A gene for blood flow
15-10 million years ago
Humans, chimpanzees and gorillas are all descended from an unknown extinct ape. In this ancestor, a gene called RNF213 began evolving rapidly. This may have boosted the flow of blood to the brain by widening the carotid artery. In humans, RNF213 mutations cause Moyamoya disease, in which the artery is too narrow.
See other: What Makes Humans Human?