Currently post-doc at PalaeoHub in York, looking at growth patterns in Homo sapiens and Neandertals. For more recent papers, please head to my ResearchGate profile (https://www.researchgate.net/profile/Lou_Albessard). I started off studying -and excavating- European Neolithic and protohistoric archaeology and somehow ended up doing a PhD on the evolution of the human brain and skull, so who knows where archaeology and prehistory are going to take me next! I'm particularly interested in staying in touch with the later prehistory/protohistory worlds. And with European archaeology in general (yes, even recent. I did once excavate a 1950s toilet after all).
The frontal sinuses are cavities inside the frontal bone located at the junction between the face... more The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species’ holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus . Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species.
Il existe chez les espèces du genre Homo une diversité morphologique crânienne et cérébrale impor... more Il existe chez les espèces du genre Homo une diversité morphologique crânienne et cérébrale importante, et les interactions de ces deux éléments sont complexes. De manière générale, au cours de l’évolution de ce taxon, le neurocrâne prend une importance croissante par rapport au bloc facial en raison d’une expansion cérébrale marquée. Cependant, les modalités de cette expansion sont multiples, et elle se met en place chez les différentes espèces via des modifications morphologiques qui leur sont propres. Mise à part l’augmentation du volume cérébral, l’endocrâne témoigne de réorganisations neuroanatomiques. Ces différents facteurs - volume et organisation – ainsi que les contraintes morpho-fonctionnelles diverses exercées sur la face externe du crâne, sont susceptibles de résulter en une variété de relations morphologiques et spatiales entre le neurocrâne et l’endocrâne. Il est donc pertinent de documenter ces relations afin de pouvoir par la suite mieux appréhender la variabilité e...
Il existe chez les especes du genre Homo une diversite morphologique crânienne et cerebrale impor... more Il existe chez les especes du genre Homo une diversite morphologique crânienne et cerebrale importante, et les interactions de ces deux elements sont complexes. De maniere generale, au cours de l’evolution de ce taxon, le neurocrâne prend une importance croissante par rapport au bloc facial en raison d’une expansion cerebrale marquee. Cependant, les modalites de cette expansion sont multiples, et elle se met en place chez les differentes especes via des modifications morphologiques qui leur sont propres. Mise a part l’augmentation du volume cerebral, l’endocrâne temoigne de reorganisations neuroanatomiques. Ces differents facteurs - volume et organisation – ainsi que les contraintes morpho-fonctionnelles diverses exercees sur la face externe du crâne, sont susceptibles de resulter en une variete de relations morphologiques et spatiales entre le neurocrâne et l’endocrâne. Il est donc pertinent de documenter ces relations afin de pouvoir par la suite mieux apprehender la variabilite e...
Modern human and Neanderthal faces present clear morphological differences at all ontogenetic sta... more Modern human and Neanderthal faces present clear morphological differences at all ontogenetic stages. Their post-natal ontogenetic allometric trajectories diverge [1] and in both species, as the various components of the mid-face develop and grow, bone facial remodelling is thought to play a key role in adapting them to their final adult form. In modern humans, maxillary growth is characterised by bone resorption on the anterior surface, whereas in Neanderthals extensive bone deposition is the common finding [2]. This morphogenetic difference is present by approximately 5 years of age [2]. During development, crania are loaded by forces applied to the masticatory system in feeding and manipulation. These change over time, as diet (e.g. weaning) and paramasticatory behaviour change. Differences are known to exist in adults between Homo sapiens and Neanderthals, with Homo sapiens relatively more efficient at generating bite forces but less able to support the strains and deformations produced by such forces [3,4]. Differences in mid-facial form between these species might be expected to be influenced and to influence the distribution and magnitude of strains experienced during masticatory system loading. Since bone adapts to loads, such differences might underlie and contribute to the distinctive distributions of facial remodelling fields in both species and so, to differences in craniofacial growth. The present study explores the ontogeny of modern human and Neanderthal biting resistance as a preliminary to assessing potential associations between the distributions of facial strains arising from biting and facial remodelling among hominins. Our aim is to see if any differences in strains exist during post-natal ontogeny. We test the null hypothesis that modes and magnitudes of cranial deformation do not differ between modern humans and Neanderthals at each age stage when exposed to similar constraints. We used ontogenetic series of Neanderthals and modern humans ranging from newborn to adult. Using 44 landmarks and 201 sliding semilandmarks multivariate regressions of cranial shape on size were used to create three surfaces representing the mean infant, juvenile, and adult stages. These surfaces were converted into finite element models and constrained and loaded in a standardised way to simulate right first incisor and P4/dm2 biting. Applied forces and material properties were identical among models to control all variables except craniofacial form. We compared the resulting deformations, maps of von Mises strains and tensile and compressive strains in the maxilla. The resulting deformations differ in both mode and magnitude between modern humans and Neanderthals. In both incisor and P4/dm2 biting simulations, modelled strains decrease between infants and adults, as is to be expected given differences in size. The infant modern human presents higher strains than the infant Neanderthal over the anterior and inferior maxilla in both biting simulations. This is reversed in the juvenile models and the strains are more similar in adults. Finally, for both biting simulations, modern humans and Neanderthals deform differently, reflecting the differences in developed strains at each age stage. These findings reflect differences in the dynamics of facial growth between modern humans and Neanderthals. Moreover, the differences in strains in the infant, juvenile maxillae in modern humans and Neanderthals model may to some extent underlie and explain the differences in maxillary surface remodelling in these two species. Further work on a wider range of models and loading scenarios is needed to explore this issue further. Acknowledgments: We would like to thanks D. Shapiro, Joan T. Richtsmeier, G. Holoborow, S. Black and L. Scheuer for the information and access to Bosma and Dundee-Scheuer human skeletal collections. For the access and permission to their fossil materials, we would like to thanks the different institutes and their collaborators: Musée national d’Histoire naturelle, Musée de l’Homme (Paris, France), Musée national de la Préhistoire and his director J.J. Cleyet Merle, Museum of Natural History (London, UK), Patrick Semal and the Institut Royal des Sciences naturelles de Belgique (Bruxelle, Belgique), Jean Jacques Hublin and Philipp Gunz from Max Planck Institute for Evolutionary Anthropology (Leizpig, Germany), Luca Bondioli and the Pigorini Museum (Università di Padova, Italy).We would also like to thank the Dan David Center of Human Evolution and Biohistory Research, Shmunis family anthropological institute, Sackler Faculty of Medicine, Tel Aviv University (Tel Aviv, Israel) for granting access to Amud 1. Finally, we thank the NESPOS platform for access to modern and fossil material. References: [1] Krovitz, G. E., 2003. Shape and growth differences between Neandertals and modern humans: grounds for a species-level distinction?. Cambridge Studies in Biological and Evolutionary Anthropology, 320-342.…
The frontal sinuses are cavities inside the frontal bone located at the junction between the face... more The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species' holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species.
Cervical vertebrae not only protect the spinal cord but also are the insertion and origin points ... more Cervical vertebrae not only protect the spinal cord but also are the insertion and origin points for muscles related to the movement of the head, upper limb, and trunk, among others, and are thus important elements in primate evolution. While previous work has been undertaken on the first two cervical vertebrae, there is a dearth of studies on the subaxial cervical spine in hominines. In this paper, we provide detailed morphological information on two important aspects of the subaxial cervical vertebrae (C3 - C7): mid-sagittal morphology and superior facet orientation. We studied large samples of African apes including modern humans and the most complete fossil hominin subaxial cervical vertebrae using both traditional and geometric morphometrics. There are significant differences between extant hominoids related to the relative length and orientation of the spinous process as well as to the orientation of the articular facets, which are related to size, locomotion, and neck posture...
The cranium (Broken Hill 1 or BH1) from the site previously known as Broken Hill, Northern Rhodes... more The cranium (Broken Hill 1 or BH1) from the site previously known as Broken Hill, Northern Rhodesia (now Kabwe, Zambia) is one of the best preserved hominin fossils from the mid-Pleistocene. Its distinctive combination of anatomical features, however, makes its taxonomic attribution ambiguous. High resolution microCT, which has not previously been employed for gross morphological studies of this important specimen, allows a precise description of the internal anatomical features of BH1, including the distribution of cranial vault thickness and its 2 internal composition, paranasal pneumatisation, pneumatisation of the temporal bone and endocranial anatomy. Relative to other chronologically and taxonomically relevant specimens, BH1 shows unusually marked paranasal pneumatisation and a fairly thick cranial vault. For many of the features analysed, this fossil does not exhibit the apomorphic conditions observed in either Neandertals or Homo sapiens. Its morphology and the general shape...
The anatomical asymmetries of the human brain are the subject of a great deal of scientific inter... more The anatomical asymmetries of the human brain are the subject of a great deal of scientific interest because of their links with handedness and lateralized cognitive functions. Information about lateralization in humans is also available from the post-cranial skeleton, particularly the arm bones, in which differences in size and shape are related to hand/arm preference. Our objective here is to characterize the possible correlations between the endocranial and post-cranial asymmetries of an archaeological sample. This, in turn, will allow us to try to identify and interpret prospective functional traits in the archaeological and fossil records. We observe that directional asymmetry (DA) is present both for some endocranial and humeral traits because of brain lateralization and lateralized behaviors, while patterns of fluctuating asymmetry (FA) vary. The combined study of these anatomical elements and of their asymmetries can shed light on the ways in which the body responds to depen...
Cranial anatomical features play a prominent part in the definition of extinct Homo taxa and in s... more Cranial anatomical features play a prominent part in the definition of extinct Homo taxa and in species identification in fossils. Thus, knowledge of cranial morphology considered within its geochronological framework is essential to the understanding of the evolution, chronology, and dispersal of the genus Homo. The brain is also a valuable object of study for research on human evolution, because of features such as its large size and a high encephalization quotient in some Homo species, as well as the complexity of human cognition. However, the joint evolution of endo- and ectocranial anatomies is still little studied, and landmarks representing cerebral anatomy rather than inner cranial bone anatomy are still rarely used. This exploratory piece of research examines endo- and ectocranial profiles in samples representing 3 Homo taxa: Homo sapiens (fossil and recent specimens), Homo erectus, and Homo neanderthalensis. We used 2D geometric morphometrics to analyze the shape of the en...
The frontal sinuses are cavities inside the frontal bone located at the junction between the face... more The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species’ holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus . Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species.
Il existe chez les espèces du genre Homo une diversité morphologique crânienne et cérébrale impor... more Il existe chez les espèces du genre Homo une diversité morphologique crânienne et cérébrale importante, et les interactions de ces deux éléments sont complexes. De manière générale, au cours de l’évolution de ce taxon, le neurocrâne prend une importance croissante par rapport au bloc facial en raison d’une expansion cérébrale marquée. Cependant, les modalités de cette expansion sont multiples, et elle se met en place chez les différentes espèces via des modifications morphologiques qui leur sont propres. Mise à part l’augmentation du volume cérébral, l’endocrâne témoigne de réorganisations neuroanatomiques. Ces différents facteurs - volume et organisation – ainsi que les contraintes morpho-fonctionnelles diverses exercées sur la face externe du crâne, sont susceptibles de résulter en une variété de relations morphologiques et spatiales entre le neurocrâne et l’endocrâne. Il est donc pertinent de documenter ces relations afin de pouvoir par la suite mieux appréhender la variabilité e...
Il existe chez les especes du genre Homo une diversite morphologique crânienne et cerebrale impor... more Il existe chez les especes du genre Homo une diversite morphologique crânienne et cerebrale importante, et les interactions de ces deux elements sont complexes. De maniere generale, au cours de l’evolution de ce taxon, le neurocrâne prend une importance croissante par rapport au bloc facial en raison d’une expansion cerebrale marquee. Cependant, les modalites de cette expansion sont multiples, et elle se met en place chez les differentes especes via des modifications morphologiques qui leur sont propres. Mise a part l’augmentation du volume cerebral, l’endocrâne temoigne de reorganisations neuroanatomiques. Ces differents facteurs - volume et organisation – ainsi que les contraintes morpho-fonctionnelles diverses exercees sur la face externe du crâne, sont susceptibles de resulter en une variete de relations morphologiques et spatiales entre le neurocrâne et l’endocrâne. Il est donc pertinent de documenter ces relations afin de pouvoir par la suite mieux apprehender la variabilite e...
Modern human and Neanderthal faces present clear morphological differences at all ontogenetic sta... more Modern human and Neanderthal faces present clear morphological differences at all ontogenetic stages. Their post-natal ontogenetic allometric trajectories diverge [1] and in both species, as the various components of the mid-face develop and grow, bone facial remodelling is thought to play a key role in adapting them to their final adult form. In modern humans, maxillary growth is characterised by bone resorption on the anterior surface, whereas in Neanderthals extensive bone deposition is the common finding [2]. This morphogenetic difference is present by approximately 5 years of age [2]. During development, crania are loaded by forces applied to the masticatory system in feeding and manipulation. These change over time, as diet (e.g. weaning) and paramasticatory behaviour change. Differences are known to exist in adults between Homo sapiens and Neanderthals, with Homo sapiens relatively more efficient at generating bite forces but less able to support the strains and deformations produced by such forces [3,4]. Differences in mid-facial form between these species might be expected to be influenced and to influence the distribution and magnitude of strains experienced during masticatory system loading. Since bone adapts to loads, such differences might underlie and contribute to the distinctive distributions of facial remodelling fields in both species and so, to differences in craniofacial growth. The present study explores the ontogeny of modern human and Neanderthal biting resistance as a preliminary to assessing potential associations between the distributions of facial strains arising from biting and facial remodelling among hominins. Our aim is to see if any differences in strains exist during post-natal ontogeny. We test the null hypothesis that modes and magnitudes of cranial deformation do not differ between modern humans and Neanderthals at each age stage when exposed to similar constraints. We used ontogenetic series of Neanderthals and modern humans ranging from newborn to adult. Using 44 landmarks and 201 sliding semilandmarks multivariate regressions of cranial shape on size were used to create three surfaces representing the mean infant, juvenile, and adult stages. These surfaces were converted into finite element models and constrained and loaded in a standardised way to simulate right first incisor and P4/dm2 biting. Applied forces and material properties were identical among models to control all variables except craniofacial form. We compared the resulting deformations, maps of von Mises strains and tensile and compressive strains in the maxilla. The resulting deformations differ in both mode and magnitude between modern humans and Neanderthals. In both incisor and P4/dm2 biting simulations, modelled strains decrease between infants and adults, as is to be expected given differences in size. The infant modern human presents higher strains than the infant Neanderthal over the anterior and inferior maxilla in both biting simulations. This is reversed in the juvenile models and the strains are more similar in adults. Finally, for both biting simulations, modern humans and Neanderthals deform differently, reflecting the differences in developed strains at each age stage. These findings reflect differences in the dynamics of facial growth between modern humans and Neanderthals. Moreover, the differences in strains in the infant, juvenile maxillae in modern humans and Neanderthals model may to some extent underlie and explain the differences in maxillary surface remodelling in these two species. Further work on a wider range of models and loading scenarios is needed to explore this issue further. Acknowledgments: We would like to thanks D. Shapiro, Joan T. Richtsmeier, G. Holoborow, S. Black and L. Scheuer for the information and access to Bosma and Dundee-Scheuer human skeletal collections. For the access and permission to their fossil materials, we would like to thanks the different institutes and their collaborators: Musée national d’Histoire naturelle, Musée de l’Homme (Paris, France), Musée national de la Préhistoire and his director J.J. Cleyet Merle, Museum of Natural History (London, UK), Patrick Semal and the Institut Royal des Sciences naturelles de Belgique (Bruxelle, Belgique), Jean Jacques Hublin and Philipp Gunz from Max Planck Institute for Evolutionary Anthropology (Leizpig, Germany), Luca Bondioli and the Pigorini Museum (Università di Padova, Italy).We would also like to thank the Dan David Center of Human Evolution and Biohistory Research, Shmunis family anthropological institute, Sackler Faculty of Medicine, Tel Aviv University (Tel Aviv, Israel) for granting access to Amud 1. Finally, we thank the NESPOS platform for access to modern and fossil material. References: [1] Krovitz, G. E., 2003. Shape and growth differences between Neandertals and modern humans: grounds for a species-level distinction?. Cambridge Studies in Biological and Evolutionary Anthropology, 320-342.…
The frontal sinuses are cavities inside the frontal bone located at the junction between the face... more The frontal sinuses are cavities inside the frontal bone located at the junction between the face and the cranial vault and close to the brain. Despite a long history of study, understanding of their origin and variation through evolution is limited. This work compares most hominin species' holotypes and other key individuals with extant hominids. It provides a unique and valuable perspective of the variation in sinuses position, shape, and dimensions based on a simple and reproducible methodology. We also observed a covariation between the size and shape of the sinuses and the underlying frontal lobes in hominin species from at least the appearance of Homo erectus. Our results additionally undermine hypotheses stating that hominin frontal sinuses were directly affected by biomechanical constraints resulting from either chewing or adaptation to climate. Last, we demonstrate their substantial potential for discussions of the evolutionary relationships between hominin species.
Cervical vertebrae not only protect the spinal cord but also are the insertion and origin points ... more Cervical vertebrae not only protect the spinal cord but also are the insertion and origin points for muscles related to the movement of the head, upper limb, and trunk, among others, and are thus important elements in primate evolution. While previous work has been undertaken on the first two cervical vertebrae, there is a dearth of studies on the subaxial cervical spine in hominines. In this paper, we provide detailed morphological information on two important aspects of the subaxial cervical vertebrae (C3 - C7): mid-sagittal morphology and superior facet orientation. We studied large samples of African apes including modern humans and the most complete fossil hominin subaxial cervical vertebrae using both traditional and geometric morphometrics. There are significant differences between extant hominoids related to the relative length and orientation of the spinous process as well as to the orientation of the articular facets, which are related to size, locomotion, and neck posture...
The cranium (Broken Hill 1 or BH1) from the site previously known as Broken Hill, Northern Rhodes... more The cranium (Broken Hill 1 or BH1) from the site previously known as Broken Hill, Northern Rhodesia (now Kabwe, Zambia) is one of the best preserved hominin fossils from the mid-Pleistocene. Its distinctive combination of anatomical features, however, makes its taxonomic attribution ambiguous. High resolution microCT, which has not previously been employed for gross morphological studies of this important specimen, allows a precise description of the internal anatomical features of BH1, including the distribution of cranial vault thickness and its 2 internal composition, paranasal pneumatisation, pneumatisation of the temporal bone and endocranial anatomy. Relative to other chronologically and taxonomically relevant specimens, BH1 shows unusually marked paranasal pneumatisation and a fairly thick cranial vault. For many of the features analysed, this fossil does not exhibit the apomorphic conditions observed in either Neandertals or Homo sapiens. Its morphology and the general shape...
The anatomical asymmetries of the human brain are the subject of a great deal of scientific inter... more The anatomical asymmetries of the human brain are the subject of a great deal of scientific interest because of their links with handedness and lateralized cognitive functions. Information about lateralization in humans is also available from the post-cranial skeleton, particularly the arm bones, in which differences in size and shape are related to hand/arm preference. Our objective here is to characterize the possible correlations between the endocranial and post-cranial asymmetries of an archaeological sample. This, in turn, will allow us to try to identify and interpret prospective functional traits in the archaeological and fossil records. We observe that directional asymmetry (DA) is present both for some endocranial and humeral traits because of brain lateralization and lateralized behaviors, while patterns of fluctuating asymmetry (FA) vary. The combined study of these anatomical elements and of their asymmetries can shed light on the ways in which the body responds to depen...
Cranial anatomical features play a prominent part in the definition of extinct Homo taxa and in s... more Cranial anatomical features play a prominent part in the definition of extinct Homo taxa and in species identification in fossils. Thus, knowledge of cranial morphology considered within its geochronological framework is essential to the understanding of the evolution, chronology, and dispersal of the genus Homo. The brain is also a valuable object of study for research on human evolution, because of features such as its large size and a high encephalization quotient in some Homo species, as well as the complexity of human cognition. However, the joint evolution of endo- and ectocranial anatomies is still little studied, and landmarks representing cerebral anatomy rather than inner cranial bone anatomy are still rarely used. This exploratory piece of research examines endo- and ectocranial profiles in samples representing 3 Homo taxa: Homo sapiens (fossil and recent specimens), Homo erectus, and Homo neanderthalensis. We used 2D geometric morphometrics to analyze the shape of the en...
Etude en géométrie morphométrique 2D du plan sagittal médian du crâne et de l'endocrâne chez H. s... more Etude en géométrie morphométrique 2D du plan sagittal médian du crâne et de l'endocrâne chez H. sapiens, H. erectus et H. neanderthalensis.
A 2D geometric morphometrics study of the skull's and endocranium's mid-sagittal plane in H. sapiens, H. erectus and H. neanderthalensis.
Scientists have long favoured cranial features as clues to reconstruct the story of human evoluti... more Scientists have long favoured cranial features as clues to reconstruct the story of human evolution. This is because of the relative abundance of skulls in the fossil record, as well as the high number of diagnostic features observable on them. One major characteristic of human evolution is the development of large brains and of complex cognition. For this reason, the evolution of brains in fossil hominins and in Homo sapiens draws considerable scientific attention. The study of endocasts - their volume, general morphology, convolutional patterns, and the development of cognitive areas recognised in extant humans - may have little to tell us in terms of function, but it does allow for the identification of derived characters with potential phylogenic and evolutionary value. Because of the high morphological integration between the outer vault of the skull and the endocranium, it is difficult to list reliable independent diagnostic features for these two aspects of the head. The pressures on skull morphology may relate to environmental changes, diet, modifications in the sensory organs, brain development, or the use of articulate language, whereas the brain undergoes reorganisations which may be due to the development of cognitive areas. There is however very little literature concerning the joint evolution of the skull and endocast. We will present some morphometrical data derived from a sample of fossil and extant hominins, aiming at starting to clarify the relationship between the morphologies of the skull’s outer vault and the endocranium throughout the evolution of the genus Homo.
Although the size and morphology of the brain are considered one of the most characteristic trait... more Although the size and morphology of the brain are considered one of the most characteristic traits of Homo sapiens, variations in cerebral morphology throughout the recent evolution of our species are poorly documented.
Human cerebral asymmetries are known to have functional correlates, and to be reflected on endocr... more Human cerebral asymmetries are known to have functional correlates, and to be reflected on endocranial casts. However, the extent to which the neurocranium adapts to the development of the cerebral asymmetries is not known. In order to investigate this question, we have digitized 5 landmarks and 400 surface semi-landmarks on the virtual neurocrania of 39 extant Homo sapiens, and 29 landmarks and over 800 surface semi-landmarks on their virtual endocasts, following a protocol adapted from Kitchell (2015) [1]. We mirrored each skull and endocast and their landmarks, and digitized surface semi-landmarks on the mirrored objects following the same protocol. We produced cartographies of the distances between original and mirrored specimens (asymmetries) after Procrustes superimposition. We then compared, for each individual, the gross asymmetry patterns of the neurocranium to those of the endocast. Finally, we obtained maps of neurocranial bone thickness, which we compared to the asymmetry patterns observed. Our results show that, for each individual, the asymmetry of the neurocranium is very similar to that of the endocast in its spatial pattern, but is reduced in its degree. Bone thickness is not influenced by the patterns of asymmetry. This suggests that the asymmetry of the neurocranium is tightly linked to brain development, to the exclusion of external factors, and that bone structure is unaffected by these patterns of asymmetry. [1] Kitchell, Lindsey M. Asymmetry of the Modern Human Endocranium. Diss. INSTITUTE OF ARCHAEOLOGY, University College London 2015
Despite the taxonomic, evolutionary and functional importance of both cranial and endocranial cha... more Despite the taxonomic, evolutionary and functional importance of both cranial and endocranial characters in the field of palaeoanthropology, there remains a lot to investigate about the patterns of joint evolution of the skull and endocranium, and about the influence of brain growth and cerebral organisation on cranial anatomy. This research is part of a wider doctoral project aiming at clarifying the relations between the morphologies of the neurocranium and the brain throughout hominin evolution. It draws on the growing wealth of knowledge about either the evolution of the brain (studied through endocranial casts) or that of the skull, in order to better understand the morphological integration of these two elements. We have therefore developed protocols using both cranial and cerebral features, an approach which is rare among current studies. It is well-accepted that large brains are an evolutionary specificity of Homo sapiens and a major contribution to its success, as they allowed this species to perform complex cognitive tasks. Throughout the evolution of the genus Homo, endocranial capacity has increased steadily, reaching its highest means in Neandertals and Homo sapiens. However, while Neandertals retained an elongated braincase and brain, as seen in earlier Homo species, in Homo sapiens this growth came with derived features such as a rounded skull and brain. It has been suggested that these differences in adult morphologies between Homo sapiens and Neandertals result from a globularisation phase during ontogeny [1]. Overall, although both cranial and endocranial characters are used in order to differentiate Homo species and to assign fossils to different taxa, the extent to which cranial and endocranial morphologies co-vary in the genus Homo is not known. Both cranial and endocranial morphologies in Homo sapiens appear unusual when compared with all other Homo species. At the intraspecific level, the organisation of the cerebral lobes within the Homo sapiens species has been shown to have changed since the Upper Palaeolithic (for instance in surface area and in the proportions of sagittal measurements for each lobe [2]). In the same time, the average cranial capacity was shrinking and the skulls and skeletons were becoming more gracile. This study addresses the co-evolution of the Homo sapiens brain and skull, by analyzing patterns of variation through time (using Upper Palaeolithic, epipalaeolithic and extant samples) and by comparing Homo sapiens to other Homo species in order to assess its specificities within the genus. The questions we have attempted to answer are: does the morphology of the brain and skull in Homo sapiens significantly deviate from the patterns seen in other Homo species or not? Can allometry explain the Homo sapiens pattern? Can we clarify the timeline of the apparition of the Homo sapiens pattern and of its subsequent evolutions? In order to answer these questions, we have used a protocol in 2D geometric morphometrics on the mid-sagittal plane (modified from [3]), as well as traditional morphometrics on the entire skull and endocranium. We used data derived from the inner and outer cranial vaults, as well as morphological loci which allow us to gather data about brain organization, such as the anterior and posterior extension of the frontal, parietal and occipital lobes on the mid-saggital plane. We explored morphometrical variations in a sample of 77 Homo sapiens (40 extant, 15 Epipalaeolithic, 22 Upper Palaeolithic) and 22 non-sapiens Homo specimens (8 Neandertals, 11 Homo erectus sensu lato, 4 other mid-Pleistocene Homo). We then cross-examined the results in order to address the questions above. Our results show specificities in Homo sapiens morphology compared with other Homo species, and differences across Homo sapiens groups. For instance, they suggest that there are more differences between the midsagittal morphologies of Homo sapiens and the other Homo species than there are between any of the other Homo species, despite the enlarged brains of both Homo sapiens and Neandertals and the morphological changes that this growth caused. Our results also show re-organisations in the relative lengths of cerebral lobes in Homo sapiens since the Upper Palaeolithic, suggesting a gradual shift to the pattern seen in extant humans.
[1] Gunz, Ph., Neubauer, S., Golovanova, L., Doronichev, V., Maureille, B., Hublin, J-J., 2012. A uniquely modern human pattern of endocranial development. Insights from a new cranial reconstruction of the Neandertal newborn from Mezmaiskaya. J. Hum. Evol. 62, 300-313. [2] Balzeau, A., Grimaud-Hervé, D., Détroit, F., Holloway, R.L., Combès, B., Prima, S., 2013. First description of the Cro-Magnon 1 endocast and study of brain variation and evolution in anatomically modern Homo sapiens. Bull. Mém. Soc. Anthropol. Paris 25,1-18. [3] Albessard, L.,Grimaud-Hervé, D., Balzeau, A., 2016. Evolution of cranial and endocranial profiles in Homo species: A study in 2D geometric morphometrics. BMSAP 28,3-4.
We warmly thank the researchers and curators who kindly gave us access to material.
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Papers by Lou Albessard-Ball
A 2D geometric morphometrics study of the skull's and endocranium's mid-sagittal plane in H. sapiens, H. erectus and H. neanderthalensis.
In order to investigate this question, we have digitized 5 landmarks and 400 surface semi-landmarks on the virtual neurocrania of 39 extant Homo sapiens, and 29 landmarks and over 800 surface semi-landmarks on their virtual endocasts, following a protocol adapted from Kitchell (2015) [1]. We mirrored each skull and endocast and their landmarks, and digitized surface semi-landmarks on the mirrored objects following the same protocol. We produced cartographies of the distances between original and mirrored specimens (asymmetries) after Procrustes superimposition. We then compared, for each individual, the gross asymmetry patterns of the neurocranium to those of the endocast. Finally, we obtained maps of neurocranial bone thickness, which we compared to the asymmetry patterns observed.
Our results show that, for each individual, the asymmetry of the neurocranium is very similar to that of the endocast in its spatial pattern, but is reduced in its degree. Bone thickness is not influenced by the patterns of asymmetry.
This suggests that the asymmetry of the neurocranium is tightly linked to brain development, to the exclusion of external factors, and that bone structure is unaffected by these patterns of asymmetry.
[1] Kitchell, Lindsey M. Asymmetry of the Modern Human Endocranium. Diss. INSTITUTE OF ARCHAEOLOGY, University College London 2015
It is well-accepted that large brains are an evolutionary specificity of Homo sapiens and a major contribution to its success, as they allowed this species to perform complex cognitive tasks. Throughout the evolution of the genus Homo, endocranial capacity has increased steadily, reaching its highest means in Neandertals and Homo sapiens. However, while Neandertals retained an elongated braincase and brain, as seen in earlier Homo species, in Homo sapiens this growth came with derived features such as a rounded skull and brain. It has been suggested that these differences in adult morphologies between Homo sapiens and Neandertals result from a globularisation phase during ontogeny [1].
Overall, although both cranial and endocranial characters are used in order to differentiate Homo species and to assign fossils to different taxa, the extent to which cranial and endocranial morphologies co-vary in the genus Homo is not known. Both cranial and endocranial morphologies in Homo sapiens appear unusual when compared with all other Homo species. At the intraspecific level, the organisation of the cerebral lobes within the Homo sapiens species has been shown to have changed since the Upper Palaeolithic (for instance in surface area and in the proportions of sagittal measurements for each lobe [2]). In the same time, the average cranial capacity was shrinking and the skulls and skeletons were becoming more gracile.
This study addresses the co-evolution of the Homo sapiens brain and skull, by analyzing patterns of variation through time (using Upper Palaeolithic, epipalaeolithic and extant samples) and by comparing Homo sapiens to other Homo species in order to assess its specificities within the genus.
The questions we have attempted to answer are: does the morphology of the brain and skull in Homo sapiens significantly deviate from the patterns seen in other Homo species or not? Can allometry explain the Homo sapiens pattern? Can we clarify the timeline of the apparition of the Homo sapiens pattern and of its subsequent evolutions?
In order to answer these questions, we have used a protocol in 2D geometric morphometrics on the mid-sagittal plane (modified from [3]), as well as traditional morphometrics on the entire skull and endocranium. We used data derived from the inner and outer cranial vaults, as well as morphological loci which allow us to gather data about brain organization, such as the anterior and posterior extension of the frontal, parietal and occipital lobes on the mid-saggital plane. We explored morphometrical variations in a sample of 77 Homo sapiens (40 extant, 15 Epipalaeolithic, 22 Upper Palaeolithic) and 22 non-sapiens Homo specimens (8 Neandertals, 11 Homo erectus sensu lato, 4 other mid-Pleistocene Homo). We then cross-examined the results in order to address the questions above.
Our results show specificities in Homo sapiens morphology compared with other Homo species, and differences across Homo sapiens groups. For instance, they suggest that there are more differences between the midsagittal morphologies of Homo sapiens and the other Homo species than there are between any of the other Homo species, despite the enlarged brains of both Homo sapiens and Neandertals and the morphological changes that this growth caused. Our results also show re-organisations in the relative lengths of cerebral lobes in Homo sapiens since the Upper Palaeolithic, suggesting a gradual shift to the pattern seen in extant humans.
[1] Gunz, Ph., Neubauer, S., Golovanova, L., Doronichev, V., Maureille, B., Hublin, J-J., 2012. A uniquely modern human pattern of endocranial development. Insights from a new cranial reconstruction of the Neandertal newborn from Mezmaiskaya. J. Hum. Evol. 62, 300-313.
[2] Balzeau, A., Grimaud-Hervé, D., Détroit, F., Holloway, R.L., Combès, B., Prima, S., 2013. First description of the Cro-Magnon 1 endocast and study of brain variation and evolution in anatomically modern Homo sapiens. Bull. Mém. Soc. Anthropol. Paris 25,1-18.
[3] Albessard, L.,Grimaud-Hervé, D., Balzeau, A., 2016. Evolution of cranial and endocranial profiles in Homo species: A study in 2D geometric morphometrics. BMSAP 28,3-4.
We warmly thank the researchers and curators who kindly gave us access to material.