Nuevo enfoque morfométrico para el estudio de la biomecánica y adaptación de los homininos del Plio-Pleistoceno

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Geografía e Historia, leída el 06-10-2021En la presente tesis doctoral titulada “Nuevo enfoque morfométrico para el estudio dela biomecánica y adaptación de los homininos del Plio-Pleistoceno” se presenta una nueva metodología para el análisis de los huesos largos de grandes simios a partir del uso de modelos tridimensionales, haciendo especial hincapié en la interpretación biomecánica de los restos fósiles relativos a especies de nuestra familia evolutiva. Los recientes hallazgos de nuevas especies fósiles humanas han puesto de manifiesto la gran complejidad de nuestra historia evolutiva y las dificultades que entraña su interpretación. Añadido a esto, el estudio de los huesos largos (húmero, radio, cúbito, fémur, tibia y fíbula) de especies homininas anteriores a la nuestra resulta especialmente problemático por una serie de razones entre las que destaca la obtención de información a partir de restos de pequeño tamaño que, en ocasiones, aparecen muy fragmentados en los yacimientos. Asimismo, existen otro tipo de limitaciones que afectan al estudio de la morfología y biomecánica de los huesos largos, entre las que se encuentran la baja integridad del registro fósil y la escasez de restos postcraneales, la dificultad para delimitar los factores que influyen en la morfología de los huesos y que, por lo tanto, pueden mermar la estimación del vínculo existente entre morfología y función, y el uso de muestras comparativas que incluyen un número muy limitado de grupos y morfologías. Esta tesis doctoral tiene como objetivo principal el desarrollo de un nuevo enfoque morfométrico para el estudio de la biomecánica y adaptación de los homininos del Plio-Pleistoceno apoyado en una caracterización muy detallada de la morfologíaexterna de los huesos largos y la implementación de modelos de clasificación de alta precisión...In the present doctoral thesis entitled "A new morphometric approach to the study of Plio-Pleistocene hominin biomechanics and adaptation" a new 3D methodology for the analysis of great ape long bones with special emphasis on the biomechanical interpretation of human fossil remains is introduced. Recent findings of human fossil specimens and taxa have revealed the great complexity of our evolutionary history and the difficulties involved in its comprehension and interpretation. Moreover, the study of hominin long bone remains (humerus, radius, ulna, femur, tibia, fibula) in Palaeoanthropologyis particularly problematic due to the difficulties involved in the analysis of fragmentary skeletal elements that in many occasions are merely represented by small diaphyseal portions. On top of that, there are several additional limitations that affect our ability to study fossil long bone morphology and draw biomechanical inferences, such as the scarcity and poor integrity of the fossil record; the delimitation of the factors that influence morphology and that might diminish the link between bone morphologyand function; and the widespread use of limited modern reference samples that encompass low degrees of interspecific variability. The main objective of the present research is the development of a new morphometric approach to the study of Plio-Pleistocene hominin biomechanics and adaptation that relies on the detailed quantitative characterisation of the external long bone morphology and the implementation of powerful classification methods...Fac. de Geografía e HistoriaTRUEunpu

A Novel Approach for the Shape Characterisation of Non-Melanoma Skin Lesions Using Elliptic Fourier Analyses and Clinical Images

[EN] The early detection of Non-Melanoma Skin Cancer (NMSC) is crucial to achieve the best treatment outcomes. Shape is considered one of the main parameters taken for the detection of some types of skin cancer such as melanoma. For NMSC, the importance of shape as a visual detection parameter is not well-studied. A dataset of 993 standard camera images containing different types of NMSC and benign skin lesions was analysed. For each image, the lesion boundaries were extracted. After an alignment and scaling, Elliptic Fourier Analysis (EFA) coefficients were calculated for the boundary of each lesion. The asymmetry of lesions was also calculated. Then, multivariate statistics were employed for dimensionality reduction and finally computational learning classification was employed to evaluate the separability of the classes. The separation between malignant and benign samples was successful in most cases. The best-performing approach was the combination of EFA coefficients and asymmetry. The combination of EFA and asymmetry resulted in a balanced accuracy of 0.786 and an Area Under Curve of 0.735. The combination of EFA and asymmetry for lesion classification resulted in notable success rates when distinguishing between benign and malignant lesions. In light of these results, skin lesions’ shape should be integrated as a fundamental part of future detection techniques in clinical screening.SIJunta de Castilla y Leó

An Evaluation of Landmark-Based Methods to Explore Tooth Score Morphology: A Case Study on Felids and Hyenids

Taphonomic studies aim to identify the modifying agents that intervene in bone assemblages found at archaeopaleontological sites. Carnivores may modify, accumulate, or scavenge skeletal parts inflicting tooth marks, including scores, on the cortical surface. Several works have studied tooth score morphology to discern which carnivore group modified the bone assemblages, achieving different results. In the present study, different methods based on the use of landmarks and semilandmarks have been tested to describe and analyze the score profile cross-sections of spotted and brown hyenas, leopards, and lions. According to our results, the already published seven-landmark method is useful in order to differentiate between carnivore species from different families (e.g., felids and hyenids). Meanwhile, felid species (e.g., leopards and lions) cannot be consistently distinguished using any of the methods tested here. In contrast, hyenid species can be morphologically differentiated. On the other hand, the use of semilandmarks does not generally improve morphological characterization and distinction, but low numbers of landmarks and the inclusion of the score’s deepest point might provide the best results when semi-automatic semilandmark models are preferred to avoid sampling biases.The grant IJC2020-043576-I funded by MCIN/AEI/10.13039/501100011033 and the “European Union NextGenerationEU/PRTR” has been awarded to M.C.A. The grant RYC2021-034813-I funded by MCIN/AEI/10.13039/501100011033 and the European Union “NextGenerationEU”/PRTR has been awarded to M.Á.M.-G. During the development of the present work, J.A. was funded by the Euskal Herriko Unibertsitatea [ESPDOC21/05]. L.A.C. is funded by the Spanish Ministry of Science, Innovation and Universities by an FPI Predoctoral grant PRE2019-089411 associated with project RTI2018-099850-B-I0

Spilled ink blots the mind: A reply to Merrit et al. (2018) on subjectivity and bone surface modifications

Categorical variables identifying microscopic features of cut marks produce high accuracy in discrimination of bone surface modifications, but are vulnerable to variable degrees of inter-analyst subjectivity. Metric analyses of cut mark width and depth are presented by Merritt et al. (2018) as a more objective method of identifying cut marks. However, this uni(bi)variate method has shown very high rates of mark classification error when structurally similar marks are compared. Furthermore, within-sample comparison carried out via subsampling shows that different datasets of metric values, obtained with the same type of tool and raw material, are subject to such a high degree of variability that significant differences of homogeneous subsamples are repeatedly obtained, thus preventing any useful analogs to be made. Additionally, this much higher stochastic variability depends on limited knowledge of the contextual processes that intervene in cut mark metric properties, as well as on a mismatch between theoretical premises on the immanent-configurational process-trace dynamics and their confusion during experimental praxis. The selection of specific contextual variables and disregard of others, in addition to the combination of different tool types and raw materials, distorts the resulting cut mark properties. This indicates that even when attempting to use exclusively metric numeric variables, subjectivity is a conditioning factor in analyzing and interpreting cut marks

Geometric Morphometrics and Machine Learning Models Applied to the Study of Late Iron Age Cut Marks from Central Spain

Recently the incorporation of artificial intelligence has allowed the development of valuable methodological advances in taphonomy. Some studies have achieved great precision in identifying the carnivore that produced tooth marks. Additionally, other works focused on human activity have managed to specify what type of tool or raw material was used in the filleting processes identified at the sites. Through the use of geometric morphometrics and machine learning techniques, the present study intends to analyze the cut marks of the Ulaca oppidum (Solosancho, Ávila, Spain) in order to identify the type of tools used during carcass modification. Although the Ulaca oppidum is an Iron Age site, the results suggest that most of the cut marks were produced with flint tools.During the development of the present work J.A. was funded by the Euskal Herriko Unibertsitatea [ESPDOC21/05]. This work has been partially funded by the Ministerio de Ciencia e Innovación (project PID2021-123721OB-I00 funded by MCIN/AEI/10.13039/501100011033/FEDER, UE) and Fundación Española para la Ciencia y la Tecnología (FCT-21-17318). M.Á.M.-G. and C.S.B. acknowledges the grant RYC2021-034813-I and RYC2021-034720-I respectively, funded by MCIN/AEI/10.13039/501100011033 and by European Union “NextGenerationEU”/PRTR

En busca del primer Homo: gestión de la investigación arqueológica en la Garganta de Olduvai (Tanzania)

[EN] The sites at Olduvai Gorge (Tanzania) constitute a unique venue for the study of the first members of the genus Homo. The large amount of fossils recovered and the good state of preservation of these sites have boosted archaeological research in the Gorge throughout the years. The Olduvai Paleoanthropology and Paleoecology Project (TOPPP) research team, present at the Gorge since 2006, launched the construction of the Aguirre-Mturi Scientific Station within the limits of the Ngorongoro National Park with the aim of improving the working conditions and provide a safe working space. The safeguard of the archaeological materials was also one of the cornerstones during the design process and building of the station. The laboratory allows almost immediate cleaning, analysis and restoration of the materials recovered during field work. Meanwhile, in Spain, the Institute of Evolution in Africa (IDEA), current headquarters of the TOPPP team, was founded with the aim of promoting the study of African paleoanthropology and the origins of humankind in Africa. Along with the research work, TOPPP strives to bring the scientific knowledge to the general public in several ways, including the management of temporary and permanent exhibitions in Spain and Tanzania.[ES] Los yacimientos de la Garganta de Olduvai (Tanzania) constituyen un enclave único para el estudio de los primeros representantes del género Homo. La buena preservación de estos yacimientos y la cantidad de fósiles hallados en ellos posibilita que se sigan desarrollando excavaciones arqueológicas en este lugar. El equipo de investigación The Olduvai Paleoanthropology and Paleoecology Project (TOPPP), que trabaja en estos yacimientos desde 2006, promovió la construcción de la Estación Científica Aguirre-Mturi con el propósito de mejorar las condiciones laborales del personal investigador y de hacer del campamento un lugar seguro de trabajo. Durante el proceso de creación y construcción se tuvo en cuenta la salvaguarda de los materiales arqueológicos, y gracias a la existencia de un laboratorio en el campamento, es posible realizar tareas como la limpieza, el análisis y la restauración del material recuperado. En España, la creación del Instituto de Evolución en África (IDEA), sede actual del equipo TOPPP, nace con el objetivo de promover el estudio de la paleoantropología africana y el origen del ser humano en África. Junto a los trabajos de investigación, TOPPP realiza una intensa actividad divulgativa donde destaca la creación de exposiciones temporales y permanentes en España y Tanzania.A la Comisión para la Ciencia y la Tecnología (COSTECH), a la Autoridad del Área de Conservación del Ngorongoro (NCAA) y al Departamento de Antigüedades y al Ministerio de Turismo y Recursos Naturales en Tanzania por el permiso para investigar en la Garganta de Olduvai. Al Ministerio de Ciencia, Innovación y Universidades por el proyecto concedido (HAR2017-82463-C4-1-P) y por la financiación para los contratos predoctorales de Formación de Profesorado Universitario (FPU) de MVR y JA; al Ministerio de Cultura a través del Instituto de Patrimonio Cultural de España por las ayudadas concedidas para Proyectos Arqueológicos en el Exterior, y a la Fundación Palarq por las ayudas para apoyar las Misiones de Arqueología y Paleontología Españolas en el en el extranjero.Peer reviewe

Early Pleistocene faunivorous hominins were not kleptoparasitic, and this impacted the evolution of human anatomy and socio-ecology

Humans are unique in their diet, physiology and socio-reproductive behavior compared to other primates. They are also unique in the ubiquitous adaptation to all biomes and habitats. From an evolutionary perspective, these trends seem to have started about two million years ago, coinciding with the emergence of encephalization, the reduction of the dental apparatus, the adoption of a fully terrestrial lifestyle, resulting in the emergence of the modern anatomical bauplan, the focalization of certain activities in the landscape, the use of stone tools, and the exit from Africa. It is in this period that clear taphonomic evidence of a switch in diet with respect to Pliocene hominins occurred, with the adoption of carnivory. Until now, the degree of carnivorism in early humans remained controversial. A persistent hypothesis is that hominins acquired meat irregularly (potentially as fallback food) and opportunistically through klepto-foraging. Here, we test this hypothesis and show, in contrast, that the butchery practices of early Pleistocene hominins (unveiled through systematic study of the patterning and intensity of cut marks on their prey) could not have resulted from having frequent secondary access to carcasses. We provide evidence of hominin primary access to animal resources and emphasize the role that meat played in their diets, their ecology and their anatomical evolution, ultimately resulting in the ecologically unrestricted terrestrial adaptation of our species. This has major implications to the evolution of human physiology and potentially for the evolution of the human brain

Statistical Comparison between Low-Cost Methods for 3D Characterization of Cut-Marks on Bones

In recent years, new techniques for the morphological study of cut marks have become essential for the interpretation of prehistoric butchering practices. Different criteria have been suggested for the description and classification of cut marks. The methods commonly used for the study of cut marks rely on high-cost microscopy techniques with low portability (i.e., inability to work in situ), such as the 3D digital microscope (3D DM) or laser scanning confocal microscopy (LSCM). Recently, new algorithmic developments in the field of computer vision and photogrammetry, have achieved very high precision and resolution, offering a portable and low-cost alternative to microscopic techniques. However, the photogrammetric techniques present some disadvantages, such as longer data collection and processing time, and the requirement of some photogrammetric expertise for the calibration of the cameras and the acquisition of precise image orientation. In this paper, we compare two low-cost techniques and their application to cut mark studies: the micro-photogrammetry (M-PG) technique presented, developed, and validated previously, and a methodology based on the use of a structured light scanner (SLS). A total of 47 experimental cut marks, produced using a stainless steel knife, were analyzed. The data registered through virtual reconstruction was analyzed by means of three-dimensional geometric morphometrics (GMM)