New research suggests the cerebellum expanded up to six times faster than was previously believed.
These findings suggest that technical intelligence was just as important if not more so than social intelligence in human evolution, Cell Press reported.
"Our results highlight a previously unappreciated role of the cerebellum in ape and human brain evolution that has the potential to refocus researchers' thinking about how and why the brains in these species have become distinct and to shift attention away from an almost exclusive focus on the neocortex as the seat of our humanity," said Robert Barton of Durham University in the United Kingdom.
The cerebellum has always been known to be primarily involved in movement, but new findings suggest it contains an unusually large number of densely packed neurons and is involved in a variety of functions.
"In humans, the cerebellum contains about 70 billion neurons-four times more than in the neocortex," Barton said. "Nobody really knows what all these neurons are for, but they must be doing something important."
In the past the neocortex has gotten the most attention; because of its size the regions is believed to have the largest rate of expansion, but this may just be because of the relative size of the animal in question. By using a comparative method that controlled for differences in the way the two brain regions correlate. The team found both human and non-human apes stray from the tight tight correlation in size between the cerebellum and neocortex seen across other primates due to the rapid evolution of the cerebellum.
The findings suggest the cerebellum is involved in "temporal organization of complex behavioral sequences" such as tool making.
The study establishes the cerebellum as "a new frontier for investigations into the neural basis of advanced cognitive abilities," the researchers concluded.
The findings were published Oct. 2 in the journal Current Biology.
