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Formerly Sapient Species

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Many works of Speculative Fiction explore the definition and nature of humanity, and how changing conditions, technology and culture may push our current understanding of what makes us human. Despite how far a given work's humans may vary from the norm, however, they will typically retain some measure of higher intelligence and technology. Still, some works go further than this and explore what would happen if the things we consider most central to our nature, our brains and tool-making intelligence, were stripped away as well.


The result of this is a creature, usually a human, that lost its self-awareness and higher intelligence and become a simple beast. Depending on the setting, this may be the extent of the modifications or the creature may also display any degree of physical changes — fur, increased or decreased size, altered proportions, claws and fangs, or anything else pertaining to whichever ecological niche it now fills. The most common version is a creature resembling a non-human primate or a Frazetta Man in appearance and behavior, but it's not entirely uncommon to see humans transformed into aquatic, seal- or whale-like creatures.

In certain cases, in inversions of humanity's usual relationship with beasts, animalistic humans may be paired with sapient animals who keep them as livestock and beasts of burden or hunt them like prey.


There are a few reasons for why a work might portray such beings. One is shock value and emotional impact. Intelligence and a status above that of other creatures are fairly central to how we view ourselves, and recognizably human creatures with no intelligence or awareness can be profoundly unsettling to deal with, both from an Uncanny Valley perspective and from the standpoint of seeing ourselves reduced to such a lowly status. Seeing humans kept as domestic animals, whether by the descendants of their own pets and livestock or by other humans, can also be very unsettling.

Another reason is to make a point about natural selection and subvert Goal-Oriented Evolution, especially the idea that humans are bound to become more "perfect" or intelligent over time. Animals routinely lose previously characteristic or advantageous traits when these cease to be useful or become too expensive to maintain — birds becoming flightless is a textbook example of this. Complex brains are enormous energy and resource sinks and it's entirely feasible that, in a situation where complex thought would not provide a clear survival benefit, natural selection would favor the loss of large brains, as less intelligent humans could then allocate the resources that would have gone into them somewhere more beneficial.


The primary issue with this concept is that sapience is a minor singularity in the system of evolution, a singularity being a point in a system where the normal rules no longer apply. Complex intelligence allows creatures to develop new behaviors and technologies to respond to changing needs and environmental pressures, negating significant advantages to long-term physical changes. Even a deficiency in sustenance, the one challenge tailored to sapience's only drawback, could be overcome by improving farming technology or even by directly removing whatever was causing the sustenance deficiency. Note, however, that isn't an absolute factor — a number of historic human societies are known to have died out or severely declined due to drastic environmental changes, for example.

While humans are the ones most commonly used in this, it's also possible to apply this concept to any sapient species. The concepts of downfallen grace, shock at formerly-intelligent beasts and unsentimental evolution can just as easily be applied to fantasy races or alien species.

See also Human Subspecies and Our Humans Are Different, as most examples of this are human. For less extreme versions, where humanity still regresses but remains sapient, see Future Primitive, Feudal Future, and Stupid Future People (and, looking from the opposite end, Advanced Ancient Humans). May overlap with Human Pet and People Zoo. See also Was Once a Man for instances where individuals are transformed into monstrous or degraded forms that may or may not still be sapient.

Contrast Transhuman, for situations where humans become more intelligent, as well as Uplifted Animal and Animal Is the New Man.


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    Anime & Manga 
  • Super-Conductive Brains Parataxis: Giant, unintelligent humanoids called "surdlers" are fitted with mechanical implants and used for construction and war. It turns out that they're the descendant of humans, while the "humans" in the story are Lilliputians.

    Card Games 
  • Magic: The Gathering: Long ago, much of the plane of Dominaria was ruled by the Elder Dragons, immensely powerful and intelligent beings who were often skilled magic-users and the rulers of entire humanoid civilizations. They eventually all but wiped themselves out in internecine warfare, with the losers being stripped of their legs and wings to become the wurms, mindless beasts resembling massive snakes. The winners also regressed over time; modern dragons, while still technically sapient, are little more than feral predators with lifestyles limited to hunting, gathering treasure and defending their territories, while some fell still further and became drakes, smaller creatures with no forelimbs and which are now purely animalistic beasts.

    Comic Books 
  • Sonic the Hedgehog (Archie Comics): Pre-Genesis Wave, the Tasmanian Devils used to be sapient alongside the other Mobian races but were subjected to genetic engineering by the Echidnas in ancient times, turning them bestial. By the present day, Thrash the Devil is the last of the sapient tasmanians and seeks to make the Echidnas pay for what they did to his kind.
  • The Books of Magic has a borderline example; in the far future that Mister E brings Timothy to, humans who have devolved into vaguely insectoid creatures and still have the power of using (simple) speech, but have lost all awareness of their history and all signs of advanced civilization have vanished. Instead their only concern is hunting for the food they call "sea spiders".
  • The Humans: Apes reign as the dominate species and humans (or "skins", due to their hairlessness) are animals used as manual labor, lab rats, pets, and so on.

    Fan Works 
  • Dungeon Keeper Ami: Chaotic magic can transform intelligent creatures into these, altering their bodies and minds until they count as "mindless neutral creature[s]".
  • Power Rangers Wing Force implies this to be the case with Goldar's species during his 10,000 years in the Dumpster.

    Films — Animation 
  • WALL•E: This was the original plan for the film. The titular robot's adventure would have brought him into the contact with a race of simple-minded blob creatures, with the end of the film revealing that said blobs were actually the descendants of the human race after fleeing Earth and spending too much time in zero gravity. Instead, the movie shows this trope in action — humanity is still human, but is gradually regressing and becoming fatter, lazier, and slower due to a constant reliance on machines and junk food. The animators explained that they wanted to make them resemble oversized babies to reflect the symbolic degradation of the human mind from complex to simple.

    Films — Live-Action 
  • The Descent: The characters trapped underground are continuously menaced by pale humanoid creatures known as crawlers. They're actually descended from cavemen which never left the caves, instead evolving into savage, Morlock-like predators that hunt by echolocation.
  • Planet of the Apes: In the ape-dominated future, humans have regressed into non-sapient creatures about as intelligent as chimps are today.

  • All Tomorrows has an alien species conquer a spacefaring human empire and genetically engineer the inhabitants of various colony planets into whatever forms pleased them as a form of grotesque punishment for their perceived crimes. The results were tremendously varied, including titanic elephant-like creatures, bat- and pterosaur-like fliers, various aquatic strains, ferocious predators and tick-like parasites. Many died out after the departure of the Qu, but others survived to form complex ecologies. Some of these post-humans eventually re-evolve sapience and rebuild a new galactic civilization, but others do not:
    • One population was genetically modified to never be able to develop sapience again and became domesticated pack animals to their own former livestock, a species of large lizards which independently developed sapience.
    • The mantelopes were unique in being left their sapience, but were modified to be essentially human ungulates with no grasping limbs. This left them entirely unable to manipulate their environment and their sapience largely useless. Natural selection eventually caused them to regress to animality — there was no use in growing large brains if they couldn't do anything with them, and as grazers they had no need to use their brains to find food since food was all around them. The book treats this as being largely a merciful end to their sorry lot.
    • Many strains simply never happen to redevelop sapience, and fade into animalistic obscurity.
  • Blindsight: Discussed. The aliens in the book, known as "scramblers", are highly intelligent but at the same time lack any form of sapience or self-awareness — everything they do is instinctive, up to and including constructing interstellar spacecraft. The same is true of the vampires, which are an anthrophagic offshoot of humanity. The narrator muses that self-awareness is, from an evolutionary perspective, wasteful and unproductive, and he wonders whether truly sapient species like humanity are doomed to lose their sapience in the long run.
  • Conan the Barbarian: After the cataclysm that destroyed the previous Thurian Age, several human groups (including King Kull's birth people, the Atlanteans), fall into savagery and devolve into animalistic ape-men shortly thereafter. Some later redevelop their old intelligence, and Cimmerians like Conan himself are explicitly descended from them. The "man-apes" that still turn up in Conan's time are the descendants of those who didn't re-evolve back into humans.
  • Diaspora is set in a far future where most of humanity has been rendered unrecognizable through various forms of Brain Uploading and Transhumanism. One of the latter groups is the Dream Apes, whose ancestors deliberately removed their capacity for speech and most of their sapience in a wholesale renunciation of modern society.
  • The Elric Saga: Humans who join the Chaos Legions devolve into bestial half-man, half-animal things, becoming whichever animal was nearest to their human nature.
  • Evolution: The third part, "Descendants", depicts the regression of humanity back into non-sapient, tree-dwelling primates. In the section's first chapter, a squadron of soldiers are awakened from cryostasis an uncertain number of millennia into the future and encounter a troop of hairy feral posthumans. By thirty million years hence, they have returned to being arboreal apes. Their nests vaguely resemble small buildings that they decorate with glass fragments to ward off predators, but they are otherwise little different from a chimp or australopithecine. Numerous other posthuman species have emerged by this point, including arboreal hunters, elephantine giants "farmed" by carnivorous rats and burrowing creatures living in underground hives. By half a billion years hence, when life on Earth is coming to an end, posthumans are the last mammals: small, russet-furred monkey-like animals that live in chemical thrall to a species of tree.
  • In The Family Tree by Sheri S. Tepper, one plot strand is set on Earth in the distant future, with a big twist partway through revealing that all the characters in that plot strand are talking animals and that the dumb creatures they use as beasts of burden are what's left of the human race.
  • Galápagos: The castaways stranded on the Galapagos islands, the only surviving humans after a nuclear war, eventually evolve into non-sapient seal-like creatures. As they have no predators and little competition and most of their food is in the sea, being streamlined swimmers is more advantageous to them than being intelligent, and their frontal lobes are greatly reduced as their foreheads become sloped back to minimize water resistance while swimming.
  • In "The Locusts" by Larry Niven and Steven Barnes, once mankind colonizes another planet, all of humanity (both on Earth and in the new colony) starts giving birth to Homo erectus erectusnote  children instead of Homo sapiens.
  • H. P. Lovecraft:
    • "The Beast In The Cave" describes cave-dwelling humans who degenerated into savage monsters.
    • "The Rats in the Walls": The de la Poer family sated its cannibalistic appetites by breeding "human pigs" in immense underground food pens. The breeding stock was so inbred and twisted towards the end that some of them had devolved into quadrupeds, and they had largely lost the capacity for thought.
  • The Forsaken Children: The humanimals are descended from humans that were brought to the magus world and went feral, only to be domesticated by the fae. They're pretty harmless, only half as tall as normal humans, but humans and any creature that stems from humans usually find them unnerving.
  • Last and First Men:
    • After the Earth's transformation into a barely habitable hothouse world, the one surviving band of First Men splits into two groups. One forms a small outpost in the tropics of northern Siberia and hangs onto existence for a few million until conditions cool and it's able to spread south into Asia and eventually evolve into the Second Men. The other crosses the Atlantic, losing most of its members in the attempt. Three survivors are shipwrecked into the barely habitable jungles of Labrador and, through inbreeding and the hostile climate, evolve into animals that, on encountering the Second Men long after, have come to resemble giant baboons more than anything else and often become livestock to the sapient descendants of the original crew's pet monkeys.
    • On the mostly oceanic Venus, where the Fifth Men's descendants became highly reliant on the sea for sustenance, some actively evolved into seal-like sub-men with sharp teeth, streamlined bodies, legs shrunken into rudders, and arms and hands transformed into flippers still retaining the thumb and forefinger.
    • After the Ninth Men's civilization collapses due the harsh conditions on Neptune, they degenerate into a number of animal species, most quadrupedal to deal with Neptune's high gravity and including hoofed grazers, predators, seal- and later porpoise-like aquatic forms and minute flying humans descended from a bat-like glider. This remains the nature of humanity until a rabbit-like species redevelops sapience and evolves into the Tenth Men.
      Nowhere did the typical human form survive. There were only beasts, fitted by structure and instinct to some niche or other of their infinitely diverse and roomy world.
  • Man After Man: An Anthropology of the Future: After humanity devastates the natural environment and wipes out most forms of large vertebrate life, the far-future human civilization decides to create new species of animal from the only remaining genetic stock — i.e. humanity — in order to fill the numerous niches left empty. This results in four species of nonsapient humans being created — large, hairy tundra-dwellers to take over the role of musk oxen and mammoths, Australopithecus-like forest-dwellers meant to fill in the niches once occupied by deer and bears, digitigrade plains-dwellers to act as herding grazers, and apelike arboreal jungle-dwellers. Some of these species re-evolve sapience, but others remain animals. Notable are the tundra-dwellers, who evolve into numerous megafaunal herbivores; numerous predatory and even parasitic forms descended from the forest-dwellers; and the jungle-dwellers, who secluded in unchanging canopies filled with food and without dangers never had reason to develop into anything other than placid, mindless beasts.
  • In "Null P" by William Tenn, humanity, a quarter million years after abandoning civilization, ends up as pets for the now dominant dog culture. Their only purpose is throwing sticks for their masters to bring back.
  • Planet of the Apes: Soror's Human Aliens used to have their own civilization, before falling into decadence and degenerating into animals as the increasingly intelligent apes overtook them.
  • Ringworld: When the Pak Protectors built the Ringworld, they introduced no animal life to it beyond their own kind, some food animals and microfauna. As such, when the Pak empire collapsed and the Pak Breeders (Homo habilis) were left on their own, the Breeders radiated to fill the various empty niches in the massive world they found themselves in. Many of their descendants are now sapient, but others — such as the predatory vampires — remain little more than cunning animals.
  • Star Wars Legends: The Kwa, three-meter-tall reptilian humanoids who ruled one of the galaxy's precursor empires, mostly died out when their empire fell. The survivors were stranded on their homeworld, Dathomir, lost their civilization and gradually evolved into beasts. Their descendants, the Kwi, are essentially big, blue and featherless dinosaurs — their regained elongated bodies, long tails and muzzles somewhere along the line. They're no longer able to speak, and are simply intelligent animals.
  • The Time Machine:
    • Downplayed in the main body of the work. By the year 802,701 humanity differentiates into the Eloi, childish beings of limited mental powers, and the Morlocks, brutish apes who prey upon them while maintaining the machines that sustain them by long-ingrained instinct. While they're still nominally sapient — the Eloi are little beyond dull-minded, although it's not clear how intelligent the Morlocks are or aren't — neither species retains much of its ancestors' creativity, awareness or higher intelligence.
    • Played much straighter in a lost chapter, named "The Grey Man" as published separately at a later date. It depicts the time traveler going further and further into the future, by an unnamed number (but according to his instruments many, many thousands) of years, where earth had become a bleak, barren desert with grey skies and a dimmed sun, and not even the faintest remains of Eloi and Morlock civilizations. There, he finds a group of small, furry animals, akin to tail-less rabbits who are soon hunted by a large centipede-like creature. Startingly, before the monster appears, he knocks one of these little animals unconscious with a rock, and, upon further examination, finds out these creatures have human traits...
  • Uplift: (Nearly) all sapient species are Uplifted Animals, and it's not unheard of for a species to "un-uplift" themselves for various reasons.
    • The Karrank% were uplifted to act as living mining equipment, and after their patrons were exterminated for such blatant client abuse they were given the planet Kithrup and allowed to return to their pre-sapient state. When the Streaker arrives on Kithrup they find no trace of the Karrank% until a brain-damaged dolphin figures out the island they're on is their larval stage.
    • In The Uplift Storm trilogy, two of the refugee species illegally settling Jijo undergo this process.
      • The Glavers fled the civilized galaxies to escape species-wide debts, and have degenerated into near-sophont herd animals, which some genetic pirates ironically consider for uplift.
      • Some Tytlal came to Jijo so that they might survive if something happened to their patrons and became unintelligent "noor beasts" though some "Watchers" remain anonymously sapient.
  • The War Against the Chtorr: This appears to be the place that humans will eventually fill once the Earth is transformed to a completely Chtorran ecology. There are herds of humans in some of the ruined cities that are no longer sapient, and being around them too much can somehow draw other humans into joining them. Its uncertain whether an infectious agent is involved or something else. The fourth book reveals that the "bunnydogs" and "libbits" mistaken for Chtorran lifeforms are in fact transformed human children or their descendants. In the Chtorran ecology they are non-sapient fast-breeding cattle. There are hints that some of the Chtorran lifeforms were also once more sapient than they are now.

    Live-Action TV 
  • Blake's 7: In "Terminal", the titular location is an artificial planet made to recreate the history of life on Earth on an accelerated timescale. When the heroes encounter savage ape-like creatures, they assume them to be humanity's ancestors. Later, however, Servalan reveals that evolution on Terminal was accelerated even greater than anticipated.
    Servalan: The creature you saw is not what man developed from. It is what man will become.
  • Doctor Who:
    • In "Gridlock", the Macra, who appeared in the original series serial "The Macra Terror" as cunning behind-the-scenes manipulators, are shown to have devolved into mindless beasts many centuries into the future.
    • "Orphan 55" has the Doctor discover that the titular planet is a far future Earth, devastated by nuclear war and environmental collapse, and that the native inhabitants (the savage ghoul-like Dregs) are the last descendants of humans who evolved to survive the wasteland.
  • Primeval: The Mer Creatures, savage and bestial amphibious predators from Future Earth that look something like a cross between a seal and an ape, are speculated to be descendants of humans, though it's never confirmed.
  • Star Trek: Voyager: In "Threshold", Tom Paris undergoes "accelerated evolution" into a non-sapient salamander-like creature. The writer stated that his idea was that, in the distant future, humanity would evolve beyond the need for sapience due to technology providing for all our material needs.
  • Wayward Pines: The majority of humans has devolved into predatory animals known as "abnormals" or "abbies".

    Tabletop Games 
  • Exalted: The Dragon Kings are an odd example. By nature, they are born with animal-level intellects and must be taught by their elders how to be sapient and capable of speech and civilization. The many disasters that marked the history of Creation took a very heavy toll on the Dragon King empires, however, and as fewer and fewer of them were left who were able to give this guidance the young of the species were left unable to make the leap to true sapience. By the setting's present, outside of a few isolated holdouts, the once-great rulers of much of Creation are left as nothing more than feral animals hunting and dying in the wilderness.
  • Numenera:
    • The interior of Nachant, a giant hollow artifact orbiting the sun, is home large swarms of mechanical beetle-like creatures called orolins, which infest the structure like very aggressive vermin. The orolins are in fact degenerate descendants of the otolins, a species of larger and sapient mechanical beings, who find orolins terrifying on a spiritual level.
    • The fishlike ranthra of Xeobrenicus once possessed an advanced technological culture, but deliberately caused themselves to regress to an animal-like, pre-sapient state with only some instinctively-ingrained tool use in order to shed the anxieties and stress inherent in civilized life.
  • Pathfinder: The cyclopes are a species in the process of becoming this. In the past, they were highly civilized and ruled a number of powerful empires. However, their intense hunger proved too taxing on resources to sustain and these civilizations all collapsed, leaving cyclops-kind a collection of primitive tribes. Modern cyclopes are stuck as scattered primitives, as they drain too many resources to be able to form more than small, nomadic tribes, and most live in pairs or alone, and are often driven to surrender entirely to their hunger, giving up on civilization and living as solitary hunters. The ultimate end of this process is transformation into great cyclopes, hulking brutes with no trace of higher intellect or culture, who live alone in the wilderness as little more than tool-using beasts. The number of feral and great cyclopes is constantly on the rise, while civilized cyclopes are fewer and fewer, and the species seems largely doomed to fully descending into animalism.
  • RuneQuest: In Glorantha, one of the Praxian tribes, the Morokanth, consists of nomadic humanoid tapirs who herd non-sapient humans to use as pack beasts and food. In ages past, the human tribes and their totem animals were presumably both sapient, until the chief Praxian god decided to hold a series of lotteries between each tribe and its totem to determine who would be the eater (sapient herders responsible for the well-being of their herds) and eaten (able to forage for sustenance in the Praxian wastes, but stripped of sapience). Humans won four out of the five lotteries, but the tribe with the Morokanth as its totem wasn't as lucky. They modern Morokanth can also turn captive normal humans into nonsapient herd-men, but don't expect a last-minute rescue by The Cavalry if they try to do this to you — the Morokanth are Praxians, and the surrounding human Praxian tribes feel a stronger cultural kinship towards them than a species one towards any poor schlubs who got themselves in that particular pickle.
  • Warhammer: While no proof one way or the other has ever emerged, some in-universe scholars and Ogres speculate that the Yhetees, ferocious, white-furred beasts native to the highest peaks, began as Ogres who adapted to the bitter chill of the Ancient Giant Lands during the Great Migration, over time becoming sub-tribal predators with only the simplest remnants of tool use.
  • Warhammer 40,000:
    • The Kroot, a sort-of avian, humanoid alien species, are able to taste individual parts of the DNA they eat and incorporate them into themselves, and their Shapers can direct their kin to eat primarily certain species so as to ensure genetic traits will be passed on to the next generation of Kroot. This often leads to specialized variations on the average Kroot body plan, but continuously eating too much of certain species risks a permanent regression to a bestial state. Several subspecies have been formed this way, like the vaguely-canine Kroothounds, apelike Krootoxen, and carnosaurid Knarlocs, which are now used as beasts of burden and battle.
    • Rogue Trader: A quirk of the planet Orn's biosphere causes the minds of sapient beings who stay there too long to gradually degrade into a non-sapient state. A large colony of aggressive creatures that nests in an immense wrecked vessel is believed to be descended from the crew of an alien colony ship that became stranded on Orn, the crew's frantic attempts to repair their vessel gradually losing their purpose and planning and becoming little more than an instinctive Cargo Cult carried on mindlessly by their bestial descendants.

  • BIONICLE: On Bara Magna, after the colossal disaster of the Shattering, the surviving tribes were left to survive in the wasteland that was left as best as they could. Most of them managed fairly well, but members of the Sand Tribe, the Vorox and the Zesk, eventually devolved into savage primitives roaming the desert. Later, we see members of the Sand Tribe who actually faired much better - instead of being stuck in the miserable desert, they were stranded on the bountiful forest moon, and have actually become quite advanced; they're also not happy with the way the other tribes have treated their relatives.

    Video Games 
  • The Elder Scrolls:
    • The Falmer were originally the graceful Snow Elves, possessing a culture rivaling the Altmer (High Elves). However, after facing near-extinction at the hands of the Nords, the Falmer turned to their estranged Dwemer kin for aid. The Dwemer agreed to take in the surviving Falmer, but only if they blinded and mutated themselves with toxic fungi, Invoking this trope. For centuries the Dwemer used the Falmer as servants and slaves, and may have performed experiments on them that caused them to further mutate into their present form. When the Dwemer abruptly vanished from Nirn, the Falmer were left behind as a race of blind, subterranean, Morlock-like beasts with a primitive, xenophobic tribal culture. So significant was the de-evolution of the Falmer that it affected their very souls, turning them from "black" sapient souls into the "white" souls of creatures. By the time of Skyrim, the Falmer seem to be regaining some of their lost sentience, forging better weapons and armor from farmed Chaurus chitin and practicing crude alchemy to create poisons from the plentiful mushrooms that grow in their underground lairs. The author of one in-game book in Skyrim even believes that the Falmer may be preparing to wage war on their surface dwelling ancestral enemies, which would be bad news for the already war-torn Skyrim. The Dawnguard expansion introduces Knight-Paladin Gelebor, the last surviving uncorrupted Falmer. He too believes the race is recovering its lost sentience, though it will be quite some time (if ever) that they fully recover.
    • The Dreugh, a race of aquatic humanoid octopi, once ruled the world in a previous kalpa, or cycle of time. However, that was one of the 12 worlds which were destroyed and the remnants pieced together to create Nirn. The Dreugh of early Nirn were still intelligent, but that diminished over time as their civilization fell and their intelligence devolved. Now, like the Falmer, their de-evolution from an intelligent, sapient race with their own civilization has included their souls becoming white, like those of animals.
  • Fire Emblem: In the Archanea games, dragons are highly intelligent beings who in ancient times had built a great civilization that used to rule the world. Their age was brought to an end by a physical and mental degeneration that struck seemed to have no cure; to avoid it, most dragons became Manaketes, humans capable of taking dragon form, as remaining in human shape for most of their lives allowed them to escape this disease. Some dragons wouldn't or couldn't do this, however, and over time degenerated into mindless beasts. The earth dragon tribe, in particular, flatly refused to become Manaketes and fully transformed into bestial monsters; the wyverns are also implied to have originated in this manner.
  • Metroid:
    • Metroid Prime: This was the fate of the Chozo on Tallon IV. After abandoning Zebes and its technological advances in an attempt to return to their more natural, mystical roots, they eventually ascended to the spiritual plane... but when a Phazon meteor struck the surface, their souls were pulled back to the planet and driven mad, making them insane, violent "Chozo Ghosts" that attack anyone who approaches.
    • Metroid Prime 3: Corruption: The Reptilicus once had an advanced space-faring civilization on Bryyo, but a planet-devastating Magic Versus Science war combined with the spread of Phazon following a Leviathan impact resulted in them becoming bestial mutants.
  • Star Control II: In the backstory, the Ur-Quans won a Slave Revolt against their taskmasters, the Dnyarri, and decreed that death was too lenient. The remaining Dnyarris were lobotomized into unthinking animals, now serving the Ur-Quans as living translators known as "Talking Pets". When the Umgah unknowingly undid the lobotomy on one, the resulting Neo-Dnyarri showed exactly why they were The Dreaded. A single specimen was able to mind control the entire Umgah homeworld along with its fleet, but you will need to enlist his help in the final battle against the Ur-Quans.
  • Stellaris:
    • The Baol, one of the setting's Recursive Precursors, were a peaceful Hive Mind of Plant People that came under attack by a Proud Warrior Race called the Grunur. The trauma of the extermination campaign was so devastating to the Baol that many of them devolved into non-sapience to escape it. The last sapient Baol, when informed of this by the player, decides that it's for the best, dying shortly afterward.
    • Your science ships might come across a planet that show signs of an abandoned farming settlement made by a technologically primitive but obviously sapient species, but the only plausible species found on the planet is a race of feral Lizard Folk. Investigation of the situation would eventually reveal that it was indeed those lizards who built it... during a time when they were also the host of a slug-like symbiote species that attaches to the brain stem of an animal that increased their intelligence; the lizards became suspicious of the slugs at some point and tore them off in fits of rage, reverting back to their previous pre-sapient state.

  • The Petri Dish: A story arc features an alternate universe in which the super-intelligent squirrels have taken over civilization because a virus has killed half the human population and rendered the other half stupid and mute like monkeys.
  • In TwoKinds, this is the fate of any Keidran that stays in feral mode for too long; they become less and less sapient until they forget how to turn back.
  • Unity is set on a Generation Ship populated by several species that evolved from terrestrial animals, with no sign of humans until the "plains apes" many use as livestock appear.

    Web Original 
  • Neopets has two batlike species: Korbats, which are a type of Neopet, and Barbats, which are mindless "petpets" (the pets of Neopets). There's a rumour in-universe that Barbats are cursed Korbats, but it's never been confirmed.
  • Orion's Arm:
    • "Abdicators" are entities which, for whichever reason, have chosen to move down one or more toposophic levels rather than proceeding upwards into increasing levels of transhuman intelligence. This generally refers to Transhumans who have moved down to lower transhuman levels or to human-level intelligence, but also covers people who have regressed to animalistic states.
      • The Epimethean Movement engineered itself into a species of primitive hominids, Homo epimetheus, about as intelligent as non-human apes. Their stated goal was to embrace a technology- and language-less existence in order to be closer to the true nature of the cosmos, but it seems that this was part on an elaborate scam by the foundation of sapient humans and AIs that were entrusted with their funds and possessions. The downgraded epimetheans, however, notably outlived the foundation by millennia.
      • Snarks are creatures resembling mammalian crocodiles derived from human stock. They were created when the natives of a strife-torn colony world, reasoning that a non-sapient but well-adapted animal species will likely endure for millions of years in an existence free of stress and grief, engineered themselves into non-sapient ambush hunters modeled after some of the most enduring creatures of all, the crocodiles. Notably, when snarks are artificially uplifted, they almost always want to be downlifted back to their original state.
    • Among the various Human Subspecies are "pet humans", who are usually genetically engineered for low intelligence and neoteny. They're most popular among splices and provolves, seeing as their ancestors were frequently kept as pets, working animals and livestock. Their ownership is almost universally outlawed in human-dominated areas.

    Western Animation 
  • In Samurai Jack, the Woolies were a race of highly intelligent, peaceful but very large, strong beings with a bipedal stance. By the time Jack encounters them, however, they've been reduced to beasts of burden by the Chritchellites, who use technology that render them quadrupedal, animal-like in behavior, and their language reduced to grunts and roars. Eventually averted, however, when Jack deduces what actually happened and finds a way to restore the Woolies to their former selves while annihilating their captors.


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