One of the novel’s core themes is the coming-of-age journey or bildungsroman. The novel’s status as a bildungsroman encompasses more than one character, for it includes both Sophie’s experience of trying to reunite with her mother and Otto’s experience of becoming an independent bonobo. Thus, despite being different species, both adolescents transition from child to adult by overcoming the same experiences during their journey. At the novel’s beginning, both Sophie and Otto depend on the adults around them to make decisions. Sophie initially feels like an adult when video-chatting with her father, as if being on the other side of the world from him makes her independent. However, her impulsive decision to buy Otto demonstrates her immaturity and lack of understanding about how the world works. Sophie later reflects, “It was my buying Otto that encouraged the man to come here with these two more bonobos. I sat down right where I was. My legs refused to hold me up” (35). Her residual childishness is further demonstrated in the fact that, despite knowing that she made the wrong decision, Sophie only assumes responsibility for Otto’s care when Florence insists upon it. As Sophie navigates her new role as Otto’s mother, the young ape has his own struggles to overcome as he tries to adapt to his new surroundings and regain his health.