Posts Tagged 'encephalization'

Brain ontogeny

Hublin et al 2015After that recent article on endocasts, the team from the Max Planck Institute has now published one more review, this time on brain ontogeny and life history. This paper introduces issues concerning encephalization, energy budget, birth, maturation, ecology, and culture. It provides also many general perspectives on hominid paleoneurology, resuming much paleontological evidence published in the last decade. It is a good and effective recompilation of literature and concepts, integrating morphometrics, development, and evolution. It is part of a special issue dedicated to brain, birthweight and the immune system.

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.

Frontal matters

Saccopastore 1 (EBruner)A re-evaluation of brain volumetric data, adjusting for scaling and phylogeny, adds further evidence against the hypothesis of morphological changes in the frontal lobes for our species. Despite a century of firm claims on the patent role of the frontal lobes in our evolution, there are now many different indications suggesting that those statements were probably excessive and not well demonstrated. It seems that there is no clear specific change in the general morphology of the frontal lobes in Homo sapiens, and even the correspondence between anatomy and functions has lost strength. We must take into consideration the possibility that differences may be subtle but important. A minor shift from the general tendency may be irrelevant for the statistical thresholds but important in biological terms (for example, this can be the case for white matter proportions). There may be also changes which have not been detected yet, as well as changes that are not evident from gross morphometrics. Furthermore, even if volumetric changes in our frontal lobes are those expected for our large brain size, the increase in terms of absolute size is patent, and this may be a relevant difference anyway. Throughout this debate, it is interesting to note how the paleoneurological information is generally ignored. Despite the many inferences on the evolutionary changes in the brain human form, there is no mention of the notable advances published on the evolution of brain geometry in our species. This is even more imprudent when considering that anthropology is currently employing very complete and powerful morphometric tools, while in neuroscience most data still refers only to general size measures. However, even using just basic morphometric variables, we know that modern humans and Neandertals experienced at least a change in the proportions of the frontal areas. Excluding the fossil evidence from the debate does not seem to be a good idea, at least when dealing with evolutionary studies.

Pandora

Endocast (C Zollikofer and M Ponce de León)Christoph Zollikofer and Marcia Ponce de León have published a review on human evolution and endocasts: Pandora’s Growing Box. The article provides comments on topics mostly related to brain size, brain growth,  encephalization, cranial evolution, and comparative neuroscience. There are useful notes and images on the correspondence between brain and endocast.

Brain scaling in mammals

A recent paper by Boddy and colleagues provides an excellent and updated review on encephalization in mammals. Theories and methodologies are introduced and compared, and a sample of 630 living species is used to evaluate encephalization according to phylogeny. The allometric scaling of brain and body size is discussed in extant and extinct taxa. On the same issue, have also a look to this paper by David Alba on encephalization and intelligence, with relevant methodological cues.


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  • Stáňa
    A new PhD student in the team working on craniovascular anatomy! Stanislava Eisová was in our laboratory few years ago, publishing a paper on parietal bone and vessels in which she investigated correlations between craniovascular morphology, skull size, and bone thickness. She got a Master Degree in Anthropology of Past Populations at the University of […] […]

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