Posts Tagged 'Morphological integration'

Vault and base

This week we have published a study on the integration between the parietal and temporal morphology in the human skull. Modern humans display large and bulging parietal lobes and bones, and large and projecting temporal lobes. It is possible that the latter (the anterior displacement of the temporal lobes) can be a spatial secondary consequence of the former (the enlargement of the parietal district). This survey on adult skulls suggests that this is not the case: parietal bulging and temporal displacement are apparently independent and not related. Nonetheless, when one of these districts undergoes a major variation (bulging in the case of the parietal bone, vertical stretching in the case of the middle cranial fossa), the other undergoes a spatial rotation: shape does not change, but the orientation varies according to the global cranial modification. The enlargement/reduction of the parietal bone have thus a major effect on head orientation, and it is also associated with facial proportions. Hence, it turns out that the general enlargement of the parietal district, a species-specific character of modern human brain and skull, has probably influenced the functional axis of the head, with possible consequences on body organization and posture. These results once more recall the importance of an integrated analysis between brain and braincase and, more generally, of a system-based approach to functional craniology.

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Modular brain

Gomez-Robles et al (2014)One of the main achievements in anatomy and morphometrics has been the introduction of the concepts of integration and modularity. Characters (and genes) are no longer interpreted as individual and independent units, but integrated into structural and functional systems. This does not mean that everything is integrated, and we should recognize that integration and modularity are based on both continuous and discontinuous hierarchies presenting many different degrees of relationship. There may be distinct combinations, and very different situations. Analyzing the structure of covariance of the endocranial base in modern humans, I suggested that local influences can be more relevant that general and long-range factors, in shaping the endocranial districts. An admixture of effects from brain, face, posture, muscles, physiology and biomechanics, makes local factors decisive to mould the specific endocranial areas. Similar results were obtained when analyzing the covariance patterns of the midsagittal brain morphology. Now Aida Gómez-Robles and colleagues have published a decisive analysis: the whole brain in three dimensions. The integration among brain parts is modest, and largely based on spatial proximity. Local factors are crucial in moulding the brain areas, at least in terms of their morphology and position. Initially one can be deceived if expecting to find a more integrated system. But at the same time such an independent organization suggests that local form changes can be analyzed considering the local context, the morphology being less contaminated by external (long-range) effects. Interpretations are easier if only local factors must be evaluated. This is something extremely relevant when dealing with evolutionary neuroanatomy, paleoneurology, and functional craniology. And then there is an issue on evolvability: the authors suggest that such limited integration can facilitate evolutionary changes.


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  • Fall 2017 CCA Course Offerings
    The Center for Cognitive Archaeology is offering three exciting classes this semester: Neurocognition of Art, Cognitive Evolution, and Neandertal Cognition. Follow the link below for detailed information. https://www.uccs.edu/~cca/

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  • Eye-brain spatial relationship
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