The core function of the cerebellum is to help us coordinate voluntary movements. But, a new study at Duke University has revealed the region may have undergone evolutionary changes that have to do much more than its role in regulating our motor skills. 

Much of the attribution for executive functions, such as moral reasoning and decision making is given to the prefrontal cortex, and now the cerebellum has lately been fueling curiosity among the researchers for its unheralded involvement in cognitive function.

The cerebellum (highlighted) may have played a key role in human evolution [Image credit: dana.org]

In the study, the team looked at the cerebellum and the prefrontal cortex in humans, chimpanzees and rhesus macaque monkeys. Then they assessed which part of the genomes from both brain regions had the methyl group attached to them. 

DNA methylation is an epigenetic mechanism that modulates the function of  genetic materials, thereby affecting how our genes express. Studying the patterns of this methylation helps differentiate active and inactive genes in a species. They are different for different body parts and vary among species. 

Upon examining the genomes, they found that compared to chimpanzees and rhesus macaques, the ones extracted from humans exhibited greater patterns of methylation (epigenetic differences) in the cerebellum than the prefrontal cortex, suggesting there had been more changes in the cerebellum in human brain evolution.

It’s difficult to establish the role the methylation changes exactly played, but a handful of genes that demonstrated different methylation patterns in the cerebellum are known to be involved in strengthening or weakening connections between neurons, a process responsible for learning and consolidating memories. 

These changes in methylation are associated with genes involved in psychiatric conditions and neurodegeneration as well.

The cerebellum has been often left out in evolutionary studies, but this study highlighting its importance in the evolution of the human brain may change scientists’ stance on this region of the brain in subsequent researches. 

The study has been published in the journal PLOS Genetics.