Dolphins are not the only animals{{U}} (31) {{/U}}humans that use sounds in an apparently intelligent manner. Whales also use a complex system of sounds{{U}} (32) {{/U}}is similar in many ways to a human language. One type of whale even sings, and its songs can{{U}} (33) {{/U}}on for as long as three or four hours. What is more, they can be heard under water at{{U}} (34) {{/U}}of more than 300 kilometers. After analyzing one of these songs with the aid of a computer, Carl Sagan said it{{U}} (35) {{/U}}at least a million "bits" of information. This is approximately the same{{U}} (36) {{/U}}of "bits" as in a long poem like the Odyssey.
Chimpanzees also use a system of different sounds to communicate with each{{U}} (37) {{/U}}. One type of cry{{U}} (38) {{/U}}to mean something like "danger in the air" or "big bird" and another apparently means "danger on the ground" or "snake". When they{{U}} (39) {{/U}}the first cry, they hide under trees or in holes and look up at the sky. The second cry causes them to hide in the upper{{U}} (40) {{/U}}of trees and to stare nervously at the grass. Chimpanzees are also{{U}} (41) {{/U}}of learning sign language. So are gorillas. One chimp called Washoe learned to{{U}} (42) {{/U}}about 160 separate signs meaning{{U}} (43) {{/U}}things as "Give me a drink" and "banana". Washoe even{{U}} (44) {{/U}}to swear. She had a teacher called Jack{{U}} (45) {{/U}}once refused to give her a drink. Washoe{{U}} (46) {{/U}}angrier and angrier and used several signs which{{U}} (47) {{/U}}"dirty Jack" ! A group of chimps at research institute in Atlanta, Georgia, have recently{{U}} (48) {{/U}}taught to type sentences, using a type of computer. The chimps' trainer was called Tim, and he kept correcting the{{U}} (49) {{/U}}one of the chimps made. The chimp obviously wanted Tim to stop{{U}} (50) {{/U}}him and typed out the following request: "Tim, please leave room!"