Three genes have changed since we separated from the apes. That means you have 7 billion more brain cells than a gorilla.
In 14 million years the human brain has grown from half a kilo to 1.4 kilos. We probably owe that to three recently discovered genes.
Californian researchers came across the genes when they investigated how many nerve cells form the brains of a macaque.
They cultivated this monkey's brain tissue in the laboratory and mainly looked at the so-called NOTCH genes, which are involved in the development of stem cells in fetuses.
Three genes tell our development story
It turned out that humans have three active NOTCH genes on chromosome 1 that are missing in the macaque. Even our closest relatives, the gorilla and the chimpanzee, do not have the genes.
They are unique to us and say something about our development history.
The first gene was created 14 million years ago as a partial copy of a gene on chromosome 1, before we separated ourselves from the other apes.
11 million years later, the gene was repaired, after which our brains began to grow. Later the gene was copied twice more.
Other researchers discovered that the three genes code for a protein that causes the stem cells of the brain to divide into four instead of two nerve cells.
As a result, we form more nerve cells than monkeys.
Brains grew by chance
One of our chromosomes underwent three changes, so we have a larger brain than our relatives.