Language

• Language has long been seen as the province of humans alone. Children pick up language naturally when exposed to it from an early age, and even though they make many grammatical and syntactical errors at first, they quickly come to understand and express language correctly long before adulthood. Many species communicate with each other---bees dance to indicate the direction of a pollen source, birds sing to attract a potential mate, prairie dogs emit a particular bark to signal the proximity of a predator---but most scientists do not regard these instinctual behaviors as language like human speech. Since all attempts to teach primates to speak have failed (perhaps because apes are unable to use their lips and tongues to produce it), some researchers have chosen American Sign Language (ASL) to establish inter-species communication, as well as learn more about language itself.
  
  

ASL

• ASL, or American Sign Language, was developed first in Europe and later in the United States so that the deaf could communicate with each other and hearing people. It is a rich and complex language spoken through hand gestures, body movements, facial expressions, and finger spelling. Because primates already use this kind of behavior to communicate with each other in the wild, mid 20th-century scientists theorized that it would be easier and more natural for primates to learn.
  
  

Washoe

• In the 1960s Washoe, a female chimpanzee, was raised in the home of researchers Allen and Beatrix Gardner as if she were a deaf human child. She was taught American Sign Language and over the course of four years learned 250 unique signs. The Gardners reported that Washoe even created new words, such as "water bird" when she saw a swan on a lake. She also renamed objects, calling the refrigerator "open food drink" instead of "cold box" as the researchers taught her. Washoe's adopted son Loulis picked up his mother's signing abilities by simply observing her and the three other chimpanzees that had been taught ASL from an early age.
  
  

Koko

• Koko the Gorilla can understand over 2,000 spoken words and gesture over 1,000 signs, according to developmental psychologist Dr. Penny Patterson, who has worked with Koko since 1972. There are many films and videos about Koko, and even an Internet chat in 1998. In this online conversation, Koko indicated that her favorite food was "apple drink". Koko has tried to teach sign language to her pet cats and stuffed toys, as well as her gorilla companions.
  
  

Controversy

• Many scientists believe that primates like Washoe and Koko are not really using language to communicate, but are simply forming stimulus-response chains in order to please their trainers or acquire food, much like dogs rolling over to obtain a treat. Other scientists believe that primates are capable of expressing their thought sand feelings through sign language and cite evidence of apes forming complex expressions by combining signs in unique and novel ways. The proponents of primate success point out instances of apes teaching sign language to other apes or of young apes learning sign language through observation. Opponents to this theory respond by claiming that primates are simply not equipped mentally to grasp the complexity and nuance of human language.