Koko, a gorilla said to have mastered American Sign Language, died in the US state of California at the age of 46 on June 19, 2018. Born at the San Francisco Zoo in 1971, Koko was said to have an IQ of between 75 and 95. The average IQ for humans is 100. | CGTN

Koko was a western lowland gorilla famous for her ability to understand and use sign language. She had formed a deep bond with her childhood companion, a fellow gorilla named Michael. When Michael passed away, Koko fell into a deep depression she stopped playing, smiling, and even signing as much. For six months, she barely expressed any joy. In 2001, Robin Williams was invited to meet Koko. Known for his boundless humor and heart, Robin entered the room and something incredible happened. Koko i