Koko the Gorilla: A Story of Intelligence, Love, and a Powerful Message for Humanity

On July 4, 1971, amidst the celebrations of Independence Day in the United States, a baby gorilla was born at the San Francisco Zoo. She was named Hanabiko, meaning “fireworks child” in Japanese, later affectionately shortened to “Koko.” No one could have foreseen that this tiny gorilla would grow up to revolutionize humanity’s understanding of animal intelligence, emotions, and communication.

A Difficult Start

Koko’s early life was far from easy. As an infant, she fell ill and had to be separated from her mother for medical treatment. Tragically, when she was reintroduced to her mother, she was rejected. Alone and isolated, she was placed in a cage with unfamiliar gorillas. Her only source of comfort was a plush toy gorilla that she treated as a surrogate mother, often hugging it for reassurance during her difficult early years. For months, Koko lived in a small, temporary enclosure at the zoo with little enrichment, making her early days particularly lonely.

But fate had extraordinary plans for Koko. In 1972, a young graduate student from Stanford University named Francine “Penny” Patterson took an interest in her. Penny was conducting PhD research on communication with great apes and wanted to teach a gorilla sign language. At the time, gorillas were not considered particularly intelligent compared to other primates, and many viewed them as aggressive animals. Penny’s experiment would challenge and ultimately change these assumptions forever.

Learning to Communicate

Teaching Koko sign language was no easy task. Unlike humans, who can have their hands guided into the correct positions, Koko refused to let anyone touch her. Penny had to patiently show Koko objects and repeatedly demonstrate the corresponding signs over and over again. Despite the challenges, Koko proved to have an extraordinary ability to learn. By the age of three, she had mastered around 200 signs in American Sign Language (ASL). Over time, her vocabulary grew to over 1,000 words, and she could understand even more.

Koko didn’t just learn the names of objects; she could express emotions and comment on what she saw. For example, when shown a picture of another ape about to take a bath—something Koko disliked—she signed, “I cry.” Upon seeing a horse with a bridle in its mouth, she signed, “Horse sad teeth.” These moments demonstrated her ability to empathize and understand the world around her in ways previously thought impossible for animals.

Koko also displayed a remarkable sense of humor. Once, she jokingly called herself a “good bird” and claimed she could fly, only to admit she was kidding. On another occasion, she mischievously pulled Penny’s hair, then laughed and signed an apology. These examples revealed that Koko possessed what scientists call “theory of mind”—the ability to understand that other beings have thoughts and feelings different from her own.

Her linguistic creativity was equally astonishing. If she didn’t know the name of an object, she invented one by combining familiar words. For instance, she called Penny’s ring a “finger bracelet,” a logical description for a ring. She referred to a mask as an “eye hat” and coined the term “cold candy” for ice cream. These moments proved that Koko wasn’t just memorizing signs; she truly understood their meanings and could creatively combine them to express new concepts.

A Life of Love and Loss

One of the most touching chapters in Koko’s life was her deep affection for kittens. For her birthday in 1984, she made a special request: she wanted a cat as a gift. Her caretakers brought her several stray kittens to choose from, and Koko carefully examined each one before selecting a small, tailless gray kitten she named “All Ball.” Despite her enormous size, Koko was incredibly gentle with her tiny pet, carrying him on her back, hugging him, and even attempting to nurse him.

Tragically, later that year, All Ball escaped from the enclosure and was hit by a car. Koko’s reaction to the loss stunned even seasoned scientists. Upon hearing the heartbreaking news, she sat in silence, seemingly in shock. Then, she began making soft moaning sounds—the deep, sorrowful vocalizations gorillas use to express grief. She signed words indicating sadness, such as “bad” and “sad,” and repeatedly signed “sleep cat,” as if trying to come to terms with the fact that her beloved friend had fallen asleep forever. For days, Koko displayed profound grief, refusing to play, withdrawing socially, and even losing her appetite.

Over the years, Koko adopted several more kittens, including Smoky, Lipstick, and others, demonstrating her enduring love for caring for small animals. Her ability to experience loss and express sorrow made her seem even more human.

A Window into Her Inner World

Koko’s intelligence extended far beyond language. She could draw at the level of a four-year-old child, sketching her favorite toys and elements of the world around her. She even passed the mirror self-recognition test, immediately recognizing herself in her reflection—a feat most gorillas cannot achieve.

She loved watching movies, with her favorite being Tea with Mussolini. Emotional scenes deeply moved her, and she often turned away during sad moments to avoid becoming upset. She also had a special fondness for Mr. Rogers’ Neighborhood. When she met Fred Rogers in person, she immediately recognized him and signed “love” while touching his sweater.

Understanding Death

One of the most fascinating aspects of Koko’s personality was her understanding of death. When shown a skeleton and asked if it was alive or dead, she signed “dead.” When asked where dead gorillas go, she signed “comfortable hole” and blew a gentle goodbye kiss. These moments revealed a profound awareness of mortality and left many wondering just how deeply Koko grasped the concept of life and death.

A Message for Humanity

In her later years, Koko became an ambassador for nature, urging humans to take better care of the planet and its creatures. She once signed a chilling message: “Nature is watching you. Fix Earth. Help Earth.” It was as if she understood the fragility of the world and felt a sense of responsibility for her fellow gorillas still living in the wild.

A Peaceful Goodbye

On June 19, 2018, just weeks before her 47th birthday, Koko passed away peacefully in her sleep. Her caretakers noted that she had spent a calm day surrounded by those who loved her. Her passing was mourned by millions around the world, and her legacy continues to inspire efforts in conservation and research.

Koko’s Legacy

Koko’s story remains one of the most extraordinary examples of interspecies communication, emotion, and intelligence ever recorded. She showed the world that animals are capable of love, humor, grief, and even philosophical reflection. Her final message to humanity—urging us to protect the Earth—serves as a powerful reminder of our responsibility to care for the planet and all its inhabitants.

Koko’s life was a testament to the incredible bond that can exist between humans and animals. Her story reminds us that intelligence and emotion are not exclusive to humans and challenges us to see the world through a lens of compassion and respect for all living beings.