T. The whole genome sequencing strategy and molecular dating allowed us to detect the accumulation of local mtDNA diversity to 5,138 +/- 3,633 YBP. Similarly, theY-chromosome gene pool reveals high frequencies of the Near Eastern J1 and the North African E1b1b1b lineages, both generally known to have expanded within North Africa during the Neolithic. These results provide another piece of evidence of the relatively young population history of North Africa.