The Hairy Ape by Eugene O'Neill centers around a working-class character, Yank. Yank represents the paralysis of the industrial worker in 1922, though the themes of isolation, paralysis as related to class structure, and regression of humanity still make the play relevant.
Yank is described as a strong and brutish character, similar to that of an animal. He is used as a fireman on a Transatlantic Ocean Liner for the upper class. On the ocean liner he is ignored by the rich, and he is misunderstood by the poor men he works with. A sense of isolation exists as a theme in the play and as a characterization of Yank, himself.
Yank is paralyzed in his position as an animalistic worker that is used to drive society but is ignored by it. O'Neill uses Yank to describe the essential recession of humanity. Industrialization turned humans into beings more resemblant of animals than intellectualized beings. His argument is not only that the poor industrial workers are animalistic, but that the rich are also animalistic for failing to understand their human counterparts. Mildred is an example of this fact in the play, as she professes her need to help the poor but is unable to truly connect with classes other than her own.
O'Neill's play describes the unique tragedy of industrialization. Society drove forward and developed great technological achievements, but humanity regressed into a class structure that resembled animal hierarchy. Yank is pulled into a gorilla's cage and killed in the end of the play, symbolizing the impossibility of breaking free of our predetermined place in society.