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Am J Phys Anthropol (be + j_phy_anthropol)
Selected AbstractsViolence and weapon-related trauma at Puruchuco-Huaquerones, PeruAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2010Melissa S. Murphy Abstract Conquest of indigenous peoples in North America is understood primarily through ethnohistorical documents, archaeological evidence, and osteological analyses. However, in the Central Andes, the colonial enterprise and its effects are understood only from postcontact historical and ethnohistorical sources. Few archaeological and bioarchaeological studies have investigated Spanish Conquest and colonialism in the Andean region [for exceptions see Klaus and Tam: Am J Phys Anthropol 138 (2009) 356,368; Wernke, in press; and Quilter, in press]. Here we describe bioarchaeological evidence of violence from the cemeteries of Huaquerones and 57AS03 within the archaeological zone of Puruchuco-Huaquerones, Peru (circa A.D. 1470,1540). A total of 258 individuals greater than 15 years of age were analyzed for evidence of traumatic injuries. Individuals were examined macroscopically and evidence of traumatic injuries was analyzed according to the skeletal element involved, the location of the injury on the skeletal element, and any additional complications of the injury. This study examines and compares the evidence of perimortem injuries on skeletonized individuals from the two cemeteries and focuses specifically on the interpretation of weapon-related perimortem injuries. Evidence of perimortem trauma is present in both cemeteries (18.6%, 48/258); however, the frequency of injuries in 57AS03 is greater than that in Huaquerones (25.0% vs. 13.0%). Several injuries from 57AS03 are consistent with documented cases of injuries from firearms and 16th Century European weapons. We believe that the nature and high frequency of perimortem trauma at 57AS03 provide evidence of the violence that occurred with Spanish Conquest of the Inca Empire. Am J Phys Anthropol 142:636,649, 2010. © 2010 Wiley-Liss, Inc. [source] Brief communication: The London atlas of human tooth development and eruptionAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2010S.J. AlQahtani Abstract The aim of this study was to develop a comprehensive evidence-based atlas to estimate age using both tooth development and alveolar eruption for human individuals between 28 weeks in utero and 23 years. This was a cross-sectional, retrospective study of archived material with the sample aged 2 years and older having a uniform age and sex distribution. Developing teeth from 72 prenatal and 104 postnatal skeletal remains of known age-at-death were examined from collections held at the Royal College of Surgeons of England and the Natural History Museum, London, UK (M 91, F 72, unknown sex 13). Data were also collected from dental radiographs of living individuals (M 264, F 264). Median stage for tooth development and eruption for all age categories was used to construct the atlas. Tooth development was determined according to Moorrees et al. (J Dent Res 42 (1963a) 490,502; Am J Phys Anthropol 21 (1963b) 205,213) and eruption was assessed relative to the alveolar bone level. Intraexaminer reproducibility calculated using Kappa on 150 teeth was 0.90 for 15 skeletal remains of age <2 years, and 0.81 from 605 teeth (50 radiographs). Age categories were monthly in the last trimester, 2 weeks perinatally, 3-month intervals during the first year, and at every year thereafter. Results show that tooth formation is least variable in infancy and most variable after the age of 16 years for the development of the third molar. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source] Brief communication: Dynamic plantar pressure distribution during locomotion in Japanese macaques (Macaca fuscata)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Eishi Hirasaki Abstract To better place the form and motion of the human foot in an evolutionary context, understanding how foot motions change when quadrupeds walk bipedally can be informative. For this purpose, we compared the pressures beneath the foot during bipedal and quadrupedal walking in Japanese macaques (Macaca fuscata). The pressure at nine plantar regions was recorded using a pressure mat (120 Hz), while the animals walked on a level walkway at their preferred speeds. The results revealed substantial differences in foot use between the two modes of locomotion, and some features observed during bipedal walking resembled human gait, such as the medial transfer of the center of pressure (COP), abrupt declines in forefoot pressures, and the increased pressure beneath the hallux, all occurring during the late-stance phase. In particular, the medial transfer of the COP, which is also observed in bonobos (Vereecke et al.: Am J Phys Anthropol 120 (2003) 373,383), was due to a biomechanical requirement for a hind limb dominant gait, such as bipedal walking. Features shared by bipedal and quadrupedal locomotion that were quite different from human locomotion were also observed: the heel never contacted the ground, a foot longitudinal arch was absent, the hallux was widely abducted, and the functional axis was on the third digit, not the second. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Stature estimation formulae for indigenous North American populationsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Benjamin M. Auerbach Abstract Stature estimation methods for adult indigenous humans from the Americas have generally relied on a limited number of regression equations. The available equations, however, are not broadly applicable to the diversity of the populations that lived in the New World prior to European colonization. Furthermore, some equations that have been used were originally derived from inappropriate reference samples, such as the "Mongoloid" group measured by Trotter and Gleser (Am J Phys Anthropol 16 [1958] 79-123). This study develops new stature estimation equations for long bones of the lower limb from a geographically diverse sample of North American archaeological sites. Statures were reconstructed from 967 skeletons from 75 archaeological sites using the revised Fully anatomical technique (Raxter et al., Am J Phys Anthropol 130 [2006] 374-384). Archaeological samples were grouped according to general body proportions, using relative tibia and femur length to stature as guides. On the basis of differences in these proportions, three broad groupings were identified: a high latitude "arctic" group, a general "temperate" group, and a Great Plains group. Sex-specific ordinary least squares regression formulae were developed based on femoral and tibial lengths for each of these groups. Comparisons of the new stature estimation equations with previously available equations were conducted using several archaeological test samples. In most cases, the new stature estimation equations are more precise than those previously available, and we recommend their use throughout most of North America. The equations developed by Genovés for Mesoamerican and US Southwest samples are a useful alternative for these regions. Applicability of the new equations to South American samples awaits further testing. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Brief communication: Bone remodeling rates in Pleistocene humans are not slower than the rates observed in modern populations: A reexamination of Abbott et al. (1996)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Margaret Streeter Abstract Bone histomorphometry has been applied to the lower limb cortical bone of Pleistocene humans to establish age at death and to determine bone remodeling rates (Abbott et al.: Am J Phys Anthropol 226 (1996) 307,313). Both of these procedures require the determination of osteon density and mean osteon size. Previous analyses of Middle and Late Pleistocene human lower limb bones have produced bone remodeling rates that are slower than those determined in a more recent archeological sample. Recalculation of the data reported in Abbott et al.: Am J Phys Anthropol 226 (1996) 307,313) has revealed mathematical errors in the remodeling rates reported for the Pleistocene humans. The corrected remodeling rates for the Pleistocene group are similar to the values obtained in the more recent comparative sample. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Joint orientation and function in great ape and human proximal pedal phalangesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Nicole L. Griffin Abstract Previous studies have referred to the degree of dorsal canting of the base of the proximal phalanx as an indicator of human-like metatarsophalangeal joint function and thus a diagnostic trait of habitual bipedality in the fossil record. Here, we used a simple method to investigate differences in forefoot function on a finer scale. Building on Duncan et al.'s (Am J Phys Anthropol 93 [1994] 67,81) research, we tested whether dorsal canting reflects differences between sexes in locomotor behavior, whether habitual shoe wear influences dorsal canting in humans, and whether proximal joint morphology differs between rays in Pan and humans. Our results corroborate previous research in showing that humans have proximal phalanges with joint orientations that are significantly more dorsal than, but overlap with, those of great apes. We also found that male gorillas have significantly more dorsally canted second proximal phalanges than their female counterparts, while the opposite pattern between the sexes was found in Pan troglodytes. Inter-ray comparisons indicate that Pan have more dorsally canted first proximal phalanges than second proximal phalanges, while the opposite pattern was found in humans. Minimally shod humans have slightly but significantly more dorsally canted second proximal phalanges than those of habitually shod humans, indicating that phalanges of unshod humans provide the most appropriate comparative samples for analyses of early hominins. Overall, our analysis suggests that though the measurement of dorsal canting is limited in its sensitivity to certain intraspecific differences in function, phalangeal joint orientation reflects interspecific differences in joint function, with the caveat that different patterns of forefoot function during gait can involve similar articular sets of metatarsophalangeal joints. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] Brief communication: Forelimb compliance in arboreal and terrestrial opossumsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2010Daniel Schmitt Abstract Primates display high forelimb compliance (increased elbow joint yield) compared to most other mammals. Forelimb compliance, which is especially marked among arboreal primates, moderates vertical oscillations of the body and peak vertical forces and may represent a basal adaptation of primates for locomotion on thin, flexible branches. However, Larney and Larson (Am J Phys Anthropol 125 [2004] 42,50) reported that marsupials have forelimb compliance comparable to or greater than that of most primates, but did not distinguish between arboreal and terrestrial marsupials. If forelimb compliance is functionally linked to locomotion on thin branches, then elbow yield should be highest in marsupials relying on arboreal substrates more often. To test this hypothesis, we compared forelimb compliance between two didelphid marsupials, Caluromys philander (an arboreal opossum relying heavily on thin branches) and Monodelphis domestica (an opossum that spends most of its time on the ground). Animals were videorecorded while walking on a runway or a horizontal 7-mm pole. Caluromys showed higher elbow yield (greater changes in degrees of elbow flexion) on both substrates, similar to that reported for arboreal primates. Monodelphis was characterized by lower elbow yield that was intermediate between the values reported by Larney and Larson (Am J Phys Anthropol 125 [2004] 42,50) for more terrestrial primates and rodents. This finding adds evidence to a model suggesting a functional link between arboreality,particularly locomotion on thin, flexible branches,and forelimb compliance. These data add another convergent trait between arboreal primates, Caluromys, and other arboreal marsupials and support the argument that all primates evolved from a common ancestor that was a fine-branch arborealist. Am J Phys Anthropol, 2010. © 2009 Wiley-Liss, Inc. [source] The natural endocast of Taung (Australopithecus africanus): Insights from the unpublished papers of Raymond Arthur DartAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue S49 2009Dean Falk Abstract Dart's 1925 announcement of Australopithecus africanus (Dart: Nature 115 [1925] 195,199) was highly controversial, partly because of an interpretation of the Taung natural endocast that rested on an erroneous identification of the lambdoid suture as the lunate sulcus. Unpublished materials from the University of Witwatersrand Archives (Dart, unpublished material) reveal that Dart reacted to the controversy by: 1) describing and illustrating the entire sulcal pattern on the Taung endocast, in contrast to just two sulcal identifications in 1925, 2) identifying a hypothetical part of the lambdoid suture and revising his description of the lunate sulcus, and 3) bolstering his argument that Taung's brain was advanced by detailing expansions in three significant cortical association areas. Four unpublished illustrations of Dart's identifications for sulci and sutures on the Taung endocast are compared here with those published by Keith (Keith: New discoveries relating to the antiquity of man (1931)), Schepers (Schepers: The endocranial casts of the South African ape-men. In: Broom R, Schepers GWH, editors. The South African fossil ape-men; the Australopithecinae [1946] p 155,272), and Falk (Falk: Am J Phys Anthropol 53 [1980] 525,539), and the thorny issue of the location of the lunate sulcus is revisited in light of new information. Archival materials reveal that Dart believed that Taung's brain was reorganized globally rather than in a mosaic manner, and that the shapes of certain cortical association areas showed that Australopithecus was closer to Pithecanthropus than to the living apes. Although a few of Dart's hitherto-unpublished sulcal identifications, including his revision for the lunate sulcus, were questionable, his claim that the Taung endocast reproduced a shape that was advanced toward a human condition in its prefrontal cortex and caudally protruded occipital lobe was correct. Yrbk Phys Anthropol 52:49,65, 2009. © 2009 Wiley-Liss, Inc. [source] Bone microstructure in juvenile chimpanzeesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Dawn M. Mulhern Abstract 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/mm2, mean Haversian canal area of 0.0016 ± 0.0007 mm2, and mean osteon area of 0.033 ± 0.006 mm2. The humerus has a mean OPD of 4.72 ± 1.57/mm2, mean Haversian canal area of 0.0013 ± 0.0003 mm2, and mean osteon area of 0.033 ± 0.005 mm2. 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/mm2, 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. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] The type specimen (LB1) of Homo floresiensis did not have Laron SyndromeAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Dean Falk Abstract The type specimen (LB1) of Homo floresiensis has been hypothesized to be a pathological human afflicted with Laron Syndrome (LS), a type of primary growth hormone insensitivity (Hershkovitz et al.: Am J Phys Anthropol 134 [2007] 198,208). Comparing measurements, photographs and three-dimensional, computed-tomography reconstructions of LB1 with data and diagnoses from the literature on LS, we critically evaluate numerous skull and postcranial traits that Hershkovitz etal. identified as being shared by LB1 and patients with LS. The statements regarding most of these traits are new to the clinical literature and lack quantitative support. LB1 and patients with LS differ markedly in the size and shape of the cranium; thickness and pneumatization of cranial bones; morphology of the face, mandible, teeth, and chin; form of the shoulder, wrist, and pelvis; and general body proportions including relative foot size. Claims that patients with LS are similar to LB1 in displaying protracted scapulae, short clavicles, low degrees of humeral torsion, flaring ilia, and curved tibiae are not supported by data or corroborating images. Some points of similarity (e.g., femoral neck-shaft angle, femoral bicondylar angle, and estimated stature) can be found in other hominins, and cannot be considered diagnostic. From our review and analysis, we conclude that LB1 did not suffer from LS. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] Stature estimation in an early medieval (XI-XII c.) Polish population: Testing the accuracy of regression equations in a bioarcheological sampleAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Giuseppe Vercellotti Abstract Accurate stature estimation from skeletal remains can foster useful information on health and microevolutionary trends in past human populations. Stature can be estimated through the anatomical method and regression equations. The anatomical method (Fully: Ann Med Leg 36 [1956] 266,273; Raxter et al.: Am J Phys Anthropol 130 [2006] 374,384) is preferable because it takes into account total skeletal height and thus provides more accurate estimates, but it cannot be applied to incomplete remains. In such circumstances, regression equations allow estimates of living stature from the length of one or few skeletal elements. However, the accuracy of stature estimates from regression equations depends on similarity in body proportions between the population under examination and those used to calibrate the equations. Since genetic affinity and body proportions similarity are not always clearly known in bioarcheological populations, the criteria for selection of appropriate formulae are not always straightforward. This may lead to inaccurate stature estimates and imprecise accounts of past life conditions. Prompted by such practical and theoretical concerns this study aimed at (1) estimating living stature in an early medieval (XI-XII c.) Polish sample (40 male; 20 female) through the anatomical method and developing population-specific regression formulae; and (2) evaluating the accuracy of estimates obtained with regression methods commonly employed in European populations. Results indicate that when applied to the skeletal remains from Giecz, our formulae provide accurate estimates, with non-age-corrected formulae performing better than age-corrected ones. Our formulae provide better estimates than those calibrated on recent populations and their use in medieval Polish populations is preferable. Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] Brief communication: Evaluating grandmother effectsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Kristen Hawkes Abstract Women who have outlived child-bearing have long been described as postreproductive. But contributions they make to the survival or fertility of their descendants enhance the reproduction of their genes. Consequently, natural selection affects this characteristic stage of human life history. Grandmother effects can be measured in data sets that include births and deaths over several generations, but unmeasured covariates complicate the task. Here we focus on two complications: cohort shifts in mortality and fertility, and maternal age at death. We use the Utah Population Database to show that longevity of grandmothers may be associated with fewer grandchildren, as reported by Madrigal and Melendez-Obando (Am J Phys Anthropol 136 (2008) 223,229) for a Costa Rican sample, even when grandmother effects are actually positive. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Brief communication: Paleohistopathological analysis of pathology museum specimens: Can periosteal reaction microstructure explain lesion etiology?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Darlene A. Weston Abstract The assertion that the microstructure of periosteal new bone formation can be used to differentiate between disease etiologies (Schultz: Yrbk Phys Anthropol 44 2001 106,147; Schultz: Identification of pathological conditions in human skeletal remains, 2nd ed. London: Academic Press 2003 73,109) was tested in a pilot-study, using diagnosed bone specimens from St George's Hospital Pathology Museum, London, UK. Embedded bone specimens exhibiting pathological periosteal new bone formation were examined using scanning electron microscopy in back-scattered electron imaging mode (SEM-BSE). The results suggest that several histological features (i.e. Grenzstreifen, Polsters, and sinuous lacunae) deemed to be diagnostic of specific pathological conditions are of no specific diagnostic value, as they are encountered in pathological conditions of differing disease etiology. These results tie in with a previous investigation demonstrating a lack of diagnostic qualitative or quantitative characteristics seen in the macroscopic and radiographic appearance of periosteal reactions (Weston: Am J Phys Anthropol 137 2008 48,59). Am J Phys Anthropol, 2009. © 2009 Wiley-Liss, Inc. [source] Asymmetry of the os pubis: Implications for the Suchey-Brooks methodAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Rebecca S. Overbury Abstract Studies of skeletal development frequently document populational incidences of bilateral asymmetry. Degenerative morphological skeletal changes, attributed to age related and irregular ossification, may also progress asymmetrically, either as the result of asymmetric biomechanical factors expressed over the lifespan, asymmetric expression of physiological processes, or progressive magnification of asymmetry acquired previously during development. This study illustrates the effects of bilateral asymmetry on age at death estimates obtained from human skeletal remains. The Suchey-Brooks method, which uses the pubic symphyseal face for age estimation (Katz and Suchey, Am J Phys Anthropol 69 1986 427,435), was selected for the study based on its widespread use. Asymmetry in the Suchey-Brooks symphyseal age phases was found in over 60% of a sample composed of 20th century White male individuals from 18 to 86 years of age (N = 130). However, results suggest that the presence of asymmetry does not compromise the accuracy of the Suchey-Brooks method if the morphologically older symphyseal face of an asymmetric individual is used to estimate age at death. In addition, weak directional asymmetry and a correlation between age and asymmetry were found. This suggests that a comparison of asymmetry in this area with that in other skeletal areas, where the factors originating and influencing asymmetry are better understood, may be useful in better understanding the biological processes which underlie the age markers used in the Suchey-Brooks method. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Estimation and evidence in forensic anthropology: Sex and raceAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2009Lyle W. Konigsberg Abstract Forensic anthropology typically uses osteological and/or dental data either to estimate characteristics of unidentified individuals or to serve as evidence in cases where there is a putative identification. In the estimation context, the problem is to describe aspects of an individual that may lead to their eventual identification, whereas in the evidentiary context, the problem is to provide the relative support for the identification. In either context, individual characteristics such as sex and race may be useful. Using a previously published forensic case (Steadman et al. (2006) Am J Phys Anthropol 131:15,26) and a large (N = 3,167) reference sample, we show that the sex of the individual can be reliably estimated using a small set of 11 craniometric variables. The likelihood ratio from sex (assuming a 1:1 sex ratio for the "population at large") is, however, relatively uninformative in "making" the identification. Similarly, the known "race" of the individual is relatively uninformative in "making" the identification, because the individual was recovered from an area where the 2000 US census provides a very homogenous picture of (self-identified) race. Of interest in this analysis is the fact that the individual, who was recovered from Eastern Iowa, classifies very clearly with [Howells 1973. Cranial Variation in Man: A Study by Multivariate Analysis of Patterns of Difference Among Recent Human Populations. Cambridge, MA: Peabody Museum of Archaeology and Ethnology; 1989. Skull Shape and the Map: Craniometric Analyses in the Dispersion of Modern Homo. Cambridge, MA: Harvard University Press]. Easter Islander sample in an analysis with uninformative priors. When the Iowa 2000 Census data on self-reported race are used for informative priors, the individual is clearly identified as "American White." This analysis shows the extreme importance of an informative prior in any forensic application. Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Brief communication: High-resolution assessment of the dental developmental pattern and characterization of tooth tissue proportions in the late Upper Paleolithic child from La Madeleine, FranceAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2009Priscilla Bayle Abstract Affinities and differences in dental maturational patterns between modern humans and Neanderthals remain a matter of discussion. In particular, deciduous teeth are rare for Late Pleistocene humans, and few entire sequences have been detailed for their developmental status. Here, we report the results from the 3D virtual reconstruction and structural analysis of the deciduous lower dentition (nine teeth in situ) of the child from La Madeleine (LM4), France, the first Upper Paleolithic specimen detailed so far by means of high-resolution microtomography (,CT). With respect to the modern dental developmental standards, age at death of this individual is now more likely estimated within the interval 3,4 years. LM4 lacks the slight discrepancy between a proportionally advanced stage of mineralization of the deciduous first molar and a relatively delayed maturational level of the incisors, which is found in Neanderthals (Bayle et al.: J Hum Evol 56 [2009] 66,75). By using a Bayesian approach, we calculated the probability that its maturational sequence is found within the extant human variation as represented by a tomographic (CT) reference sample of 45 children scored according to the same protocol (Liversidge and Molleson: Am J Phys Anthropol 123 [2004] 172,180). Results show that the specific sequence of this Magdalenian individual is found three times in the comparative sample included in this study. LM4 absolute tooth size and relative dental tissue proportions are close to the modern human figures (characterized by proportionally reduced dentine volumes) and lie systematically below the values shown by the Neanderthal child from Roc de Marsal, France (OIS 5a). Am J Phys Anthropol 2009. © 2009 Wiley-Liss, Inc. [source] Functional implications of radial diaphyseal curvatureAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Ignasi Galtés Abstract A recent study (Galtés et al.: Am J Phys Anthropol 135 (2008) 293-300) demonstrated that during pronation, pronator teres exerts a favorable force for radial lateral bending. On the basis of this finding, we hypothesized that the pattern of muscular loading exerted on the radius by this muscle might play a role as a mechanical stimulus involved in radial bowing. The current work relates the hypertrophy of the forearm muscles to the degree of lateral curvature of the radial diaphysis. The analysis is based on an original osteometrical index to estimate radial curvature, and it applies a visual reference method to grade the osteological appearance of 10 entheses of 104 radii from archaeological and contemporary samples. Using these morphological data as an indirect method to measure the association between muscular hypertrophy and bone curvature, this study reveals that the pattern of muscular loading exerted on the apex of the radial shaft by the pronator teres muscle may play an important role as a mechanical stimulus involved in diaphyseal bowing. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Masticatory stress and the mechanics of "wishboning" in colobine jawsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009David J. Daegling Abstract Cercopithecoid monkeys experience relatively high strains along the lingual aspect of the mandibular symphysis because of lateral transverse bending of the mandibular corpora ("wishboning") during mastication. Hylander (Am J Phys Anthropol 64 (1984) 1,46; Am Zool 25 (1985) 315,330) demonstrated that the distribution of strains arising from wishboning loads is comprehensible with reference to the mechanics of curved beams. Theory of curved beams suggests that lingual tensile strains are some multiple of labial compressive strains, yet limitations of experimental methods and uncertainty in estimating parameters needed for theoretical calculations have confounded attempts to characterize the magnitude of this disparity of normal strains. We evaluate the theoretical disparity of normal strains in wishboning in comparison to in vitro strains collected under controlled loads for a sample of mandibles representing two colobine species (N = 6). These data suggest that in colobine monkeys, maximum normal lingual strains should be at least twice maximum labial strains. In addition, we reexamine the distribution of symphyseal stress under an assumption of asymmetric bending, a general approach for calculation of stress appropriate for members that lack a plane of symmetry and are bent along an axis that is not coincident with the member's principal axes. Under asymmetric bending in colobine mandibles, the effect of symphyseal inclination on lingual strain is mitigating at the superior transverse torus and exacerbating at the inferior transverse torus. Relative compliance of colobine mandibular bone further supports the hypothesis that the structural and material properties of the colobine mandibular symphysis do not represent a morphological strategy for minimizing masticatory strain. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] Hip extensor EMG and forelimb/hind limb weight support asymmetry in primate quadrupedsAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 3 2009Susan G. Larson Abstract Higher weight support on the hind limb than forelimb is among the distinctive characteristics of primate quadrupeds. Although often assumed to be due to a more posteriorly positioned whole body center of mass, there are little data to support such a difference. Reynolds (1985. Am J Phys Anthropol 67:335,349) notes that the distribution of forces on the limbs can also be influenced by average limb posture, but suggests that this effect is too small to account for the asymmetry in weight support observed in primates. Instead, he proposes that high hind limb forces are brought about by an active process of shifting weight off the forelimbs and onto the hind limbs through use of hind limb retractors. In this study, we use video records of walking animals to explore the degree to which average limb posture in primates and other quadrupedal mammals deviates from vertical, and use electromyography to test Reynolds' model of hind limb retractor activity and posterior weight shift. The limb posture results indicate that primate forelimbs oscillate about a vertical or slightly retracted axis, and though the hind limbs are slightly protracted, the magnitude of deviation from vertical is too small to have a major effect on weight support distribution. The electromyographic results reveal higher levels of hip extensor activity in antipronograde primates that bear a higher proportion of weight on their hind limbs. This lends support to Reynolds' suggestion that some primates use muscles to actively shift weight onto hind limbs to relieve stresses on forelimbs less well structured for weight support. Am J Phys Anthropol, 2009. © 2008 Wiley-Liss, Inc. [source] A new method for estimating age-at-death from the first rib,AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2009Elizabeth A. DiGangi Abstract A new method for estimating adult age-at-death from the first rib was developed as a modification of the Kunos et al. (Am J Phys Anthropol 110 (1999) 303,323) method. Data were collected on three aspects of the first rib (costal face, rib head, and tubercle facet) for 470 known-age males of Balkan ancestry collected as evidence during investigations conducted by the International Criminal Tribunal for the former Yugoslavia (ICTY). Ages-at-death range from 12 to 90 years (mean of 47.7 years). Several variables were extracted from the original study utilizing all three skeletal aspects of the first rib. This list was modified to 11 variables as preliminary tests on seriations of the samples were undertaken. A cumulative probit model with age measured on a log scale was used to calculate the mean and standard deviation of the ages-of-transition for each component. Multivariate analysis of the three components was also performed. The lowest correlation (r = 0.079, controlling for age) was between the geometric shape of the costal face and the surface texture of the tubercle facet. Assuming a correlation of zero, these two traits were used to calculate the highest posterior density regions for estimating individual ages-at-death. Age-at-death estimates generated from 50 and 95% posterior density regions indicate that this method captures age-related change reaching the ninth decade. The Bayesian statistical approach used here produced a valuable and promising new method for estimating age-at-death. Additional research is necessary to determine if these highest posterior density regions produce results highly correlated with age in other samples and its applicability to females. Am J Phys Anthropol 2009. © 2008 Wiley-Liss, Inc. [source] Do mandibular cross-sectional properties and dental microwear give similar dietary signals?AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2006Jason M. Organ Abstract Previous animal experimental work evaluating the effects of dietary consistency on mastication was generally limited to studies of either mandibular structure or rates and types of tooth wear. Control groups fed hard diets (HD) consistently exhibited increased cortical remodeling and/or bone strength when compared to groups fed soft diets (SD). Results of tooth-wear studies showed faster rates of tooth wear in HD animals. This study evaluates the effects of dietary differences on both mandibular structural morphology and postcanine dental microwear in the same animals. We examined mandibles and dentitions from eight miniature swine, raised from 4 weeks to 9 months of age on HD and SD (n = 4, each group). Mandibular structural properties were calculated from peripheral quantitative computed tomography slices at the dp3,dp4 and dp4,M1 junctions. Dental microwear analysis was performed on mandibular lingual crushing facets of dp4 and M1, using photomicrographs of high-resolution casts taken at 500× magnification in a scanning electron microscope. Our results suggest that between the dp3,dp4 contact, HD animals have mandibles that are stronger and more rigid mediolaterally than SD animals. At the dp4,M1 contact, HD animals have mandibles that are stronger and more rigid mediolaterally, dorsoventrally, and in torsion than SD animals. Dental microwear results indicate that SD pigs have higher incidences of pitting and more overall microwear features on their premolars than do HD pigs, yet there are no significant differences in molar microwear morphology between the dietary groups. Near-significant correlations exist between pit size and dorsoventral bending strength, but only for HD pigs. These results suggest that dietary consistency significantly affects both mandibular structure and dental microwear, yet direct correlations between the two are complicated by a number of factors Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source] Estimating chimpanzee population size with nest counts: validating methods in Taï National ParkAMERICAN JOURNAL OF PRIMATOLOGY, Issue 6 2009Célestin Yao Kouakou Abstract Successful conservation and management of wild animals require reliable estimates of their population size. Ape surveys almost always rely on counts of sleeping nests, as the animals occur at low densities and visibility is low in tropical forests. The reliability of standing-crop nest counts and marked-nest counts, the most widely used methods, has not been tested on populations of known size. Therefore, the answer to the question of which method is more appropriate for surveying chimpanzee population remains problematic and comparisons among sites are difficult. This study aimed to test the validity of these two methods by comparing their estimates to the known population size of three habituated chimpanzee communities in Taï National Park [Boesch et al., Am J Phys Anthropol 130:103,115, 2006; Boesch et al., Am J Primatol 70:519,532, 2008]. In addition to transect surveys, we made observations on nest production rate and nest lifetime. Taï chimpanzees built 1.143 nests per day. The mean nest lifetime of 141 fresh nests was 91.22 days. Estimate precision for the two methods did not differ considerably (difference of coefficient of variation <5%). The estimate of mean nest decay time was more precise (CV=6.46%) when we used covariates (tree species, rainfall, nest height and age) to model nest decay rate, than when we took a simple mean of nest decay times (CV=9.17%). The two survey methods produced point estimates of chimpanzee abundance that were similar and reliable: i.e. for both methods the true chimpanzee abundance was included within the 95% estimate confidence interval. We recommend further research on covariate modeling of nest decay times as one way to improve the precision and to reduce the costs of conducting nest surveys. Am. J. Primatol. 71:447,457, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||