A study led by Soojin Yi at UC Santa Barbara reveals that the remarkable specialization of the human brain is driven by differences in gene expression, rather than just the presence of genes. Despite sharing over 95% of their genome with chimpanzees, humans display a higher productivity in gene expression related to brain function. The research, published in the Proceedings of the National Academy of Sciences, indicates that as cell types in the human brain have evolved, they have not only become more numerous but highly specialized. By employing advanced techniques to analyze individual brain cell nuclei, the team discovered that 5-10% of the 25,000 genes studied exhibited differences in expression, with a notable increase in specialization when examining cell subtypes. Human glial cells, which make up more than half of the brain’s cellular composition, demonstrated significant differences, particularly oligodendrocytes, which enhance neuronal signal efficiency. Yi suggests that the evolution of the human brain’s complexity is linked to both neuron and glial cell evolution. Future research aims to explore gene expression across different brain regions and throughout human evolutionary history, emphasizing that differential gene expression is fundamental to understanding human brain evolution.
