The apes are the animals that fascinate people the most. The reason is not hard to see. Of all the world's creatures, the apes are closest to us in form and behavior. They can stand upright, they have fingernails and fingerprints, large brains, and expressive faces. Most of all, they have an obvious intelligence that both amuses and puzzles us. So great is the resemblance of the apes to humans that they are called anthropoid, or "man-like" apes. The DNA of humans differs from that of chimpanzees by less than two percent.