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OBJECTIVES: South African Africans have been reported to have experienced negative or null secular trends in stature and other measures of skeletal structure across the 19th and 20th centuries, presumably due to poor living conditions during a time of intensifying racial discrimination. Here, we investigate whether any secular trend is apparent in limb bone strength during the same period. MATERIALS AND METHODS: Cadaver-derived skeletons (n = 221) were analyzed from female and male South African Africans who were born between 1839 and 1970, lived in and around Johannesburg, and died between 1925 and 1991 when they were 17-90 years of age. For each skeleton, a humerus and femur were scanned using computed tomography, and mid-diaphyseal cross-sectional geometric properties were calculated and scaled according to body size. RESULTS: In general linear mixed models accounting for sex, age at death, and skeletal element, year of birth was a significant (p < .05) negative predictor of size-standardized mid-diaphyseal cortical area (a proxy for resistance to axial loading) and polar moment of area (a proxy for resistance to bending and torsion), indicating a temporal trend toward diminishing limb bone strength. No significant interactions were detected between year of birth and age at death, suggesting that the decline in limb bone strength was mainly due to changes in skeletal maturation rather than severity of age-related bone loss. DISCUSSION: Limb bone strength is thus potentially another feature of the skeletal biology of South African Africans that was compromised by poor living conditions during the 19th and 20th centuries.
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Apartheid/história , População Negra , Fêmur/anatomia & histologia , Úmero/anatomia & histologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antropologia Física , População Negra/história , População Negra/estatística & dados numéricos , Diáfises/anatomia & histologia , Feminino , História do Século XIX , História do Século XX , Humanos , Masculino , Pessoa de Meia-Idade , África do Sul , Adulto JovemRESUMO
We describe a partial innominate, YGSP 41216, from a 12.3 Ma locality in the Siwalik Group of the Potwar Plateau in Pakistan, assigned to the Middle Miocene ape species Sivapithecus indicus. We investigate the implications of its morphology for reconstructing positional behavior of this ape. Postcranial anatomy of extant catarrhines falls into two distinct groups, particularly for torso shape. To an extent this reflects different although variable and overlapping positional repertoires: pronograde quadrupedalism for cercopithecoids and orthogrady for hominoids. The YGSP innominate (hipbone) is from a primate with a narrow torso, resembling most extant monkeys and differing from the broader torsos of extant apes. Other postcranial material of S. indicus and its younger and similar congener Sivapithecus sivalensis also supports reconstruction of a hominoid with a positional repertoire more similar to the pronograde quadrupedal patterns of most monkeys than to the orthograde patterns of apes. However, Sivapithecus postcranial morphology differs in many details from any extant species. We reconstruct a slow-moving, deliberate, arboreal animal, primarily traveling above supports but also frequently engaging in antipronograde behaviors. There are no obvious synapomorphic postcranial features shared exclusively with any extant crown hominid, including Pongo.
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Quadril/anatomia & histologia , Hominidae/anatomia & histologia , Animais , Paquistão , Análise de Componente Principal , Fatores de TempoRESUMO
Background: Orthodontic diagnostic standards generally use the cranial base as a reference and rely on samples selected by orthodontists. Objective: The purpose of this study was to provide male and female standards for a novel non-radiographic approach for orthodontic diagnosis that utilizes 3D dentofacial photogrammetry using the eyes and natural head orientation as references instead of the cranial base. Methods: One hundred and eighty females and 200 males between the ages of 18 and 35 years from 2 modeling agencies were orthodontically screened for near ideal occlusion. Subjects that met the inclusion criteria were rated by a sample of 40 lay people for attractiveness on a visual analogue scale. The final sample that had 3D facial and dental imaging included 49 subjects 25 males and 24 females with near ideal occlusion and considered attractive by the public. Results: Inter and Intra-examiner ICC were greater than 0.8 for both landmarking and indexing. Relative to a coronal plane contacting the pupils (MC), the mean sagittal position of the alar curvature (representing the nasomaxillary complex) was 14.36 ± 3.08 mm in males and 12.4 ± 3.58 mm in females. The sagittal position of soft tissue pogonion relative to the pupils was 14.84 ± 3.63 mm in males and 12.78 ± 5.68 mm in females. The angle between the alar curvature and pogonion relative to the pupils was 9° in males and 10° in females. With the exception of the occlusal plane which was steeper in females, no ratios or angular facial measurements showed a significant gender difference. Relative to MC, males had more proclined upper incisors (20° vs 16°) and more retroclined Lower incisors (27° vs 31°; P > 0.05). A Procrustes ANOVA and permutation test showed that the shapes of males and females are different enough to be considered two distinct populations. Conclusions: 1. When using the proposed method for orthodontic diagnosis, male and female patients should be compared to their respective dentofacial standards. 2. Validation of the proposed method and standards on an orthodontic population is underway to determine the scope its use.
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Má Oclusão/diagnóstico , Fotogrametria/métodos , Fotografia Dentária/métodos , Adolescente , Adulto , Cefalometria/métodos , Face/anatomia & histologia , Feminino , Humanos , Incisivo/anatomia & histologia , Masculino , Má Oclusão/terapia , Variações Dependentes do Observador , Ortodontia Corretiva , Valores de Referência , Caracteres Sexuais , Adulto JovemRESUMO
OBJECTIVES: To study the effects of urbanization on physical fitness (PF), we compare PF between urban and rural children from western Kenya. We hypothesize that active rural children are stronger, more flexible, and have greater endurance, and that PF differences are predictive of endurance running performance. METHODS: We recruited an age-matched, cross-sectional sample of participants (55 males, 60 females; 6-17 years) from schools near Eldoret, Kenya. PF and anthropometrics were assessed using the FITNESSGRAM®. General linear mixed models (GLMM) and path analyses tested for age, sex, and activity group differences in PF, as well as the effects of PF variables on mile run time. RESULTS: On average, urban participants had greater body mass (36.8 ± 15.9 vs. 31.9 ± 10.9 kg) but were not taller than rural participants (1.4 ± 0.2 vs. 1.4 ± 0.2 cm). Greater urban body mass appears driven by higher body fat (28.2 ± 9.4 vs. 16.8 ± 4.4%), which increased with age in urban but not rural participants. GLMM analyses showed age effects on strength variables (P<0.05) and sex differences in hip flexibility, sit-ups, and mile run (P<0.05). There were few differences in PF between groups except rural participants had stronger back muscles (18.2 ± 4.5 vs. 14.18 ± 4.3 cm) and faster mile times (6.3 ± 0.7 vs. 7.9 ± 2.0 min). Body composition and abdominal strength were predictive of mile time (P < 0.06), but the path analysis revealed a network of interacting direct and indirect effects that influenced endurance performance. CONCLUSIONS: Although differences in endurance and body composition are marked between urban and rural groups, strength and flexibility are not always correlated with overall activity levels. Am. J. Hum. Biol. 28:514-523, 2016. © 2015 Wiley Periodicals, Inc.
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Composição Corporal , Força Muscular , Aptidão Física , Amplitude de Movimento Articular , Adolescente , Criança , Estudos Transversais , Feminino , Humanos , Quênia , Masculino , População Rural , População UrbanaRESUMO
The evolution of cooperative breeding is particularly complex in humans because many other traits that directly affect parental care (shorter birth intervals, increased offspring survivorship, juvenile dependence, and older ages at dispersal) also emerge during the Pleistocene. If human cooperative breeding is ancient, it likely evolved in a hominin lacking a fully modern life history. However, the impact that changing life history traits has on parental care and cooperative breeding has not been analytically investigated. We develop an exploratory model to simulate an economic problem that would have arisen over the course of hominin life history evolution to identify those transitions that produced the strongest pressures for cooperative childrearing. The model generates two central predictions. First, help within maternal-offspring groups can support early changes in juvenile dependence, dispersal age, birth intervals, and fertility. If so, maternal-juvenile cooperation may be an important but understudied step in the evolution of human cooperative breeding. Second, pressure to recruit adult cooperation is most pronounced under more derived conditions of late dispersal and later ages of juvenile dependence, with a strong interaction at short birth intervals. Our findings indicate that changes in life history traits that affect parental care are critical in considering background selective forces that shaped the evolution of cooperative breeding.
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Evolução Biológica , Comportamento de Ajuda , Hominidae/fisiologia , Comportamento Materno , Reprodução , Animais , Feminino , Modelos Biológicos , MãesRESUMO
Many species of large wildlife have declined drastically worldwide. These reductions often lead to profound shifts in the ecology of entire communities and ecosystems. However, the effects of these large-wildlife declines on other taxa likely hinge upon both underlying abiotic properties of these systems and on the types of secondary anthropogenic changes associated with wildlife loss, making impacts difficult to predict. To better understand how these important contextual factors determine the consequences of large-wildlife declines on other animals in a community, we examined the effects of three common forms of large-wildlife loss (removal without replacement [using fences], removal followed by replacement with domestic stock, and removal accompanied by crop agricultural use) on small-mammal abundance, diversity, and community composition, in landscapes that varied in several abiotic attributes (rainfall, soil fertility, land-use intensity) in central Kenya. We found that small-mammal communities were indeed heavily impacted by all forms of large-wildlife decline, showing, on average: (1) higher densities, (2) lower species richness per site, and (3) different species assemblages in sites from which large wildlife were removed. However, the nature and magnitude of these effects were strongly context dependent. Rainfall, type of land-use change, and the interaction of these two factors were key predictors of both the magnitude and type of responses of small mammals. The strongest effects, particularly abundance responses, tended to be observed in low-rainfall areas. Whereas isolated wildlife removal primarily led to increased small-mammal abundance, wildlife removal associated with secondary uses (agriculture, domestic stock) had much more variable effects on abundance and stronger impacts on diversity and composition. Collectively, these results (1) highlight the importance of context in determining the impacts of large-wildlife decline on small-mammal communities, (2) emphasize the challenges in extrapolating results from controlled experimental studies to predict the effects of wildlife declines that are accompanied by secondary land-uses, and (3) suggest that, because of the context-dependent nature of the responses to large-wildlife decline, large-wildlife status alone cannot be reliably used to predict small-mammal community changes.
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Animais Selvagens , Biodiversidade , Tamanho Corporal , Animais , Conservação dos Recursos Naturais , Quênia , Dinâmica PopulacionalRESUMO
Zooarchaeologists frequently use the relative abundance of skeletal elements in faunal assemblages in conjunction with foraging theory models to infer subsistence decisions made by prehistoric hunter-gatherers. However, foraging models applied to ethnoarchaeological cases have had variable success linking skeletal transport decisions with foraging predictions. Here, we approach this issue with the well-known Hadza data to statistically model the skeletal element transport decisions in response to distance from the residential hub and the number of carriers available for carcass transport. We compare our modeling approach to the traditional skeletal element utility curves from Binford's work with the Nunamiut, and to the more recently proposed Shannon evenness measure. Our approach, based on standard yet powerful statistical modeling techniques, can help researchers gain increased insight into the prey part transport responses of hunter-gatherers. Our analyses treat individual prey skeletal elements by body size as the response variable. The results of this analysis suggest that utility curves, and the Shannon evenness approach as a proxy for utility curves, are problematic for making statements about prehistoric foraging from zooarchaeological data. Transport distance does not explain a significant portion of small prey (size class 2) skeletal element transport variation. However, distance explains a great deal of transport variation in large prey (size classes 4 and 5). Inferences from skeletal element profiles should be made relative to prey body size and the discard probability of individual elements. Understanding the influence of these variables allows construction of a framework for testing archaeological element profiles against ethnographically derived transport models.
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Arqueologia , Tamanho Corporal , Comportamento Alimentar , Hominidae/fisiologia , Modelos Biológicos , Animais , Antropologia Cultural , Cadeia Alimentar , HumanosRESUMO
This study addresses how the human temporal bone develops the population-specific pattern of morphology observed among adults and at what point in ontogeny those patterns arise. Three-dimensional temporal bone shape was captured using 15 landmarks on ontogenetic series of specimens from seven modern human populations. Discriminant function analysis revealed that population-specific temporal bone morphology is evident early in ontogeny, with significant shape differences among many human populations apparent prior to the eruption of the first molar. As early as five years of age, temporal bone shape reflects population history and can be used to reliably sort populations, although those in closer geographic proximity and molecular affinity are more likely to be misclassified. The deviation of cold-adapted populations from this general pattern of congruence between temporal bone morphology and genetic distances, identified in previous work, was confirmed here in adult and subadult specimens, and was revealed to occur earlier in ontogeny than previously recognized. Significant differences exist between the ontogenetic trajectories of some pairs of populations, but not among others, and the angles of these trajectories do not reflect genetic relationships or final adult temporal bone size. Significant intrapopulation differences are evident early in ontogeny, with differences becoming amplified by divergent trajectories in some groups. These findings elucidate how the congruence between adult human temporal bone morphology and population history develops, and reveal that this pattern corresponds closely to that described previously for facial ontogeny.
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Osso Temporal/anatomia & histologia , Adaptação Biológica , Adulto , Antropologia Física , Humanos , Imageamento Tridimensional , Grupos Populacionais/classificação , Análise de Componente Principal , Especificidade da EspécieRESUMO
Following the near extinction of bison (Bison bison) from its historic range across North America in the late 19th century, novel bison conservation efforts in the early 20th century catalyzed a popular widespread conservation movement to protect and restore bison among other species and places. Since Allen's initial delineation (1876) of the historic distribution of North American bison, subsequent attempts have been hampered by knowledge gaps about bison distribution and abundance prior to and following colonial arrival and settlement. For the first time, we applied a multidisciplinary approach to assemble a comprehensive, integrated geographic database and meta-analysis of bison occurrence over the last 200,000 years, with particular emphasis on the 450 years before present. We combined paleontology, archaeology, and historical ecology data for our database, which totaled 6438 observations. We derived the observations from existing online databases, published literature, and first-hand exploration journal entries. To illustrate the conservative maximum historical extent of occurrence of bison, we created a concave hull using observations occurring over the last 450 years (n = 3379 observations), which is the broadly accepted historical benchmark at 1500 CE covering 59% of the North American continent. Although this distribution represents a historic extent of occurrence-merely delineating the maximum margins of the near-continental distribution-it does not replace a density-based approach reconstructing potential historical range distributions, which identifies core and marginal ranges. However, we envision the observations contained in this database will contribute to further research in the increasingly evidence-based disciplines of bison ecology, evolution, rewilding, management, and conservation. There are no copyright or proprietary restrictions on these data, and this data paper should be cited when the data are reused.
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Bison , Animais , América do Norte , EcologiaRESUMO
Δ9-tetrahydrocannabinol (THC) is the intoxicating constituent of cannabis and is responsible for the drug's reinforcing effects. Retrospective human studies suggest that cannabis use during adolescence is linked to long-term negative psychological outcomes, but in such studies it is difficult to distinguish the effects of THC from those of coexisting factors. Therefore, translationally relevant animal models are required to properly investigate THC effects in adolescents. However, though the relevance of these studies depends upon human-relevant dosing, surprisingly little is known about THC pharmacology and its effects on behavior and brain activity in adolescent rodents-especially in females. Here, we conducted a systematic investigation of THC pharmacokinetics, metabolism and distribution in blood and brain, and of THC effects upon behavior and neural activity in adolescent Long Evans rats of both sexes. We administered THC during an early-middle adolescent window (postnatal days 27-45) in which the brain may be particularly sensitive to developmental perturbation by THC. We determined the pharmacokinetic profile of THC and its main first-pass metabolites (11-hydroxy-THC and 11-nor-9-carboxy-THC) in blood and brain following acute injection (0.5 or 5 mg/kg, intraperitoneal). We also evaluated THC effects on behavioral assays of anxiety, locomotion, and place conditioning, as well as c-Fos expression in 14 brain regions. Confirming previous work, we find marked sex differences in THC metabolism, including a female-specific elevation in the bioactive metabolite 11-hydroxy-THC. Furthermore, we find dose-dependent and sex-dependent effects on behavior, neural activity, and functional connectivity across multiple nodes of brain stress and reward networks. Our findings are relevant for interpreting results of rat adolescent THC exposure studies, and may lend new insights into how THC impacts the brain in a sex-dependent manner.
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Dronabinol , Alucinógenos , Animais , Encéfalo , Dronabinol/farmacologia , Feminino , Masculino , Ratos , Ratos Long-Evans , Estudos RetrospectivosRESUMO
Modern Homo sapiens engage in substantial ecosystem modification, but it is difficult to detect the origins or early consequences of these behaviors. Archaeological, geochronological, geomorphological, and paleoenvironmental data from northern Malawi document a changing relationship between forager presence, ecosystem organization, and alluvial fan formation in the Late Pleistocene. Dense concentrations of Middle Stone Age artifacts and alluvial fan systems formed after ca. 92 thousand years ago, within a paleoecological context with no analog in the preceding half-million-year record. Archaeological data and principal coordinates analysis indicate that early anthropogenic fire relaxed seasonal constraints on ignitions, influencing vegetation composition and erosion. This operated in tandem with climate-driven changes in precipitation to culminate in an ecological transition to an early, pre-agricultural anthropogenic landscape.
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Addiction is a chronic relapsing disorder, and during recovery many people experience several relapse events as they attempt to voluntarily abstain from drug. New preclinical relapse models have emerged that capture this common human experience, and mounting evidence indicates that resumption of drug seeking after voluntary abstinence recruits neural circuits distinct from those recruited during reinstatement after experimenter-imposed abstinence, or abstinence due to extinction training. Ventral pallidum (VP), a key limbic node involved in drug seeking, has well-established roles in conventional reinstatement models tested following extinction training, but it is unclear whether this region also participates in more translationally relevant models of relapse. Here we show that chemogenetic inhibition of VP neurons decreased cocaine-, context-, and cue-induced relapse tested after voluntary, punishment-induced abstinence. This effect was strongest in the most compulsive, punishment-resistant rats, and reinstatement was associated with neural activity in anatomically defined VP subregions. VP inhibition also attenuated the propensity of rats to display "abortive lever pressing," a species-typical risk assessment behavior seen here during punished drug taking, likely resulting from concurrent approach and avoidance motivations. These results indicate that VP, unlike other connected limbic brain regions, is essential for resumption of drug seeking after voluntary abstinence. Since VP inhibition effects were strongest in the most compulsively cocaine-seeking individuals, this may also indicate that VP plays a particularly important role in the most pathological, addiction-like behavior, making it an attractive target for future therapeutic interventions.
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Prosencéfalo Basal/efeitos dos fármacos , Prosencéfalo Basal/fisiologia , Cocaína/administração & dosagem , Comportamento de Procura de Droga/fisiologia , Punição , Animais , Condicionamento Operante/efeitos dos fármacos , Feminino , Masculino , Ratos Long-Evans , RecidivaRESUMO
Early-life adversity increases the risk for emotional disorders such as depression and schizophrenia. Anhedonia, thought to be a core feature of these disorders, is provoked by our naturalistic rodent model of childhood adversity (i.e., rearing pups for one week in cages with limited bedding and nesting, LBN). Drug use and addiction are highly comorbid with psychiatric disorders featuring anhedonia, yet effects of LBN on drug-seeking behavior and the reward and stress-related circuits that underlie it remain unknown. Here we examined the effects of LBN on cocaine intake and seeking, using a battery of behavioral tests measuring distinct aspects of cocaine reward, and for comparison, chocolate intake. We also examined activation of neurons within the pleasure/reward and stress circuits following cocaine in LBN and control rats. Early-life adversity reduced spontaneous intake of palatable chocolate, extending prior reports of sucrose and social-play anhedonia. In a within-session cocaine behavioral economic test, LBN rats self-administered lower dosages of cocaine under low-effort conditions, consistent with a reduced hedonic set-point for cocaine, and potentially anhedonia. In contrast, cocaine demand elasticity was not consistently affected, indicating no major changes in motivation to maintain preferred cocaine blood levels. These changes were selective, as LBN did not cause an overt anxiety-like phenotype, nor did it affect sensitivity to self-administered cocaine dose, responding for cocaine under extinction conditions, cocaine- or cue-induced reinstatement of cocaine seeking, or locomotor response to acute cocaine. However, high Fos expression was seen after cocaine in both reward- and stress-related brain regions of LBN rats, including nucleus accumbens core, central amygdala, and lateral habenula. In contrast, hypothalamic orexin neuron activation after cocaine was significantly attenuated in LBN rats. Together, these findings demonstrate enduring effects of early-life adversity on both reward- and fear/anxiety-related neural circuits, as well as anhedonia-like reductions in consumption of natural and drug rewards.
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Modern morphometrics provides powerful methods to quantify size and shape variation. A basic requirement is a list of coordinates that define landmarks; however such coordinates must represent homologous structures across specimens. While many biological objects consist of easily identified landmarks to satisfy the assumption of homology, many lack such structures. One potential solution is to mathematically place semi-landmarks on an object that represent the same morphological region across specimens. Here, we illustrate a recently developed pipeline to mathematically define semi-landmarks from the mouse baculum (penis bone). Our methods should be applicable to a wide range of objects.
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Osso e Ossos/diagnóstico por imagem , Dissecação/métodos , Pênis/diagnóstico por imagem , Tomografia Computadorizada por Raios X , Animais , Osso e Ossos/anatomia & histologia , Insetos , Masculino , Camundongos , Pênis/anatomia & histologiaRESUMO
Understanding the effects of anthropogenic disturbance on zoonotic disease risk is both a critical conservation objective and a public health priority. Here, we evaluate the effects of multiple forms of anthropogenic disturbance across a precipitation gradient on the abundance of pathogen-infected small mammal hosts in a multi-host, multi-pathogen system in central Kenya. Our results suggest that conversion to cropland and wildlife loss alone drive systematic increases in rodent-borne pathogen prevalence, but that pastoral conversion has no such systematic effects. The effects are most likely explained both by changes in total small mammal abundance, and by changes in relative abundance of a few high-competence species, although changes in vector assemblages may also be involved. Several pathogens responded to interactions between disturbance type and climatic conditions, suggesting the potential for synergistic effects of anthropogenic disturbance and climate change on the distribution of disease risk. Overall, these results indicate that conservation can be an effective tool for reducing abundance of rodent-borne pathogens in some contexts (e.g. wildlife loss alone); however, given the strong variation in effects across disturbance types, pathogen taxa and environmental conditions, the use of conservation as public health interventions will need to be carefully tailored to specific pathogens and human contexts.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
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Agricultura , Mudança Climática , Vetores de Doenças , Roedores , Zoonoses/epidemiologia , Zoonoses/transmissão , Animais , Conservação dos Recursos Naturais , Quênia , Prevalência , Saúde Pública , Zoonoses/etiologiaRESUMO
Early childhood growth has many downstream effects on future health and reproduction and is an important measure of offspring quality. While a tradeoff between family size and child growth outcomes is theoretically predicted in high-fertility societies, empirical evidence is mixed. This is often attributed to phenotypic variation in parental condition. However, inconsistent study results may also arise because family size confounds the potentially differential effects that older and younger siblings can have on young children's growth. Additionally, inconsistent results might reflect that the biological significance associated with different growth trajectories is poorly understood. This paper addresses these concerns by tracking children's monthly gains in height and weight from weaning to age five in a high fertility Maya community. We predict that: 1) as an aggregate measure family size will not have a major impact on child growth during the post weaning period; 2) competition from young siblings will negatively impact child growth during the post weaning period; 3) however because of their economic value, older siblings will have a negligible effect on young children's growth. Accounting for parental condition, we use linear mixed models to evaluate the effects that family size, younger and older siblings have on children's growth. Congruent with our expectations, it is younger siblings who have the most detrimental effect on children's growth. While we find statistical evidence of a quantity/quality tradeoff effect, the biological significance of these results is negligible in early childhood. Our findings help to resolve why quantity/quality studies have had inconsistent results by showing that sibling competition varies with sibling age composition, not just family size, and that biological significance is distinct from statistical significance.
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Intervalo entre Nascimentos , Desenvolvimento Infantil , Irmãos , Fatores Etários , Antropometria , Tamanho Corporal , Peso Corporal , Pré-Escolar , Coleta de Dados , Características da Família , Feminino , Fertilidade , Humanos , Masculino , México , Fenótipo , População RuralRESUMO
Cranial and temporomandibular joint (TMJ) form has been shown to reflect masticatory forces and mandibular range of motion, which vary in relation to feeding strategy. Similarly, the dentition, as the portion of the masticatory apparatus most directly involved in triturating food items, strongly reflects dietary profile. Fine control over condylar and mandibular movements guides the teeth into occlusion, while the topography and position of the dental arcade mediate mandibular movements. We hypothesize that masticatory, and particularly TMJ, morphology and dental form covary in predictable ways with one another and with diet. We employed three-dimensional geometric morphometric techniques to examine inter-specific variation in ten platyrrhine species. Landmarks were collected on six datasets describing the upper and lower molars, cranium, glenoid fossa, mandible, and mandibular condyle; two-block partial least squares analyses were performed to assess covariation between cranial morphology, dentition, and diet. Significant relationships were identified between the molars and the cranium, mandible, and glenoid fossa. Some of these shape complexes reflect feeding strategy; for example, higher crowned/cusped dentitions, as found in primates consuming larger quantities of structural carbohydrates (e.g., Alouatta and Saimiri), correspond to anteroposterior longer and deeper glenoid fossae. These results indicate strong covariance between dental and TMJ form, aspects of which are related to feeding behavior. However, other aspects of morphological variation display a strong phylogenetic signal; we must therefore examine further ways in which to control for phylogeny when examining covariation in interspecific masticatory form.
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Cebidae/anatomia & histologia , Cebidae/fisiologia , Matemática , Crânio/anatomia & histologia , Crânio/fisiologia , Articulação Temporomandibular/anatomia & histologia , Dente/anatomia & histologia , Animais , Feminino , Alimentos/classificação , Masculino , Mandíbula/anatomia & histologia , Mastigação/fisiologia , Filogenia , Amplitude de Movimento Articular/fisiologia , Articulação Temporomandibular/fisiologia , Dente/fisiologiaRESUMO
Runners are often categorized as forefoot, midfoot or rearfoot strikers, but how much and why do individuals vary in foot strike patterns when running on level terrain? This study used general linear mixed-effects models to explore both intra- and inter-individual variations in foot strike pattern among 48 Kalenjin-speaking participants from Kenya who varied in age, sex, body mass, height, running history, and habitual use of footwear. High speed video was used to measure lower extremity kinematics at ground contact in the sagittal plane while participants ran down 13 meter-long tracks with three variables independently controlled: speed, track stiffness, and step frequency. 72% of the habitually barefoot and 32% of the habitually shod participants used multiple strike types, with significantly higher levels of foot strike variation among individuals who ran less frequently and who used lower step frequencies. There was no effect of sex, age, height or weight on foot strike angle, but individuals were more likely to midfoot or forefoot strike when they ran on a stiff surface, had a high preferred stride frequency, were habitually barefoot, and had more experience running. It is hypothesized that strike type variation during running, including a more frequent use of forefoot and midfoot strikes, used to be greater before the introduction of cushioned shoes and paved surfaces.
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Pé/fisiologia , Marcha , Corrida , Sapatos , Adolescente , Adulto , Antropometria , Atletas , Fenômenos Biomecânicos , Feminino , Humanos , Quênia , Masculino , Reprodutibilidade dos Testes , Gravação em Vídeo , Adulto JovemRESUMO
Just as modern nation-states struggle to manage the cultural and economic impacts of migration, ancient civilizations dealt with similar external pressures and set policies to regulate people's movements. In one of the earliest urban societies, the Indus Civilization, mechanisms linking city populations to hinterland groups remain enigmatic in the absence of written documents. However, isotopic data from human tooth enamel associated with Harappa Phase (2600-1900 BC) cemetery burials at Harappa (Pakistan) and Farmana (India) provide individual biogeochemical life histories of migration. Strontium and lead isotope ratios allow us to reinterpret the Indus tradition of cemetery inhumation as part of a specific and highly regulated institution of migration. Intra-individual isotopic shifts are consistent with immigration from resource-rich hinterlands during childhood. Furthermore, mortuary populations formed over hundreds of years and composed almost entirely of first-generation immigrants suggest that inhumation was the final step in a process linking certain urban Indus communities to diverse hinterland groups. Additional multi disciplinary analyses are warranted to confirm inferred patterns of Indus mobility, but the available isotopic data suggest that efforts to classify and regulate human movement in the ancient Indus region likely helped structure socioeconomic integration across an ethnically diverse landscape.