Koko signs “(lower) fake tooth” as a request for one of her human friends to come see her in the yard.
The sign “fake tooth” originated with the late Barbara Hiller, a co-founder of the Gorilla Foundation, who had several gold-capped molars that Koko found fascinating.
Koko later differentiated this sign into two signs: “lower fake tooth,” referring to the small circle of caregiver friends who work in her immediate vicinity; and “upper fake tooth,” referring to the wider circle of volunteers and staff who work in the research office up the hill from her quarters.
Fascinating!
