An interdisciplinary team of researchers led by biologists at the University of Massachusetts Amherst has investigated the links between gene expression and brain evolution across 18 primate species. The findings, published in eLife, provide valuable insights into the nuances of brain activity and the evolution of the human brain.
The researchers collected brain tissue samples from zoos and body donors, and then sequenced the RNA transcripts from each sample to generate a comprehensive map of the 17,000 genes expressed in each primate's brain. They compared the fully-sequenced RNA transcriptomes to better understand the links between genomics and evolution, as well as the potential implications for neurodegenerative diseases.
Previous studies have sequenced the RNA in primate brains, but on a much more limited scale. "If we are going to figure out what makes humans unique among primates," says senior author Courtney Babbitt, "we're going to have to study a wider selection of primates, and no one has looked at such a large sample before."
The team's findings reveal a remarkable degree of variation in gene expression across the 18 primate species, even between closely related species like humans and chimpanzees. While the majority of the variation seems to be primarily explainable by species evolution, the researchers identified particular genes for further study that may help explain the evolution of specific primate brains.
"It's one of the great evolutionary paradoxes: humans and chimps have pretty much the same genes, and yet we're so different," adds Babbitt. "To figure out what makes us human, we're going to have to look at the genetic expression of a wide range of our evolutionary cousins, and that's exactly what we've begun to do with this study."
The researchers believe that their findings could provide insight into the nuances of brain activity across different regions, as well as shed light on various human neurodegenerative disorders, such as Alzheimer's disease.