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This gene is responsible for the large size of our brain

The human brain and its evolution have interested scientists for a long time. A recent study sheds light on the role of a gene responsible for allowing the human brain to grow so large.

Why is our brain so big compared to our height? Indeed, the human brain beats that of all mammals when considering its encephalization coefficient. It is seven times more massive than the theoretical mass calculated for an animal of equivalent body mass. Part of the answer to this vast question lies in the presence of a strictly human gene: ARHGAP11B. The latter is involved in the expansion of the neocortex, the youngest brain region from an evolutionary point of view.

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The gene responsible for brain expansion

Scientists from German Primate Center introduced the ARHGAP11B gene into chimpanzee organoids. These synthetic organs obtained in the laboratory reproduce, in a simplified way, the structure of the brain and make it possible not to carry out experiments on living animals. ” Our study shows that this gene in chimpanzee organoids causes an increase in the number of brain stem cells and neurons that play a crucial role in the extraordinary mental abilities of humans “, explains Michael Heide, first author of the study published in EMBO Reports.

On the other hand, if the ARHGAP11B gene is absent in human organoids, the number of brain stem cells falls to the same level as in chimpanzees. ” We were therefore able to show that ARHGAP11B plays an important role in the development of the neocortex during human evolution. concludes Michael Heide.