The story begins one million years in the past: 1986 A.D. Mary Hepburn and her husband Roy were supposed to attend the maiden voyage of the wildly publicized Bahía de Darwin, a cruise ship ("The Nature Cruise of the Century!") that takes tourists and sightseers to the famous Galápagos Islands off the coast of Ecuador. Unfortunately, Roy dies from a brain tumor shortly before the cruise. So it goes.
Mary, grief stricken, takes the flight to Ecuador to honor the commitment she made with her husband. Also attending the cruise are American con artist James Wait, Japanese inventor Zenji Hiroguchi and his pregnant wife Hisako, American financier Andrew Macintosh and his blind daughter Selena, and an oddball assortment of other characters. Unfortunately for the passengers, the captain crashes the boat on the island after a storm and strands them there without much hope for rescue.
Following a series of events including a worldwide financial crisis, a disease which renders all humans on the planet (except the shipwrecked survivors) infertile, and a looming nuclear war, this group of mismatched tourists suddenly become the last fertile members of humanity, and thus the progenitors of a whole new and totally different human race.
This novel is Vonnegut's take on Darwin's theory of evolution, human nature, and other topics. The novel makes mention of the problems associated with "the oversized human brain," which Vonnegut argues as the source for a lot of humanity's problems (e.g. humans lie, cheat, and fight one another because their advanced brains give them the capacity to do so).
This work provides examples:
- Anachronic Order: Vonnegut just loves this trope. The narrator will constantly throw out tidbits about what the future is like left and right.
- Adam and Eve Plot: Sort of... just replace Adam with a drunk, racist sea captain and Eve with six pre-teen girls (the last of an isolated tribe from the rainforest) and a fur-covered teenager who looks like Chewbacca, and then throw in a blind girl, a depressed Japanese woman, and a suicidal widow, and you've pretty much got the cast. At least it tries to avoid Hollywood Science.
- Anti-Climax: Vonnegut actually goes so far as to point out which characters will die. Considering the novel takes place over about a million years, this is all of them. However, he also makes note of when characters die, and how soon in relation to the immediate plot.
- Apocalypse How: A little of column 3a, a little of column 3b — the human species dies out over the majority of the Earth except for one group that evolves into non-sapient seal-like animals, due to a combination of natural causes (a plague) and artificial ones (a nuclear war).
- Better Than Sex: Colonel Reyes launches a missile from his aircraft and tells his friend that the experience felt better than sexual intercourse.
- The Cameo: Dwayne Hoover, the main character of Breakfast of Champions, briefly turns up in a flashback when he hires a young James Wait to mow his lawn, which results in Wait having an affair with Hoover's wife and fathering her child.
- Crapsack World: In the far distant past of 1986, the world is on the verge of World War III, most countries (including Ecuador, Peru, Turkey, Mexico, and more) are all starving to death. Keep in mind this book was written in 1985.
- Depopulation Bomb: Humanity goes extinct outside of the Galapagos (both then, and forever and ever) due to a bacteria which feeds only on the ovaries of humans that evolved at a book fair in Germany.
- Dumb Is Good: According to the narrator, all the problems of the human race are caused by humans' oversized brains.
- Evolutionary Levels: Averted, the future surviving humans look like little more than seals, and have the intelligence to match.
- Foregone Conclusion: The human race all dies out, except for these seal-people on one island of the Galapagos. The author even marks those who are going to die with a big, fat star in front of their names.
- Humans Are Bastards: Apparently, yes. The narrator states continually through the book how our sentience is the root of our problems and considers their future forms — hands sealed up in flippers, redundant big brains atrophied by evolution — to be an improvement.
- I Love Nuclear Power: Little Akiko's fur coat is due to radiation her grandmother received in the Hiroshima bombing.
- In Your Nature to Destroy Yourselves : Hey, it's a Kurt Vonnegut novel. This trope is pretty much a given.
- Just Before the End: Humanity is about to be wiped out by a bacteria, but none of the characters know this.
- New Eden: Future humanity's existence can be considered this... if not for the fact that they'll never know it, having lost the capacity to even conceive the word "Eden". Indeed, by the end, the narrator describes it as an endless safari.
- Oh, and X Dies: Characters who'll die soon are marked with an asterisk before their names.
- Our Ghosts Are Different: They are human souls who refuse to go into the afterlife (well, until they get bored), can read minds, and can manifest from time to time. The narrator is one.
- Only You Can Repopulate My Race: The entire future human race. And there is inbreeding. A lot of inbreeding, though the effects are met head-on.
- Painting the Medium: The narrator muses that his father — the science fiction author Kilgore Trout — would sometimes try to get his books adapted as movies, but they were always scuppered by having one vital scene that could never be included in a film. Then he describes how, after sex with the ship's captain, the island's only adult woman extracts his sperm from herself and impregnates the girls with it. No Galapagos movie, then.
- Posthumous Narration: The entire story is told by Leon Trout (the estranged son of Vonnegut's recurring character Kilgore Trout) who died during the construction of the ship that brought the original colonists to the islands.
- Sterility Plague: The bacteria that destroys the ovaries of every woman on Earth, except for the ones who make it to Galapagos.
- Stupid Future People: The castaways' descendants end up evolving into non-sapient animals. It's argued for the better in this case.
- Transhuman Aliens: The human race by the end of the novel looks like, well, seals. They lack language and technology, have flippers for hands and feet and long snouted skulls, become fertile at six and rarely live past thirty.
- Unreliable Narrator: The ghost telling the story frequently inserts his criticisms of his cast, as well as diatribes against the human brain. Of course, by telling the story at all, he exempts himself, as he's already dead.