Introducing the brain: genes driving human brain size (Introduction)

by David Turell , Wednesday, December 06, 2023, 19:03 (351 days ago) @ David Turell

Just discovered:

https://phys.org/news/2023-12-reveals-genes-humans-primates-cognitive.html

"An international team led by researchers at the University of Toronto has uncovered over 100 genes that are common to primate brains but have undergone evolutionary divergence only in humans—and which could be a source of our unique cognitive ability.

"The researchers, led by Associate Professor Jesse Gillis ...found the genes are expressed differently in the brains of humans compared to four of our relatives—chimpanzees, gorillas, macaques and marmosets. (my bold)

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"'The team, which includes researchers from Cold Spring Harbor Laboratory and the Allen Institute for Brain Science in the U.S, created a brain map for each primate species based on single-cell analysis, a relatively new technique that enables more specific genetic sequencing than standard methods. They used a BRAIN Initiative Cell Census Network (BICCN) dataset created from samples taken from the middle temporal gyrus of the brain.

"'In all, the team found 139 genes that are common across the primate groups but highly divergent in their expression in human brains. These genes displayed a stronger ability to withstand mutations without impacting their function, suggesting they may have evolved under more relaxed selective pressure.

"'The genes that have diverged in humans must be tolerant to change," said Hamsini Suresh, first author on the study and a research associate at the Donnelly Center. "This manifests as tolerance to loss-of-function mutations, and seems to allow for rapid evolutionary change in the human brain."

"'Our higher cognitive function may have resulted from the adaptive evolution of human brain cells to a multitude of less threatening mutations over time. It's also worth noting that around a quarter of the human-divergent genes identified in the study are associated with various brain disorders. (my bold)

"'The divergent genes the researchers identified are found in 57 brain cell types, grouped by inhibitory neurons, excitatory neurons and non-neurons. A quarter of the genes were only expressed differently in neuronal cells, also known as gray matter, and half were only expressed differently in glial cells, which are white matter.'"

Comment: the findings are not surprising when we look at the differences in mental ability. That these special genes relate to disease states simply shows how important the genes are.