The researchers isolated different subpopulations of human brain stem cells and precisely identified, which genes are active in which cell type. In doing so, they noticed the gene ARHGAP11B: it is only found in humans and in our closest relatives, the Neanderthals and Denisova-Humans, but not in chimpanzees. This gene manages to trigger brain stem cells to form a bigger pool of stem cells. In that way, during brain development more neurons can arise and the cerebrum can expand. The cerebrum is responsible for cognitive functions like speaking and thinking.
Humans may in part owe their big brains to a DNA "typo" in their genetic code, research suggests.
The mutation was also present in our evolutionary "cousins" - the Neanderthals and Denisovans.
However, it is not found in humans' closest living relatives, the chimpanzees.
As early humans evolved, they developed larger and more complex brains, which can process and store a lot of information.
Last year, scientists pinpointed a human gene that they think was behind the expansion of a key brain region known as the neocortex.