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Sambaqui Zé Espinho : o que uma análise paleobiológica pode demonstrar sobre este grupo pré-colonial do litoral brasileiro?

Amaral, Marco Túlio Alves Amorim do
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Dissertação de Mestrado
POR
Relevância na Pesquisa
16.78%
O Sambaqui Zé Espinho é um sítio arqueológico localizado no litoral do Estado do Rio de Janeiro, na região denominada Planície Maré de Guaratiba, situada em uma área de intersecção ambiental entre o mar aberto e o continente, considerada por muitos como um local rico em recursos naturais, com datações entre 2.260 ± 160 A.P. à 1.180 ± 170 A.P., sendo constituído por uma série esquelética de 24 indivíduos, aos quais 15 esqueletos adultos apresentavam-se em condições apropriadas para a realização do presente trabalho. Através de uma análise paleobiológica, propomo-nos a conhecer a vida e saúde dos habitantes, munindo-nos de uma abordagem macroscópica, nas quais foram coletadas informações sobre sexo, idade, estatura, índices de robustez e achatamento, assim como variações morfológicas que manifestavam-se na constituição esquelética dos indivíduos. No que concerne a patologia oral, foram registrados dados sobre a prevalência de cáries, desgaste dentário, perda dentária ante mortem, abcessos e doença periodontal, limitando-nos a não registrar a presença de cálculos, uma vez que a influência de concreções orgânicas impossibilitava qualquer registro. Pareceu-nos oportuno conhecer melhor a saúde dos indivíduos também acedendo à informações sobre patologias degenerativas...

Comparison of the entheseal changes of the os coxae of Portuguese males (19th-20th centuries) with known occupation

Campanacho, Vanessa; Santos, Ana Luísa
Fonte: John Wiley & Sons Publicador: John Wiley & Sons
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
28.02%
The possible association between entheseal changes and activity has been widely studied. However many questions remain. This study aims to assess if occupation and physical activity influences the age at which entheseal changes appear in the iliac crest, retroauricular area, iliac tuberosity, ischial tuberosity and obturator foramen. Absence or presence of ossification exostosis and stress lesions was recorded in os coxae from 130 males (19 to 88 years old) from Lisbon and Coimbra identified skeletal collections. The individuals were divided into two groups, based upon to the recorded occupations: manual (n = 69) and non-manual (n = 61). The sample was also divided according to an osteological indicator of physical activity: the femur robusticity index (55 are robust and 54 are gracile femora). The individuals from manual and robust groups were considered to have had physically demanding occupations, while the non-manual and gracile groups represent individuals with less demanding activities. The asymmetry of entheseal changes between left and right sides of the same individuals was tested with a Chi-square test. And the influence of occupation and physical activities on the age of appearance of entheseal changes were tested using logistic regression. Statistically significant asymmetry was not found between left and right bones (p <0.05). However...

Nuances da vida e da morte no cotidiano da cidade de Salvador da Bahia seiscentista: a busca de evidências em um estudo paleobiológico

Mendonça, Teresa Cristina de Sousa
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Tese de Doutorado
POR
Relevância na Pesquisa
16.78%
Os esqueletos e os dentes são fontes documentais antropológicas que atuam como registo ou memória das circunstâncias que afetaram o indivíduo durante sua vida. O objetivo do presente estudo é tirar o máximo de ilações sobre a vida e a morte dos indivíduos inumados no espaço cemiterial da Antiga Igreja da Sé, em Salvador, na Bahia, a partir das características demográficas e patológicas da amostra. Salvador foi a capital do Império Português nas Américas até 1763. No contexto social urbano, a Igreja da Sé destacou-se como espaço religioso, político e social e pela localização estratégica serviu de fortificação para portugueses e espanhóis durantes as invasões holandesas. Os enterramentos na Igreja da Sé eram feitos no adro e no interior. As situações de deposição dos corpos vinculada com o status social dos indivíduos sepultados na Antiga Igreja da Sé foram evidenciadas arqueologicamente. Foram analisados 159 esqueletos, 39 resgatados do interior da igreja e 120 do adro. Destes, 31 indivíduos exibem mutilações dentárias, um provável indício da procedência africana. Em relação a longevidade, apenas três indivíduos faleceram com mais de 50 anos, um homem e duas mulheres. A análise demográfica revelou que 25% dos indivíduos têm menos de 19 anos...

Os sepultados de Jabuticabeira II, SC - insights e inferências sobre padrões fenotípicos, análise de modo de vida e organização social através de marcadores de estresse músculo-esqueletal; The buried people of Jabuticabeira II, SC - insights and inferences about phenotypic patterns, way of life analysis and social organization by musculo-skeletal markers

Abbas, Adam Reiad
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 17/04/2013 PT
Relevância na Pesquisa
28.02%
Os marcadores de estresse músculo-esqueletal (MSMs), assim denominados, surgem pela primeira vez em 1995 no trabalho pioneiro de Hawkey e Merbs. De lá pra cá, diversos estudos se prestaram a aprimorar o método desenvolvido pelos pesquisadores e, ainda, associar de maneira mais concreta os graus de desenvolvimento de enteses a atividades desenvolvidas ao longo da vida de um indivíduo. Sob tais circunstâncias, buscamos neste trabalho a verificação da implementação de uma metodologia de análise revisada, testada e aprimorada dos marcadores de estresse músculo-esqueletal e a possibilidade de correlação entre os graus de desenvolvimento das enteses estudadas com as possíveis atividades desenvolvidas pelos indivíduos analisados, provenientes do sambaqui costeiro catarinense Jabuticabeira II (JAB-II). A escolha pela análise dos remanescentes ósseos deste sítio decorreu da vasta informação disponível em relação aos mesmos e ao sítio em si, provindos de outros trabalhos desenvolvidos previamente. Assim, estudos de paleopatologia e arqueologia possibilitaram melhores interpretações dos resultados obtidos pelas análises de MSMs. Neste trabalho procuramos adaptar a metodologia desenvolvida por Mariotti (2004,2007) para amostras antigas (mais de 2000 anos atrás) e de baixa conservação. Além disso...

Age at death determination from morphological changes in the clavicle: from adolescence to adulthood - the impact of environmantal factors

Faria, Fernando Alexander Eiras, 1982-
Fonte: Universidade de Lisboa Publicador: Universidade de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2011 ENG
Relevância na Pesquisa
18.41%
Tese de mestrado. Biologia (Biologia Humana e Ambiente). Universidade de Lisboa, Faculdade de Ciências, 2011; A determinação da idade à morte é um dos principais desafios que se apresentam numa identificação individual a partir de restos humanos ósseos. Obter a idade que o indivíduo tinha aquando da morte é uma tarefa complicada e que vai aumentando de grau de dificuldade à medida que a idade do indivíduo aumenta. Até ao final da sua formação e erupção, os dentes representam indicadores muito precisos da idade (Hillson, 1996). Durante a infância e adolescência, o comprimento dos ossos longos e a fusão epifisária aparecem como as formas mais fiáveis da determinação da idade. A partir dos 18 anos, o terceiro molar está muitas vezes já erupcionado, e muitas das principais epifises começam a estar fundidas à medida que o corpo deixa de crescer (Cardoso, 2008). A partir desta altura a precisão dos métodos começa a decaír drasticamente e após os 30 anos os indicadores usados para determinar a idade em indivíduos adultos prendem-se com degeneração dos ossos, degeneração esta que está muito menos dependente de factores genéticos e muito mais dependente de factores ambientais, como a nutrição, o clima e principalmente a actividade física (Scheuer e Black...

The early Upper Paleolithic human skeleton from the Abrigo do Lagar Velho (Portugal) and modern human emergence in Iberia

Duarte, Cidália; Maurício, João; Pettitt, Paul B.; Souto, Pedro; Trinkaus, Erik; van der Plicht, Hans; Zilhão, João
Fonte: The National Academy of Sciences Publicador: The National Academy of Sciences
Tipo: Artigo de Revista Científica
Publicado em 22/06/1999 EN
Relevância na Pesquisa
16.78%
The discovery of an early Upper Paleolithic human burial at the Abrigo do Lagar Velho, Portugal, has provided evidence of early modern humans from southern Iberia. The remains, the largely complete skeleton of a ≈4-year-old child buried with pierced shell and red ochre, is dated to ca. 24,500 years B.P. The cranium, mandible, dentition, and postcrania present a mosaic of European early modern human and Neandertal features. The temporal bone has an intermediate-sized juxtamastoid eminence. The mandibular mentum osseum and the dental size and proportions, supported by mandibular ramal features, radial tuberosity orientation, and diaphyseal curvature, as well as the pubic proportions align the skeleton with early modern humans. Body proportions, reflected in femorotibial lengths and diaphyseal robusticity plus tibial condylar displacement, as well as mandibular symphyseal retreat and thoracohumeral muscle insertions, align the skeleton with the Neandertals. This morphological mosaic indicates admixture between regional Neandertals and early modern humans dispersing into southern Iberia. It establishes the complexities of the Late Pleistocene emergence of modern humans and refutes strict replacement models of modern human origins.

Appendicular robusticity and the paleobiology of modern human emergence

Trinkaus, Erik
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 25/11/1997 EN
Relevância na Pesquisa
16.78%
The emergence of modern humans in the Late Pleistocene, whatever its phylogenetic history, was characterized by a series of behaviorally important shifts reflected in aspects of human hard tissue biology and the archeological record. To elucidate these shifts further, diaphyseal cross-sectional morphology was analyzed by using cross-sectional areas and second moments of area of the mid-distal humerus and midshaft femur. The humeral diaphysis indicates a gradual reduction in habitual load levels from Eurasian late archaic, to Early Upper Paleolithic early modern, to Middle Upper Paleolithic early modern hominids, with the Levantine Middle Paleolithic early modern humans being a gracile anomalous outlier. The femoral diaphysis, once variation in ecogeographically patterned body proportions is taken into account, indicates no changes across the pre-30,000 years B.P. samples in habitual locomotor load levels, followed by a modest decrease through the Middle Upper Paleolithic.

Genomic data support the hominoid slowdown and an Early Oligocene estimate for the hominoid–cercopithecoid divergence

Steiper, Michael E.; Young, Nathan M.; Sukarna, Tika Y.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.78%
Several lines of indirect evidence suggest that hominoids (apes and humans) and cercopithecoids (Old World monkeys) diverged around 23–25 Mya. Importantly, although this range of dates has been used as both an initial assumption and as a confirmation of results in many molecular-clock analyses, it has not been critically assessed on its own merits. In this article we test the robusticity of the 23- to 25-Mya estimate with ≈150,000 base pairs of orthologous DNA sequence data from two cercopithecoids and two hominoids by using quartet analysis. This method is an improvement over other estimates of the hominoid–cercopithecoid divergence because it incorporates two calibration points, one each within cercopithecoids and hominoids, and tests for a statistically appropriate model of molecular evolution. Most comparisons reject rate constancy in favor of a model incorporating two rates of evolution, supporting the “hominoid slowdown” hypothesis. By using this model of molecular evolution, the hominoid–cercopithecoid divergence is estimated to range from 29.2 to 34.5 Mya, significantly older than most previous analyses. Hominoid–cercopithecoid divergence dates of 23–25 Mya fall outside of the confidence intervals estimated...

Human patellar articular proportions: recent and Pleistocene patterns

TRINKAUS, ERIK
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/2000 EN
Relevância na Pesquisa
16.78%
The degrees of mediolateral asymmetry of the patellar articular facet, as well as the median and lateral articular angles of the facet, were compared across samples of recent humans and of Pleistocene archaic and modern fossil humans. All samples exhibit considerable variability in these patellar proportions. The articular angles are similar across the different samples, but there is a trend towards decreasing lateral angles with decreasing robusticity. The archaic humans exhibit significantly more symmetry of the medial and lateral facets than do any of the recent human samples. However, given the variability in medial versus lateral patellofemoral contact forces documented for extant humans and the roles of the distal oblique portions of vastus medialis and vastus lateralis in patellar stabilisation, it is unclear to what extent this variation in patellar articular proportions may affect knee kinesiology. The contrasts may be related to different levels of patellar stability and/or musculoskeletal hypertrophy, but they appear unlikely to have affected primary knee function.

Ontogeny of long bone geometry in capuchin monkeys (Cebus albifrons and Cebus apella): implications for locomotor development and life history

Young, Jesse W.; Fernández, David; Fleagle, John G.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.78%
Studies of a diverse array of animals have found that young individuals often have robust bones for their body size (i.e. augmented cross-sectional dimensions), limiting fracture risk despite general musculoskeletal immaturity. However, previous research has focused primarily on precocial taxa (e.g. rodents, lagomorphs, bovids, goats and emu). In this study, we examined the ontogenetic scaling of humeral and femoral cross-sectional robusticity in a mixed-longitudinal sample of two slow-growing, behaviourally altricial capuchin monkeys. Results showed that, when regressed against biomechanically appropriate size variables (i.e. the product of body mass and bone length), humeral and femoral bending strengths generally scale with negative allometry, matching the scaling patterns observed in previous studies of more precocial mammals. Additionally, bone strength relative to predicted loads (e.g. ‘safety factors’) peaks at birth and rapidly decreases during postnatal growth, falling to less than 5 per cent of peak values by weaning age. We suggest that increased safety factors during early ontogeny may be an adaptation to mitigate injury from falling during initial locomotor efforts. Overall, the results presented here suggest that ontogenetic declines in relative long bone strength may represent a common pattern among mammals that is perhaps preadaptive for different purposes among different lineages.

A 150-Year Conundrum: Cranial Robusticity and Its Bearing on the Origin of Aboriginal Australians

Curnoe, Darren
Fonte: SAGE-Hindawi Access to Research Publicador: SAGE-Hindawi Access to Research
Tipo: Artigo de Revista Científica
Publicado em 20/01/2011 EN
Relevância na Pesquisa
28.02%
The origin of Aboriginal Australians has been a central question of palaeoanthropology since its inception during the 19th Century. Moreover, the idea that Australians could trace their ancestry to a non-modern Pleistocene population such as Homo erectus in Southeast Asia have existed for more than 100 years, being explicitly linked to cranial robusticity. It is argued here that in order to resolve this issue a new program of research should be embraced, one aiming to test the full range of alternative explanations for robust morphology. Recent developments in the morphological sciences, especially relating to the ontogeny of the cranium indicate that character atomisation, an approach underpinning phylogenetic reconstruction, is fraught with difficulties. This leads to the conclusion that phylogenetic-based explanations for robusticity should be reconsidered and a more parsimonious approach to explaining Aboriginal Australian origins taken. One that takes proper account of the complex processes involved in the growth of the human cranium rather than just assuming natural selection to explain every subtle variation seen in past populations. In doing so, the null hypothesis that robusticity might result from phenotypic plasticity alone cannot be rejected...

A Preliminary Analysis of Correlations between Chewing Motor Patterns and Mandibular Morphology across Mammals

Vinyard, Christopher J.; Williams, Susan H.; Wall, Christine E.; Doherty, Alison H.; Crompton, Alfred W.; Hylander, William L.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
17.45%
The establishment of a publicly-accessible repository of physiological data on feeding in mammals, the Feeding Experiments End-user Database (FEED), along with improvements in reconstruction of mammalian phylogeny, significantly improves our ability to address long-standing questions about the evolution of mammalian feeding. In this study, we use comparative phylogenetic methods to examine correlations between jaw robusticity and both the relative recruitment and the relative time of peak activity for the superficial masseter, deep masseter, and temporalis muscles across 19 mammalian species from six orders. We find little evidence for a relationship between jaw robusticity and electromyographic (EMG) activity for either the superficial masseter or temporalis muscles across mammals. We hypothesize that future analyses may identify significant associations between these physiological and morphological variables within subgroups of mammals that share similar diets, feeding behaviors, and/or phylogenetic histories. Alternatively, the relative peak recruitment and timing of the balancing-side (i.e., non-chewing-side) deep masseter muscle (BDM) is significantly negatively correlated with the relative area of the mandibular symphysis across our mammalian sample. This relationship exists despite BDM activity being associated with different loading regimes in the symphyses of primates compared to ungulates...

Pedal Claw Curvature in Birds, Lizards and Mesozoic Dinosaurs – Complicated Categories and Compensating for Mass-Specific and Phylogenetic Control

Birn-Jeffery, Aleksandra V.; Miller, Charlotte E.; Naish, Darren; Rayfield, Emily J.; Hone, David W. E.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 05/12/2012 EN
Relevância na Pesquisa
16.78%
Pedal claw geometry can be used to predict behaviour in extant tetrapods and has frequently been used as an indicator of lifestyle and ecology in Mesozoic birds and other fossil reptiles, sometimes without acknowledgement of the caveat that data from other aspects of morphology and proportions also need to be considered. Variation in styles of measurement (both inner and outer claw curvature angles) has made it difficult to compare results across studies, as have over-simplified ecological categories. We sought to increase sample size in a new analysis devised to test claw geometry against ecological niche. We found that taxa from different behavioural categories overlapped extensively in claw geometry. Whilst most taxa plotted as predicted, some fossil taxa were recovered in unexpected positions. Inner and outer claw curvatures were statistically correlated, and both correlated with relative claw robusticity (mid-point claw height). We corrected for mass and phylogeny, as both likely influence claw morphology. We conclude that there is no strong mass-specific effect on claw curvature; furthermore, correlations between claw geometry and behaviour are consistent across disparate clades. By using independent contrasts to correct for phylogeny...

Isotopic evidence of early hominin diets

Sponheimer, Matt; Alemseged, Zeresenay; Cerling, Thure E.; Grine, Frederick E.; Kimbel, William H.; Leakey, Meave G.; Lee-Thorp, Julia A.; Manthi, Fredrick Kyalo; Reed, Kaye E.; Wood, Bernard A.; Wynn, Jonathan G.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.78%
Carbon isotope studies of early hominins from southern Africa showed that their diets differed markedly from the diets of extant apes. Only recently, however, has a major influx of isotopic data from eastern Africa allowed for broad taxonomic, temporal, and regional comparisons among hominins. Before 4 Ma, hominins had diets that were dominated by C3 resources and were, in that sense, similar to extant chimpanzees. By about 3.5 Ma, multiple hominin taxa began incorporating 13C-enriched [C4 or crassulacean acid metabolism (CAM)] foods in their diets and had highly variable carbon isotope compositions which are atypical for African mammals. By about 2.5 Ma, Paranthropus in eastern Africa diverged toward C4/CAM specialization and occupied an isotopic niche unknown in catarrhine primates, except in the fossil relations of grass-eating geladas (Theropithecus gelada). At the same time, other taxa (e.g., Australopithecus africanus) continued to have highly mixed and varied C3/C4 diets. Overall, there is a trend toward greater consumption of 13C-enriched foods in early hominins over time, although this trend varies by region. Hominin carbon isotope ratios also increase with postcanine tooth area and mandibular cross-sectional area, which could indicate that these foods played a role in the evolution of australopith masticatory robusticity. The 13C-enriched resources that hominins ate remain unknown and must await additional integration of existing paleodietary proxy data and new research on the distribution...

Pelvic girdle and fin of Tiktaalik roseae

Shubin, Neil H.; Daeschler, Edward B.; Jenkins, Farish A.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.78%
The earliest tetrapods have robust limbs, particularly hind limbs that are enlarged and supported by a number of modifications to the pelvic girdle. In contrast, the closest relatives of tetrapods maintain small and weakly ossified pelvic appendages as compared with the pectorals. This observation has led to the “front wheel drive” hypothesis that held that the closest relatives of tetrapods emphasized pectoral support and locomotion whereas significant pelvic support and locomotion was a tetrapod innovation. The discovery of pelvic girdle and fin material of the tetrapodomorph Tiktaalik roseae reveals a transitional stage in the origin of the pelvic girdle and appendage: although retaining primitive skeletal architecture, these elements are enhanced in size and robusticity much like tetrapods.

Bone microstructure and the evolution of growth patterns in Permo-Triassic therocephalians (Amniota, Therapsida) of South Africa

Huttenlocker, Adam K.; Botha-Brink, Jennifer
Fonte: PeerJ Inc. Publicador: PeerJ Inc.
Tipo: Artigo de Revista Científica
Publicado em 08/04/2014 EN
Relevância na Pesquisa
16.78%
Therocephalians were a speciose clade of nonmammalian therapsids whose ecological diversity and survivorship of the end-Permian mass extinction offer the potential to investigate the evolution of growth patterns across the clade and their underlying influences on post-extinction body size reductions, or ‘Lilliput effects’. We present a phylogenetic survey of limb bone histology and growth patterns in therocephalians from the Middle Permian through Middle Triassic of the Karoo Basin, South Africa. Histologic sections were prepared from 80 limb bones representing 11 genera of therocephalians. Histologic indicators of skeletal growth, including cortical vascularity (%CV) and mean primary osteon diameters (POD), were evaluated in a phylogenetic framework and assessed for correlations with other biologically significant variables (e.g., size and robusticity). Changes in %CV and POD correlated strongly with evolutionary changes in body size (i.e., smaller-bodied descendants tended to have lower %CV than their larger-bodied ancestors across the tree). Bone wall thickness tended to be high in early therocephalians and lower in the gracile-limbed baurioids, but showed no general correlation with cross-sectional area or degree of vascularity (and...

Enigmatic Cranial Superstructures among Chamorro Ancestors from the Mariana Islands: Gross Anatomy and Microanatomy

Heathcote, Gary M.; Bromage, Timothy G.; Sava, Vincent J.; Hanson, Douglas B.; Anderson, Bruce E.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.78%
This study focuses on the gross anatomy, anatomic relations, microanatomy, and meaning of three enigmatic, geographically-patterned, quasi-continuous superstructures of the posterior cranium. Collectively known as occipital superstructures (OSS), these traits are the occipital torus tubercle (TOT), retromastoid process (PR), and posterior supramastoid tubercle (TSP). When present, TOT, PR and TSP develop at posterior cranial attachment sites of the upper trapezius, superior oblique and sternocleidomastoid muscles, respectively. Marked expression and co-occurrence of these OSS are virtually circumscribed within Oceania and reach highest recorded frequencies in proto-historic Chamorros (CHamoru) of the Mariana Islands. Prior to undertaking scanning electron microscopy (SEM) work, our working multifactorial model for OSS development was that early-onset, long-term, chronic activity-related microtrauma at enthesis sites led to exuberant reactive or reparative responses in a substantial minority of genetically predisposed (and mostly male) individuals. SEM imaging, however, reveals topographic patterning that questions, but does not negate, activity-induction of these superstructures. While OSS appear macroscopically as relatively large and discrete phenomena...

The Influence of Life History and Sexual Dimorphism on Entheseal Changes in Modern Humans and African Great Apes

Milella, Marco
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 24/09/2014 EN
Relevância na Pesquisa
17.8%
Entheseal changes have been widely studied with regard to their correlation to biomechanical stress and their usefulness for biocultural reconstructions. However, anthropological and medical studies have demonstrated the marked influence of both age and sex on the development of these features. Studies of entheseal changes are mostly aimed in testing functional hypotheses and are mostly focused on modern humans, with few data available for non-human primates. The lack of comparative studies on the effect of age and sex on entheseal changes represent a gap in our understanding of the evolutionary basis of both development and degeneration of the human musculoskeletal system. The aim of the present work is to compare age trajectories and patterns of sexual dimorphism in entheseal changes between modern humans and African great apes. To this end we analyzed 23 postcranial entheses in a human contemporary identified skeletal collection (N = 484) and compared the results with those obtained from the analysis of Pan (N = 50) and Gorilla (N = 47) skeletal specimens. Results highlight taxon-specific age trajectories possibly linked to differences in life history schedules and phyletic relationships. Robusticity trajectories separate Pan and modern humans from Gorilla...

Estradiol, estrogen receptor alpha, and osteogenic responses to mechanical loading

Devlin, Maureen J.; Fukai, Naomi; Lieberman, Daniel; Olsen, Bjorn R.
Fonte: John Wiley & Sons Publicador: John Wiley & Sons
EN_US
Relevância na Pesquisa
17.45%
Despite evidence that mechanical loads can induce diaphyseal bone growth, there is little consensus about how, and to what extent, strain affects human skeletal phenotype. This project tests a mechanism of mechanotransduction in bone that may underlie variation in human skeletal robusticity. One hypothesis of particular relevance to humans is that hormones, particularly estradiol (E2) and its receptor, estrogen receptor alpha (ER-a), affect mechanotransduction in osteoblasts. Previous experiments demonstrate that E2 increases osteogenic responses to loading, but the mechanism involved is unclear. This project tests the hypothesis that E2 affects osteogenesis by upregulating ER-a, making osteoblasts more sensitive to mechanical loading. To test this hypothesis, 36 ovarie c-tomized C57BL/6J mice were divided into normal, high, and low E2 treatment groups implanted with 0.25 mg, 2.5 mg, or placebo E2 pellets. Half of the mice in each E2 group were fed normal mouse pellets, while half were fed a soft paste made from the same pellets. Results indicate that in the lateral mandibular corpus, hard diet animals exhibit 260% (high E2), 21% (low E2), and 82% (placebo) more growth than soft diet animals (p=0.01 to 0.03). In situ hybridization shows that ER-a is expressed in mandibular osteoblasts and hypertrophic chondrocytes...

Scaling Patterns and Ecological Correlates of Postcranial Skeletal Robusticity in Canis and Ursus: Implications for Human Evolution

Doyle, Sara Kathleen
Fonte: Universidade Duke Publicador: Universidade Duke
Tipo: Dissertação Formato: 4815267 bytes; application/pdf
Publicado em //2009 EN_US
Relevância na Pesquisa
37.8%

There has been a trend toward decreasing skeletal robusticity in the genus Homo throughout the Pleistocene, culminating in the gracile postcrania of living modern humans. This change is typically attributed to changing tool technologies and subsistence patterns among human groups. However, other mammalian groups also experience a similar change in their postcranial strength over the same time period. It is proposed in this dissertation that ecological variables are correlated with measures of postcranial strength and may be a better explanation for Holocene skeletal gracilization in humans, as well as in other mammalian genera. This hypothesis is investigated through a close examination of the scaling patterns in two extant genera, Canis and Ursus, and a comparison of scaling patterns and relative strength of different species of Canis, including a fossil species that provides information about temporal change. Measurements of limb length, joint surface area, bone diameter, and strength measurements derived from radiographic images of long bone midshafts of North American specimens of Canis, (including the fossil Canis dirus) and Ursus were collected. Scaling patterns of the cross-sectional variables on limb length and joint surfaces were analyzed for the interspecific and intraspecific samples.

The first hypothesis tested was that Canis scales with geometric similarity of cross-sectional variables on bone length and body mass...