Old Man's War sits in the military science fiction genre but themes of the ethics of life extension, friendship, marriage, the significance of mortality, what makes one human, and individual identity are present within the novel.
[13] Aging plays its biggest role near the beginning of the novel with the CDF being able to find a way to reverse the effects of aging.[
citation needed] The themes of marriage and friendship are explored in the characterization of John Perry through his continued love of his dead wife and his later meetings with Jane.
[14] When it comes to identity and humanity John Perry is the focus of attention and his characteristics by the end of the novel determine whether or not the reader believes John Perry is still human.
Synopsis[edit]
John Perry, a 75-year-old retired advertising writer, joins the Colonial Defense Forces who protect human interplanetary colonists. Volunteers sign letters of intent and provide DNA samples at age 65, which John and his now deceased wife Kathy had done ten years prior to the beginning of the story. After visiting his wife's grave to say goodbye (as volunteers can never return to Earth), Perry takes a
space elevator to the CDF ship
Henry Hudson, where he meets Thomas, Jessie, Harry, Alan, Susan and Maggie, fellow retiree volunteers. They dub themselves the "Old Farts".
Following a series of sometimes unusual psychological and physical tests, Perry's mind is transferred to a new body based on his genetic material. His new body is a younger version of himself, but
genetically engineered with enhanced musculature, green skin, and yellow cat-like eyes. He now possesses enormous strength and dexterity,
nanobot-enhanced
artificial blood, enhanced eyesight and other senses, and most critically, a
BrainPal—a neural interface that, among other capabilities, allows Perry to communicate with other members of the CDF via thought.
