In 1979, Sue Savage-Rumbaugh, had started using a bonobo named Matata in her studies. Matata was the first bonobo to be used in these studies and it was expected that she would do well as bonobos were thought to be generally more intelligent than common chimpanzees but the results were not encouraging. (1) Her adopted son Kanzi, however, seemed fascinated by the keyboard that she  was trying to learn to use. (2) At about the age of two, Kanzi began to spontaneously use the keyboard to initiate a game of "chase". (3) At this point Matata had spent 2 years on language training and mastered very few lexigrams. She would become frustrated with the fact that she couldn't seem to make her trainer understand what she wanted. It was thought that Matata's problem was that she started language training at the age of 10 years, possibly too old for language acquisition.

On the first official day of language training, Kanzi astonished his trainers by knowing and using several keys on the keyboard correctly to name items and to announce his intention. It appeared that although his adopted mother Matata never mastered the keyboard, Kanzi had been paying attention. (4) After 17 months, Kanzi had a vocabulary of about fifty symbols and was regularly using combinations of words. Unlike some other apes, Kanzi's multi word utterances seemed to reflect real comprehension and 90% of these were spontaneous. (5) Rumbaugh also believed that many of Kanzi's communications had a character of novelty and functioned to suggest completely new actions and alternatives to the normal way of doing things. He also used three world utterances to indicate someone other than himself as the agent or recipient of an action such as tickle or chase. (6)

The next major breakthrough that Rumbaugh noted was that Kanzi seemed to be capable of understanding human speech. This fact was amazing in itself but seemed even more incomprehensible because there was no attempt to train Kanzi to understand spoken language.

This wasn't a new concept. Understanding of human language was reported with Washoe and other apes but was refuted by Herbert Terrace in 1979. (7) In response to this, Rumbaugh reported:

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