Publications by authors named "Markus Bastir"

91 Publications

Comparative anatomy and 3D geometric morphometrics of the El Sidrón atlases (C1).

J Hum Evol 2020 12 1;149:102897. Epub 2020 Nov 1.

Museo Nacional de Ciencias Naturales (CSIC), Department of Paleobiology, Paleoanthropology Group, J.G. Abascal 2, 28006, Madrid, Spain.

The first cervical vertebra (atlas, C1) is an important element of the vertebral column because it connects the cranial base with the cervical column, thus helping to maintain head posture and contributing to neck mobility. However, few atlases are preserved in the fossil record because of the fragility of this vertebra. Consequently, only eight well-preserved atlases from adult Neandertals have been recovered and described. Here, we present nine new atlas remains from the El Sidrón Neandertal site (Asturias, Spain), two of which (SD-1643 and SD-1605/1595) are sufficiently well preserved to allow for a detailed comparative and three-dimensional geometric morphometric analysis. We compared standard linear measurements of SD-1643 and SD-1605/1595 with those of other Neandertal atlases and carried out three-dimensional geometric morphometric analyses to compare size and shape of SD-1643 and SD-1605/1595 with those of 28 Pan (Pan troglodytes and Pan paniscus), a broad comparative sample of 55 anatomically modern humans from African and European populations, and other fossil hominins (Neandertals, Homo antecessor, Paranthropus boisei). The El Sidrón atlas fossils show typical features of the Neandertal atlas morphology, such as caudal projection of the anterior tubercle, gracility of both the posterior tubercle and the tuberosity for the insertion of the transverse ligament, and an anteroposteriorly elongated neural canal. Furthermore, when compared with atlases from the other taxa, Neandertals exhibit species-specific features of atlas morphology including a relatively lower lateral mass height, relatively narrower transverse foramina, and flatter and more horizontally oriented articular facets. Some of these features fit with previous suggestions of shorter overall length of the cervical spine and potential differences in craniocervical posture and mobility. Our results may support a different spinopelvic alignment in this species, as the atlas morphology suggests reduced cervical lordosis.
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http://dx.doi.org/10.1016/j.jhevol.2020.102897DOI Listing
December 2020

Early development of the Neanderthal ribcage reveals a different body shape at birth compared to modern humans.

Sci Adv 2020 Oct 7;6(41). Epub 2020 Oct 7.

University of Bordeaux, CNRS, MCC, PACEA, UMR5199, Pessac, France.

Ontogenetic studies provide clues for understanding important paleobiological aspects of extinct species. When compared to that of modern humans, the adult Neanderthal thorax was shorter, deeper, and wider. This is related to the wide Neanderthal body and is consistent with their hypothetical large requirements for energy and oxygen. Whether these differences were already established at birth or appeared later during development is unknown. To delve into this question, we use virtual reconstruction tools and geometric morphometrics to recover the 3D morphology of the ribcages of four Neanderthal individuals from birth to around 3 years old: Mezmaiskaya 1, Le Moustier 2, Dederiyeh 1, and Roc de Marsal. Our results indicate that the comparatively deep and short ribcage of the Neanderthals was already present at birth, as were other skeletal species-specific traits. This morphology possibly represents the plesiomorphic condition shared with , and it is likely linked to large energetic requirements.
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http://dx.doi.org/10.1126/sciadv.abb4377DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7541074PMC
October 2020

Geometric morphometrics of adolescent idiopathic scoliosis: a prospective observational study.

Eur Spine J 2021 Mar 5;30(3):612-619. Epub 2020 Sep 5.

Virtual Morphology Lab, Museo Nacional de Ciencias Naturales - Consejo Superior de Investigaciones Científicas, J.G. Abascal 2, 28006, Madrid, Spain.

Objective: Adolescent idiopathic scoliosis is the most prevalent type of scoliosis, and its consequences on the human torso have not been deeply studied. In spite of being a 3D condition, clinical management is circumscribed to 2D images among health-care professionals. GMM is a well-recognized tool in the study of 3D shape and symmetry.

Methods: Twenty-four subjects with AIS and 24 controls were subjected to surface scan. Digitization and shape data were extracted and submitted to GMM analysis. 3D shape and asymmetry were correlated with Cobb angle in subjects with X-ray availability. Comparisons of mean shapes were done between each group and its symmetric average shape and between each group at two states: initial and 6 months after.

Results: AIS and controls show similar areas of asymmetry, being significantly higher in quantity in AIS (PD = 0.045; PD 0.037; p < 0.001). Significant correlation was observed between Cobb angle and Procrustes asymmetry (r = 0.38; p = 0.01) as happened with 3D shape (r = 0.11; p < 0.001). No significant changes were observed in the 3D shape of both groups 6 months after (AIS, p = 0.51; control, p = 0.304).

Conclusion: The greater asymmetry observed in AIS was expectable, but the similarity of areas of asymmetry in both groups made us suspect of directional asymmetry in the human torso that could explain the high prevalence of right scoliosis observed in nature. The shape of the torso and the asymmetry should be considered as variables to study in AIS due to its correlation with Cobb angle. Progression of the deformities was not observed in our study, maybe due to short-term follow-up.
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http://dx.doi.org/10.1007/s00586-020-06583-5DOI Listing
March 2021

Assessing thoraco-pelvic covariation in Homo sapiens and Pan troglodytes: A 3D geometric morphometric approach.

Am J Phys Anthropol 2020 11 30;173(3):514-534. Epub 2020 Aug 30.

Departamento de Paleobiología, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.

Objectives: Understanding thoraco-pelvic integration in Homo sapiens and their closest living relatives (genus Pan) is of great importance within the context of human body shape evolution. However, studies assessing thoraco-pelvic covariation across Hominoidea species are scarce, although recent research would suggest shared covariation patterns in humans and chimpanzees but also species-specific features, with sexual dimorphism and allometry influencing thoraco-pelvic covariation in these taxa differently.

Material And Methods: N = 30 adult H. sapiens and N = 10 adult Pan troglodytes torso 3D models were analyzed using 3D geometric morphometrics and linear measurements. Effects of sexual dimorphism and allometry on thoraco-pelvic covariation were assessed via regression analyses, and patterns of thoraco-pelvic covariation in humans and chimpanzees were computed via Two-Block Partial Least Squares analyses.

Results: Results confirm the existence of common aspects of thoraco-pelvic covariation in humans and chimpanzees, and also species-specific covariation in H. sapiens that is strongly influenced by sexual dimorphism and allometry. Species-specific covariation patterns in chimpanzees could not be confirmed because of the small sample size, but metrics point to a correspondence between the most caudal ribs and iliac crest morphology that would be irrespective of sex.

Conclusions: This study suggests that humans and chimpanzees share common aspects of thoraco-pelvic covariation but might differ in others. In humans, torso integration is strongly influenced by sexual dimorphism and allometry, whilst in chimpanzees it may not be. This study also highlights the importance not only of torso widths but also of torso depths when describing patterns of thoraco-pelvic covariation in primates. Larger samples are necessary to support these interpretations.
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http://dx.doi.org/10.1002/ajpa.24103DOI Listing
November 2020

Three-dimensional geometric morphometrics of thorax-pelvis covariation and its potential for predicting the thorax morphology: A case study on Kebara 2 Neandertal.

J Hum Evol 2020 10 14;147:102854. Epub 2020 Aug 14.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), J.G. Abascal 2, 28006, Madrid, Spain.

The skeletal torso is a complex structure of outstanding importance in understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as researchers apply their own anatomical expertise to the process. Among different fossil reconstruction methods, 3D geometric morphometric techniques have been increasingly used in the last decades. Two-block partial least squares analysis has shown great potential for predicting missing elements by exploiting the covariation between two structures (blocks) in a reference sample: one block can be predicted from the other one based on the strength of covariation between blocks. The first aim of this study is to test whether this predictive approach can be used for predicting thorax morphologies from pelvis morphologies within adult Homo sapiens reference samples with known covariation between the thorax and the pelvis. The second aim is to apply this method to Kebara 2 Neandertal (Israel, ∼60 ka) to predict its thorax morphology using two different pelvis reconstructions as predictors. We measured 134 true landmarks, 720 curve semilandmarks, and 160 surface semilandmarks on 60 3D virtual torso models segmented from CT scans. We conducted three two-block partial least squares analyses between the thorax (block 1) and the pelvis (block 2) based on the H. sapiens reference samples after performing generalized Procrustes superimposition on each block separately. Comparisons of these predictions in full shape space by means of Procrustes distances show that the male-only predictive model yields the most reliable predictions within modern humans. In addition, Kebara 2 thorax predictions based on this model concur with the thorax morphology proposed for Neandertals. The method presented here does not aim to replace other techniques, but to rather complement them through quantitative prediction of a virtual 'scaffold' to articulate the thoracic fossil elements, thus extending the potential of missing data estimation beyond the methods proposed in previous works.
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http://dx.doi.org/10.1016/j.jhevol.2020.102854DOI Listing
October 2020

Response to Letter to the Editor by Dr Rios and Dr Cardoso.

J Anat 2020 12 13;237(6):1189-1191. Epub 2020 Aug 13.

Department of Paleobiology, Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.

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http://dx.doi.org/10.1111/joa.13267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7704225PMC
December 2020

Rib cage anatomy in Homo erectus suggests a recent evolutionary origin of modern human body shape.

Nat Ecol Evol 2020 09 6;4(9):1178-1187. Epub 2020 Jul 6.

Centre for Human Evolution Research, Department of Earth Sciences, The Natural History Museum, London, UK.

The tall and narrow body shape of anatomically modern humans (Homo sapiens) evolved via changes in the thorax, pelvis and limbs. It is debated, however, whether these modifications first evolved together in African Homo erectus, or whether H. erectus had a more primitive body shape that was distinct from both the more ape-like Australopithecus species and H. sapiens. Here we present the first quantitative three-dimensional reconstruction of the thorax of the juvenile H. erectus skeleton, KNM-WT 15000, from Nariokotome, Kenya, along with its estimated adult rib cage, for comparison with H. sapiens and the Kebara 2 Neanderthal. Our three-dimensional reconstruction demonstrates a short, mediolaterally wide and anteroposteriorly deep thorax in KNM-WT 15000 that differs considerably from the much shallower thorax of H. sapiens, pointing to a recent evolutionary origin of fully modern human body shape. The large respiratory capacity of KNM-WT 15000 is compatible with the relatively stocky, more primitive, body shape of H. erectus.
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http://dx.doi.org/10.1038/s41559-020-1240-4DOI Listing
September 2020

Late subadult ontogeny and adult aging of the human thorax reveals divergent growth trajectories between sexes.

Sci Rep 2020 07 1;10(1):10737. Epub 2020 Jul 1.

CNRS, MCC, PACEA, UMR5199, University of Bordeaux, Allée Geoffroy Saint Hilaire Bat. B8, CS 50023, 33615, Pessac Cedex, France.

Sexual dimorphism is an important feature of adult thorax morphology, but when and how sex-related differences in the ribcage arise during ontogeny is poorly known. Previous research proposed that sex-related size differences in the nasal region arise during puberty. Therefore, we explore whether ribcage sexual dimorphism also arises at that time and whether this sexual dimorphism is maintained until old age. We measured 526 (semi)landmarks on 80 CT-based human ribcage reconstructions, on individuals ranging from 7 to 65 year-old. The 3D coordinates were submitted to the Procrustes superimposition and analyzed. Our results show that the trajectories of thorax size and shape between sexes diverge at around 12 years of age, and continue slightly diverging until old age. The differential ontogenetic trends cause adult male ribcages to become deeper, shorter, and wider than female. Our results are consistent with the evidence from the cranial respiratory system, with the development of sexual dimorphism probably related to changes in body composition during puberty combined with changes in the reproductive system.
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http://dx.doi.org/10.1038/s41598-020-67664-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329879PMC
July 2020

Krapina atlases suggest a high prevalence of anatomical variations in the first cervical vertebra of Neanderthals.

J Anat 2020 09 21;237(3):579-586. Epub 2020 May 21.

Department of Anatomy and Human Embryology, Giaval Research Group, Faculty of Medicine, University of Valencia, Valencia, Spain.

The first cervical vertebra, atlas, and its anatomical variants have been widely studied in Homo sapiens. However, in Neanderthals, the presence of anatomical variants of the atlas has been very little studied until very recently. Only the Neanderthal group from the El Sidrón site (Spain) has been analysed with regard to the anatomical variants of the atlas. A high prevalence of anatomical variants has been described in this sample, which points to low genetic diversity in this Neanderthal group. Even so, the high prevalence of anatomical variations detected in El Sidrón Neanderthal atlases needs to be confirmed by analysing more Neanderthal remains. In this context, we analysed the possible presence of anatomical variants in the three Neanderthal atlases recovered from the Krapina site (Croatia) within the Neanderthal lineage. Two of the three Krapina atlases presented anatomical variations. One atlas (Krapina 98) had an unclosed transverse foramen and the other (Krapina 99) presented a non-fused anterior atlas arch. Moreover, an extended review of the bibliography also showed these anatomical variations in other Middle and Upper Pleistocene hominins, leading us to hypothesise that anatomical variations of the atlas had a higher prevalence in extinct hominins than in modern humans.
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http://dx.doi.org/10.1111/joa.13215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7476204PMC
September 2020

Morphometric analysis of the costal facet of the thoracic vertebrae.

Anat Sci Int 2020 Sep 25;95(4):478-488. Epub 2020 Apr 25.

Laboratory of Functional Anatomy, Université Libre de Bruxelles, Brussels, Belgium.

Various studies have examined morphometric features of the vertebrae to understand the functional aspects of the spine. Geometric analysis of vertebral zygapophyseal facets has also been related to functional and clinical aspects of the spine, but no quantitative investigation of the costotransverse joint facet is found in the literature. The costal facet geometry may partly determine the mechanical interaction between the rib cage and spine for trunk stabilization during functional tasks and during breathing. Therefore, the present study proposes a method for estimating the 3D geometric features of the costal facets of the first 10 thoracic vertebrae (Th1-Th10). Series of landmarks (95 ± 43) were placed on 258 costal facets from a sample of 14 asymptomatic individuals to determine their 3D location and orientation. The relative location of the costal facet was used to investigate symmetry and asymmetry components of the overall vertebrae shape variation among thoracic levels using 3D geometric morphometric methods. Results showed significant variation in sagittal orientation (inclination angle) between levels with a gradual cephalic orientation in the lower levels. No significant difference was observed on transverse orientation (declination angle). The shape of the costal facet was flatter at Th1 and from Th5 to Th10 and more concave from Th2 to Th4. An average difference of 7° between right and left facet orientation in both sagittal and transverse plane was demonstrated. Asymmetry of costal facet relative location was also detected and significantly influenced by the thoracic level. Nevertheless, location and orientation of the costal facets seem to be independent features of vertebrae morphology.
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http://dx.doi.org/10.1007/s12565-020-00544-0DOI Listing
September 2020

Analyses of the neandertal patellae from El Sidrón (Asturias, Spain) with implications for the evolution of body form in Homo.

J Hum Evol 2020 04 5;141:102738. Epub 2020 Mar 5.

Group of Paleoanthropology MNCN-CSIC, Department of Paleobiology, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, Madrid, Spain.

The evolution of the body form in Homo and its potential morphological connection to the arrangement of different skeletal systems is of major interest in human evolution. Patella morphology as part of the knee is potentially influenced by body form. Here, we describe for the first time the patellae remains recovered at El Sidrón Neandertal site and analyze them in a comparative evolutionary framework. We aim to clarify whether morphometric features frequently observed in Neandertal and modern human patellae are retained from a primitive anatomical arrangement or whether they represent derived features (apomorphies). For this purpose, we combine analyses of discrete features, classic anthropological measurements, and 3D geometric morphometrics based on generalized Procrustes analysis, mean size and shape comparisons, and principal components analysis. We found a size increment of the patella in hominin evolution, with large species showing a larger patella. Modern humans and Neandertals exhibit overall larger patellae, with maximum values observed in the latter, likely as a consequence of their broader body shape. Also, some Neandertals display a thicker patella, which has been linked to larger quadriceps muscles. However, Neandertals retain a primitive morphology in their patellar articular surfaces, with similar-sized lateral and medial articular facets, leading to a more symmetrical internal face. This feature is inherited from a primitive Homo ancestor and suggests a different configuration of the knee in Neandertals. Conversely, Homo sapiens exhibits an autoapomorphic patellar anatomy with expanded lateral articular facets. We propose that these distinct configurations of the patella within Homo may be a consequence of different body forms rather than specific functional adaptations of the knee. Thus, the slender body form of modern humans may entail a medial reorientation of the tibial tuberosity (patellar ligament), allowing lateral surface expansion. These anatomical evolutionary variations may involve subtle secondary differences in bipedalism within Homo.
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http://dx.doi.org/10.1016/j.jhevol.2019.102738DOI Listing
April 2020

Association between ribs shape and pulmonary function in patients with Osteogenesis Imperfecta.

J Adv Res 2020 Jan 22;21:177-185. Epub 2019 Oct 22.

Giaval Research Group, Department of Anatomy and Human Embryology, Faculty of Medicine, University of Valencia, Av. Blasco Ibanez, 15, 46010 Valencia, Spain.

The aim of the present study was to test the hypothesis that ribs shape changes in patients with OI are more relevant for respiratory function than thoracic spine shape. We used 3D geometric morphometrics to quantify rib cage morphology in OI patients and controls, and to investigate its relationship with forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1), expressed as absolute value and as percentage of predicted value (% pred). Regression analyses on the full sample showed a significant relation between rib shape and FEV1, FVC and FVC % pred whereas thoracic spine shape was not related to any parameter. Subsequent regression analyses on OI patients confirmed significant relations between dynamic lung volumes and rib shape changes. Lower FVC and FEV1 values are identified in OI patients that present more horizontally aligned ribs, a greater antero-posterior depth due to extreme transverse curve at rib angles and a strong spine invagination, greater asymmetry, and a vertically short, thoraco-lumbar spine, which is relatively straight in at levels 1-8 and shows a marked kyphosis in the thoraco-lumbar transition. Our research seems to support that ribs shape is more relevant for ventilator mechanics in OI patients than the spine shape.
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http://dx.doi.org/10.1016/j.jare.2019.10.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7015465PMC
January 2020

Three-dimensional analysis of sexual dimorphism in the soft tissue morphology of the upper airways in a human population.

Am J Phys Anthropol 2020 01;171(1):65-75

Universidad Politécnica de Cartagena, Departamento de Ingeniería Térmica y de Fluidos, Cartagena, Spain.

Objectives: Several studies have analyzed the sexual dimorphism of the skeletal cranial airways. This study aimed to quantify the three-dimensional (3D) morphology of the soft tissues of the upper airways in a human population. We addressed hypotheses about morphological features related to respiratory and energetic aspects of nasal sexual dimorphism.

Methods: We reconstructed 3D models of 41 male and female soft tissue nasal airways from computed tomography data. We measured 280 landmarks and semilandmarks for 3D-geometric morphometric analyses to test for differences in size and 3D morphology of different functional compartments of the soft tissue airways.

Results: We found statistical evidence for sexual dimorphism: Males were larger than females. 3D features indicated taller and wider inflow tracts, taller outflow tracts and slightly taller internal airways in males. These characteristics are compatible with greater airflow in males.

Discussion: The differences in 3D nasal airway morphology are compatible with the respiratory-energetics hypothesis according to which males differ from females because of greater energetic demands. Accordingly, structures related to inflow and outflow of air show stronger signals than structures relevant for air-conditioning.
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http://dx.doi.org/10.1002/ajpa.23944DOI Listing
January 2020

Workflows in a Virtual Morphology Lab: 3D scanning, measuring, and printing.

J Anthropol Sci 2019 Dec 30;96:107-134. Epub 2019 Aug 30.

Comunicación y Programas Públicos, Museo Nacional de Ciencias Naturales (MNCN-CSIC); J. G. Abascal 2, 28006 Madrid, Spain.

The aim of this paper is to give a practical overview, showing how recent available digital technology can be combined to build a laboratory capable to produce 3D (and reproduce in 3D) anatomical models for research, teaching and museum exhibitions on topics related to anatomy, morphology in natural sciences, biology and medicine. We present workflows in our Virtual Morphology Lab that can be used for research, training (museum, academic), and external service. We first review different surface scanning equipment and post-processing techniques that are useful for scanning in museum collections and provide technical recommendations for hard- and software as well as storing media on the web. This section is followed by an overview of available software packages for rigorous and effective 3D measurements of landmarks and sliding semi-landmarks, providing extensive supplementary information with guiding manuals for self-teaching in these cutting-edge but complicated research methods. We review briefly most recent work on virtual GM and describe ways for representing results in form of 3D images and 3D prints (outputs). The last part is dedicated to a summary of our experience in 3D-printing using FDM technology of differently sized printers and thermoplastic materials. Finally, we discuss the above-described workflows and its potential applications in research (paleo, biomedical), teaching and museums pedagogics.
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http://dx.doi.org/10.4436/JASS.97003DOI Listing
December 2019

3D geometric morphometric analysis of variation in the human lumbar spine.

Am J Phys Anthropol 2019 11 15;170(3):361-372. Epub 2019 Aug 15.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.

Objectives: The shape of the human lumbar spine is considered to be a consequence of erect posture. In addition, several other factors such as sexual dimorphism and variation in genetic backgrounds also influence lumbar vertebral morphology. Here we use 3D geometric morphometrics (GM) to analyze the 3D morphology of the lumbar spine in different human populations, exploring those potential causes of variation.

Material And Methods: We collected 390 (semi) landmarks from 3D models of the CT scans of lumbar spines of seven males and nine females from a Mediterranean population (Spain, Israel) and seven males and either females from a South African population for geometric morphometric (GM) analysis. We carried out Generalized Procrustes Analysis, Principal Components, and Regression analyses to evaluate shape variation; and complemented these analyses with the Cobb Method.

Results: The Mediterranean sample was considerably more lordotic than the South African sample. In both populations, female lumbar spines showed proportionally narrower and more craniocaudally elongated lumbar segments than in males. In addition, the point of maximum curvature in females tended to be located more inferiorly than in males.

Discussion: Our results show that sexual dimorphism is an important factor of lumbar spine variation that mainly affects features of lumbar spine robustness (height proportions) and the structure-but not the degree-of its curvature. Differences in lordosis, however, are clearer at the inter-population level. This reflects previous conflicting studies casting doubts on pregnancy as an adaptive factor influencing lordosis. Other factors, for example, shape of the individual lumbar vertebrae and intervertebral discs and their relative proportions within the lumbar spine should be considered when exploring variation in vertebral column morphology.
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http://dx.doi.org/10.1002/ajpa.23918DOI Listing
November 2019

Three-dimensional analysis of sexual dimorphism in ribcage kinematics of modern humans.

Am J Phys Anthropol 2019 06 1;169(2):348-355. Epub 2019 Apr 1.

Universite de Bordeaux, CNRS, MCC, De la Prehistoire a l'Actuel: Culture, Environnement et Anthropologie, (PACEA), Pessac, France.

Objectives: Sexual dimorphism is an important biological factor underlying morphological variation in the human skeleton. Previous research found sex-related differences in the static ribcage, with males having more horizontally oriented ribs and a wider lower ribcage than females. Furthermore, a recent study found sex-related differences in the kinematics of the human lungs, with cranio-caudal movements of the caudal part of the lungs accounting for most of the differences between sexes. However, these movements cannot be quantified in the skeletal ribcage, so we do not know if the differences observed in the lungs are also reflected in sex differences in the motion of the skeletal thorax.

Materials And Methods: To address this issue, we quantified the morphological variation of 42 contemporary human ribcages (sex-balanced) in both maximal inspiration and expiration using 526 landmarks and semilandmarks. Thoracic centroid size differences between sexes were assessed using a t test, and shape differences were assessed using Procrustes shape coordinates, through mean comparisons and dummy regressions of shape on kinematic status. A principal components analysis was used to explore the full range of morphological variation.

Results: Our results show significant size differences between males and females both in inspiration and expiration (p < .01) as well as significant shape differences, with males deforming more than females during inspiration, especially in the mediolateral dimension of the lower ribcage. Finally, dummy regressions of shape on kinematic status showed a small but statistically significant difference in vectors of breathing kinematics between males and females (14.78°; p < .01).

Discussion: We support that sex-related differences in skeletal ribcage kinematics are discernible, even when soft tissues are not analyzed. We hypothesize that this differential breathing pattern is primarily a result of more pronounced diaphragmatic breathing in males, which might relate to differences in body composition, metabolism, and ultimately greater oxygen demand in males compared to females. Future research should further explore the links between ribcage morphological variation and basal metabolic rate.
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http://dx.doi.org/10.1002/ajpa.23829DOI Listing
June 2019

3D virtual reconstruction of the Kebara 2 Neandertal thorax.

Nat Commun 2018 10 30;9(1):4387. Epub 2018 Oct 30.

Department of Sports Therapy, Faculty of Health Professions, Ono Academic College, 5545001, Kiryat Ono, Israel.

The size and shape of the Neandertal thorax has been debated since the first discovery of Neandertal ribs more than 150 years ago, with workers proposing different interpretations ranging from a Neandertal thoracic morphology that is indistinguishable from modern humans, to one that was significantly different from them. Here, we provide a virtual 3D reconstruction of the thorax of the adult male Kebara 2 Neandertal. Our analyses reveal that the Kebara 2 thorax is significantly different but not larger from that of modern humans, wider in its lower segment, which parallels his wide bi-iliac breadth, and with a more invaginated vertebral column. Kinematic analyses show that rib cages that are wider in their lower segment produce greater overall size increments (respiratory capacity) during inspiration. We hypothesize that Neandertals may have had a subtle, but somewhat different breathing mechanism compared to modern humans.
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http://dx.doi.org/10.1038/s41467-018-06803-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6207772PMC
October 2018

Ribcage measurements indicate greater lung capacity in Neanderthals and Lower Pleistocene hominins compared to modern humans.

Commun Biol 2018 16;1:117. Epub 2018 Aug 16.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal 2, 28006, Madrid, Spain.

Our most recent fossil relatives, the Neanderthals, had a large brain and a very heavy body compared to modern humans. This type of body requires high levels of energetic intake. While food (meat and fat consumption) is a source of energy, oxygen via respiration is also necessary for metabolism. We would therefore expect Neanderthals to have large respiratory capacities. Here we estimate the pulmonary capacities of Neanderthals, based on costal measurements and physiological data from a modern human comparative sample. The Kebara 2 male had a lung volume of about 9.04 l; Tabun C1, a female individual, a lung volume of 5.85 l; and a Neanderthal from the El Sidrón site, a lung volume of 9.03 l. These volumes are approximately 20% greater than the corresponding volumes of modern humans of the same body size and sex. These results show that the Neanderthal body was highly sensitive to energy supply.
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http://dx.doi.org/10.1038/s42003-018-0125-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6123625PMC
August 2018

The torso integration hypothesis revisited in Homo sapiens: Contributions to the understanding of hominin body shape evolution.

Am J Phys Anthropol 2018 12 27;167(4):777-790. Epub 2018 Sep 27.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales, Madrid, Spain.

Objectives: Lower thoracic widths and curvatures track upper pelvic widths and iliac blades curvatures in hominins and other primates (torso integration hypothesis). However, recent studies suggest that sexual dimorphism could challenge this assumption in Homo sapiens. We test the torso integration hypothesis in two modern human populations, both considering and excluding the effect of sexual dimorphism. We further assess covariation patterns between different thoracic and pelvic levels, and we explore the allometric effects on torso shape variation.

Material And Methods: A sex-balanced sample of 50 anatomically connected torsos (25 Mediterraneans, 25 Sub-Saharan Africans) was segmented from computed tomography scans. We compared the maximum medio-lateral width at seventh-ninth rib levels with pelvic bi-iliac breadth in males and females within both populations. We measured 1,030 (semi)landmarks on 3D torso models, and torso shape variation, mean size and shape comparisons, thoraco-pelvic covariation and allometric effects were quantified through 3D geometric morphometrics.

Results: Females show narrow thoraces and wide pelves and males show wide thoraces and narrow pelves, although this trend is more evident in Mediterraneans than in Sub-Saharans. Equal thoracic and pelvic widths, depths and curvatures were found in absence of sexual dimorphism. The highest strength of covariation was found between the lowest rib levels and the ilia, and allometric analyses showed that smaller torsos were wider than larger torsos.

Conclusions: This is the first study testing statistically the torso integration hypothesis in anatomically connected torsos. We propose a new and more complex torso integration model in H. sapiens with sexual dimorphism leading to different thoracic and pelvic widths and curvatures. These findings have important implications in hominin body shape reconstructions.
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http://dx.doi.org/10.1002/ajpa.23705DOI Listing
December 2018

Over 100 years of Krapina: New insights into the Neanderthal thorax from the study of rib cross-sectional morphology.

J Hum Evol 2018 09 6;122:124-132. Epub 2018 Jul 6.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), José Gutiérrez Abascal s/n, 28006 Madrid, Spain.

The Krapina costal sample was studied by Gorjanović-Kramberger in the early twentieth century. He pointed out unique features in the sample such as the rounder rib cross-section, which was recently confirmed in other Neanderthal specimens. Round rib cross-sections are characteristic of Homo ergaster, suggesting this may be plesiomorphic for Pleistocene Homo, but it is unknown whether Homo antecessor also had this rib shape. Furthermore, the influence of allometry on the cross-sectional shape of ribs is still unknown. The large costal sample from Krapina allows us to address these issues. We quantified cross-section morphology at the midshaft throughout a closed curve of one landmark and nine sliding semilandmarks in the Krapina costal remains (n = 7), as well as in other Neanderthals (n = 50), H. antecessor (n = 3) and modern humans, both fossil (n = 12) and recent (n = 160). We used principal components analysis and mean comparisons to explore interspecific differences, regression analysis to investigate allometry, and partial least squares analysis to examine covariation of cross-section shape and overall rib morphology. Neanderthal cross-sections tended to be larger than those of recent humans except for the Krapina and Tabun remains. Regarding shape, inter-group differences were found only in the diaphragmatic thorax, where Neanderthal and H. antecessor ribs were statistically significantly rounder than those of modern humans. Allometry accounted for covariation of size on shape, but the Neandertal and modern human trajectories had different slopes. While our results based on the Krapina costal sample are similar to previous findings, we also make several new insights: 1) the cross-section morphology observed in Neanderthals was probably present in H. antecessor, albeit less marked; 2) the distinct roundness of Neanderthal cross-sections is not related to size; 3) rounder cross-sections are correlated with ribs presenting less curvature in cranial view and a low degree of torsion in recent humans. These results are important for the interpretation of fragmentary Neanderthal costal remains, and the fact that the differences are marked only in the diaphragmatic thorax could have implications for breathing kinematics.
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http://dx.doi.org/10.1016/j.jhevol.2018.05.009DOI Listing
September 2018

Reevaluation of 'endocostal ossifications' on the Kebara 2 Neanderthal ribs.

J Hum Evol 2018 09 10;122:33-37. Epub 2018 May 10.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), J. G. Abascal 2, 28006 Madrid, Spain.

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http://dx.doi.org/10.1016/j.jhevol.2018.04.011DOI Listing
September 2018

Reconstructing the Neanderthal brain using computational anatomy.

Sci Rep 2018 04 26;8(1):6296. Epub 2018 Apr 26.

Research Institute, Kochi University of Technology, Kochi, 782-8502, Japan.

The present study attempted to reconstruct 3D brain shape of Neanderthals and early Homo sapiens based on computational neuroanatomy. We found that early Homo sapiens had relatively larger cerebellar hemispheres but a smaller occipital region in the cerebrum than Neanderthals long before the time that Neanderthals disappeared. Further, using behavioural and structural imaging data of living humans, the abilities such as cognitive flexibility, attention, the language processing, episodic and working memory capacity were positively correlated with size-adjusted cerebellar volume. As the cerebellar hemispheres are structured as a large array of uniform neural modules, a larger cerebellum may possess a larger capacity for cognitive information processing. Such a neuroanatomical difference in the cerebellum may have caused important differences in cognitive and social abilities between the two species and might have contributed to the replacement of Neanderthals by early Homo sapiens.
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http://dx.doi.org/10.1038/s41598-018-24331-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5919901PMC
April 2018

Pulling faces.

Authors:
Markus Bastir

Nat Ecol Evol 2018 06;2(6):923-924

Paleoanthropology Group, Department of Paleobiology, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain.

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http://dx.doi.org/10.1038/s41559-018-0550-2DOI Listing
June 2018

Response to Comment on "The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain)".

Science 2018 03;359(6380)

Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK.

The comment by DeSilva challenges our suggestion that brain growth of the El Sidrón J1 Neandertal was still incomplete at 7.7 years of age. Evidence suggests that endocranial volume is likely to represent less than 90% adult size at El Sidrón as well as Neandertal male plus Krapina samples, in line with further evidence from endocranial surface histology and dural sinus groove size.
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http://dx.doi.org/10.1126/science.aar3820DOI Listing
March 2018

Neck function in early hominins and suspensory primates: Insights from the uncinate process.

Am J Phys Anthropol 2018 07 28;166(3):613-637. Epub 2018 Feb 28.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (MNCN-CSIC), Madrid 28006, Spain.

Objectives: Uncinate processes are protuberances on the cranial surface of subaxial cervical vertebrae that assist in stabilizing and guiding spinal motion. Shallow uncinate processes reduce cervical stability but confer an increased range of motion in clinical studies. Here we assess uncinate processes among extant primates and model cervical kinematics in early fossil hominins.

Materials And Methods: We compare six fossil hominin vertebrae with 48 Homo sapiens and 99 nonhuman primates across 20 genera. We quantify uncinate morphology via geometric morphometric methods to understand how uncinate process shape relates to allometry, taxonomy, and mode of locomotion.

Results: Across primates, allometry explains roughly 50% of shape variation, as small, narrow vertebrae feature the relatively tallest, most pronounced uncinate processes, whereas larger, wider vertebrae typically feature reduced uncinates. Taxonomy only weakly explains the residual variation, however, the association between Uncinate Shape and mode of locomotion is robust, as bipeds and suspensory primates occupy opposite extremes of the morphological continuum and are distinguished from arboreal generalists. Like humans, Australopithecus afarensis and Homo erectus exhibit shallow uncinate processes, whereas A. sediba resembles more arboreal taxa, but not fully suspensory primates.

Discussion: Suspensory primates exhibit the most pronounced uncinates, likely to maintain visual field stabilization. East African hominins exhibit reduced uncinate processes compared with African apes and A. sediba, likely signaling different degrees of neck motility and modes of locomotion. Although soft tissues constrain neck flexibility beyond limits suggested by osteology alone, this study may assist in modeling cervical kinematics and positional behaviors in extinct taxa.
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http://dx.doi.org/10.1002/ajpa.23448DOI Listing
July 2018

Eco-geographic adaptations in the human ribcage throughout a 3D geometric morphometric approach.

Am J Phys Anthropol 2018 06 8;166(2):323-336. Epub 2018 Feb 8.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales, Madrid, Spain.

Objectives: According to eco-geographic rules, humans from high latitude areas present larger and wider trunks than their low-latitude areas counterparts. This issue has been traditionally addressed on the pelvis but information on the thorax is largely lacking. We test whether ribcages are larger in individuals inhabiting high latitudes than in those from low latitudes and explored the correlation of rib size with latitude. We also test whether a common morphological pattern is exhibited in the thorax of different cold-adapted populations, contributing to their hypothetical widening of the trunk.

Materials And Methods: We used 3D geometric morphometrics to quantify rib morphology of three hypothetically cold-adapted populations, viz. Greenland (11 individuals), Alaskan Inuit (8 individuals) and people from Tierra del Fuego (8 individuals), in a comparative framework with European (Spain, Portugal and Austria; 24 individuals) and African populations (South African and sub-Saharan African; 20 individuals).

Results: Populations inhabiting high latitudes present longer ribs than individuals inhabiting areas closer to the equator, but a correlation (p < 0.05) between costal size and latitude is only found in ribs 7-11. Regarding shape, the only cold adapted population that was different from the non-cold-adapted populations were the Greenland Inuit, who presented ribs with less curvature and torsion.

Conclusions: Size results from the lower ribcage are consistent with the hypothesis of larger trunks in cold-adapted populations. The fact that only Greenland Inuit present a differential morphological pattern, linked to a widening of their ribcage, could be caused by differences in latitude. However, other factors such as genetic drift or specific cultural adaptations cannot be excluded and should be tested in future studies.
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http://dx.doi.org/10.1002/ajpa.23433DOI Listing
June 2018

3D analysis of sexual dimorphism in size, shape and breathing kinematics of human lungs.

J Anat 2018 02 17;232(2):227-237. Epub 2017 Nov 17.

Paleoanthropology Group, Museo Nacional de Ciencias Naturales (CSIC), Madrid, Spain.

Sexual dimorphism in the human respiratory system has been previously reported at the skeletal (cranial and thoracic) level, but also at the pulmonary level. Regarding lungs, foregoing studies have yielded sex-related differences in pulmonary size as well as lung shape details, but different methodological approaches have led to discrepant results on differences in respiratory patterns between males and females. The purpose of this study is to analyse sexual dimorphism in human lungs during forced respiration using 3D geometric morphometrics. Eighty computed tomographies (19 males and 21 females) were taken in maximal forced inspiration (FI) and expiration (FE), and 415 (semi)landmarks were digitized on 80 virtual lung models for the 3D quantification of pulmonary size, shape and kinematic differences. We found that males showed larger lungs than females (P < 0.05), and significantly greater size and shape differences between FI and FE. Morphologically, males have pyramidal lung geometry, with greater lower lung width when comparing with the apices, in contrast to the prismatic lung shape and similar widths at upper and lower lungs of females. Multivariate regression analyses confirmed the effect of sex on lung size (36.26%; P < 0.05) and on lung shape (7.23%; P < 0.05), and yielded two kinematic vectors with a small but statistically significant angle between them (13.22°; P < 0.05) that confirms sex-related differences in the respiratory patterns. Our 3D approach shows sexual dimorphism in human lungs likely due to a greater diaphragmatic action in males and a predominant intercostal muscle action in females during breathing. These size and shape differences would lead to different respiratory patterns between sexes, whose physiological implications need to be studied in future research.
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http://dx.doi.org/10.1111/joa.12743DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5770305PMC
February 2018

3D geometric morphometrics of thorax variation and allometry in Hominoidea.

J Hum Evol 2017 12 1;113:10-23. Epub 2017 Sep 1.

Department of Mechanical Engineering, Faculty of Science and Technology, Keio University, Yokohama 223-8522, Japan.

Ever since the seminal papers of Keith and Schultz, hominoid primate ribcages have been described as either "funnel-" or "barrel-shaped." Following this dichotomic typology, it is currently held that Homo sapiens and hylobatids (gibbons and siamangs) share a barrel-shaped ribcage and that they are more similar to each other than to the funnel-shaped thoraces of great apes (Gorilla, Pan, and Pongo). Other researchers hypothesized that thoracic width and the invagination of the thoracic spine into the thorax are related to allometry. However, analyses that take into account the complex three-dimensional (3D) shape of the ribcage are lacking. Here, we address hypotheses about thorax shape and evolution using 3D morphometrics of thoraces in anatomical connection obtained by computed tomography scans of 23 hominoid cadavers and 10 humans and examining thorax compartments composed of seven ribs (1-7 thorax) and of 11 ribs (1-11 thorax). In the 1-7 thorax analyses, the human thorax is uniquely flat because of torsion of the upper and central ribs, differing from all non-human hominoids including hylobatids. In the 1-11 thorax analyses, humans are markedly different from African great apes, with hylobatids and orangutans intermediate. In full shape space analyses, affinities between orangutans and humans on the one hand and between hylobatids and African great apes on the other are evident. Therefore, we reject the hypothesis that humans and hylobatids bear any special affinities in overall 3D thorax shape to each other. We find that larger thoraces are wider and flatter, with a more invaginated spine, supporting the allometric hypothesis. Hominoid thorax variation shows complex interactions between allometry, rib curves, torsion, and declination, and the morphology of the costo-vertebral joint and the thoracic vertebral column. When considering functional specializations alongside phylogenetic relationships, an overly simplistic dichotomy between funnel-shaped and barrel-shaped thoraces is not supported.
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http://dx.doi.org/10.1016/j.jhevol.2017.08.002DOI Listing
December 2017

External and internal ontogenetic changes in the first rib.

Am J Phys Anthropol 2017 12 23;164(4):750-762. Epub 2017 Sep 23.

Laboratorio de Poblaciones del Pasado (LAPP). Departamento de Biología, Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain.

Objectives: First ribs bear information about thorax morphology and are usually well preserved, compared to other ribs, in bone/fossil samples. Several studies have addressed ontogeny of the first rib by studying changes in bone microanatomy and rib morphology separately, but no studies have combined both approaches to study how internal and external changes covary during ontogeny. The aim of this project is to fill this gap in our knowledge.

Materials And Methods: We applied 3D geometric morphometrics of sliding semilandmarks to 14 first ribs of Homo sapiens to quantify rib curvature and mid-shaft cross-section outline. Ontogenetic variation was addressed throughout a principal component analysis (PCA). Additionally, we made histological sections at the mid-shaft of the same ribs and studied tissue matrix composition and compartmentalization. Finally, we performed partial least squares (PLS) and regression analyses to study covariation between rib morphology and compartmentalization variables.

Results: PCA shows that first ribs increase their curvature over the course of ontogeny and the rib midshaft becomes less rounded during ontogeny. In addition, the sternal end becomes more medially oriented during ontogeny and the relative head-tubercle distance becomes longer. Compartmentalization shows a decrease in the area occupied by mineralized tissues and an increase in the area occupied by non-mineralized tissues over the course of ontogeny, which covaries with mid-shaft cross-section shape.

Conclusions: Our results show detailed variation in rib morphology along with histological changes in bone tissue compartmentalization and, for the first time, the correlation between the two. This could be related to muscle attachments on the 1st rib and also to changes in breathing mode, from diaphragmatic in perinatals to pulmonary in adults, which could also have implications for understanding thorax evolution.
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http://dx.doi.org/10.1002/ajpa.23313DOI Listing
December 2017

The growth pattern of Neandertals, reconstructed from a juvenile skeleton from El Sidrón (Spain).

Science 2017 09;357(6357):1282-1287

Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK.

Ontogenetic studies help us understand the processes of evolutionary change. Previous studies on Neandertals have focused mainly on dental development and inferred an accelerated pace of general growth. We report on a juvenile partial skeleton (El Sidrón J1) preserving cranio-dental and postcranial remains. We used dental histology to estimate the age at death to be 7.7 years. Maturation of most elements fell within the expected range of modern humans at this age. The exceptions were the atlas and mid-thoracic vertebrae, which remained at the 5- to 6-year stage of development. Furthermore, endocranial features suggest that brain growth was not yet completed. The vertebral maturation pattern and extended brain growth most likely reflect Neandertal physiology and ontogenetic energy constraints rather than any fundamental difference in the overall pace of growth in this extinct human.
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http://dx.doi.org/10.1126/science.aan6463DOI Listing
September 2017