Last week, researchers nearly doubled the amount of neocortex brain cells in some developing mice, and in some cases, created brain folds like in human brains, thanks to what’s being called the “big brain” gene.
No, the scientists weren’t just out to make a live-action reboot of Pinky and the Brain. They were testing the significance of gene ARHGAP11B, later dubbed the big brain gene, in human evolutionary development. Turns out the gene is critical to humans’ large neocortex and is a stark difference between us and primates.
According to Science, the study began when researchers in Dresden, Germany, started looking at aborted human fetal tissue to understand why the human neocortex becomes so much larger in early development than in other mammals, like rodents.
Lead author Marta Florio explained to Live Science the importance of the neocortex.
“The neocortex is so interesting because that’s the seat of cognitive abilities, which, in a way, make us human — like language and logical thinking.”
Within the fetal tissue samples, they found the big brain gene, along with 55 others, are present in human and neanderthal brains, along with other extinct human-like species, but not in rodents.
Out of those 56 genes, ARHGAP11B was the most active in the human neural progenitor cells. That big brain gene was already suspected to be a key component to human evolution, and ironically the gene itself is tiny, just 804 letters long.
Several years ago, researchers discovered the gene is just the incomplete fragment of a larger gene, but it was duplicated and became part of the human genome. The big brain gene is not present in chimpanzees, leading scientists to believe it came into existence after the future humans split off from their ape ancestors.
Florio explained, “[I]t is so cool that one tiny gene alone may suffice to affect the phenotype of the stem cells, which contributed the most to the expansion of the neocortex.”
Neurobiologist Victor Borrell, who wasn’t involved in the study, is also excited about the discovery, according to Science.
“This study represents a major milestone in our understanding of the developmental emergence of human uniqueness.”
Of course, the researchers needed some confirmation about the gene’s significance, and that’s where big-brained mice come in.
In a subsequent experiment, they put the big brain gene into developing mice, doubling the size of their neocortex region. The experiment served as additional proof that ARHGAP11B is essential to growing a bigger brain.
So… does that mean they made smarter mice with human-like cognitive abilities?
According to Live Science, we don’t really know. The scientists did not test the rodents’ intelligence (one assumes they disposed of the mice before they got a chance to take over the world).
Nevertheless, just having more brain cells isn’t the beginning and end of human intelligence, according to neurobiologist and study co-author Wieland Huttner. How those cells link together and how they’re formed have importance too.
Nevertheless, Florio explained that testing lab-created big-brained mice could be a future research project.
The full study on the big brain gene comes from the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, and can be found in Science Journal here.
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