Koko, The Famous Gorilla Who Used Sign Language, Has Died

This past Tuesday, the western lowland gorilla known as Koko died at age 46. Koko was famous for her ability to speak sign language and for her emotional depth and intelligence. Over the course of Koko’s life, she became something of a worldwide celebrity. Koko was capable of understanding more than 2000 words of English and communicating with over 1000 different signs.

The impressive language Koko possessed made her the most notable member of her entire species, the Western lowland gorilla which is currently classified as critically endangered by the International Union for Conservation of Nature. Koko’s ability to communicate and understand various forms of language made her valuable to conservationists and scientists who studied the abilities of the great apes.


The Life Of Koko

Barbara King, a professor of anthropology from the College of William and Mary, explains that Koko shed a vast amount of light on the cognitive abilities of the great apes. Says King of Koko:

Because she was smart enough to comprehend and use aspects of our language, Koko could show us what all great apes are capable of: reasoning about their world, and loving and grieving the other beings to whom they become attached.

Koko was initially taught sign language by researcher Francine Patterson in 1972. While she lived the first years of her life at San Francisco Zoo, Koko was soon moved to Stanford where Patterson and collaborator Ronald Cohn would work together and create The Gorilla Foundation. The Gorilla Foundation relocated to a facility in the Santa Cruz Mountains during 1979 and Koko went with them.

Koko played an integral part in learning what we now know about the language skills of gorillas, that they have language abilities similar to that of small children. The fact that Koko was taught sign language allowed her to communicate with researchers and for researchers to learn a great deal about her thoughts and feelings, something that wasn’t possible when researchers relied solely on verbal communication (which is significantly more one-way). The research revealed that gorillas had emotions similar to humans. Koko seemed to love a kitten she adopted, and appeared genuinely distraught when learning of the pet’s death, signaling that she was “sorry” and “crying”.


Research conducted with Koko even suggests that she may have had a sense of humor. According to an article published by Slate, when Koko was asked “what can you think of that’s hard?” she replied with both “rocks” and “work”. Koko reportedly even once tied the shoelaces of her trainer together and then asked her trainer to “chase” her.

Koko maintained a close relationship with her trainer Patterson all throughout her life. The two would converse with one another, play games together and Patterson would also prepare meals for Koko.

Animal Languages

Koko’s astonishing language abilities and emotional depth challenged old dogmas that animals didn’t have language abilities or emotionally rich lives. While debate continues to rage about the level of language that animals like chimpanzees and meerkats possess, Koko’s use of sign language inspired not only more research into the language abilities of the great apes, but also research into the language abilities of other animals.

In the decades since Koko began using sign language to communicate with researchers, substantial research has been done on the vocalizations of African forest elephants, bottlenose dolphins, and prairie dogs. Some linguists, such as Noam Chomsky and Steven Pinker, contend that research into animal language has largely exaggerated the degree to which animals can be said to have “language”, describing it as an artifact of both a human tendency to anthropomorphize animals and animals learning to respond to humans in a way that may elicit positive rewards.  The point is worth considering. Though controversial among scientists as to whether animal communication can really be called “language” in the sense that we use it, Koko certainly played a large role in inspiring research into animal communication.

There were attempts by The Gorilla Foundation to get Koko to mate with other gorillas, potentially passing on her astonishing gift for language. However, all these attempts were unsuccessful.


The Western Lowlands Gorilla

Koko also played an important role in the increasing awareness of the public about the costs of human activity on wild gorilla populations and the costs of research on individual animals. King says it’s important to remember that Koko’s impressive linguistic abilities manifested only a result of the highly unnatural way she was raised, in confinement away from natural habitats.

Koko’s species, the western lowland gorilla, Is a subspecies of the Western guerrilla that lives within the lowland swarms and secondary forests of central Africa in countries like Equatorial Guinea, the Central African Republic, Cameroon, and the Republic of the Congo. The gorillas favor swampland where food is more plentiful in both the wet and dry season than other areas of Africa. They typically eat things like tree bark, wild celery, fruit, shoots, and roots.

A female western lowland gorilla with her young. Photo: By Greg Hume – Own work, CC BY-SA 3.0,

Gorillas are not normally kept in captivity, though the western lowlands gorilla is an exception to this rule. The western lowland gorilla has displayed many different forms of intelligence outside of the use of language. The species has been documented constructing tools out of natural material to help them collect food, such as sticks to reach ants or the use of a stick to measure the depth of water.

Human activity has threatened populations of the western lowland gorilla, as well as other gorilla species. Like other large animals in Africa, the gorillas are often hunted for meat that is sold in the bushmeat trade. Logging operations as well as the destruction of swampland for construction projects have eliminated much of their habitat and placed a heavy strain on the remaining gorilla populations. Gorillas are also vulnerable to outbreaks of diseases like ebola, and the combined threat of disease, deforestation, and poaching has devastated gorilla populations across equatorial Africa. There are only somewhere between 50,000 to 125,000 individual lowland gorillas across Africa, with the World Wildlife Federation’s official estimate coming in at 100,000 individuals.

A statement released by the Gorilla Foundation said that it would “continue to honor Koko’s legacy” by exhaustively researched sign language and other forms of communication in the great apes, and also by backing conservation projects in Africa and around the world.



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