Big brain evolution: changes in sapiens skull shape (Evolution)

by David Turell @, Thursday, January 25, 2018, 22:10 (26 days ago) @ David Turell

Our brains reached their volume/size about 300,000 years ago, and changed from a more oblong shape to a more globular form by the last 40,000 years, as use of the brain altered its lobes:

https://www.inverse.com/article/40511-brain-shape-homo-sapiens

"In a study published Wednesday in Science Advances, researchers from the Max Planck Institute for Evolutionary Anthropology announced that the earliest Homo sapiens did not have globular brains like we have today. Instead, their brains had a shape intermediate between that of Homo erectus and that of the Neanderthals, both of which were somewhat more elongated horizontally. The brain, the authors write, gradually became globular over evolutionary time, and those changes in turn, induced neurological shifts that coincide with archaeological evidence of modern behavior. (my bold)

***

"According to the new paper, the size of the early Homo sapiens brain entered the range of modern human brain size as early as 300,000 years ago, but its globular, round features emerged only 40,000 years ago. This unexpected revelation means that the brain reached its current shape much later than anticipated during evolution.

"To come to this conclusion, the team used tomographic scans and 3-D analysis to create virtual endocranial casts of 20 different Homo sapiens fossils. These fossils were divided into three groups: the oldest came from North and East Africa and represented the earliest known representatives of humans after the population split with Neanderthals, others lived in East Africa and the Eastern Mediterranean regions between 130,000 to 100,000 groups, and the final group lived between 35,000 to 10,000 years ago.

***

"Globularity itself likely didn’t give us advantages, says Neubauer, but the features that contributed to the rounding probably did: the bulging of parietal areas and the bulging of the cerebellum. The parietal lobe is an important hub in connecting brain regions and is involved in functions like orientation, attention, and the sensorimotor transformations that underlie planning and visuospatial integration. Meanwhile, the cerebellum relates to motor-related functions, like balance, as well as integral functions like working memory, language, affective processing, and social cognition. It’s likely that the emergence of these skills prompted the “human revolution.”

“'It’s also interesting to point out that, in present-day humans, brain globularity emerges developmentally during a few months around the time of birth,” says Neubauer.
“Our new data therefore suggests evolutionary changes to early brain development in a critical and vulnerable period for neural wiring and cognitive development.'”

Comment: My bold supports the theory that artifacts show behaviors the brain is capable of producing. As the brain molded itself into slightly new shapes due to lobe developments with new applications and implementations, the skull adapted to the new spatial requirements. The obvious implication is that as the new species of H. sapiens received its new-sized larger brain, it had to spend time learning to use it creating the newer shape. Size first, use second could not be clearer.


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