Posts Tagged 'multiple-variance Brownian motion approach'

Brains and teeth

gomez-robles-et-al-pnas2017In anthropology it is commonly accepted that the evolution of larger brains was associated with the reduction of posterior teeth. Factors ranging from diet to cognitive ability have been used to explain this inverse correlation between cerebral complexity and masticatory structures. Aida Gómez-Robles and colleagues have analyzed brain and teeth changes using a multiple-variance Brownian motion approach, providing evidence against a brain-teeth phylogenetic association. Brain shape was analyzed by using eight linear variables as measured on endocasts. Teeth shape was analyzed through geometric morphometrics. The study found that endocranial proportions and dental geometry are largely characterized by similar rates of variation, which are indicative of a neutral and non-directional pattern of evolution. Brain size and tooth size show different rates of change throughout the phylogenetic tree, and the hypothesis of a reciprocal and inverse correlation is not supported. This seems to suggest independent factors at environmental and/or genetic level. Two characters show faster rates of change in specific lineages, and are probably associated with specific selective and adaptive processes: brain size in early Homo and brain globularity in Homo sapiens. The first result suggests that brain evolution in the genus Homo is strongly based on size increase rather than on changes of specific cortical proportions. However, caution is needed in this sense: the study is based on simple linear metrics such as arcs and chords, and reflects only the external appearance of endocranial anatomy. Despite these limitations, this result is consistent with other kinds of evidence. The second result reflects an exception to this size-only pattern of change: the globular brain shape in modern humans. Parietal lobe variations are again an issue.


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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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  • Researchers develop non-invasive deep brain stimulation method
    Researchers at MIT have developed a new method of electrically stimulating deep brain tissues without opening the skullSince 1997, more than 100,000 Parkinson’s Disease patients have been treated with deep brain stimulation (DBS), a surgical technique that involves the implantation of ultra-thin wire electrodes. The implanted device, sometimes referred to as […]

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