Death Announcement of Celebrity Gorilla Sparks Debate on Her Sign Language Abilities

The announcement of the death of Koko, a famed gorilla, has revived previous debates on her American Sign Language (ASL) skills. The western lowland gorilla, who died last June, rose to fame for her ability to communicate using ASL. Francine Patterson, an animal psychologist, began training Koko to use a version of ASL when she was around a year old. According to her instructors, Koko used ASL as a means to express her thoughts and emotions. Koko was also reportedly able to grasp around 2,000 spoken English words and could communicate using 1,000 signs. Upon the announcement of the gorilla’s death, several news organizations highlighted Koko’s mastery of ASL. However, some language experts and scientists doubted Koko’s ability to communicate using ASL. They emphasized that Koko did not really learn ASL but rather a modified version of signs used in ASL. They added that most of Koko’s signs were derived from conventional gestures. Herbert Terrace, a scientist who also taught sign language to a primate, said that Koko’s interactions with trainers and caretakers did not occur spontaneously and were probably prompted. In 2015, NGOs Gorilla Foundation and NOE Conservation produced a video for the COP21 Climate Change Conference in Paris. The video showed Koko using ASL to explain the value of protecting nature. However, the video’s press release stated that Koko’s “speech” was scripted and that she was given a briefing on climate change. While biological anthropologist Barbara King believes that Koko could grasp unique signs and gestures, she asserted that there is no proof of Koko’s ability to understand complex ecological concepts.