A new study published in the Cell Press journal Current Biology on October 2 could rewrite the story of ape and human brain evolution. While the neocortex of the brain has been called “the crowning achievement of evolution and the biological substrate of human mental prowess,” newly reported evolutionary rate comparisons show that the cerebellum expanded up to six times faster than anticipated throughout the evolution of apes, including humans.
The cerebellum had been seen primarily as a brain region involved in movement control, adds Chris Venditti of the University of Reading. But more recent evidence has begun to suggest that the cerebellum has a broader range of functions. The cerebellum also contains an intriguingly large number of densely packed neurons.
“In humans, the cerebellum contains about 70 billion neurons—four times more than in the neocortex,” Barton says. “Nobody really knows what all these neurons are for, but they must be doing something important.”
Barton and Venditti say that the cerebellum seems to be particularly involved in the temporal organization of complex behavioral sequences, such as those involved in making and using tools, for instance. Interestingly, evidence is now emerging for a critical role of the cerebellum in language, too.
Whatever happened there didn’t seem to make that much difference to apes. So the main issue is still on the table.
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