Valeria Bernal

National University of La Plata, Eva Perón, Buenos Aires, Argentina

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Publications (49)63.6 Total impact

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    ABSTRACT: Objectives: One of the biggest challenges in the study of complex morphologies is to adequately describe shape variation. Here, we assess how the random sampling of surface points automatically obtained performs, when compared with observer-guided sampling procedures, and also evaluate the effect of sliding surface points by bending energy and minimum Procrustes distance. Material and methods: Three datasets comprising structures with disparate levels of complexity and intrasample variation are as follows: mouse molars, mouse brains, and primate endocasts. Different configurations of 3D coordinates on curves and surfaces were digitized from MRI images and CT scans using semi and fully automated procedures. Shape variables were obtained by Generalized Procrustes Superpositions before and after sliding the pseudolandmarks. Multivariate analyses were used to summarize and compare shape variation. Results: For the primate endocast, the semiautomated and automated strategies yield similar ordinations of specimens. Conversely, the semiautomated strategy better discriminates molar shapes between mouse groups. Shape differences among specimens are not adequately represented by the PCs calculated with surface pseudolandmarks. This is improved when the points are converted into semilandmarks by a sliding criterion. Discussion: Surface semilandmarks automatically obtained from 3D models are promising although they should be used with some caution in complex structures. This approach can be taken as complementary of semiautomated procedures which perform better for assessing shape variation in localized traits previously selected while automated procedures are suitable in studies aimed at comparing overall variation in shape and when there is no previous information about highly variable anatomical regions. Am J Phys Anthropol, 2016. © 2016 Wiley Periodicals, Inc.
    No preview · Article · Jan 2016 · American Journal of Physical Anthropology
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    S. Ivan Perez · Paula N. Gonzalez · Valeria Bernal
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    ABSTRACT: Studying demographic changes in past human populations is of great interest due to their role in processes of cultural change as well as the biological evolution of populations. Despite this, a general consensus about the most adequate methodological approach to this end is still lacking. Here, a new approach that combines radiocarbon frequency distributions —uncorrected and corrected by taphonomic bias— and demographic curves independently estimated with modern mitochondrial DNA (mtDNA) is used to estimate population size changes in Northwest Patagonia since the Pleistocene-Holocene transition to recent times. Results based on mtDNA sequences suggest a census size of approximately 3,000 individuals (with an estimated female effective size of ca. 750 individuals) by the initial peopling of this region around 10,000 years ago. A strong correspondence between curves based on mtDNA data and those based on archaeological radiocarbon dates (n=251) was obtained after the effect of taphonomic bias was accounted for. The demographic curves indicate that the population size was relatively stable during the earlier Early Holocene and it increased between 7,000 and 5,000 years ago, reaching a maximum size around 1,000 years ago. Then, the population size declined until present time. We conclude that demographic inferences made on the basis of radiocarbon dates are not necessarily biased but this needs to be evaluated with independent evidence in each specific geographical region.
    Full-text · Article · Dec 2015 · Journal of Archaeological Science
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    DESCRIPTION: Tradicionalmente, la descripción de las direcciones de crecimiento postnatal del hueso maxilar superior en Homo sapiens se basó en el análisis de la estructura ósea interna a partir de cortes histológicos. Sin embargo, se conoce menos en qué medida la información de la superficie ósea permite inferir los cambios en forma y las direcciones de crecimiento del maxilar con relación a otras estructuras craneofaciales. El objetivo del presente trabajo es caracterizar el crecimiento del maxilar superior mediante datos histológicos de la superficie ósea y comparar los patrones obtenidos con los cambios descriptos a nivel anatómico empleando morfometría geométrica. Se registraron las microestructuras resultantes de las actividades de formación y reabsorción celular a partir de réplicas de alta resolución obtenidas sobre la superficie perióstica de 10 maxilares izquierdos, correspondientes a individuos de 2 a 15 años procedentes de sitios arqueológicos de Pampa Grande (Salta, Argentina). A su vez se digitalizaron 53 landmarks y 65 semilandmarks sobre la superficie craneofacial a partir de tomografías computadas. Los resultados del análisis histológico mostraron un patrón de modelado óseo caracterizado por la predominancia de formación a lo largo de la porción media superior del maxilar y de reabsorción a lo largo de la región alveolar anterior y posterior. Los cambios en forma estimados mediante regresión multivariada sobre las coordenadas Procrustes indican un desplazamiento del maxilar en sentido inferior, principalmente, así como desplazamientos en sentido anterior y lateral. Se discuten los resultados obtenidos en torno a las propuestas previas formuladas para el crecimiento óseo postnatal del maxilar superior.
    Full-text · Research · Sep 2015
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    DESCRIPTION: The analysis of craniofacial morphology during ontogeny has central role in evolutionary, development and biomedical studies. The craniofacial complex has been studied from two main perspectives, the analysis of the shape and size by linear and geometric morphometrics, and the study of underlying processes by histological analysis of the bone surface. The aim of this work is to integrate these two lines of evidence to analyze the morphological changes of the mandible and provide a growth model that accounts for such changes. We analyzed a sample of human mandibles of subadult and adult individuals of European origin. Changes in shape were analyzed from coordinates of landmarks and regressions of shape coordinates on size. Areas of bone formation and resorption were identified on high-resolution replicas of the bone surface. The results indicate that variation at the anatomical scale as described by morphometric techniques, is broadly consistent with that inferred from the distribution of the areas of bone modeling. However, important changes such as rotational movements of the mandible with growth could be detected only through morphometric analysis. Also, both types of data showed differences in the directions of change inferred for the mandibular symphysis. This work highlights the importance of integrating histological and morphometric data to understand the patterns and processes of morphological change in ontogeny
    Full-text · Research · Sep 2015
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    ABSTRACT: Native human populations from South America display high levels of craniofacial variation encompassing gracile and robust skulls. Nevertheless, the processes of bone modeling by which morphological variation among populations were attained, remain poorly understood. Here we analyze the relationship between patterns of bone formation and resorption and morphometric variation in the upper face of adults belonging to farmers and hunter-gatherers from northwestern and south Argentina. Our analyses reveal a common pattern of bone modeling of the malar bone characterized by the presence of formation areas. Thus, the larger size and greater development of malar bone exhibited by hunter-gatherers would be linked to a greater magnitude of bone formation activity. Conversely, the glabella and the superciliary arch presented both formation and resorption areas with a variable distribution among individuals. In the extreme corresponding to more robust morphologies, the great development of the glabella is related to the presence of large formation fields, both in the upper region and toward the frontonasal suture. The less robust morphologies show resorption fields at the upper margin of the glabella, which would contribute to the weaker development of this region. The superciliary arch showed a complex relationship between its morphometric and histological variation; the individuals located at both extremes of the shape space presented large resorption areas located on its upper margin. Overall, our results show the existence of intraspecific variation in the patterns of bone modeling in the human upper face. Anat Rec, 2014. © 2014 Wiley Periodicals, Inc.
    Full-text · Article · Oct 2014 · The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology
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    ABSTRACT: Ecological factors can be important to shape the patterns of morphological variation among human populations. Particularly, diet plays a fundamental role in craniofacial variation due to both the effect of the nutritional status-mostly dependent on the type and amount of nutrients consumed-on skeletal growth and the localized effects of masticatory forces. We examine these two dimensions of diet and evaluate their influence on morphological diversification of human populations from southern South America during the late Holocene. Cranial morphology was measured as 3D coordinates defining the face, base and vault. Size, form, and shape variables were obtained for 474 adult individuals coming from 12 samples. Diet composition was inferred from carious lesions and δ(13) C data, whereas bite forces were estimated using traits of main jaw muscles. The spatial structure of the morphological and ecological variables was measured using correlograms. The influence of diet composition and bite force on morphometric variation was estimated by a spatial regression model. Cranial variation and diet composition display a geographical structure, while no geographical pattern was observed in bite forces. Cranial variation in size and form is significantly associated with diet composition, suggesting a strong effect of systemic factors on cranial growth. Conversely, bite forces do not contribute significantly to the pattern of morphological variation among the samples analyzed. Overall, these results show that an association between diet composition and hardness cannot be assumed, and highlight the complex relationship between morphological diversification and diet in human populations. Am J Phys Anthropol, 2014. © 2014 Wiley Periodicals, Inc.
    Full-text · Article · Sep 2014 · American Journal of Physical Anthropology
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    ABSTRACT: The results of archaeological and bioarchaeological research are presented from an area located in the lower Gualcamayo River Basin (in the northwestern part of the Province of San Juan), which includes sites with surface and sub-surface material, as well as burials from a period between 2300 and 1100 bp. Using these results, ideas for the development or expansion of agropastoral practices in northwest San Juan are discussed. Based on this, arguments are presented in favor of the possibility that there was an expansion of agropastoral groups from the northeastern valleys after 2100 bp. It is also argued that these societies did not incorporate maize as an important resource in their diets during at least 1000 years.
    Full-text · Chapter · Aug 2014
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    Lumila Menendez · Paula Novellino · Valeria Bernal

    Full-text · Chapter · Jan 2014
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    Full-text · Chapter · Jan 2014
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    ABSTRACT: Una pregunta central en biología evolutiva del desarrollo es cómo los mecanismos del desarrollo contribuyen a la variación fenotípica de los organismos. Particularmente, son los procesos de modelado y remodelado óseo los que explican cómo ocurren los cambios en tamaño y forma de estructuras morfológicas complejas durante la ontogenia. En este trabajo analizamos la ontogenia de la mandíbula mediante una aproximación que combina técnicas de morfometría geométrica para cuantificar los cambios anatómicos en la morfología ósea y técnicas histológicas para inferir las dinámicas de crecimiento de cada componente esquelético. Analizamos 87 mandíbulas de individuos entre 7 y 48 años de la colección de Esqueletos Identificados de la Universidad de Coimbra (Portugal) descritas mediante 16 landmarks tridimensionales. El patrón de modelado óseo (PMO) se obtuvo mediante la identificación de los rasgos microestructurales vinculados a procesos de formación (fibras de colágeno) y reabsorción del hueso (lagunas de Howship) sobre la superficie de hueso de la mandíbula de 12 individuos. Los cambios en forma obtenidos a partir de la regresión de las coordenadas Procrustes sobre el Log del tamaño centroide muestran el desplazamiento inferior de los landmarks del cuerpo y la rama posterior, el desplazamiento superior del cóndilo y posterior de la rama anterior. Los vectores de crecimiento inferidos a partir del PMO indican el crecimiento anterior de la sínfisis, crecimiento lateral del cuerpo mandibular y crecimiento posterior y lateral de la rama. Finalmente, se discute el grado de similitud de estos patrones de variación.
    Full-text · Conference Paper · Jun 2013
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    Valeria Bernal · S. Ivan Perez · Paula N. Gonzalez

    Full-text · Dataset · Apr 2013
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    Valeria Bernal · S. Ivan Perez · Paula N. Gonzalez
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    ABSTRACT: "The developmental processes that contribute to variation of morphological traits are the subject of considerable interest when attempting to understand phenotypic evolution. It is well demonstrated that most characteristics of tooth pattern can be modified by tinkering conserved signal pathways involved in dental development. This effect can be evaluated by comparing developmental models with naturally occurring variation within explicit phylogenetic contexts. Here, we assess whether evolutionary changes in lower molar (M) ratios among platyrrhines were channelled by alterations in the balance of activators and inhibitors as predicted by the inhibitory cascade (IC) model (Kavanagh et al. in Nature 449:427–432, 2007). Ordinary linear regression adjusted to M2/M1 versus M3/M1 ratios of 38 species of platyrrhines indicated that the slope and intercept were significantly different from the IC model. Conversely, when the phylogeny was incorporated into the regression analyses (PGLS), variation in molar ratios did not differ from the developmental model. PGLS also showed that changes in molar proportions are not an allometric effect associated with body size. Discrepancies between phylogenetically corrected and non-corrected analyses are mainly due to the departure of Callitrichines from the predicted values. This subfamily displays agenesis of M3 with higher than expected M2/M1 ratios, indicating that M3 fails to develop even when the inhibition by M1 on the subsequent molars is not increased. Our results show that evolution in molar ratios is concordant with slight changes in the proportion of activators and inhibitors that regulate molar development; however, other processes are required to account for variation in the number of teeth."
    Full-text · Article · Apr 2013 · Journal of Evolutionary Biology
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    ABSTRACT: Desde mediados de 1940, el área de Barrancas, departamento de Maipú en la provincia de Mendoza, ha sido fuente de hallazgos de restos humanos. El presente trabajo tiene como objetivos realizar una actualización sintética de la información bioarqueológica de los sitios enterratorio recuperados previamente en el área y dar a conocer los hallazgos del sitio arqueológico B6, un enterratorio múltiple con características únicas en el área. ABStRAct BURIAL SITES IN THE BARRANCAS AREA, MAIPÚ, MENDOZA, ARGENTINA. Since the middle of the 1940s the area of Barrancas, Maipú, Mendoza province, has been a source of discoveries of human remains. The objective of this paper is twofold: first, to update the information on burial sites previously discovered in the area; and, second, to present the finds from archaeological site B6, a multiple burial site with unique features from the area.
    Full-text · Article · Jan 2013 · Intersecciones en Antropología
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    ABSTRACT: Previous studies have shown that ecological factors had a significant role in shaping the patterns of craniofacial variation among South American populations. Here, we evaluate whether temperature and diet contributed to facial diversification in small geographic areas. Facial size and shape of 9 osteological samples from central Patagonia (Argentina) were described using 2D landmarks and semilandmarks. Data on mean annual temperature, diet composition (δ13C and δ15N values) and femoral head maximum breadth, used as a proxy of body mass, were obtained for each sample. We then tested the association of body mass and the ecological variables with facial morphology using spatial regression techniques and a model selection approach. Akaike Information Criterion, produced disparate results for both components of facial morphology. The best model for facial size included temperature and body mass proxy, and accounted for more than 80% of variation in size. Lower temperatures were related to larger facial sizes. Body mass was negatively associated with facial size and showed no relationship with the temperature. This suggests a relatively independent variation of cranial traits and body mass at the spatial scale studied here. Facial shape was not associated with the temperature or diet composition, contrasting with the patterns observed at larger spatial scales. Our results point out that the effect of climatic variables on cranial traits might be a source of morphological differentiation not only at large scales but also in small geographic areas, and that size and shape display a differential preservation of environmental signals.
    Full-text · Article · Jan 2013 · HOMO - Journal of Comparative Human Biology
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    Natalia Brachetta Aporta · Valeria Bernal
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    ABSTRACT: Craniofacial morphology observed in adult individuals results from modeling and remodeling mechanisms that underlie bone growth dynamics. Therefore, the study of these mechanisms is essential for understanding the histological basis of changes in shape and size. We present an approach that combines geometric morphometric techniques to quantify anatomical changes in shape with microscopic techniques that identify traits related to processes of bone formation and resorption. We analyzed a set of landmarks and semilandmarks on images of 52 skulls of human adults from Patagonia and Northwest Argentina to describe facial variation. The principal component analysis on these variables showed differences in the degree of development of the glabella and malar. Individuals representing the extremes of variation in shape were selected for high-resolution replicas of the glabella, superciliary arch and malar. The metalized surfaces of each cast were analyzed with a scanning electron microscope and an incident light optical microscope in order to identify: a) textures characterized by the presence of collagen fibers, which are evidence of formation processes, and b) lacunar textures produced by the action of osteoclasts in bone absorption regions. Finally, we compared the spatial distribution, shape and size of the areas of bone formation and absorption between individuals. The results are discussed in the context of the factors responsible for inter-population differentiation.
    Full-text · Conference Paper · Sep 2012
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    Virginia A. Cobos · Claudia Della Negra · Valeria Bernal

    Preview · Article · Jul 2012
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    VERÓNICA S LEMA · CLAUDIA DELLA NEGRA · VALERIA BERNAL
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    ABSTRACT: This paper presents the results obtained from the analysis of grinding artefacts recovered in Aqui-huecó (3.700 AP) and Michacheo (1.860 años AP) archaeological sites from the Neuquen province. Such analysis involved the identification of plant microremains adhered to their surfaces. Results show processing of Prosopis sp pods in both sites and of Zea mays grains in Michacheo. This last site also has ceramic sherds, therefore at ca. 2.000 AP there was a broadening of the technological base together with food resources. Analysis of archaeological contexts point to the association of these artefacts and the burial of adult female individuals along Late Holocene. Bioanthropological evidence show an increase in the presence of caries and a reduction of dental wear around 2.000 A P, which might have been associated to the incorporation of new resources and technology, although the stable isotope analysis suggest the absence of diets rich in C4 plants -such as corn- among these populations.
    Full-text · Article · Dec 2011 · Magallania
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    Paula N Gonzalez · S Ivan Perez · Valeria Bernal
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    ABSTRACT: Modifications of ontogenetic allometries play an important role in patterning the shape differentiation among populations. This study evaluates the influence of size variation on craniofacial shape disparity among human populations from South America and assesses whether the morphological disparity observed at the interpopulation level resulted from a variable extension of the same ontogenetic allometry, or whether it arose as a result of divergences in the pattern of size-related shape changes. The size and shape of 282 adult and subadult crania were described by geometric morphometric-based techniques. Multivariate regressions were used to evaluate the influence of size on shape differentiation between and within populations, and phylogenetic comparative methods were used to take into account the shared evolutionary history among populations. The phylogenetic generalized least-squares models showed that size accounts for a significant amount of shape variation among populations for the vault and face but not for the base, suggesting that the three modules did not exhibit a uniform response to changes in overall growth. The common slope test indicated that patterns of evolutionary and ontogenetic allometry for the vault and face were similar and characterized by a heightening of the face and a lengthening of the vault with increasing size. The conservation of the same pattern of shape changes with size suggests that differences in the extent of growth contributed to the interpopulation cranial shape variation and that certain directions of morphological change were favored by the trait covariation along ontogeny.
    Full-text · Article · Nov 2011 · The Anatomical Record Advances in Integrative Anatomy and Evolutionary Biology
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    V Bernal · L.H. Luna
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    ABSTRACT: The aim of this paper is to conduct a historical analysis of the research-oriented studies related to dental anthropology in Argentina, evaluate its current state and discuss future expectations and perspectives. In this country, anthropological studies based on analysis of dentition have been scarce and even temporarily discontinued, since they began in the late nineteenth century, simply following the course of the predominant theoretical and methodological approaches over time. Early papers, guided mainly by evolutionary ideas, were oriented towards establishing the taxonomic position of humans through the description and comparison of morphological and morphometric aspects of the dental crown and root. Later studies mainly described types of intentional modifications (i.e. dental mutilations) and tooth wear in the context of Historic-Cultural School. However, they failed to constitute valid lines of research over time. In recent years, there has been a significant change in dental studies, mainly as a result of the interest in evaluating the adaptive aspects of human populations within biocultural settings. One of the most relevant lines of studies has been the bioarchaeological analysis of health and stress indicators, such as enamel hypoplasia, caries and tooth wear in hunter-gatherer and farmer societies. More recently, the study of discrete and metric dental traits began, with a goal to contribute to the study of evolution and inter-populational biological relations among South American groups. Since teeth contain valuable information not only about the environment in which the individual lived, but also about the action of neutral and non-neutral factors on human groups, the consolidation of ongoing studies will contribute to knowledge of various aspects of the adaptation and evolution of native American populations.
    Full-text · Article · Sep 2011 · Homo: internationale Zeitschrift fur die vergleichende Forschung am Menschen
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    Leandro H Luna · Valeria Bernal
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    ABSTRACT: This paper describes and discusses the research in the field of dental anthropology in Argentina. It has been presented at the symposium entitled "The development of dental research in Argentine Biological Anthropology: current status and perspectives", coordinated by the authors at the IX National Meeting of Biological Anthropology of Argentina, Puerto Madryn, 20th-23rd October 2009. The aim of the symposium was to present new results and future prospects of this discipline in the country and to create a forum for discussion of current research within this field. Six contributions that focused on the study of teeth from different perspectives and analysed bioarchaeological samples from different areas of Argentina (Central Highlands, Pampa and Patagonia) were presented. After the presentations, a discussion about the state of the art of dental research in the country was generated, in which the need for the generation of methodological consensus on the criteria for the evaluation of the variables considered was stated, so that research conducted in different areas can be compared. In short, the contributions of this symposium provide insights into the diversity of dental anthropology in contemporary Argentina and the potential of these types of studies to gain important information about biological and cultural aspects of the native populations in the country.
    Full-text · Article · Sep 2011 · Homo: internationale Zeitschrift fur die vergleichende Forschung am Menschen

Publication Stats

578 Citations
63.60 Total Impact Points

Institutions

  • 2004-2016
    • National University of La Plata
      • • División de Antropología
      • • Facultad de Ciencias Naturales y Museo
      Eva Perón, Buenos Aires, Argentina
  • 2011
    • University of Buenos Aires
      Buenos Aires, Buenos Aires F.D., Argentina
  • 2007-2009
    • National Scientific and Technical Research Council
      Buenos Aires, Buenos Aires F.D., Argentina