How Human Brains Outgrew Apes: Stem Cell Study Compares Gene Activity in Humans, Chimps, and Gorillas

An international team led by Prof. Mareike Albert at TUD Dresden University of Technology has uncovered a key mechanism behind the human brain's remarkable size. Using lab-grown brain organoids from stem cells, the researchers compared early brain development in humans, chimpanzees, and gorillas. They found that the difference is not new genes, but how shared genes are regulated and expressed. In humans, certain genes stay active longer, leading to more brain cell production and a larger cerebral cortex. This discovery helps explain why human brains are roughly three times larger than those of our closest living relatives. It also sheds light on the evolutionary changes that shaped human cognition. The study, published in a leading journal, highlights the power of organoid models to study brain evolution without invasive research on endangered apes. As scientists refine these models, we may soon understand not just brain size, but the origins of complex human traits like language and abstract thought.