Basic Trope: A species of sapient beings regresses to an animal-like state.
- Straight: After the apocalypse, humans become non-sapient, chimp-like predators.
- Exaggerated:
- All that's left of post-apocalypse humanity is vegetative Meat Moss descended from free-growing tumors.
- All sapient species in the story's world regress into an animalistic state.
- Downplayed:
- After the apocalypse, humans become dim, caveman-like beings with only simple tool use and language.
- A species of cunning, tool-using animals evolves to become less intelligent.
- Justified: The post-apocalypse humans adapt to life as patient ambush predators, where off-the-cuff problem solving isn't as important as metabolic efficiency.
- Subverted: The post-apocalypse humans regress to a caveman-life lifestyle and seem poised to descend into a fully primordial state, until one tribe redevelops the use of fire and invents complex tools again.
- Double Subverted: The tool-using tribe dies in a plague epidemic, and the remaining posthumans keep going as before.
- Inverted: An animal species evolves sapience.
- Averted: The setting's humans are not depicted as losing intelligence, language skills or tool-use.
- Defied: The survivors of the apocalypse note a very worrying trend in how more and more culture and technology is being lost, and try to preserve as much active culture as they can.
- Zig-Zagged: A cycle emerges where sapient civilizations arise and collapse, their survivors become animals, some of these animalistic offshoots re-develop sapience, and their civilizations eventually fall and restart the process.
- Played for Drama: The work uses humanity's loss of sapience as a means to philosophize about human nature, the blind march of evolution, and what qualities make or define a person.
