Why is human brain big? Scientists discover the molecular reason

Humans are closely related to other primates like Chimpanzees, Gorillas and so on. But what sets humans apart is intelligence. It is this alone that puts man at the top of global food chain and elevates the species to global dominance. We may lack the power, agility and speed of primates but with our intelligence, we have been able to overcome all these impediments.

Human brain is also larger than great apes. A healthy human brain reaches volume of 1500 cm3 in adulthood. Compare this with Gorillas (500cm3) and Chimpanzees (400 cm3) and we come to know the edge human intelligence has.

Scientists have now found the molecular reason behind why human brain is so big. Researchers at Medical Research Council’s Laboratory of Molecular Biology in Cambridge and others published their finding in the journal Cell.

To understand and compare brain development process, the researchers took cells from human, Gorilla and Chimpanzee brains. They were reprogrammed into stem cells. Then they were grown in a way that they formed respective brain organoids, that is, little lumps of brain.

After several weeks, human brain organoids showed the biggest growth. The neural progenitor cells in human brains divided more quickly than it did in Gorilla and Chimpanzee samples. Scientists found that a gene by the name of Zeb2 was responsible for quick growth of human brain.

This gene functions as a molecular switch, which when turned on, results in an increased division of cells and thereby more growth of human brains compared to great apes.