Functional craniology

Bruner et al (Front Neuroanat 2014)Chet Sherwood and Suzana Herculano-Houzel are editing a Frontiers volume entitled “The Human Brain’s Place in Nature: Evolution of Large Brains”, cross listed between Frontiers in Neuroanatomy and Frontiers in Human Neuroscience. There you can find review and research papers dealing with pros and cons of evolving large brains. Our article presents issues in functional craniology, with topics joining evolution and medicine. The article begins with an introduction to functional craniology and brain-braincase structural relationships. Features associated with sutures and brain spatial organization are interesting in evolutionary neuroanatomy and in surgery as well. Brain thermoregulation is a major factor in both fields, and modelling can help to test the influence of brain form changes in heat dissipation patterns. Changes in the frontal lobes proportions and position during human evolution are discussed as a probable background for visual impairment, in particular myopia, because of spatial conflicts between brain and orbits. The dilation of the parietal areas in modern humans and the complexity of the deep parietal elements are then integrated with information on neurodegenerative processes, in particular Alzheimer’s disease, in an evo-neuro perspective. Evolutionary neuroanatomy and medicine share information, tools, methods, and samples, being interested in the same characters and processes for different reasons and different targets. Functional craniology is the bridge we use to integrate these fields.

Brains and endocasts

Kobayashi et al 2014In the second volume of the recent publication on dynamics of learning in Neanderthals and modern humans there are two interesting papers by Yasushi Kobayashi and colleagues on the relationships between skull, brain, and endocast. They present results from five macaques (Macaca fascicularis), comparing head, skull, brain, and endocranial mould, by traditional dissection and digital imaging. In the first article they show a remarkable correspondence between brain and endocast morphology. The principal sulci and gyri of the cortex can be easily recognized on the mould, with a reliability which is definitely encouraging for those working in paleoneurology. Of course, we know that in small brains the endocranial imprints are more evident than in large brains, and the same comparison in hominids may be more difficult. In the second paper, they analyze the correspondence between sutures and sulci (the coronal suture and the arcuate sulcus, in particular). Again, results are reassuring for those making brain inferences from fossil remains, because at least in this case the spatial relationship is constant and reliable. These are essential data in paleoneurology, and we need more studies like these, with more samples, more species, more features.

Dynamics of learning

Dynamics of Learning 2014The talks from the Tokyo meeting on learning processes in Neanderthals and modern humans are now published in two books by Springer. The first volume is on cultural perspectives, the second volume is on cognitive and physical perspectives. Cultural anthropologists, paleontologists, archaeologists, sociologists, medical doctors, and psychologists collaborate in a joint project coordinated by several Japanese universities and research institutions (like the Kochi University of Technology and the Keio University) to evaluate whether differences in learning abilities may have influenced the competition between modern humans and Neanderthals. In volume two there is a review of mine on Neanderthals’ paleoneurology, presenting the current information we have on the anatomical and morphological endocranial changes associated with the Neanderthal lineage. The paper evidences structural constraints and functional limits which may have characterized the spatial organization of the Neanderthal braincase.

The Skull Box

The Skull BoxThe Skull Box is a new blog for students working and collaborating in different research lines at my paleoneurology lab. Posts published there will present comments, information, and resources on functional craniology, cranial evolution, neuroanatomy, brain evolution, and morphometrics, bridging human biology, anthropology, paleontology, neuroscience, and medicine. The blog has three main aims. First, it is a source of information for topics associated with human brain and skull evolution. Second, it helps to promote blogging in human evolution and anthropology, fields in which many web resources are still undervalued. Third, it is useful to train students in writing and communicating science. All these three targets are essential for our research fields, and whatever minor advance in any of these directions is a success. Have a look at the blog!

What made us human?

Photo by Steve McCurryThe International School of Ethology presents a new meeting, entitled “What made us human? Biological and cultural evolution in Homo sapiens“. The meeting will be held at Erice, Sicily, on October 15-18, 2014. A web page is available with program and updating information. The main topic will be the evolution of cognitively modern behaviour. The meeting is directed by Stefano Parmigiani, Telmo Pievani, and Ian Tattersall, and it will include talks in cognitive sciences, paleontology, archaeology, neurobiology, linguistics, genetics, medicine, and psychology, with a large list of speakers.  Registration is now open, have a look!

Precuneus

Bruner et al JA2014Paleoneurological studies based on endocranial geometry suggested that a spatial dilation of the deep parietal areas was the major morphological difference between modern and non modern human brains. In our species, the morphogenetic change associated with this parietal bulging was then localized in a very early post-natal period, in a  stage which is absent in chimpanzees or in Neandertals. In the meanwhile the deep parietal areas were demonstrated to have also special cytoarchitectonic elements in modern humans, to be the main functional and structural node of the human brain organization, to be critically involved in major cognitive capacities through the fronto-parietal connections, to be central to the default mode network, and to be essential in human-specific cognitive processes involving imagination and simulation. Such specific parietal modifications have been also tentatively associated with species-specific vulnerability to neurodegeneration in our species. Actually, the early stages of Alzheimer’s disease are associated with metabolic, functional and structural impairments at the deep parietal areas, like the precuneus. These brain districts have been scarcely studied in term of morphology because of their difficult position, multifunctional roles, and blurred anatomical boundaries. Through a MRI shape analysis of adult human brains we have now identified the main character associated with individual brain variation in our species: the geometry of the precuneus. With a negligible effect of brain size or sex, the proportions of the precuneus are the main determinant of the midsagittal brain geometry. The brain morphological variation of the human genus and the brain morphological variation among adult modern humans share the same pattern: parietal bulging. And, at least for modern humans, this pattern is strictly determined by one single character: the longitudinal extension of the precuneal area. Evolutionary and functional evidence both converge toward the neural element which is at the same time the most variable at intra-specific level, strongly influencing our brain form. Many coincidences, which may be the result of the delicate spatial position of the deep parietal areas in the overall brain geometry. Or may there be more than this?

Language and hybrids

JASs2013 (cover)

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We have published the new volume of the Journal of Anthropological Sciences (JASs 2013). It includes many papers on evolution and cognition, mainly on language. The volume  includes reviews on biolinguistics, language evolution, and reproductive isolation in Neandertals. There is a whole forum dedicated to language and hybridization in human evolution, with nine articles discussing issues in paleogenomics. Papers are, as usually, free to download.


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