The number of neurons in the human brain is three times that of chimpanzees and gorilla brains! Why is the human brain bigger than the brains of other apes? Writing in the latest issue of Cell, British scientists say they have discovered for the first time, why the human brain is getting bigger — a key molecular switch, ZEB2, or play a key role in it.
In the latest study, a team led by Madeleine Lancaster of the MRC Laboratory of Molecular Biology, Medical Research Council compared “brain-like organs” grown from stem cells from humans, gorillas, and chimpanzees. The study found that similar to the actual brain, human brain organs grow larger than lye-like organs.
The researchers explain that in the early stages of brain development, neurons are formed by stem cells (neurogenic cells), which are initially cylindrical, making it easy for them to split into identical-shaped child cells. The more neural precursor cells proliferate, the more neurons appear later. As the cells mature, proliferation slows, and the cells elongate to form an ice cream-like cone.
The study found that human ancestral cells remain cylindrical for longer periods than other apes, during which time they divide more frequently and produce more cells. Therefore, this difference in the rate of conversion from nerve ancestral cells to neurons means that human cells have more time to reproduce.
To reveal the genetic mechanisms that lead to these differences, the researchers compared gene expression in human and other apelike brain organs and found that a gene called ZEB2 starts faster in gorilla brain organs than in human brain organs.
They then delayed the functioning of ZEB2 in the gorilla brain, which was found to slow down the maturation of the ancestral cells and make the gorilla brain’s organs more humanlike. Conversely, the earlier start-up of the ZEB2 gene in human ancestral cells promotes the premature transformation of human organs, making them more like apelike organs.
Lancaster said: “Our new study provides some preliminary insights into the differences in human brain development that distinguish us from our next of kin – other apes, the most significant difference between us and other apes are that our brains are larger. ”
The remarkable difference between humans and other mammals is that the human brain is larger, even when compared to primates as close relatives of humans. Behind this conclusion, which sounds commonplace, lies a great deal of scientific mystery. Scientists have tried to explain the phenomenon from an evolutionary perspective, and a neurological point of view, what is the underlying mechanism? Uncovering this mystery will further advance scientists’ understanding of human brain development.