Devolution Device

A fine weapon and/or experimental prototype that does one thing and one thing only, reverse the effects of evolution on creatures! In particular, this device is often used to turn humans into something more apelike, often a modern Gorilla, or a Neanderthal. A bird or lizard can be turned into a giant dinosaur that can then be used to terrorize all those people that called you mad. That'll show 'em.

Often used for comic effect, this is an understated device that could cause chaos. Consider how much you use that is designed for intended species use only. Ape hands could crush a keyboard or phone, it would be hard to convince a saber-toothed cat to use a litter box, and dolphins and whales would sprout legs and doggy paddle to the surface. And that’s if you’re lucky and keep cognitive abilities across Evolutionary Levels.

Note that in Real Life, a creature's cells contain "dormant" genes from its ancestors. However, to have this affect a life form, it would require the selective DNA changes on pretty much every cell in the body to change species.

Anime and Manga

 * In Yu-Gi-Oh! GX, Jim uses fossil-themed monsters of three categories, Cenozoic (least powerful), Mesozoic (medium-powerful), and Paleozoic (most powerful), meaning that the older the time period, the stronger the monster is. This Trope is applied with his Spell Card Time Stream, which can devolve a Cenozoic monster into a Mesozoic, or a Mesozoic into a Paleozoic.

Card Games

 * One of the first-generation Pokémon trading cards was Devolution Spray, used to devolve a Pokemon to its previous state, removing all status effects in the process. Mew's first card also had an ability called "Devolution Beam", which did exactly the same thing.

Comics

 * There was a devo ray used in an X-Men story in the 80s: most of the ones hit with it turned into apes but Nightcrawler devolved into something more feline looking.
 * The De-Evolutionaries in Zot have these. Back to the trees! The Church of De-Evolution, a gang of ranting nutcases armed with Transformation Ray Guns that turn whoever they shoot into chimpanzees. It's played almost entirely for laughs. McCloud says this is because they represented what he considered the least plausible outcome of our relationship with technology. (The other end of the scale is 9-Jack-9, if you're interested.)
 * The Devolutionizing Machine in this page from a Wonder Woman comic. It changes a crocodile into a Tyrannosaurus Rex and elephants into mastodons.
 * During Marvel's Kree-Skrull War, Ronan the Accuser busted out the old monkey-making de-evolutionary ray as part of his plan against Earth.
 * One comic book crossover, JLApe, used this as Gorilla Grodd's plan, although it was careful not to mention (d)evolution. Derivative plans were used by Grodd in other works.
 * One episode of Justice League Unlimited had Gorilla Grodd construct a "devolution" ray (his own words) that turned humans into humanoid gorillas... including Superman, who is not human at all. After his plan failed even Lex Luthor complained how stupid the whole thing sounded and used it as the pretext to take over the Legion sooner than he planned. Fridge Brilliance makes one realize it's actually an effective plan, causing complete chaos for all humans as nothing works right for them any more. It's just incredibly selfish, as he's the only one who gains from that.
 * DC Universe Online has Grodd using a similar plan.
 * In the story "The Evolution-Devolution Man", in issue #93 of Tales of the Unexpected, this scientist invented a doodad that looked like a giant telephone handset, one end of which shot out a ray that could make creatures evolve while the opposite end devolved them. It malfunctioned and shot both beams at him, causing his body to devolve into that of an ape, then a monkey, then a lemur and finally a lizard, while his head evolved to the point where he could fix the device telekinetically despite his lack of hands.
 * This once happened to the Teen Titans. Notably, alien Starfire devolved into a Catgirl rather than an ape.

Film

 * Super Mario Bros: King Koopa has one of these, he uses it to make the closest thing to a Goomba in the film. The most extreme use of it comes when it's used to.
 * We're Back! A Dinosaur's Story: Professor Screweyes has evil pills called Brain Drain, the opposite of his brother's Brain Grain that grants sapience, which he uses to turn the kids into monkeys and the newly intelligent dinos back to their animal states.

Literature
"Among the forest-covered hills of the northwest exist wandering bands of ape-men, without human speech, or the knowledge of fire or the use of implements. They are the descendants of the Atlanteans, sunk back into the squalling chaos of jungle-bestiality from which ages ago their ancestors so laboriously crawled. To the southwest dwell scattered clans of degraded, cave-dwelling savages, whose speech is of the most primitive form, yet who still retain the name of Picts, which has come to mean merely a term designating men — themselves, to distinguish them from the true beasts with which they contend for life and food. It is their only link with their former stage."
 * "Wilding" a short science fiction story by Jane Yolen features teenagers going to Wilding parks, where radiation de-evolves them into primitive simian ancestral forms for the purpose of recreation. It's a Does This Remind You of Anything? of recreational drug use, except it's perfectly legal.
 * The serum version was used in a Sherlock Holmes story.
 * The climax of H. Rider Haggard's She has . Darwin's theories had only recently entered the public consciousness when the book was written and the whole story is about the fear of "devolving" since people were scared that it might work backwards at the time.
 * In Robert E. Howard's "The Hyborian Age", the Backstory to Conan, the fall of the Atlantis produced devolution:


 * There is also a short story by Philip K. Dick, called Strange Eden, that successfully makes every mistake about evolution mentioned here. It's about an astronaut that finds an attractive and immortal female Goddess-like alien on a far-away world. Immediately he wants to sleep with her, but she warns him that in doing so he will magically begin to rapidly evolve. Thinking that this will lead him to become a superior being like her (and for the obvious reason), the astronaut accepts the offer. However, it turns out that humanity's set evolutionary path is that we will evolve into bestial cat-creatures — exactly why is never stated — and so the astronaut is stuck as the alien woman's pet forever.

Live Action TV

 * 3rd Rock from the Sun: "Liam Neesan" (a character, not the actor or even played by the actor) had a ray gun that turned people into monkeys. He planned to use it on the human race, but Dick Solomon stopped him by turning him into a monkey.
 * The New Outer Limits: Serum form, a meek bio-anthropologist developed it and used it on himself, turning him into an aggressive quasi-caveman.
 * Star Trek several examples:
 * "Genesis", an episode of The Next Generation where the crew began "devolving" into various lower animals with no rhyme or reason. They tried to justify the stock "devolution" story with Techno Babble about "activating the introns in the genetic code". At the time, the idea of introns as "fossil" or "junk" DNA left over from a species' ancestors was still in vogue. (There actually is "junk" DNA, but most of it seems to be deactivated viral code or parasitic "jumping genes" instead of fragments of formerly-useful genes. Occasionally transcription errors happen to make some of this into something useful to the organism; it's believed that the mutation that prevented the mammalian immune system from rejecting the placenta of a fetus might have come from such viral junk, for example.)
 * Star Trek Voyager took considerable fire for "Threshold", in which a flight test at Ludicrous Speeds caused a character to "evolve" rapidly (just enough technobabble was applied to work around the fact that individuals do not themselves evolve; technically, he "experienced mutations consistent with the pattern of human evolution"), whose end-state was to turn him into a giant salamander with a Fu Manchu mustache. The fact that so many fans complained that "That's not evolving; it's devolving!" shows that TV has corrupted our understanding of evolution — there's no such thing as "devolving": evolution does not lead inevitably toward bigger, smarter creatures who would necessarily seem "more advanced" by human standards. Brannon Braga says this was the idea he tried to get across, but admits he failed spectacularly.
 * In the Farscape episode "My Three Crichtons", an alien probe produced both "de-evolved" and "super-evolved" versions of Crichton.
 * Deconstructed when the probe explains that the two extra Crichtons are just two of the millions of alternate versions of humanity that the probe was simulating and cataloging. They just happen to be a caveman and big-brained superhuman. And just to nail the point home, D'argo comforts a worried Crichton that the "super-evolved genius" form is just a possible evolution.
 * Doctor Who:
 * In the story "Ghost Light", a clergyman is turned into a monkey by a Sufficiently Advanced Alien; it is justified, however, by suggesting that this is not "de-evolution" as such, because the alien could have turned him into anything and only chose the monkey form to mock the clergyman's anti-Darwinist beliefs. (Another character, for instance, is transformed into stone instead.)
 * Buffy the Vampire Slayer: The episode "Beer Bad", where enchanted beer turned a bunch of college guys and Buffy into cave-people.
 * Parodied in Garth Marenghi's Darkplace, where a mad scientist invents a serum that causes people to devolve back into apes. Half the hospital accidentally drinks it, despite the fact it turns water bright green, and is transferred in urine.

Music

 * The nerd folk song "De-Evolving" by Jonathan Coulton. The protagonist describes "de-evolving" into a monkey. It's funny, but inaccurate.

Tabletop RPG

 * Ghostbusters International adventure Hot Rods of the Gods. After Meera undergoes his magical power-up he uses the tablet to fire a red devolvo ray at the Ghostbusters. When hit by this ray a person becomes hairy, has their arms grow to knee-length, their jaw juts out like a stereotypical "ape man" and their intelligence decreases somewhat. The effect wears off in about 30 minutes.
 * Many superhero Role Playing Games — like Mutants and Masterminds and the original Marvel Superheroes Role-Playing Game — include, among the list of powers available to players, some sort of "Hyper-Evolution" power that lets a hero shift up and down along their "evolutionary path," generally affording them the ability to "devolve" into cave-man form (temporarily lower their intelligence to raise their strength).
 * In Mayfair Games' DC Heroes RPG this was covered by the Mutation power.
 * Mutant Futrue. The Ancestral Form mutation can reverse a creature to a previous stage in its evolution, such as changing a human being into a Homo Erectus.

Video Games

 * The Commodore64 game Dino Eggs had as a hazard the possibility of getting bit by a spider and suffering "devolution" into a spider due to genetic contamination. Seriously.
 * Congo from Congos Caper devolves back into a monkey from a boy when he takes damage.
 * The Dinaurians in Fossil Fighters have ray-guns that de-evolve humans into "theriodonta", rat-like ancestral mammals.

Web Comics

 * Irregular Webcomic! [//www.irregularwebcomic.net/59.html has] one invented by Spanner. The first use made it obvious that a course of phylogenetics covering all potential targets should be required before using one.

Western Animation

 * There was a weapon in Dinosaucers, able to turn the pro- and antagonists, who are anthropomorphic sentient dinosaurs, into non-anthropomorphic, apparently non-sentient, and much bigger dinosaurs.
 * One of the human sidekicks got hit with it once, and obviously turned into a caveman.
 * The Dinosaucers had a benevolent form of this built into their suits, allowing them to assume the bodies of their dinosaur ancestors but retain their intelligence. Apparently the Tyrannos couldn't quite pull this off, so weaponized their less-advanced version of it.
 * Mighty Max used this. In one episode, a mad scientist named Dr. Zygote develops a ray that devolves anything to their prehistoric state. A bunch of human tourists become apes, Max's pet lizard becomes a dinosaur, and Virgil (a lemurian who is supposed to be the next step in human evolution) gets turned into a pterodactyl (?!) Later it's used by Dr. Zygote to turn a bunch of devolved mutated monsters into primordial ooze. He surmises that the ray "reversed their evolutionary path to the final quagmire, an evolutionary dead-end"—which really makes no sense at all. http://www.youtube.com/watch?v=owZqBj0vLXU&feature=related
 * Then in another episode, Dr. Zygote uses the ray again to further evolve himself into a more advanced form, from a big brained alien, to a lemurian, to a floating giant brain, and finally into a flash of light. at the end, he "evolved beyond good and evil" and left. There was a subversion along the way, as he became a chicken fowl-like humanoid similar to Max's Obi-Wan Virgil, who mentioned humanity will find the form enjoyable, much to Max's surprise. http://www.youtube.com/watch?v=Jm B 5 N Dezi Mk
 * The Saturday Morning Mega Man cartoon managed to take the concept of devolution to the next stage, when Dr. Wily made a chemical that caused robots to "devolve" into more primitive robots. This meant they went from robots designed to look like humans to robots designed to look like cavemen, getting stupider in the process.
 * Shouldn't they turn into toasters or something?
 * We've come a long way baby.
 * An episode of Buzz Lightyear of Star Command had a gas which did this (Buzz was turned into an apeman, Mira turned into a blue puddle of slime, Booster turns into a giant dinosaur-like creature and some highly intelligent aliens turn into red chimps).
 * Phineas and Ferb: "Phineas and Ferb's Hawaiian Vacation"—Dr. Doofenschmirtz had one, and it worked. It devolved Doof into an ape in a labcoat, and Perry into something that was more birdlike than anything else. But it was physical devolution only. Higher brain function remained intact. Doof could still speak even when he'd accidentally devolved himself into an amoeba.
 * In the Looney Tunes short "Mad as a Mars Hare", Marvin the Martian plans to use his evolution ray to advance Bugs Bunny into a "harmless but useful slave to me". Only he had it set to reverse, turning Bugs into a huge Neanderthal rabbit who easily pummels Marvin.
 * One episode of Jonny Quest the Real Adventures had Team Quest discover alien technology which let whoever used it evolve or devolve species at will. Surd gets a hold of it and uses it on Race and Dr. Quest in Questworld. This causes them to mentally devolve and act in ape-like manners, even though their bodies stay the same.