 Gary uses the novel as a vehicle to denounce both racism and the activists supporting African @-@ American rights , including his own ex @-@ wife and Marlon Brando . He also examines whether human responses to situations , including racism , are learned social behavior and whether they can be <unk> . In 1981 , it was adapted into the controversial film of the same name , in which director Samuel Fuller made various changes to the novel 's story to focus more on the dog and present a more pessimistic ending than the original novel . The film 's American release after negative press from the National Association for the Advancement of <unk> People ( NAACP ) led to concerns of boycotts . 
