Kellogg and his wife brought a seven-and-a-half-month-old female chimpanzee, Gua, to their Florida home with the intention of observing the similarities and differences in development between Gua and their human son, Donald. At the time their son, Donald was ten months old
Gua was treated like an infant in every detail; she was dressed in napkins and later in rompers, wheeled in a carriage, sat in a high chair, and slept in a bed. The Kelloggs kissed her goodnight every evening. No special effort was made to teach her spectacular stunts but rather to expose her to the same kinds of experiences a human baby would have. The experiment was carried on for nine months with careful day-by-day observations, films, and tests.
Gua displayed many human-like behaviors; she wore shoes and walked upright, ate with a spoon and drank from a glass, and imitated human gestures, acquired the ability to open doors. In some ways she surpassed Donald – especially in the motor skills of climbing and jumping, – but in other ways she lagged behind him developmentally.
Gua also quickly learned to respond to a total of ninety-five words and phrases such as ‘kiss Donald’, ‘shake hands’, and ‘show me your nose’. However, she never could learn to utter words or phrases beyond those which communicated her immediate wishes through grunts and squeals. Her toilet training lagged behind that of the boy significantly.
It became evident by the end of the experiment that Gua was falling behind the boy, particularly ‘in the matter of intellectual adaptation to human demands’. The early superiority is attributed to the fact that anthropoids in general mature earlier than humans. A monkey reaches puberty at about four years, whereas humans reach puberty between twelve and fourteen on average, with girls generally reaching puberty before boys.
It is interesting to note that even though animals can be trained and socialized to a certain extent, there are still limits to how much they can imitate human behavior. This was evident from the experiment conducted by Dr. Kellogg and his wife, where it was shown that while an animal can learn to interact with humans, there are some things that will always remain beyond their understanding.