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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 hi