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The book presents an integrative review of paleoneurology, the study of endocranial morphology in fossil species. The main focus is on showing how computed methods can be used to support advances in evolutionary neuroanatomy, paleoanthropology and archaeology and how they have contributed to creating a completely new perspective in cognitive neuroscience. Moreover, thanks to its multidisciplinary approach, the book addresses students and researchers approaching human paleoneurology from different angles and for different purposes, such as biologists, physicians, anthropologists, archaeologists and computer scientists. The individual chapters, written by international experts, represent authoritative reviews of the most important topics in the field. All the concepts are presented in an easy-to-understand style, making them accessible to university students, newcomers and also to anyone interested in understanding how methods like biomedical imaging, digital anatomy and computed and multivariate morphometrics can be used for analyzing ontogenetic and phylogenetic changes according to the principles of functional morphology, morphological integration and modularity.



Chapter 1. Introduction: Paleoneurology, Resurgent!

Much has happened in the study of paleoneurology since the turn of the 20th Century involving increasing sophistication of digital methods which permit a variety of statistical and imaging techniques that are replacing the older methods of studying endocasts, which have relied upon plaster/latex rubber copies of fossil materials and mostly qualitative statements regarding morphology and those correlations with structural and functional studies from neuroanatomy. Today, non-invasive imaging techniques allow for immediate study of b both qualitative and multivariate quantitative approaches to both fossil specimens and modern human endocranial variation. Nevertheless, a critical examination of several recent paleoneurological papers suggest that too little familiarity with actual neuroanatomy and reliance instead on digitized descriptions and statistical techniques is leading to hypotheses that fly in the face of actual neuroanatomical details. We need a much better understanding of modern human and ape neuroanatomical patterns as well as more fossil specimens, and in particular, better ethics of sharing digital information.
Ralph Holloway

Chapter 2. Neuroscience and Human Brain Evolution

Evidence from comparative neurobiological studies indicates that humans differ from other primates along several different dimensions of brain organization. Differences in cytoarchitecture, connectivity, and gene expression demonstrate that substantial remodeling of brain microstructure and molecular biology occurred during human evolution, and these changes are likely associated with cognitive specializations. The paleoneurological study of brain reorganization, however, has often been considered only on a larger scale, since the evidence from endocasts is limited to brain regions that can be detected from the traces left in the fossil record. Neuroscience offers a critical perspective on paleoneurology by investigating the microstructure and genetic mechanisms that might be responsible for brain reorganization. Recent findings suggest that neural tissue differs in its anatomical structure and molecular biology across primate species and is not uniform in its processing capabilities. Connectivity patterns can differ across species, producing selective enlargement of connected brain regions. Changes in patterns of innervation for various neurotransmitters may also occur on a microscopic scale, but can produce substantial changes in brain function and cognition. Furthermore, differential regulation of various transcription factors and genes can produce variation in the size of brain structures across primate species. Although the exact nature of brain reorganization related to the evolution of cognitive processing in humans remains to be fully defined, these findings indicate that it may have occurred through a number of different pathways. Further research in both neuroscience and paleoneurology is necessary to identify areas where brain reorganization likely occurred, along with the underlying mechanisms of evolutionary change in human brain structure and function.
Laura D. Reyes, Chet C. Sherwood

Chapter 3. Computed Tools for Paleoneurology

The availability of computed tomographic (CT) scans of fossil crania has opened a new chapter in paleoneurology. CT scans have made it possible to create virtual imprints of the braincase—so called endocasts—on the computer, even when the endocranial cavity is filled with stone matrix. CT data have also become invaluable for reconstructing partially complete or damaged fossils. Recent methodological advancements have made it possible to analyse endocranial shape using multivariate statistics and study the evolution and development of the endocranium quantitatively. Here I review (1) methods for quantifying endocranial shape, and (2) techniques of virtual fossil reconstruction. I show how these novel methods can be applied in paleoneurology, and discuss advantages and limitations of these approaches.
Philipp Gunz

Chapter 4. Functional Craniology and Brain Evolution

Anatomy and morphometrics have been experiencing a new renaissance in recent decades due to the new techniques and computed methodology used in imaging and statistics. Following this revolution, anatomical systems are currently analyzed by investigating the relationships among their components, in ontogeny and phylogeny. Accordingly, evolution is no more interpreted in terms of single and independent traits, but through integrated patterns and more comprehensive processes. In this sense, paleoneurology should be interpreted as the study of the relationships between brain and braincase during evolution. Morphogenesis is based on the functional and structural relationships between soft and hard tissues. The bones of the braincase, the cerebral cortex, the vascular networks, the connective layers and the cerebrospinal fluid constitute a balanced morphogenetic complex which constrains and influences evolutionary changes. Within this network, the brain largely shapes the bones in the upper endocranial areas, while in the lower endocranial areas the reverse relationship is more likely, due to constraints associated with the facial block and with the cranial base. Most of the spatial changes described in hominid paleoneurology are associated with the fronto-parietal lateral expansion of the endocranial volumes, and modern humans display a further dilation of the whole parietal surface. The study of endocasts can only provide information on size and shape changes associated with the neurocranial morphology, and fields like histology and neuroanatomy are necessary to support robust evolutionary hypotheses. Integration with neuropsychology and other biomedical fields is furthermore necessary to evaluate possible relationships between brain spatial organization and functional topics, such as metabolism or cognition.
Emiliano Bruner

Chapter 5. Human Brain Evolution: Ontogeny and Phylogeny

The evolution of the unique human brain included changes in the pattern of brain growth and development. Therefore investigation of ontogenetic patterns is key to improve our understanding about hominin brain evolution. Important evidence comes from so-called endocasts, i.e. endocranial casts of the bony braincase that approximate brain morphology. The pattern of ontogenetic brain size increase has been investigated for humans, apes, and our fossil relatives based on endocranial volumes and brain weights, and has been related to evolutionary brain size increases found from endocranial volumes. Furthermore, endocranial surface features have been interpreted as impressions of brain convolutions and used to interpret evolutionary brain reorganization. Overall endocranial shape however has been neglected for a long time due to methodological issues around measuring shape. Recent studies have overcome this problem and provided new insights into brain development and evolution. Here I review the current knowledge about the relationships between ontogenetic changes and evolutionary changes in endocranial size and shape and emphasize comparisons between humans and our closest extant and extinct relatives, the chimpanzees and Neanderthals. These comparisons help to understand the evolution of modern humans.
Simon Neubauer

Chapter 6. Paleoneurology and Behaviour

The discipline of Paleoneurology goes beyond the determination of biological characteristics and morphologies; it can also be used to infer behaviour in extinct species. In Paleocognition, the cognitive capacities of extinct humans can be examined through their fossil remains and the tools they left behind. This chapter examines some inferences that can be made about the origins of language based on paleoneurological and archaeological evidence. It focuses on laterality as a case study for the many behaviours that can be inferred from archaeology, and which are relevant to the origins and evolution of language. First is a review of the ontogeny of human hand preference, handedness in humans, and the hand preferences of non-human apes. Human handedness begins before birth, and develops into adulthood. All human populations have a majority of right-handers; explanations for the maintenance of a minority of left-handers are discussed. Next, the data for hand preferences and asymmetries in extinct fossil hominins are summarised. These show that species-level right-handedness has existed since Homo heidelbergensis, but there is only evidence for left-handed minorities in Neanderthals and Homo sapiens. Finally, links between language, hand skill, ancient stone tool-making, and other cultural behaviours are discussed to propose a tentative date for the origins of language.
Natalie T. Uomini

Chapter 7. Neuroarchaeology

“Neuroarchaeology” in the broad sense refers to any application of neuroscience theory and methods to archaeological questions. This includes the interpretation of archaeological materials in terms of the cognitive operations and neural substrates they are thought to imply as well as the experimental study of archaeologically-visible behaviors using neuroscience methods. The particular strengths and interests of archaeology have led neuroarchaeologists to focus on three broad themes in neuroscience theory: grounded cognition, executive function, and social cognition. Much of the published work in neuroarchaeology has consisted of attempts to apply neuroscience perspectives on these topics to interpretations of the archaeological record. Experimental neuroarchaeology, a straightforward methodological extension of conventional experimental archaeology, has been less common. This may change with the increasing availability of neuroscience methods for investigating complex, real-world behaviors. The use of neuroimaging methods to study experimental stone tool-making provides one example. Archaeology and neuroscience are united in the quest to understand human nature but remain deeply divided by disciplinary history, culture, methods, career paths, and institutional support. Whereas the utility of neuroscience methods to archaeology is clear, there has been less interest among neuroscientists in the potential contributions of archaeological strengths in the study of evolution and material culture. The future of “neuroarchaeology” as just another niche focus within archaeology or as something more will ultimately depend on its relevance to the questions and research agendas of neuroscientists.
Dietrich Stout, Erin Hecht

Chapter 8. Cognitive Archaeology and the Cognitive Sciences

Cognitive archaeology uses cognitive and psychological models to interpret the archaeological record. This chapter outlines several components that may be essential in building effective cognitive archaeological arguments. It also presents a two-stage perspective for the development of modern cognition, primarily based upon the work of Coolidge and Wynn. The first describes the transition from arboreal to terrestrial life in later Homo and the possible cognitive repercussions of terrestrial sleep. The second stage proposes that a genetic event may have enhanced working memory in Homo sapiens (specifically in terms of Baddeley’s multicomponent working memory model). The present chapter also reviews the archaeological and neurological bases for modern thinking, and the latter arguments are primarily grounded in the significance of the morphometric rescaling of the parietal lobes, which appears to have distinguished Homo sapiens from Neandertals.
Frederick L. Coolidge, Thomas Wynn, Karenleigh A. Overmann, James M. Hicks

Chapter 9. Techniques for Studying Brain Structure and Function

Recent years have seen rapid improvement in neuroscience techniques for studying brain structure and function in humans and our primate relatives. These techniques offer new routes of inquiry into our evolutionary history. This chapter offers an overview of a collection of these methods, including discussion of each technique's strengths, weaknesses, and relevance to neuroarchaeology.
Erin Hecht, Dietrich Stout

Chapter 10. A Digital Collection of Hominoid Endocasts

The major focus of this book is to provide the researcher or student with a general overview of the recent advances and updated knowledge regarding human paleoneurological research. In this context, the objective of this chapter is to provide the reader with a series of plates showing endocranial casts of several well-preserved and relevant fossil specimens representing different extinct hominid species, as well as some examples from living modern humans and great apes. Each plate depicts the external aspect of the cranium and its spatial relationship with the endocranial cavity in lateral norm, as well as a general view of each endocast viewed from all six norms. Additionally, some basic taxonomic notes collected from the literature are also provided (Groves 2001; Holloway et al. 2004; Isler et al. 2008; Wood and Lonergan 2008). With this material in hand, the reader may look at the evolutionary changes discussed in the present book regarding the evolution of the human endocranium and brain. It is worth noting that this chapter is not intended to give a detailed description of any particular specimen. For that purpose, we recommend to consult Holloway et al. (2004) extensive monograph on hominid endocasts. All specimens depicted here were digitally reconstructed from computed tomographic (CT) sections following the principles of digital anatomy (Zollikofer and Ponce de León 2005; Weber and Bookstein 2011). Missing parts of fossil crania where estimated using sliding semi-landmarks and thin-plate spline techniques as proposed elsewhere (Gunz et al. 2005, 2009). The only exception to this procedure is the Asian Homo erectus specimen Zhoukoudian XII, which consisted of surface scans of a reproduction of the original endocast made by Weindereich (1943) as well as a cast of the cranial reconstruction made by Tattersall and Sawyer (1996).
José Manuel de la Cuétara
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