Brain cerebellum___

The brains of apes and humans evolved unusually quickly when it came to the cerebellum, a part of the brain involved in control of movement, researchers say.

The finding may change what is considered special about the human brain, scientists added.

Mental Abilities:

The unique mental abilities of humans are usually attributed to the cerebral cortex, which encompasses about three-quarters of the human brain's mass. The largest part of the human cerebral cortex is the neocortex, which is thought to be key to conscious thought, sensory perception and language.
However, the cerebellum holds four times more neurons than the neocortex, suggesting the way it changed over time may have played an important role in human evolution as well.

"Our earlier work showed that evolutionary expansion of the cortex and the cerebellum were intimately linked in mammalian evolution — when one changes, so does the other,"
"In humans, the cerebellum contains about 70 billion neurons,"."Nobody really knows what all these neurons are for, but they must be doing something important."