Objectives: Genomics research has uncovered recurrent hybridization between hominin species, yet ... more Objectives: Genomics research has uncovered recurrent hybridization between hominin species, yet its morphological impact remains understudied. Non-human primate research has suggested a morphological signature of hybrid ancestry, which could be used to identify hybrids in the hominin fossil record. This pattern may include extreme size, heightened variation, and markers of developmental instability, but factors affecting these characteristics are poorly understood. Studies of non-mammalian taxa suggest that extreme morphology is more likely in early-generation hybrids and with a greater parental distance. To understand hybridization in hominins, therefore, we must use appropriate proxy taxa. Materials and Methods: Here, we use Chinese × Indian Macaca mulatta hybrids with a comparable divergence time in generations to Homo sapiens/Neanderthals and wide variation in admixture. Measuring limb lengths, body length, and weight, we investigate the relationship between admixture and size/variation. Results: Compared to previous work with more phylogenetically distant primate taxa and a focus on early generation hybrids, we found no evidence of a relationship between admixture and extreme large size, nor with increased size variation. Hybrids in our sample are relatively small but within the range of variation of the smaller parental taxon. Conclusions: Our results suggest that hybridization between closely related taxa, such as Neanderthals and H. sapiens, may lead to more subtle morphological patterns than previously anticipated. It will be necessary, however, to better understand the factors governing primate hybrid morphology before we can produce robust inferences on how hybridization has affected hominin evolution. 1 | Introduction Despite advances in ancient DNA (aDNA) research uncovering a complex history of admixture during human evolution (Gokcumen 2020; Gopalan et al. 2021), we still lack a thorough understanding of the morphological impact of gene flow between lineages and the ability to recognize hybrids in the fossil record (Harvati and Ackermann 2022; Warren et al. 2018). This is important because, given the conditions required for aDNA preservation, the assumptions inherent This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Archaeological and Anthropological Sciences, Dec 12, 2023
Understanding the factors shaping human crania has long been a goal of biological anthropology, a... more Understanding the factors shaping human crania has long been a goal of biological anthropology, and climate, diet, and population history are three of the most well-established influences. The effects of these factors are, however, rarely compared within a single, variable population, limiting interpretations of their relative contribution to craniofacial form. Jomon prehistoric foragers inhabited Japan throughout its climatic and ecological range and developed correspondingly varied modes of subsistence. We have previously demonstrated that a large sample of Jomon crania showed no clear climatic pattern; here, we examine variation in Jomon crania in more detail to determine if dietary factors and/or population history influence human intrapopulation variation at this scale. Based on well-established archaeological differences, we divide the Jomon into dietary groups and use geometric morphometric methods to analyse relationships between cranial shape, diet, and population history. We find evidence for diet-related influences on the shape of the neurocranium, particularly in the temporalis region. These shape differences may be interpreted in the context of regional variation in the biomechanical requirements of different diets. More experimental biomechanical and nutritional evidence is needed, however, to move suggested links between dietary content and cranial shape from plausible to well-supported. In contrast with the global scale of human variation, where neutral processes are the strongest influence on cranial shape, we find no pattern of population history amongst individuals from these Jomon sites. The determinants of cranial morphology are complex and the effect of diet is likely mediated by factors including sex, social factors, and chronology. Our results underline the subtlety of the effects of dietary variation beyond the forager/farmer dichotomy on cranial morphology and contribute to our understanding of the complexity of selective pressures shaping human phenotypes on different geographic scales.
Diagnosing Homo sapiens is a critical question in the study of human evolution. Although what con... more Diagnosing Homo sapiens is a critical question in the study of human evolution. Although what constitutes living members of our own species is straightforward, in the fossil record this is still a matter of much debate. The issue is complicated by questions of species diagnoses and ideas about the mode by which a new species is born, by the arguments surrounding the behavioural and cognitive separateness of the species, by the increasing appreciation of variation in the early African H. sapiens record and by new DNA evidence of hybridization with extinct species. This study synthesizes thinking on the fossils, archaeology and underlying evolutionary models of the last several decades with recent DNA results from both H. sapiens and fossil species. It is concluded that, although it may not be possible or even desirable to cleanly partition out a homogenous morphological description of recent H. sapiens in the fossil record, there are key, distinguishing morphological traits in the cranium, dentition and pelvis that can be usefully employed to diagnose the H. sapiens lineage. Increasing advances in retrieving and understanding relevant genetic data provide a complementary and perhaps potentially even more fruitful means of characterizing the differences between H. sapiens and its close relatives.
Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer gro... more Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer groups. One of the key issues regarding empty shells from beaches or fossil outcrops is determining human agency in the accumulation and modification of an assemblage. Here we investigate anthropogenic mediation in Initial Upper Palaeolithic and Early Ahmarian assemblages of Columbella rustica at Ksâr 'Akil (Lebanon). We compare perforations in the archaeological specimens with data from newly gathered Columbellidae modern death assemblages from Tenerife (Spain) using three-dimensional shell-thickness models as templates. This approach, using micro-CT scans of pristine shells to map robust and fragile zones on shell outer-surfaces, allows us to contextualise the two datasets within their natural morphology. Our results show that in natural death assemblages the vast majority of perforations occur in structurally weak zones, and their distribution can be explained by shell morphology in combination with predator activity and other post-mortem damage. In our archaeological dataset we found a higher frequency of perforations in more robust zones and a higher uniformity in their location, size and shape. This suggests human mediation in either the selection or manufacture process of C. rustica beads at Ksâr 'Akil from as early as the Initial Upper Palaeolithic and throughout the Early Ahmarian. Standardisation in perforation shape, size and distribution have been argued to be indicative of formalised manufacture processes and our results are thus more congruent with intentional bead manufacture than the selection of naturally-holed specimens.
HAL (Le Centre pour la Communication Scientifique Directe), Jan 14, 2023
Ce document a été généré automatiquement le 24 décembre 2023. Le texte seul est utilisable sous l... more Ce document a été généré automatiquement le 24 décembre 2023. Le texte seul est utilisable sous licence CC BY-NC-ND 4.0. Les autres éléments (illustrations, fichiers annexes importés) sont « Tous droits réservés », sauf mention contraire.
Objectives: The unfused human pubic symphysis has been interpreted as an obstetric adaptation to ... more Objectives: The unfused human pubic symphysis has been interpreted as an obstetric adaptation to facilitate the passage of a large-brained baby through a relatively small, bipedally adapted pelvis. The degree of fusion of the adult pubic symphysis was evaluated across primate species to gauge whether an open symphysis can be interpreted as an obstetric adaptation in humans and other primates. Materials and Methods: Symphyseal fusion was assessed in 718 individuals from 67 nonhuman primate species. Variation in fusion in specimens of known ages and sex from four species (Galago moholi, Macaca mulatta, Microcebus murinus, and Pan troglodytes) was further examined, with detailed analyses of pubic changes by age and sex carried out through logistic regressions in macaques. Results: Pubic fusion occurs in most primate species. It is observed earlier in life in males than in females in Ma. mulatta and Pa. troglodytes, only in males in Mi. murinus, and does not occur in Ga. moholi. Discussion: While delayed or absent pubic fusion is more prevalent in female primates, suggesting obstetric adaptation, there is no clear relation with childbirth constraints, as fusion is also observed in species experiencing a tight cephalopelvic fit. Other mechanisms might have evolved to facilitate birth in some species, or nonobstetric selective pressures might be counteracting the obstetric advantages of a flexible symphysis. The preservation of an open symphysis throughout life in humans and some other primates, however, can be best interpreted as convergent evolution due to obstetric selection.
Understanding the factors shaping human crania has long been a goal of biological anthropology, a... more Understanding the factors shaping human crania has long been a goal of biological anthropology, and climate, diet, and population history are three of the most well-established influences. The effects of these factors are, however, rarely compared within a single, variable population, limiting interpretations of their relative contribution to craniofacial form. Jomon prehistoric foragers inhabited Japan throughout its climatic and ecological range and developed correspondingly varied modes of subsistence. We have previously demonstrated that a large sample of Jomon crania showed no clear climatic pattern; here, we examine variation in Jomon crania in more detail to determine if dietary factors and/or population history influence human intrapopulation variation at this scale. Based on well-established archaeological differences, we divide the Jomon into dietary groups and use geometric morphometric methods to analyse relationships between cranial shape, diet, and population history. We find evidence for diet-related influences on the shape of the neurocranium, particularly in the temporalis region. These shape differences may be interpreted in the context of regional variation in the biomechanical requirements of different diets. More experimental biomechanical and nutritional evidence is needed, however, to move suggested links between dietary content and cranial shape from plausible to well-supported. In contrast with the global scale of human variation, where neutral processes are the strongest influence on cranial shape, we find no pattern of population history amongst individuals from these Jomon sites. The determinants of cranial morphology are complex and the effect of diet is likely mediated by factors including sex, social factors, and chronology. Our results underline the subtlety of the effects of dietary variation beyond the forager/farmer dichotomy on cranial morphology and contribute to our understanding of the complexity of selective pressures shaping human phenotypes on different geographic scales.
Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer gro... more Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer groups. One of the key issues regarding empty shells from beaches or fossil outcrops is determining human agency in the accumulation and modification of an assemblage. Here we investigate anthropogenic mediation in Initial Upper Palaeolithic and Early Ahmarian assemblages of Columbella rustica at Ksâr 'Akil (Lebanon). We compare perforations in the archaeological specimens with data from newly gathered Columbellidae modern death assemblages from Tenerife (Spain) using three-dimensional shell-thickness models as templates. This approach, using micro-CT scans of pristine shells to map robust and fragile zones on shell outer-surfaces, allows us to contextualise the two datasets within their natural morphology. Our results show that in natural death assemblages the vast majority of perforations occur in structurally weak zones, and their distribution can be explained by shell morphology in combination with predator activity and other post-mortem damage. In our archaeological dataset we found a higher frequency of perforations in more robust zones and a higher uniformity in their location, size and shape. This suggests human mediation in either the selection or manufacture process of C. rustica beads at Ksâr 'Akil from as early as the Initial Upper Palaeolithic and throughout the Early Ahmarian. Standardisation in perforation shape, size and distribution have been argued to be indicative of formalised manufacture processes and our results are thus more congruent with intentional bead manufacture than the selection of naturally-holed specimens.
Mid-Late Pleistocene species are reported to have sinuses of taxonomic and functional interest. F... more Mid-Late Pleistocene species are reported to have sinuses of taxonomic and functional interest. Frontal hyperpneumatisation in Homo heidelbergensis is one of few hypothesized autapomorphies of this controversial taxon and Neanderthal sinuses are also said to be distinctively large, resulting from cold adaptation and explaining diagnostic craniofacial morphology. Variation in sinus size within and between populations of recent H. sapiens has been described, but has not been quantified. Sinus variables in Mid-Late Pleistocene hominins were investigated to illuminate causes of craniofacial variation and clarify alpha taxonomy, whilst evaluating theories of sinus function and advancing the understanding of adaptation in this group. Sinus volumes were measured from CT data and geometric morphometric methods were used to identify associated shape variables in a large sample of fossil and extant hominins. Relationships were investigated between these sinus variables and taxonomic/population, dietary, and climatic variables. The results demonstrate that the sinuses have no detectable direct function in Mid-Late Pleistocene hominins but they do respond to selective pressures, such as diet and climate, indirectly via craniofacial adaptation. There is also a relationship with neutral population differences in craniofacial morphology, for at least the frontal sinus. These effects are of varying strength, and it is likely that stochastic development also plays a part in determining differences in individual volumes. Inter-taxon comparisons support frontal hyperpneumatisation as a distinctive, perhaps derived, trait in H. heidelbergensis, but show that H. sapiens has hypopneumatised maxillary sinuses, rather than H. neanderthalensis being iii hyperpneumatised. Whilst the causes of extremely large sinuses in H. heidelbergensis remain uncertain, small maxillary sinuses in H. sapiens are suggested to result from their derived craniofacial size and morphology. These conclusions build on previous studies to overturn long-standing but unfounded theories about the pneumatic influences on Neanderthal morphology and the functional nature of sinuses, whilst opening up exciting questions about relationships between strain, climate, pneumatisation, and intraspecific variation. iv For Dad, with love and thanks. v Acknowledgements I would like to thank the University of Roehampton for the studentship that enabled me to conduct this research, attend relevant courses, and present my work at conferences. The Centre for Evolutionary and Ecological Anthropology at the University also generously awarded me subsequent funding for research trips. I am grateful to all the help and support I have received from the Natural History Museum, particularly to Eileen Cox, as a PhD student partly based there. I would like to thank The Primate Society of Great Britain, The Leakey Trust, and the American Museum of Natural History for funding which allowed me to expand my sample. For kind permission and help in collecting my data I would like to thank
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.
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.
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...
Perforated shells are often used to study socially mediated behavior in past hunter-gatherer grou... more Perforated shells are often used to study socially mediated behavior in past hunter-gatherer groups. The assumption is that their exclusive symbolic function makes them ideally suited to investigate social networks, dispersal activity, and social interaction. Before making any statements regarding human behavior, however, it needs to be established whether perforated shells from archaeological assemblages were used as personal ornaments. One of the key issues regarding beach-collected marine taxa is whether beached specimens were purposefully collected, e.g., preferentially selected naturally holed specimens, or whether human-made perforations may be identified. Past studies have investigated these questions by comparing datasets from modern death assemblages of shells with archaeological collections and through manufacture and use-wear analysis (e.g., Bouzouggar et al. 2007; Vanhaeren et al. 2006) This study introduces a novel approach using μCT scans of pristine shells to create a...
Objectives: Genomics research has uncovered recurrent hybridization between hominin species, yet ... more Objectives: Genomics research has uncovered recurrent hybridization between hominin species, yet its morphological impact remains understudied. Non-human primate research has suggested a morphological signature of hybrid ancestry, which could be used to identify hybrids in the hominin fossil record. This pattern may include extreme size, heightened variation, and markers of developmental instability, but factors affecting these characteristics are poorly understood. Studies of non-mammalian taxa suggest that extreme morphology is more likely in early-generation hybrids and with a greater parental distance. To understand hybridization in hominins, therefore, we must use appropriate proxy taxa. Materials and Methods: Here, we use Chinese × Indian Macaca mulatta hybrids with a comparable divergence time in generations to Homo sapiens/Neanderthals and wide variation in admixture. Measuring limb lengths, body length, and weight, we investigate the relationship between admixture and size/variation. Results: Compared to previous work with more phylogenetically distant primate taxa and a focus on early generation hybrids, we found no evidence of a relationship between admixture and extreme large size, nor with increased size variation. Hybrids in our sample are relatively small but within the range of variation of the smaller parental taxon. Conclusions: Our results suggest that hybridization between closely related taxa, such as Neanderthals and H. sapiens, may lead to more subtle morphological patterns than previously anticipated. It will be necessary, however, to better understand the factors governing primate hybrid morphology before we can produce robust inferences on how hybridization has affected hominin evolution. 1 | Introduction Despite advances in ancient DNA (aDNA) research uncovering a complex history of admixture during human evolution (Gokcumen 2020; Gopalan et al. 2021), we still lack a thorough understanding of the morphological impact of gene flow between lineages and the ability to recognize hybrids in the fossil record (Harvati and Ackermann 2022; Warren et al. 2018). This is important because, given the conditions required for aDNA preservation, the assumptions inherent This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Archaeological and Anthropological Sciences, Dec 12, 2023
Understanding the factors shaping human crania has long been a goal of biological anthropology, a... more Understanding the factors shaping human crania has long been a goal of biological anthropology, and climate, diet, and population history are three of the most well-established influences. The effects of these factors are, however, rarely compared within a single, variable population, limiting interpretations of their relative contribution to craniofacial form. Jomon prehistoric foragers inhabited Japan throughout its climatic and ecological range and developed correspondingly varied modes of subsistence. We have previously demonstrated that a large sample of Jomon crania showed no clear climatic pattern; here, we examine variation in Jomon crania in more detail to determine if dietary factors and/or population history influence human intrapopulation variation at this scale. Based on well-established archaeological differences, we divide the Jomon into dietary groups and use geometric morphometric methods to analyse relationships between cranial shape, diet, and population history. We find evidence for diet-related influences on the shape of the neurocranium, particularly in the temporalis region. These shape differences may be interpreted in the context of regional variation in the biomechanical requirements of different diets. More experimental biomechanical and nutritional evidence is needed, however, to move suggested links between dietary content and cranial shape from plausible to well-supported. In contrast with the global scale of human variation, where neutral processes are the strongest influence on cranial shape, we find no pattern of population history amongst individuals from these Jomon sites. The determinants of cranial morphology are complex and the effect of diet is likely mediated by factors including sex, social factors, and chronology. Our results underline the subtlety of the effects of dietary variation beyond the forager/farmer dichotomy on cranial morphology and contribute to our understanding of the complexity of selective pressures shaping human phenotypes on different geographic scales.
Diagnosing Homo sapiens is a critical question in the study of human evolution. Although what con... more Diagnosing Homo sapiens is a critical question in the study of human evolution. Although what constitutes living members of our own species is straightforward, in the fossil record this is still a matter of much debate. The issue is complicated by questions of species diagnoses and ideas about the mode by which a new species is born, by the arguments surrounding the behavioural and cognitive separateness of the species, by the increasing appreciation of variation in the early African H. sapiens record and by new DNA evidence of hybridization with extinct species. This study synthesizes thinking on the fossils, archaeology and underlying evolutionary models of the last several decades with recent DNA results from both H. sapiens and fossil species. It is concluded that, although it may not be possible or even desirable to cleanly partition out a homogenous morphological description of recent H. sapiens in the fossil record, there are key, distinguishing morphological traits in the cranium, dentition and pelvis that can be usefully employed to diagnose the H. sapiens lineage. Increasing advances in retrieving and understanding relevant genetic data provide a complementary and perhaps potentially even more fruitful means of characterizing the differences between H. sapiens and its close relatives.
Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer gro... more Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer groups. One of the key issues regarding empty shells from beaches or fossil outcrops is determining human agency in the accumulation and modification of an assemblage. Here we investigate anthropogenic mediation in Initial Upper Palaeolithic and Early Ahmarian assemblages of Columbella rustica at Ksâr 'Akil (Lebanon). We compare perforations in the archaeological specimens with data from newly gathered Columbellidae modern death assemblages from Tenerife (Spain) using three-dimensional shell-thickness models as templates. This approach, using micro-CT scans of pristine shells to map robust and fragile zones on shell outer-surfaces, allows us to contextualise the two datasets within their natural morphology. Our results show that in natural death assemblages the vast majority of perforations occur in structurally weak zones, and their distribution can be explained by shell morphology in combination with predator activity and other post-mortem damage. In our archaeological dataset we found a higher frequency of perforations in more robust zones and a higher uniformity in their location, size and shape. This suggests human mediation in either the selection or manufacture process of C. rustica beads at Ksâr 'Akil from as early as the Initial Upper Palaeolithic and throughout the Early Ahmarian. Standardisation in perforation shape, size and distribution have been argued to be indicative of formalised manufacture processes and our results are thus more congruent with intentional bead manufacture than the selection of naturally-holed specimens.
HAL (Le Centre pour la Communication Scientifique Directe), Jan 14, 2023
Ce document a été généré automatiquement le 24 décembre 2023. Le texte seul est utilisable sous l... more Ce document a été généré automatiquement le 24 décembre 2023. Le texte seul est utilisable sous licence CC BY-NC-ND 4.0. Les autres éléments (illustrations, fichiers annexes importés) sont « Tous droits réservés », sauf mention contraire.
Objectives: The unfused human pubic symphysis has been interpreted as an obstetric adaptation to ... more Objectives: The unfused human pubic symphysis has been interpreted as an obstetric adaptation to facilitate the passage of a large-brained baby through a relatively small, bipedally adapted pelvis. The degree of fusion of the adult pubic symphysis was evaluated across primate species to gauge whether an open symphysis can be interpreted as an obstetric adaptation in humans and other primates. Materials and Methods: Symphyseal fusion was assessed in 718 individuals from 67 nonhuman primate species. Variation in fusion in specimens of known ages and sex from four species (Galago moholi, Macaca mulatta, Microcebus murinus, and Pan troglodytes) was further examined, with detailed analyses of pubic changes by age and sex carried out through logistic regressions in macaques. Results: Pubic fusion occurs in most primate species. It is observed earlier in life in males than in females in Ma. mulatta and Pa. troglodytes, only in males in Mi. murinus, and does not occur in Ga. moholi. Discussion: While delayed or absent pubic fusion is more prevalent in female primates, suggesting obstetric adaptation, there is no clear relation with childbirth constraints, as fusion is also observed in species experiencing a tight cephalopelvic fit. Other mechanisms might have evolved to facilitate birth in some species, or nonobstetric selective pressures might be counteracting the obstetric advantages of a flexible symphysis. The preservation of an open symphysis throughout life in humans and some other primates, however, can be best interpreted as convergent evolution due to obstetric selection.
Understanding the factors shaping human crania has long been a goal of biological anthropology, a... more Understanding the factors shaping human crania has long been a goal of biological anthropology, and climate, diet, and population history are three of the most well-established influences. The effects of these factors are, however, rarely compared within a single, variable population, limiting interpretations of their relative contribution to craniofacial form. Jomon prehistoric foragers inhabited Japan throughout its climatic and ecological range and developed correspondingly varied modes of subsistence. We have previously demonstrated that a large sample of Jomon crania showed no clear climatic pattern; here, we examine variation in Jomon crania in more detail to determine if dietary factors and/or population history influence human intrapopulation variation at this scale. Based on well-established archaeological differences, we divide the Jomon into dietary groups and use geometric morphometric methods to analyse relationships between cranial shape, diet, and population history. We find evidence for diet-related influences on the shape of the neurocranium, particularly in the temporalis region. These shape differences may be interpreted in the context of regional variation in the biomechanical requirements of different diets. More experimental biomechanical and nutritional evidence is needed, however, to move suggested links between dietary content and cranial shape from plausible to well-supported. In contrast with the global scale of human variation, where neutral processes are the strongest influence on cranial shape, we find no pattern of population history amongst individuals from these Jomon sites. The determinants of cranial morphology are complex and the effect of diet is likely mediated by factors including sex, social factors, and chronology. Our results underline the subtlety of the effects of dietary variation beyond the forager/farmer dichotomy on cranial morphology and contribute to our understanding of the complexity of selective pressures shaping human phenotypes on different geographic scales.
Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer gro... more Perforated shells are often used to study socially mediated behaviour in past hunter-gatherer groups. One of the key issues regarding empty shells from beaches or fossil outcrops is determining human agency in the accumulation and modification of an assemblage. Here we investigate anthropogenic mediation in Initial Upper Palaeolithic and Early Ahmarian assemblages of Columbella rustica at Ksâr 'Akil (Lebanon). We compare perforations in the archaeological specimens with data from newly gathered Columbellidae modern death assemblages from Tenerife (Spain) using three-dimensional shell-thickness models as templates. This approach, using micro-CT scans of pristine shells to map robust and fragile zones on shell outer-surfaces, allows us to contextualise the two datasets within their natural morphology. Our results show that in natural death assemblages the vast majority of perforations occur in structurally weak zones, and their distribution can be explained by shell morphology in combination with predator activity and other post-mortem damage. In our archaeological dataset we found a higher frequency of perforations in more robust zones and a higher uniformity in their location, size and shape. This suggests human mediation in either the selection or manufacture process of C. rustica beads at Ksâr 'Akil from as early as the Initial Upper Palaeolithic and throughout the Early Ahmarian. Standardisation in perforation shape, size and distribution have been argued to be indicative of formalised manufacture processes and our results are thus more congruent with intentional bead manufacture than the selection of naturally-holed specimens.
Mid-Late Pleistocene species are reported to have sinuses of taxonomic and functional interest. F... more Mid-Late Pleistocene species are reported to have sinuses of taxonomic and functional interest. Frontal hyperpneumatisation in Homo heidelbergensis is one of few hypothesized autapomorphies of this controversial taxon and Neanderthal sinuses are also said to be distinctively large, resulting from cold adaptation and explaining diagnostic craniofacial morphology. Variation in sinus size within and between populations of recent H. sapiens has been described, but has not been quantified. Sinus variables in Mid-Late Pleistocene hominins were investigated to illuminate causes of craniofacial variation and clarify alpha taxonomy, whilst evaluating theories of sinus function and advancing the understanding of adaptation in this group. Sinus volumes were measured from CT data and geometric morphometric methods were used to identify associated shape variables in a large sample of fossil and extant hominins. Relationships were investigated between these sinus variables and taxonomic/population, dietary, and climatic variables. The results demonstrate that the sinuses have no detectable direct function in Mid-Late Pleistocene hominins but they do respond to selective pressures, such as diet and climate, indirectly via craniofacial adaptation. There is also a relationship with neutral population differences in craniofacial morphology, for at least the frontal sinus. These effects are of varying strength, and it is likely that stochastic development also plays a part in determining differences in individual volumes. Inter-taxon comparisons support frontal hyperpneumatisation as a distinctive, perhaps derived, trait in H. heidelbergensis, but show that H. sapiens has hypopneumatised maxillary sinuses, rather than H. neanderthalensis being iii hyperpneumatised. Whilst the causes of extremely large sinuses in H. heidelbergensis remain uncertain, small maxillary sinuses in H. sapiens are suggested to result from their derived craniofacial size and morphology. These conclusions build on previous studies to overturn long-standing but unfounded theories about the pneumatic influences on Neanderthal morphology and the functional nature of sinuses, whilst opening up exciting questions about relationships between strain, climate, pneumatisation, and intraspecific variation. iv For Dad, with love and thanks. v Acknowledgements I would like to thank the University of Roehampton for the studentship that enabled me to conduct this research, attend relevant courses, and present my work at conferences. The Centre for Evolutionary and Ecological Anthropology at the University also generously awarded me subsequent funding for research trips. I am grateful to all the help and support I have received from the Natural History Museum, particularly to Eileen Cox, as a PhD student partly based there. I would like to thank The Primate Society of Great Britain, The Leakey Trust, and the American Museum of Natural History for funding which allowed me to expand my sample. For kind permission and help in collecting my data I would like to thank
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.
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.
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...
Perforated shells are often used to study socially mediated behavior in past hunter-gatherer grou... more Perforated shells are often used to study socially mediated behavior in past hunter-gatherer groups. The assumption is that their exclusive symbolic function makes them ideally suited to investigate social networks, dispersal activity, and social interaction. Before making any statements regarding human behavior, however, it needs to be established whether perforated shells from archaeological assemblages were used as personal ornaments. One of the key issues regarding beach-collected marine taxa is whether beached specimens were purposefully collected, e.g., preferentially selected naturally holed specimens, or whether human-made perforations may be identified. Past studies have investigated these questions by comparing datasets from modern death assemblages of shells with archaeological collections and through manufacture and use-wear analysis (e.g., Bouzouggar et al. 2007; Vanhaeren et al. 2006) This study introduces a novel approach using μCT scans of pristine shells to create a...
Encyclopedia of Animal Cognition and Behavior, 2020
Definition: A controversial Middle Pleistocene (~780-130 ka) hominin species, part of the same ge... more Definition: A controversial Middle Pleistocene (~780-130 ka) hominin species, part of the same genus (Homo) as extant humans. Introduction: The taxonomy and phylogeny of Homo heidelbergensis is much debated (for a review see Stringer, 2012), so much so that this period in human evolution has been dubbed the 'muddle in the Middle [Pleistocene]'. There is little agreement on which specimens should be included in H. heidelbergensis (that is to say, the group of specimens which constitute what is known as its 'hypodigm'), nor even whether it constitutes a valid species at all. Many Middle Pleistocene hominins (taxa more closely related to H. sapiens than to chimpanzees) share primitive features with earlier species, such as H. erectus, but also share derived traits with later Pleistocene specimens such as H. sapiens and Neanderthals (e.g., Rightmire, 2013). This mosaic morphology has led researchers to group them together as a single Afro-European species designation: H. heidelbergensis. Some have also suggested that additional Asian Middle Pleistocene fossils may extend the range of H. heidelbergensis (e.g., Stringer, 2012). One reason for the great interest in H. heidelbergensis is that the Middle Pleistocene is the epoch during which the H. sapiens lineage split from our sister taxa, the Neanderthals and Denisovans and H. heidelbergensis has long been considered a possible last common ancestor (LCA) for these two lineages (Buck & Stringer, 2014; Mounier et al., 2009; Rightmire, 2008; Stringer, 2012). Knowing the identity of the LCA would allow us to see which differences between our own species and Neanderthals are derived in which lineage, enabling us to better understand our own evolution and that of our closest relatives.
our current knowledge of the emergence of anatomically modern humans, and the human lineage in ge... more our current knowledge of the emergence of anatomically modern humans, and the human lineage in general, is limited, in large part because of the lack of a well preserved and well dated fossil record from Pleistocene Africa. thus, the primary aim of our research is to partly relieve this problem by virtually reconstructing and analyzing the hominin cranial remains of Kabua 1, found in Kenya in the 1950s. Most scholars have argued that Kabua 1 represents an anatomically modern Homo sapiens, although the fragmentary nature of the remains and lack of a chronometric date hinder robust phylogenetic and taxonomic assessments. this manuscript presents the first steps taken to resolve this issue, namely a set of reconstructions of the specimen that would allow comparison with the fossil record. First, we virtually removed sediment and laboratory adhesives from μct scans of the fragments. Subsequently, all fragments were separated by segmentation of the μct data and described. Finally, virtual surface projections were used in the creation of several anatomical reconstructions, based on separate reference crania. these first steps provide a framework that will be used for quantitative shape analyses that aim to more firmly place these remains in the context of human evolution.
Various diagnoses of the genus Homo have been proposed, including behavioral traits such as tool-... more Various diagnoses of the genus Homo have been proposed, including behavioral traits such as tool-making, carnivory, and hunting. However, tool-making and carnivory almost certainly began more than 2.6 million years ago, in prehuman phases of our evolution, while reliably distinguishing hunting from scavenging in the early archeological record is problematic. Here we concentrate on diagnosable morphological traits such as endocranial/brain size (relative and absolute), body shape, and cranial and dental features, allowing the recognition of a minimum of nine species of the genus Homo: H. habilis, H. rudolfensis, H. erectus, H. naledi, H. floresiensis, H. antecessor, H. heidelbergensis, H. neanderthalensis, and H. sapiens.
Special Issue: Personal Ornaments in Early Prehistory
Perforated shells are often used to study ... more Special Issue: Personal Ornaments in Early Prehistory Perforated shells are often used to study socially mediated behavior in past hunter-gatherer groups. The assumption is that their exclusive symbolic function makes them ideally suited to investigate social networks, dispersal activity, and social interaction. Before making any statements regarding human behavior, however, it needs to be established whether perforated shells from archaeological assemblages were used as personal ornaments. One of the key issues regarding beach-collected marine taxa is whether beached specimens were purposefully collected, e.g., preferentially selected naturally holed specimens, or whether human-made perforations may be identified. Past studies have investigated these questions by comparing datasets from modern death assemblages of shells with archaeological collections and through manufacture and use-wear analysis (e.g., Bouzouggar et al. 2007; Vanhaeren et al. 2006) This study introduces a novel approach using μCT scans of pristine shells to create a three-dimensional model of shell thickness in Tritia (Nassarius) gibbosula. This model is used to map robust and fragile zones on shells of this taxon. The goal of this approach is to identify structurally weak zones that would be prone to natural perforations. Heat maps of shell thickness are then used to investigate perforation locations in modern natural death and archaeological assemblages. Our results show that in natural death assemblages, most perforations occur in structurally weak zones, and that their distribution is random. In our archaeological samples, from early Upper Paleolithic contexts at Ksâr 'Akil, (Lebanon), we found that perforations in T. gibbosula mainly occur in structurally weak zones, but their distribution within these zones is not random and favors locations facilitating easy suspension (e.g., on cordage). This suggests that at Ksâr 'Akil, T. gibbolusa shells were used as beads, and that shells with conveniently located natural perforations were intentionally sought for, that humans perforated the shells themselves, or that they used a combination of both. This in turn, warrants investigations into the social and behavioral implications of these perforated beads. Further aspects of human involvement with the shells should be explored, for example, through use-wear analysis.
Uploads
Papers by Laura T Buck
of the μct data and described. Finally, virtual surface projections were
used in the creation of several anatomical reconstructions, based on separate reference crania. these first steps provide a framework that will be used for quantitative shape analyses that aim to more firmly place these remains in the context of human evolution.
Perforated shells are often used to study socially mediated behavior in past hunter-gatherer groups. The assumption is that their exclusive symbolic function makes them ideally suited to investigate social networks, dispersal activity, and social interaction. Before making any statements regarding human behavior, however, it needs to be established whether perforated shells from archaeological assemblages were used as personal ornaments. One of the key issues regarding beach-collected marine taxa is whether beached specimens were purposefully collected, e.g., preferentially selected naturally holed specimens, or whether human-made perforations may be identified. Past studies have investigated these questions by comparing datasets from modern death assemblages of shells with archaeological collections and through manufacture and use-wear analysis (e.g., Bouzouggar et al. 2007; Vanhaeren et al. 2006) This study introduces a novel approach using μCT scans of pristine shells to create a three-dimensional model of shell thickness in Tritia (Nassarius) gibbosula. This model is used to map robust and fragile zones on shells of this taxon. The goal of this approach is to identify structurally weak zones that would be prone to natural perforations. Heat maps of shell thickness are then used to investigate perforation locations in modern natural death and archaeological assemblages. Our results show that in natural death assemblages, most perforations occur in structurally weak zones, and that their distribution is random. In our archaeological samples, from early Upper Paleolithic contexts at Ksâr 'Akil, (Lebanon), we found that perforations in T. gibbosula mainly occur in structurally weak zones, but their distribution within these zones is not random and favors locations facilitating easy suspension (e.g., on cordage). This suggests that at Ksâr 'Akil, T. gibbolusa shells were used as beads, and that shells with conveniently located natural perforations were intentionally sought for, that humans perforated the shells themselves, or that they used a combination of both. This in turn, warrants investigations into the social and behavioral implications of these perforated beads. Further aspects of human involvement with the shells should be explored, for example, through use-wear analysis.