Project Nim, a recent documentary, popularized the story of a scientist who raised a newborn baby and a newborn chimpanzee together in the 1970s, looking for similarities, but this was not the first time such an experiment was attempted. In 1931, Winthrop Niles Kellogg and his wife had a son, Donald, and a "daughter" Gua. Donald was 10 months old at the start of the experiment; Gua was a seven-month-old chimpanzee, acquired from a local primate center. They were raised in the same house, in the same way. Both were fed, diapered, and casually taught in the way all parents try to teach their kids basic language and motor skills. Doctor Kellogg, a psychiatrist, studied how both babies developed, and periodically gave them tasks to complete.
The overall study, called The Ape and the Child, is of more historical than scientific interest. Gua developed, physically, a great deal faster than Donald did. Gua imitated adult behaviors, wearing shoes, opening doors using the door handle, and feeding herself with a glass and a spoon. The chimp also outperformed the human when it came to physical tests. Kellogg would, for example, shut each child in a room with a cookie suspended on a string and time how long they took to grab the cookie down.
What really worried the Kelloggs was that Donald didn't seem all that interested in outperforming Gua in verbal trials. Although the infant did better, he lagged behind other babies when it came to speech. (Fortunately, he took to toilet training well even when Gua did not.) Eventually, he started imitating the instinctive hunger barks that Gua made. The parents were no longer interested in using their baby as a control. The experiment was stopped after nine months, and Gua was returned to the primate center where the Kelloggs had acquired her.