Emeritus Professor Colin Groves was an internationally-recognized and respected taxonomist in Mammalogy and Primatology. After completing his PhD dissertation at University College London in 1966 on Gorilla skull variation and taxonomy, Colin was appointed as lecturer at the Australian National University (ANU). Colin was an integral part of the ANU Biological Anthropology Department, welcoming discussions with internationally recognized researchers and undergraduate students alike, always made himself available and believed in an “open-door” policy for teaching. For me, he was an inspirational and influential mentor, teacher, colleague and friend who was an irreplaceable part of the Australian and International Primatology and Anthropology community. An online condolence book has been organised for those wishing to pay their respects.
Virtual anatomy and inner structural morphology,
from head to toe
A tribute to Laurent Puymerail
Comptes Rendus Palevol 16 (2017)
The Finite Element Method (FEM) was developed within the framework of Engineering but has become a popular tool in bio-mechanical studies. It is natural that computational bio-mechanics and Finite Element Analysis (FEA) became increasingly promising in fossil studies where there are no examples of some taxa still living. To study the bio-mechanical responses of fossil hominids, modern humans and non-human primates are often used as comparative samples for which there are already known values. Despite this, precisely how accurately computational bio-mechanics compares with physical studies is still not well understood. The biological composition of bone and dentition is hard to replicate in computational terms with the cranium a mixture of trabecular and cortical bone while teeth comprise variable layers of enamel and dentine. The resolution required from Computed Tomography (CT) scans to accurately capture these finer biological compositions is not feasible for the heavy demands on software to analyze such FEA models with flow-effects for the number of specimens that can be included into any single study.
Godinho et al investigated the validity and sensitivity of Finite Element (FE) models using a direct comparison with a human cadaver. Results were particularly affected if the model was simplified by assigning all materials as cortical bone, including dentition and trabecular bone components. Results showed that the real and virtual skull showe d no differences in strain magnitude; differences in strain pattern (high or low strain distribution) were only partially different; simplifying the virtual model decreased the strain magnitude; simplifying the virtual model partially affected the strain pattern with the regions near the dentition, particularly the alveolar ridge, most affected.
For bio-mechanical studies, by not simplifying virtual models and attempting to designate dental and bone tissues properly acknowledges the underpinning biology of the cranium while potentially revealing sensitive adaptations of this biological structure. By adopting these changes, new variations between living and fossil humans, that have so-far been obscured by less time-consuming computational methods, could reveal unique adaptational trends that have real significance for human evolution.
The fossil record offers several possible approaches to study the evolution of the human brain. Besides cerebral size and shape, we can make inferences about cognitive functions and metabolic processes. Analyses of the craniovascular system are required to better understand both aspects. A recent article in the Royal Society Open Science journal adds new evidence into this issue comparing cerebral blood flow rate and endocranial volume in fossil hominids. The metabolic rate of the human brain is tightly related to the cerebral blood flow, which is mainly supplied by internal carotid arteries (ICAs). The authors measured the dimensions of the carotid foramen, the external opening of the carotid canal, in 35 fossil skulls, and calculate the size of the internal carotid arteries lumen. Then, they calculated the blood flow based on the shear stress, arterial lumen radius and blood viscosity (using supporting data from human and rats models). Their results show that the ICAs blood flow rate increases disproportionately in hominids, when scaled against brain volume. The authors then speculate about metabolic rate and its association with greater synaptic activity, cognitive functions, and life-history evolution. The paleoneurological information considered in the article is not much updated, and the sample includes many casts, which reliability is not comparable with original specimens. Also, inferences on cognition or life-history sound probably too much speculative when dealing with a simple carotid canal. Nonetheless, this paper supplies a good perspective in vascular biology, with a clear application in paleoanthropology. The possibility of calculating the cerebral blood flow in fossil specimens is interesting and opens new research opportunities.
New PhD student in our network! Alannah Pearson is now beginning her project on temporal lobes evolution in human and non-human primates, with a special focus on paleoneurology and functional craniology. She will be supervised by an amazing team of experts, including David Polly (Indiana University) and Colin Groves, Alison Behie and Katharine Balolia (Australian National University). A short presentation, in her own words: “I was born in Australia in 1985 and I am currently a PhD candidate at the Australian National University in Canberra. I completed a Bachelor of Arts in Archaeology and Palaeoanthropology before an Honours year specialising in Biological Anthropology analysing pre-collected craniometric data from populations in India before comparing these to William White Howells’ global craniometric datasets to assess population affinities. I recently completed a Master of Philosophy in Palaeoanthropology using CT of hominoid cranial bones examining inter- and intraspecific shape variation, phylogenetic signal, allometric and non-allometric differences. I also conducted phylogenetic analyses using Neighbour-Joining and Continuous Trait Maximum Likelihood methods. I am interested in the evolution of extant and fossil primate cranial morphology, shape and size differences between taxa. I recently became fascinated with primate cerebral evolution and shape variation with this being the direction of my PhD project. When not studying physical anthropology, I like to write fiction novels and I am currently working toward publication. I also have a keen interest in digital photography, particularly landscape and wildlife photography.” Welcome at the Laboratory of Hominid Paleoneurobiology!
Cranial capacity is one of the most studied features used in human paleoneurology. According to the completeness of the fossil skulls, direct or indirect methods have been used in estimating the cranial capacity, including water displacement, seeds, and regression statistics. However, two problems always exist when dealing with fossil skulls: the incompleteness of the specimens and the small sample size. Both limits can introduce an important uncertainty when making inferences on cranial capacity through quantitative approaches. In a recent paper published in Quaternary International we improved traditional methods for estimating cranial capacity by using measurements on brain endocast instead of skull, and by using multivariate statistical method such as Principal Component Regression (PCR) and Partial Least Square Regression (PLSR) instead of simple linear models. In this study, modern human skulls and endocasts are used as training and test data. We then applied these methods on three Homo erectus specimens and one Late Pleistocene Homo sapiens individual. When compared with traditional ones, these methods show higher reliability, and the error of the estimations approaches 50 cc. This study stresses further the importance of methodological research and correlation analysis in paleoneurology.
New student in town! Yameng Zhang is now beginning his PhD in human paleoneurology, with a joint collaboration between our lab and the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Science (IVPP – Beijing), and under the supervision of Xiujie Wu. We recently celebrated this project with a meeting entitled “Evolving Humans between Europe and Asia”. Yameng got his Master Degree working on cranial capacity estimation in fragmented fossil specimens, and collaborating in projects on fossils like Jingchuan 1, Qihe Cave and Lantian, on sexual dimorphisms in Chinese crania, and on temporal bony labyrinthine morphology. He works with digital anatomy and computed morphometrics, and his studies will focus on the spatial relationships between brain and braincase in the human genus.
Welcome on board, Mr. Zhang!
The diploic channels are placed between the vault cortical layers (external and internal). The calvarial diploe contains large and valveless diploic veins interconnected through a complex network of microscopic channels. We have now published a procedure for segmentation of diploic channels and localization of the main vessel pathways by reducing the noise of the cancellous bone. We also provide quantitative description of the diploic vessel variation in modern humans and three Neanderthals. One modern human was reformatted at three different resolutions namely high, medium and low, to estimate the effect of the pixel resolution on the final anatomical rendering. The use of computed tomography at high resolution can hamper semi-automatic segmentation of the diploic channels. Optimal resolution should be sufficient to reveal the channels without increasing noise associated with the trabecular structure. We have found that modern humans present a remarkable variation of diploic channels in their morphological patterns, being the parietal area the most vascularized. There is a correlation in the degree of vascularization of the frontal, parietal, and occipital bone, and no asymmetries can be apparently detected. The three Neanderthals analyzed in the study also display a parietal vascular network, but less developed than modern human, suggesting these vessels may be involved in evolutionary changes. The diploic network is commonly connected with the meningeal artery at the temporal fossa, with the emissary veins at the occipital bone, and with the venous sinuses at the parieto-occipital areas. The brain and braincase of our specie are characterized by larger parietal areas, and changes in the vascular organization can be associated with thermoregulation and heat management. In this sense future research may help us to understand the possible involvement of the diploic veins in brain thermoregulation. The study of diploic channels may be relevant in anthropology, medicine, paleontology, and forensic sciences.
Gizéh Rangel de Lázaro
Berger et al., 2015 recently reported a new species called Homo naledi, found at the Dinaledi Chamber in the Rising Star cave system in South Africa. This species present a mosaic of several anatomical features from Australopithecus and Homo species. The fossil remains correspond to 15 individuals from the same species. The age of the fossils remain unclear. The researchers presented a detailed comparative analysis between H. naledi and other species. They affirm that the overall morphology of H. naledi is more close to humans than to australopiths. The cranium lacks primitive features like well developed sagittal and nuchal crests. In this sense, H. naledi cranial morphology is more similar to other extinct human species that lived between four million and two million years ago, namely H. erectus, H. habilis, and H. rudolfensis. Homo skull traits include frontal and parietal bossing, cranial bones relatively thin (like H. habilis), flexed occipital and transverse torus (like H. erectus), the supraorbital torus well developed and weakly arched (as H. erectus and H. habilis) and gracile mandible; as well as their body mass and stature, are consistent with small bodied human populations, namely the lower limb, the foot and the ankle. However, Homo naledi fossils, presents some australopith-like characters as small endocranial volume (560-465 cc) and the morphology of the postcranial skeleton (trunk, shoulder, pelvis and proximal femur). Berger et al., suggest that the combination of different features presented in H. naledi is the result of a complex, and probably, polyphyletic process of different species that evolved separately in Africa.
Gizéh Rangel de Lázaro