Why did humans evolve, but chimpanzees did not? I thought the "Theory of Evolution" says that everything evolves. How come sharks haven't evolved, or the coelacanth?
Did you read the sentence? "since diverging from a common ancestor about six to eight million years ago"
Both chimps and humans have evolved. They just evolved in different directions. The chimp of today probably has no more in common with our common ancestor than we do. Evolution says a species will become better suited to its environment, not that it will necessarily evolve in a direction we perceive as "higher."
Sharks and other species may evolve little because they are supremely well-suited to an environment that has changed little in a very long time.