Scientists Uncover the Gene Responsible for Human’s Big Brain

Brain Organoid

A brain organoid about 3 millimeters in size made from the stem cells of a chimpanzee. The brain stem cells are stained red; brain stem cells that received the ARHGAP11B gene are shown in green. Credit: Jan Fischer

Brain organoids shed light on the evolution of the human brain.

Michael Heide

Dr. Michael Heide, head of the Junior Research Group Brain Development and Evolution. Credit: Sascha Bubner

Great ape animal studies have long been prohibited in Europe due to ethical concerns. An alternative to using animals in studies is the use of so-called organoids, which are three-dimensional cell structures that can be generated in the lab and are just a few millimeters in size.

These organoids can be created using pluripotent stem cells, which then subsequently develop into particular cell types like nerve cells. The study team was able to create both chimpanzee and human brain organoids by using this method.

“These brain organoids allowed us to investigate a central question concerning ARHGAP11B,” says Wieland Huttner of the Max Planck Institute of Molecular Cell Biology and Genetics, one of the three lead authors of the study.

“In a previous study, we were able to show that ARHGAP11B can enlarge a primate brain. However, it was previously unclear whether ARHGAP11B had a major or minor role in the evolutionary enlargement of the human neocortex,” says Wieland Huttner.

Human Brain Organoid

A section of a brain organoid made from the stem cells of a human. In magenta are actively proliferating brain stem cells and in yellow a subset of brain stem cells. Credit: Jan Fischer

To clarify this, the ARGHAP11B gene was first inserted into chimp organoid brain ventricle-like structures. Would the ARGHAP11B gene cause the chimpanzee brain’s brain stem cells to proliferate, which is required for the neocortex to increase in size?

“Our study shows that the gene in chimpanzee organoids causes an increase in relevant brain stem cells and an increase in those neurons that play a crucial role in the extraordinary mental abilities of humans,” said Michael Heide, the study’s lead author, who is head of the Junior Research Group Brain Development and Evolution at the German Primate Center and employee at the MPI-CBG.

When the ARGHAP11B gene was knocked out in human brain organoids or the ARHGAP11B protein’s function was inhibited, the number of these brain stem cells was reduced to that of a chimpanzee.

“We were thus able to show that ARHGAP11B plays a crucial role in neocortex development during human evolution,” says Michael Heide. Julia Ladewig of HITBR, the third of the lead authors, adds: “Given this important role of ARHGAP11B, it is furthermore conceivable that certain maldevelopments of the neocortex may be caused by mutations in this gene.”

Reference: “Human-specific ARHGAP11B ensures human-like basal progenitor levels in hominid cerebral organoids” by Jan Fischer, Eduardo Fernández Ortuño, Fabio Marsoner, Annasara Artioli, Jula Peters, Takashi Namba, Christina Eugster Oegema, Wieland B. Huttner, Julia Ladewig and Michael Heide, 13 September 2022, EMBO Reports.
DOI: 10.15252/embr.202254728

9 Comments on "Scientists Uncover the Gene Responsible for Human’s Big Brain"

  1. They won’t stop untill they make a man with a money’s brain and a monkey with a man’s brain.

  2. Now that we know for sure that brain size is a function of genetics let’s explain the 6% difference in brain size between people of sub-Saharan African descent and those of Eurasian descent. Why? End affirmative action. Flooding US universities and employers with low IQ individuals, averaging an IQ of just 85, has been detrimental for this country. It’s past time for that systemic racism to end and for America to flourish again.

  3. Beau Martin, what a racist comment. How do you explain that poodles from miniature to standard have large IQs? Brain size means nothing!

  4. Actually brain size does mean something. If you have a cranium large enough for 80 billion brain cells or one big enough for 800 billion brain cells, which person is smarter? Hmm now wait, lemme think about this for a second… hmm lmao now if a cranial vault is bigger but without this gene then in that situation you maybe right an the size has less to do with intelligence. However more room to accommodate “high end” braincells would theoretically make a person smarter more is always more. I mean that’s obvious. Unless your brains too small to comprehend that? Lol…

  5. Beau and Nick, what idiotic things to say. A bigger brain in and of itself does not mean higher intelligence. Didn’t it occur to you that even a bigger brain may lack greater and better connections for communications? I should answer that for you, no it did not.

  6. A purely scientific discovery that contributes to our broadening understanding of human evolutionary development was clearly taken out if context to further a baseless racist’s attempt to perpetuate white superiority over brain size. A A 19th century highly respected & well published Phila surgeon, Samuel Morton’s legacy as being the ‘father of racism’. Between 1830’s & 40’s used his wealthy to seek his preconceived notion that humans were distinctly 5 separate races created by individual Gods that embodied each race & were subservient to the white man’s god. Morton searched the globe for skulls/skeletons to demonstrate that whites have bigger brains & therefore of higher intelligence , followed by East Asians, Southeast Asian, Native Americans & Blacks. His self-fulfilling prophecy was aided by his biased SELECTION of skull that ‘fit’ his hypothesis. Intelligence based on brain size was widely accepted as fact in the 19th century & Morton’s stature & respect as a surgeon was lauded by his colleagues as proving the superiority of intelligence in whites which became an important ‘study’ by influential plantation owners justification for slave ownership. This is the kind of black history that Gov DeSantis & others want to BAN from being taught in schools to ‘make white kids feel guilty/responsible for atrocities inflicted by whites on black slaves! I can only conclude that Making America Great Again means going back to Jim Crow area when blacks largely stayed silent & status quo

  7. @xs it’s already been done – monkey brain in human body..Johnson, Bush ,Putin etc

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