Why do humans drive cars and not chimpanzees? What explanations can be found in our prehistory? Magnus Enquist, Stockholm University, investigates what happened when the human and chimpanzee development line parted about 5.5 million years ago. One explanation is the human ability to do things in several steps and the ability to transfer accumulated knowledge from generation to generation. The long childhood and culture of humans are other reasons. To play and learn for a long time favors knowledge development.