The relevance of the first ribs of the El Sidrón site (Asturias, Spain) for the understanding of the Neandertal thorax (original) (raw)
Related papers
Well preserved thoracic vertebrae of Neandertals are rare. However, such fossils are important as their three-dimensional (3D) spatial configuration can contribute to the understanding of the size and shape of the thoracic spine and the entire thorax. This is because the vertebral body and transverse processes provide the articulation and attachment sites for the ribs. Dorsal orientation of the transverse processes relative to the vertebral body also rotates the attached ribs in a way that could affect thorax width. Previous research indicates possible evidence for greater dorsal orientation of the transverse processes and small vertebral body heights in Neandertals, but their 3D vertebral structure has not yet been addressed. Here we present 15 new vertebral remains from the El Sidr on Neandertals (Asturias, Northern Spain) and used 3D geometric morphometrics to address the above issues by comparing two particularly well preserved El Sidr on remains (SD-1619, SD-1641) with thoracic vertebrae from other Neandertals and a sample of anatomically modern humans. Centroid sizes of El Sidr on vertebrae are within the human range. Neandertals have larger T1 and probably also T2. The El Sidr on vertebrae are similar in 3D shape to those of other Neandertals, which differ from Homo sapiens particularly in central-lower regions (T6 eT10) of the thoracic spine. Differences include more dorsally and cranially oriented transverse processes , less caudally oriented spinous processes, and vertebral bodies that are anteroposteriorly and craniocaudally short. The results fit with current reconstructions of Neandertal thorax morphology.
The meaning of Neandertal skeletal morphology
A procedure is outlined for distinguishing among competing hypotheses for fossil morphology and then used to evaluate current views on the meaning of Neandertal skeletal morphology. Three explanations have dominated debates about the meaning of Neandertal cranial features: climatic adaptation, anterior dental loading, and genetic drift. Neither climatic adaptation nor anterior dental loading are well supported, but genetic drift is consistent with the available evidence. Climatic adaptation and activity patterns are the most discussed explanations for Neandertal postcranial features. Robust empirical relationships between climate and body form in extant humans and other endotherms currently make climatic adaptation the most plausible explanation for the wide bodies and relatively short limbs of Neandertals, and many additional postcranial features are likely secondary consequences of these overall skeletal proportions. Activity patterns may explain certain Neandertal postcranial features, but unlike the situation for climate, relationships in extant humans between morphology and activities are typically not well established. For both the cranium and the postcranium, changes in diet or activity patterns may underlie why Neandertals and Pleistocene modern humans tend to be more robust than Holocene humans. cranium ͉ human evolution ͉ modern human origins ͉ postcranium
The costal skeleton of the Regourdou 1 Neandertal
Journal of human evolution, 2018
The morphology and size of the Neandertal thorax is a subject of growing interest due to its link to general aspects of body size and shape, including physiological aspects related to bioenergetics and activity budgets. However, the number of well-preserved adult Neandertal costal remains is still low. The recent finding of new additional costal remains from the Regourdou 1 (R1) skeleton has rendered this skeleton as one of the most complete Neandertal costal skeletons with a minimum of 18 ribs represented, five of which are complete or virtually complete. Here we describe for the first time all the rib remains from R1 and compare them to a large modern Euroamerican male sample as well as to other published Neandertal individuals. The costal skeleton of this individual shows significant metric and morphological differences from our modern human male comparative sample. The perceived differences include: dorsoventrally large 1st and 2nd ribs, 3rd ribs with a very closed dorsal curvat...
The Neandertal vertebral column: 1-The cervical spine
This paper provides a metric analysis of the Neandertal cervical spine in relation to modern human variation. All seven cervical vertebrae have been analysed. Metric data from eight Neandertal individuals are compared with a large sample of modern humans. The significance of morphometric differences is tested using both z-scores and two-tailed Wilcoxon signed rank tests. The results identify significant metric and morphological differences between Neandertals and modern humans in all seven cervical vertebrae. Neandertal vertebrae are mediolaterally wider and dorsoventrally longer than modern humans, due in part to longer and more horizontally oriented spinous processes. This suggests that Neandertal cervical morphology was more stable in both mid-sagittal and coronal planes. It is hypothesized that the differences in cranial size and shape in the Neandertal and modern human lineages from their Middle Pleistocene ancestors could account for some of the differences in the neck anatomy between these species.Este artículo proporciona un análisis métrico de la columna cervical de los Neandertales, comparándola a la variación presente en los humanos modernos. Las siete vértebras cervicales han sido analizadas: datos métricos de siete Neandertales son comparados a una gran muestra de humanos modernos. El grado de significación de las diferencias morfométricas es testado usando z-scores y la prueba de signos de Wilcoxon con dos colas. Los resultados de este estudio indican que hay diferencias métricas y morfológicas significativas entre los Neandertales y los humanos modernos en todas las vértebras cervicales. Las vértebras cervicales de los Neandertales son más anchas mediolateralmente y más largas dorsoventralmente, en parte debido a apófisis espinosas más largas y orientadas más horizontalmente. Esto sugiere que el cuello de los Neandertales era más estable tanto en el plano medio-sagital como en el plano coronal. Hipotetizamos que las diferencias en el tamaño y forma del cráneo acontecidas desde el Pleistoceno Medio tanto en el linaje Neandertal como en nuestro propio linaje podrían explicar algunas de las diferencias entre las dos especies.
Journal of Human Evolution, 2020
for providing access to the casts and 3D models of Kebara 2 reconstructions used in this study. Special thanks go to Asier Gómez-Olivencia for uploading the 3D virtual model of his reconstruction of Kebara 2 ribcage to the online open access repository Figshare, for kindly accepting to revise this manuscript and for helpful comments and discussions. Lastly, the authors thank Miss Abigail O'Connell (Hull York Medical School, York) for generously accepting to revise the English grammar of the last version of this manuscript. This paper is dedicated to the memory of Dennis E. Slice for his contribution to the development of geometric morphometrics methods and software. This research was supported by the Ministerio de Economía, Industria y Competitividad of Spain (AEI/FEDER, EU, grant number CGL-2015-63648-P). 3D geometric morphometrics of thorax-pelvis covariation and its potential for predicting thorax morphology: A case study on Kebara 2 Neandertal ABSTRACT The skeletal torso is a complex structure of outstanding importance to understanding human body shape evolution, but reconstruction usually entails an element of subjectivity as each researcher applies 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 (2B-PLS) 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 3 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 fixed landmarks, 720 curve semilandmarks and 160 surface semilandmarks on n = 60 3D virtual torso models segmented from CT scans. We conducted three 2B-PLS 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. Additionally, 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 the 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.
The costal skeleton of Shanidar 3 and a reappraisal of Neandertal thoracic morphology
Journal of Human Evolution, 2002
We meet with evidence of a capacious thorax in the Tabun women, especially when we take into account her stature. She had a rounded, barrel-shaped chest, ribs which were well curved, and were set more horizontally than is the case in modern people. The ribs were not wide, but thick relative to their width. The first three ribs expanded laterally quite rapidly so as to form a domeshaped top to the thorax. The ventral ends of the seventh, eighth, ninth, and tenth ribs were peculiar, being rounded and pencilshaped (McCown & Keith, 1939:124).