Introduction

Laboratory studies of mirror self-recognition (MSR) using Gallup's controlled method of face marking under anesthesia (Gallup, 1970) have yielded positive results for chimpanzees and orangutans, but negative results for gorillas (Ledbetter & Basen, 1982; Suarez & Gallup, 1980). In contrast, both observational and informally controlled studies of the language-trained gorilla Koko have yielded positive results (Patterson & Cohn, SAAH17). In this chapter, I report observations of mirror-stimulated behaviors in a group of gorillas at the San Francisco Zoo and in a group of chimpanzees at the Oakland Zoo, which support the hypothesis that gorillas in general are capable of MSR.

Observations on gorillas

At the time of my first observations (in 1978) the gorilla group at the San Francisco Zoo was composed of an adult silverback male, Bwana; his 5-yearold son, Sunshine; his 3-year-old son, Mkumbwa; Sunshine's mother, Mrs.; Mkumbwa's mother, Jacqueline; and an adult nulliparous female, Pogo. During these observations, the animals were moving freely in and out of their night cages where they could see a 15 × 60–inch mirror I had set up outside the cage. During the hour that they had access to the mirror, I took ad-lib notes on any animal that was looking in the mirror.

On this occasion, the female Pogo inadvertently marked her own face with fingerpaint when she put her face down on the cardboard she had been marking. She subsequently looked in the mirror and wiped the paint off with her hand.