" People are animists by nature, always interpreting reality in their own image. It starts early when children freely ascribe inner lives to clouds, trees, dolls, and other objects. This tendency is commercially exploited with pet rocks, chia pets, and Tamagotchi, which show remarkably little resemblance to the usual recipients of human love. The phenomenon is not even limited to our species; chimpanzees, too, care for imaginary young. Richard Wrangham observed a six-year-old juvenile, Kakama, carry and cradle a small wooden log as if it were a newborn. Kakama did so for hours on end, one time even building a nest in a tree and putting the log into it on its own. Kakama's mother was pregnant at the time. The field-worker notes: "My intuition suggested a possibility that I was reluctant, as a professional skeptical scientist, to accept on the basis of a single observation: that I had just watched a young male chimpanzee invent and then play with a doll in possible anticipation of his mother giving birth. "
― Frans de Waal , The Ape and the Sushi Master: Reflections of a Primatologist