DUF1220 is our Secret Ingredient
The brain is believed to have grown so rapidly in size and complexity because of a protein domain called DUF1220. Humans have more than 270 copies of DUF1220 in their genome whereas chimpanzees have 125, gorillas have 99 and mice have just one. The number of copies of DUF1220 shows how close an animal may be to humans.
Our Teeth Decrease in Size
Humans are the only primates whose tooth size decreases as brain size increases