The orangutan that learned sign language at the University of Tennessee was Chantek.
Chantek was a male hybrid Sumatran-Bornean orangutan born at the Yerkes Primate Research Center in Georgia. At nine months old, he moved to the University of Tennessee at Chattanooga, where anthropologist Lyn Miles led a long-term project exploring ape communication and cognition.
Raised in a highly human-oriented environment, Chantek learned signs adapted from American Sign Language and understood spoken English as well. Reports credit him with using around 150 signs, including combinations and signs he invented for unfamiliar objects. He reportedly called ketchup “tomato toothpaste” and used metal washers as money for completing chores, which he could spend on treats.
Chantek's story is sometimes mixed up with Koko, a gorilla, or Washoe, a chimpanzee; both were also associated with sign-language research. Chantek was unusual because he was an orangutan and because the project examined not only signing but also memory, categorization, tool use, social learning, and symbolic exchange. He later lived at the Yerkes center and Zoo Atlanta, where he continued communicating with caregivers until his death in 2017.