“Rapid Evolution of the Cerebellum in Humans and Other Great Apes”, 2014-10-20 (; similar):
The cerebellum expanded rapidly in parallel lineages of apes, including humans
The cerebellum increased in absolute size and relative to neocortex size
This expansion began at the origin of apes but accelerated in the great ape clade
Cerebellar expansion may have been critical for technical intelligence
Humans’ unique cognitive abilities are usually attributed to a greatly expanded neocortex, which has been described as “the crowning achievement of evolution and the biological substrate of human mental prowess”.1 The human cerebellum, however, contains 4× more neurons than the neocortex2 and is attracting increasing attention for its wide range of cognitive functions.
Using a method for detecting evolutionary rate changes along the branches of phylogenetic trees, we show that the cerebellum underwent rapid size increase throughout the evolution of apes, including humans, expanding statistically-significantly faster than predicted by the change in neocortex size. As a result, humans and other apes deviated statistically-significantly from the general evolutionary trend for neocortex and cerebellum to change in tandem, having statistically-significantly larger cerebella relative to neocortex size than other anthropoid primates.
These results suggest that cerebellar specialization was a far more important component of human brain evolution than hitherto recognized and that technical intelligence was likely to have been at least as important as social intelligence in human cognitive evolution. Given the role of the cerebellum in sensory-motor control and in learning complex action sequences, cerebellar specialization is likely to have underpinned the evolution of humans’ advanced technological capacities, which in turn may have been a pre-adaptation for language.