For nearly 20 years, human beings have been teaching chimpanzees and other apes to use the sign language of the deaf to carry on rudimentary conversations.
Now the animals are teaching each other sign language and using it to communicate among themselves, a leading chimp-language researcher reported here today.
The most closely studied example of this involves a chimp named Loulis that at the age of 10 months was placed in the care of Washoe, an adult female that in 1966 became the first chimp to learn sign language.
Washoe, which understands and uses hundreds of sign language words, immediately took to Loulis and within eight days began teaching the young chimp simple signs, by demonstration and sometimes by molding the baby's hands into the forms that represent words.
Today, at the age of 5 -- roughly comparable to the same developmental age in a human child -- Loulis has learned 55 words from Washoe and uses them in two- and three-word combinations to ask for food or to be played with.
Roger Fouts, who reported the developments at the annual meeting of the American Association for the Advancement of Science, said that when Loulis was younger, the chimp conversed chiefly with Washoe. Now, Fouts said, Loulis talks mostly with one of the three other young chimps, taught sign language elsewhere, that are housed with Washoe and Loulis. Two of the three are females, but Loulis prefers to talk and play with a young male about the same age.
Fouts, a psychologist at Central Washington University in Ellensburg, said his findings are based on analyses of the apes' interactions as recorded by a video camera when no humans were present. The animals are housed in an indoor cage on campus.
Fouts said that Washoe's first attempt to teach Loulis involved the command to "come." Washoe made the gesture and, when Loulis did not respond, Washoe walked to Loulis and pulled the baby chimp to her. After several attempts, Loulis caught on and would come when Washoe made the sign.
Once, when the apes were about to eat, Washoe taught Loulis the sign for "food" by molding the younger chimp's hand, with the fingertips together, and tapping them against its lips -- the standard sign for "food," which Washoe had learned years earlier.
Loulis also appears to have learned some vocabulary simply by imitating Washoe or the other chimps. Loulis' most complex sentences are messages such as "hurry, come tickle" and "give me that hose," a reference to a water hose with which the young chimps play.
Fouts said Washoe also appears to have learned new words from the three chimps trained elsewhere.
Fouts said there is reason to believe that the chimps' use of a simple language has made their social life more placid than might otherwise be the case. He said that when Dr. Jane Goodall visited his facility, she was struck by the chimps' low level of physical aggression compared with that of the chimps she has studied in the wild.
In a related presentation, scientists were told about a 7-year-old orangutan learning sign language at a Tennessee university. The orangutan asked to be taken for a car ride, brought along money it had earned for keeping its room clean and, the scientists were told, gave the driver directions to the local Dairy Queen.