The evolution of modern human brain shape


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Modern humans have large and globular brains that distinguish them from their extinct Homo relatives. The characteristic globularity develops during a prenatal and early postnatal period of rapid brain growth critical for neural wiring and cognitive development. However, it remains unknown when and how brain globularity evolved and how it relates to evolutionary brain size increase. On the basis of computed tomographic scans and geometric morphometric analyses, we analyzed endocranial casts of Homo sapiens fossils (N = 20) from different time periods. Our data show that, 300,000 years ago, brain size in early H. sapiens already fell within the range of present-day humans. Brain shape, however, evolved gradually within the H. sapiens lineage, reaching present-day human variation between about 100,000 and 35,000 years ago. This process started only after other key features of craniofacial morphology appeared modern and paralleled the emergence of behavioral modernity as seen from the archeological record. Our findings are consistent with important genetic changes affecting early brain development within the H. sapiens lineage since the origin of the species and before the transition to the Later Stone Age and the Upper Paleolithic that mark full behavioral modernity.

Abstract and symbolic thinking may have began to flourish in Homo Sapiens when our brains became rounder in shape.
Interesting. Dienekes wrote about the rounding of the skull a while back saying it was a progressive development:


would be very cautious with any direct simplistic relation made between form of skull and intelligence (here: capacity of abstraction?)
I have not red the paper but cephalic index is a very bad criterium; shape and proportions of certain parts of the brain could play, but even here, we have to be cautious; it seems one more serious link could the complication of brain folds, rather than CI, weight/size or rounded shape only; that said, the relative growing of certain parts of the brain can give way to some more rounding of these parts; my aim is not to say something like that never happened during mankind's evolution but that it would be "dangerous" to conclude that a systematic comparison of modern human skulls could give us serious clues to classify people about these capacities of abstraction

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