Koko, the Gorilla Signs Request for Surgery
Animal Stories from All-Creatures.org

By Jennifer Viegas, Discovery News
August 2009


Aug. 9, 2004 — Koko, a 33-year-old gorilla that was taught to communicate using American Sign Language, recently told her caregivers that she desired oral surgery to remove an aching tooth, which was extracted with success on Sunday. (To enlarge the photo of Koko pointing to her sore tooth, click on the link)

The unusual request likely marks the first time that an animal ever has used language created by humans to ask for surgery.

Lorraine Slater, development director of the Northern California- based Gorilla Foundation that houses Koko, told Discovery News that the lowland gorilla had been signing about tooth discomfort for a while before she communicated that the pain had become more intense in the past three to four weeks.

Slater said Koko's caregivers created a chart containing the numbers one through 10 with corresponding amounts of dots, as the gorilla responds to visual information.

Over the past several days, the researchers asked the gorilla on a daily basis to communicate her level of tooth pain.

"Sometimes the pain was rated a two or a three just after Koko was given medication," said Slater. "She then rated the pain as a seven and then an eight. We gave her the choice of having more medication or an operation, and Koko communicated that she desired the operation."

Slater explained that the gorilla knew what an operation was because caregivers previously gave Koko an "operation doll, similar to what young children play with," along with lessons about basic medical procedures.

"Koko in the past has told us that she was feeling under the weather, but this perhaps is the most dramatic example of her communication abilities concerning health," said Slater.

When asked if she wished to meet her doctors before the procedure, Koko said yes. On Sunday, a medical team consisting of doctors and veterinarians volunteered to examine the over 300-pound gorilla.

By all accounts, the doctors were star struck.

David Liang, an assistant professor of medicine at Stanford University who helped to conduct the medical exam, commented to the San Francisco Chronicle, "Koko's famous. It's not often that we get to work on a celebrity. Probably, Koko is less demanding."

Slater said Koko remained calm throughout the exam and even beckoned one of the doctors, who was wearing red, to come closer. Slater explained that Koko's favorite color is red.

The gorilla then signed that she wished to see the doctor's business card, which Koko examined before eating it.

"She didn’t eat anything before the surgery, so my guess is that she was very hungry," said Slater, who added that Koko now is eating baby food and doing fine, save for a bit of tooth pain.

Since the foundation was established in 1976, Koko has learned to sign over 1,000 words and she understands over 2,000 words.

According to her caregivers, the gorilla has a tested IQ of between 70-95 on a human scale, where 100 is considered "normal." Koko's companion Michael had a vocabulary of 600 words before he died four years ago.

Aside from her tooth troubles, Koko is in good shape, according to her doctors. The team that examined her on Sunday believes no medical problems should prevent her from siring children with her mate, Ndume.

Slater indicated that gorillas have given birth in their 40s, so motherhood may be in Koko's future.

"Koko is so admired that we hope to build a sense of care and concern for all gorillas, particularly as they are physiologically very similar to us," said Slater. "Somehow we need to build public momentum. With apes now being hunted to dangerously low numbers, it is critical that we all take a stand to save them from extinction."

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