The incredible story of the gorilla who was able to express her thoughts and feelings through sign language.

Every now and then, an animal comes along who gains more fame than most human celebrities.

Sometimes it’s for their looks, or for their dance moves. In other cases, like Koko the Gorilla, an animal is so special, that they force us to question our understanding of the world around us.

Koko the Gorilla attracted attention from a young age: when she began to learn sign language. She was able to pick up the signs for more than 1,000 words: a vocabulary similar to that of a human toddler.

On top of that, she could understand 2,000 words of spoken English. American sign language can be difficult for even humans to learn, so how could a gorilla pick it up so easily?

What methods were used to teach her? Why did some doctors regret giving her this skill? And what did she teach us about gorillas?

Koko was born in 1971, at the San Francisco Zoo, where she met Dr. “Penny” Patterson, a researcher who believed that gorillas could communicate with humans. Gorillas already communicate with each other using gestures, so Penny believed that sign language wouldn’t be much of a stretch.

When Koko was just 1 year old, she was already learning how to sign simple words like “food,” “drink,” and “more.” By the time she was 4 years old, she had learned more than 200 words! So what did these lessons look like? Well early on, Penny employed a combination of molding and modeling techniques to demonstrate the different signs. Molding is where you shape somone’s hands to make the sign, and modeling is where you illustrate the sign by doing it yourself.

As Koko grew up, Penny made sure to surround her with sign language. All the caregivers at the zoo would sign to each other, and say the words out loud as well so Koko could observe and absorb.

The hard work continued to pay off, as Koko started learning complex signs about abstract concepts like memories and stories. On top of that, since the doctors would always talk to her while they signed, she began to understand spoken English. In an odd way, that ended up working against them: as she learned more spoken words, the doctors could no longer have private conversations around her.

Skeptics often claim that Koko was only mimicking the signs to get rewards, but years of research showed that not only was she using the language in a sophisticated way, but she was even inventing her own signs for things she never learned.

Throughout her life, Koko’s incredible communication abilities taught humans that gorillas are much more emotionally complicated than we thought. That they care about the well-being of other gorillas, and even of their human caregivers. They’re capable of grief, reasoning, humor, and even love for other species, as demonstrated by Koko’s obsession with her pet kittens.

She had at least four little kitties over her life, naming each one herself, from “All ball,” to “Lips lipstick.” When her first kitten passed away, she demonstrated human-like mourning as she signed “cry, frown, sad, trouble.”

So, while we might just view them as animals in the zoo, Koko showed us that gorillas are capable of so much more, and that’s why she’s a Crazy Creature!