The chimpanzee taught American Sign Language by Allen and Beatrix Gardner was Washoe. Their pioneering project began in the 1960s and explored whether a chimpanzee could communicate through a visual language rather than spoken words.
The Gardners chose signing because chimpanzees lack the vocal anatomy needed to reproduce human speech clearly, but they naturally use gestures. Washoe was raised in a human-like environment, with caregivers communicating around her primarily through ASL. Researchers reported that she learned approximately 350 signs over her lifetime, although the exact counts varied according to testing standards.
Washoe’s work became a landmark in animal-language research. She was also reported to have taught some signs to her adopted son, Loulis, suggesting possible cultural transmission between chimpanzees.
The story remains scientifically debated. Critics argued that some apparent phrases could reflect prompting or interpretation rather than human-like grammar. That controversy does not change the canonical identification: the Gardners’ famous signing chimpanzee was Washoe.