At a Glance
- The study revealed that while humans and chimpanzees share nearly identical genes, differences in gene expression in brain cells significantly contribute to the uniqueness of the human brain.
- Human brain cells exhibit higher levels of gene expression compared to chimpanzee and macaque cells. Five to ten percent of genes show differences, which increase to 12 to 15 percent in specific brain cell subtypes.
- Oligodendrocytes, a glial cell responsible for insulating neurons and enhancing signal transmission, showed the largest differences in gene expression, highlighting their role in neural plasticity and brain complexity.
- Differences in gene expression across various brain cell types, such as neurons and glial cells, suggest an evolutionary adaptation supporting the human brain’s complexity and advanced functions.
- The findings pave the way for studying how gene expression differences evolved and how they contribute to human-specific traits and cognitive abilities.
Scientists at the University of California, Santa Barbara, have uncovered new insights into what makes the human brain unique compared to other primates. A study published in Proceedings of the National Academy of Sciences found that while humans and chimpanzees share almost identical genes, how these genes are expressed in different brain cells could be what sets us apart. The research focuses on how gene expression, which refers to the process where genes instruct cells to make proteins, plays a critical role in the development and function of the human brain.
The study looked at how brain cells from humans, chimpanzees, and macaques express their genes differently. By analyzing the amount of messenger RNA (mRNA) produced by genes in each species, researchers discovered that human brain cells generally have more active genes than chimpanzee cells. The team found that around 5-10% of the genes studied had differences in expression, with human cells showing higher levels of gene activity. This difference grew to as much as 12-15% when the team analyzed specific subtypes of brain cells, showing that different cell types, like neurons and glial cells, have evolved in their ways to support the complexity of the human brain.
One of the key discoveries involved glial cells, which comprise more than half of the brain’s cells. Glial cells support and protect neurons, the cells responsible for transmitting signals in the brain. Among these, oligodendrocytes were found to have the largest differences in gene expression between humans and chimpanzees. These cells help insulate neurons, speeding up their electrical signals. This increased complexity in glial cells could be linked to the human brain’s enhanced ability to adapt and change over time, a process known as neural plasticity.
While this study only examined cells from a few parts of the brain, the findings suggest that gene expression plays a crucial role in brain evolution. Professor Soojin Yi, one of the study’s authors, explained that the differences in gene expression could help explain why the human brain is so much more complex than other primates. Moving forward, Yi plans to investigate how these differences developed throughout our evolutionary history and explore how they may contribute to traits that make humans unique.
References
- Tasoff, H. & University of California-Santa Barbara. (2025, January 2). Gene expression study reveals human brain cell types becoming more specialized, not just more numerous. Phys.Org; University of California-Santa Barbara. https://phys.org/news/2025-01-gene-reveals-human-brain-cell.html
- Joshy, D., Santpere, G., & Yi, S. V. (2024). Accelerated cell-type-specific regulatory evolution of the human brain. Proceedings of the National Academy of Sciences, 121(52), e2411918121. https://doi.org/10.1073/pnas.2411918121
