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Speculative Biology

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"Speculative biology" (also referred to as "speculative zoology", though it is by no means limited to animals) is a sub-genre of science fiction that deals with evolution in the future, or in alternate timelines, the same way that many other sci-fi works discuss technology.

The most common situation discussed in these works is After the End: "What would the world be like once humans go extinct?" Another common situation is "What animal(s) could become as advanced as humans and how would they?" Other works focus on the question of "What if humans never evolved?", feature aliens on different types of planets, or just end up creating animals that could exist. Often, the aim of Evilutionary Biologist is to see how humans/certain animals would end up if he hastens their "evolution".


Speculative biology is very popular online among amateur biologists and animal fans, especially on sites like Deviantart and Reddit. This sort of work is also common in fandoms that feature fantastical animals; artists will invoke Reality Ensues and try to revamp the characters in a way that makes more biological sense. However, it's also a topic that gets professionally discussed. Several books and a few documentaries have also been created on the topic of speculative biology. Most works of speculative biology at least try to obey real-world laws of science, and if any sort of supernatural Hand Wave is involved, Magic A Is Magic A will be in full effect. Indeed, providing real-world explanations for fantastical and fictional creatures (just how do dragons breathe fire?) is another popular form of speculative biology.


That being said, many works of speculative biology are not very biologically rigorous. Many artists end up coming up with inaccurate animals and circumstances that most likely couldn't occur. Every so often however, years later a species is discovered that resembles a previously fictional animal. It's also worth nothing that our ideas of what is biologically plausible and what isn't changes all the time.note 


These works often, but not always, take the form of a Speculative Documentary. Related to Fantastic Science.


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    Fan Works 
  • Chritopher Stoll, a Deviantart-based artist, does this with his two series, A Natural History of the Fantastic (which cover mythical creatures) and PokeNatomy (which covers Pokemon).
  • Fixing RWBY: The "History" video tries to explain the faunus in a bare minimal scientific manner. In contrast, RWBY canon just goes for a "The gods did it" answer. Faunus are related to humans through a common ancestor. They're closely enough related to interbreed with humans, but faunus have various behavioral and physical differences from humans.
  • The Pokédex - Extended Fanon Edition is a Just For Fun series on This Very Wiki that takes the premise of Pokémon Up to 11 and documents the creatures as if writing a scientific article about real-world animals, dealing their biology, behavior, reproductive habits, diet and depiction in human culture.
  • Realistic Pokémon is a series of fanarts depicting interpretations of Pokémon as if they were, or had evolved from, real-life animals. Some, like Zapdos and the Eeveelutions, remain largely what they are in canon, albeit with more realistic anatomy. Others get more drastic redesigns — Giratina is interpreted as a giant insect native to extremely deep caverns (the Distortion World) where the air pressure is high enough for its larval form (Giratina's Origin Forme) to "swim" through the air. Likewise, Voltorbs are drawn as red-and-white armadillos that "explode" by violently uncoiling.
  • Tiny Sapient Ungulates is a realistic take on My Little Pony: Friendship Is Magic:
    • The ponies themselves are a species of basal ungulates with short muzzles and big ears, as well as legs still ending in five digits tipped with hoof-like nails and with some limited mobility (explaining their in-show ability to hold objects with their hooves). Pegasus wings are reimagined as lobed wings of skin supported by elongated fingers like a bat's.
    • Griffons become hexapodal birds that evolved from solitary predators. As such, they only typically interact for territorial posturing or trade and are mentally predisposed to see all forms of interaction as one of these two, explaining their aggressive and greedy behaviors.
    • Changelings become enormous four-legged insects who evolved to mimic ponies (their food source) and that feed on both emotional energy and solid matter. Their transformation in "To Where and Back Again" is interpreted as Chrysalis essentially starving her hive by denying it both physical food (as she wrongly believed they didn't need it) and the social interaction they need for optimal feeding, only allowing them to grow into stunted neotenic forms. Thorax's takeover allowed them to start feeding properly again and morph into their true adult shapes.

  • Avatar explores the moon of Pandora, detailing its atmosphere, geography and biomes, as well as the flora and fauna. Surprisingly, the creatures of Pandora show an interesting amount of evolutionary relatedness in their anatomy, all sharing a "vertebrate" body plan of six limbs, four eyes, a pair of neural whips on the head and breathing holes located on their chests. Strangely however, the local sapient species, the Na'vi, defy many of these anatomical designs and are much more Humanoid Aliens.
  • Monsterverse takes a surprisingly scientific approach on its Kaiju, featuring the likes of Godzilla and King Kong in a more scientific light and portraying them as ancient superspecies from a more-radioactive Permian period. Granted, there is a lot of Artistic License – Biology regarding how such big creatures can live in Earth's gravity or how they can sustain nutrition from radioactive material, but nonetheless the series explores the behavior, ecology and biology of the creatures of Skull Island and the Hollow Earth in a way that portrays them like an actual ecosystem that once existed in nature.

  • All Tomorrows by C.M. Kosemen chronicles the evolution of various human descendants across dozens of planets over a billion years after some nasty intervention from the Qu, a malevolent godlike alien race. It can be read here.
  • Animorphs: In the prequel novel The Ellimist Chronicles, the Ketrans play a game that revolves around slightly modifying the conditions of their chosen virtual creatures' planet in order to influence their evolution towards a specific direction. Different players' creatures can even come into contact with one another through space travel.
  • Cryptozoologicon tries to reinterpret cryptids as plausible animals.
  • Dougal Dixon is probably the Trope Maker of this genre:
    • After Man: A Zoology of the Future is a 1981 book on how Earth could evolve in the 50 million years after humans go extinct. It is one of the most famous and influential examples.
    • Man After Man: An Anthropology of the Future is a 1990 speculative fiction book that focuses on individual characters rather than whole species. It starts After the End in the 22nd century, when the Earth has been ruined by human overpopulation and destruction of the environment and the humans decide to launch spaceships to find other livable planets. Scientists created two humanoid species — the frog-like "aquamorph", and the "vaccuumorph" that only can survive in the airless voids of space — in order to help build the ships, as well as a species of gilled manatee-like humans. Other human descendants reverted to an animalistic state, becoming giant yeti-like herbivores and saber-toothed predators.
    • The New Dinosaurs: An Alternative Evolution is a 1988 book about how dinosaurs could have evolved over 68 million years if the mass extinction had not happened. Due to being made in the 1980s, the book is very outdated in many respects.
  • Expedition is a 1990 book by Wayne Barlowe about the biology, native lifeforms and ecosystems of the fictional planet Darwin IV. It was adapted into the TV movie Alien Planet by Discovery Channel.
  • The Flight Of Dragons by Peter Dickinson imagines how dragons might have existed, explaining everything from how such huge creatures could fly (they were basically living hydrogen balloons), how and why they breathed fire (once again, they were basically living hydrogen balloons) and why nobody's found any fossils (the internal chemistry necessary to be a living hydrogen balloon was so volatile they dissolved on death). This very loosely inspired elements of the animated film of the same name.
  • Fragment: Most of the action takes place an isolated island with a bizarre biosphere descended from Ediacaran and Cambrian life. However, much like Green Antarctica, it is a Death World strongly informed by Rule of Scary.
  • King Kong (2005) got a companion book called The World of Kong: A Natural History of Skull Island, where the biology of the various monsters seen in the movie, from the dinosaurs through the giant bugs to Kong himself, got described in a semi-scientific way.
  • Known Space: Niven often uses this trope. The Ringworld sub-series in particular explores the many potential hominids that Homo habilis might have diversified into, given unlimited space, no predators, and a variety of vacant ecological niches to occupy.
  • The Long Earth series explores parallel Earths, including ones where hominids developed along different lines or where other animal lineages developed intelligence instead.
  • A Memoir By Lady Trent describes a Low Fantasy world with largely the same culture and animals as real life, but also home to very diverse dragons. The dragons are given extensive analysis through the character of Lady Trent, a naturalist dedicated to studying their taxonomy, anatomy, behaviors and ecology.
  • The Mote in God's Eye: One of the plot elements is how the various subspecies of Moties evolved. Determining how this occurred is crucial in determining that some of the Motie bodies ejected from the Crazy Eddie Probe are Warriors, which exposes one of the Moties' darkest secrets.
  • The Snouters: Form and Life of the Rhinogrades, by the German zoologist Gerolf Steiner in 1957, may be one of the earliest semi-serious examples, as the book documents the bizarre endemic inhabitants of a fictional island chain, cartoonish shrew-like creatures that have evolved to do every conceivable activity with their noses (walking, eating, jumping, swimming, reproducing etc.). Despite the absurdity of the subject, the snouters are treated with absolute seriousness and strict scientific rigour.
  • What Does a Martian Look Like?, by Jack Cohen and Ian Stewart, imagines how alien life might evolve, including a lengthy speculation on how tribbles might actually work.

    Live-Action TV 
  • Alien Worlds (2020): The series alternates between describing real-life processes and events in the natural world, such as sexual selection, hunting behaviors and mass extinctions, and attempts to use this knowledge to model imagined alien ecosystems and describing the ecologies and life cycles of alien organisms.
  • Cosmos: One episode has Carl Sagan discussing a theoretical ecosystem on Jupiter in which the animals had evolved into Living Gasbags in order cope with the planet's conditions.
  • Dinosapien asks "what if non-avian dinosaurs hadn't gone extinct?" and goes with it. In it, an earthquake opens up and reveals a Lost World where dinosaurs survived the mass extinction and evolved further.
  • Doctor Who: "The Lazarus Experiment" has Richard Lazarus being mutated into a fearsome giant centipede/scorpion-like monster after an experiment with an anti-ageing machine goes wrong. The Doctor describes the monster as a creature of evolutionary potential — something that evolution could have turned humanity into if it hadn't gone the "two arms and legs, ten fingers and toes" route — lying dormant within Lazarus' genes.
  • Dragons: A Fantasy Made Real is a 2004 mockumentary where the remains of dragons are discovered in a cave. It goes onto describe how different dragon types could have evolved, how they would have worked, and why they went extinct.
  • Extraterrestrial (2005) describes imagined alien environments on two alien worlds, using them as ways to exposit on natural processes and on the possible nature of extraterrestrial life.
  • Future Cat is a documentary discussing how big cats could evolve in the future. It's also briefly mentioned that smaller cat species could start going underground, similarly to foxes.
  • The Future Is Wild is a 2002 Animal Planet documentary. It is a Spiritual Successor to the speculative evolution book After Man. In contrast to the book, the documentary says that humans simply left to live on another planet rather than went extinct. The documentary has been criticized for containing animals that are implausible, such as a giant land squid millions of years into a future where mammals have died out and other species fill their niches. Nonetheless, the documentary has a solid cult following, and was popular enough to warrant a spin-off children's show courtesy of Nelvana and Teletoon, which is something one can't really say for most of the other Speculative Biology works on this page.
  • Life After People wandered into this occasionally, most notably when it posited that descendants of the domestic house cat might, in adapting to hunt birds in the decaying remnants of vine-choked empty skyscrapers, evolve skin-fold parachutes like a rudimentary version of a flying squirrel's.
  • Mermaids: The Body Found is a 2012 mockumentary and is the Spiritual Successor to Dragons: A Fantasy Made Real. It describes how a species of ape could have evolved into an aquatic animal, eventually becoming mermaids. Unlike its predecessor, it is a Found Footage Film. It's most famous, though, for being mistaken for an actual documentary when it aired, since the disclaimer that it was a work of fiction was hard to see.
  • Natural History Of An Alien, also known as Anatomy of an Alien in the US, is a Discovery Channel series with a green alien viewing various theoretical ecosystems including the depths of Europa's oceans and a planet with 1.5 times Earth's gravity to the world of Greenworld created by Dougal Dixon and Helliconia created by Brian Aldiss.
  • Primeval dips into this, with creatures from the far future (including expies of creatures from After Man) alongside those from the distant past
  • Through The Wormhole: One episode is about how aliens could realistically look like depending on the planet they are from.

    Tabletop Games 
  • Traveller: When the game was first created, a key part of the design of its alien races was deciding not just how they evolved, but how they developed intelligence.

    Video Games 
  • Metroid Prime 2: Echoes: Scanning enemies and other alien lifeforms gives biological and behavioral details about them.
  • Pikmin dabbles in this in the enemy entries in the Piklopedia, with Olimar's notes giving them scientific names, attempting to classify the alien beasts into taxonomic families (such as the Mandiblard family, the Arachnorb family, the Grub-Dog family and the like), and describing and speculating on their behavior and ecological relationships with other species. In Pikmin 3, Alph adds his own observations on the creatures anatomy and physical structuring. Louie's notes, however, are just all about cooking them.
  • Pokémon occasionally dabbles in this, mostly through PokeDex entries that detail the creatures' biology. The Alola games specifically go into detail on the hunting habits of Pokémon. However, they're just as likely to go for Rule of Cool, and most of the "science" they contain is pure nonsense. Then again, this is a universe where almost every animal has Elemental Powers, so it's obvious realistic biology doesn't really apply in most cases.
  • Spore: The game's original premise was the creation of alien species, and making them adapt to the environment and evolve into sapient beings. However, it changed direction mid-production, leading to more cartoonish and unrealistic gameplay and art style.

    Web Original 
  • The tumblr paleoartist Alphynix has a month-long event in 2020 called "Spectember", dedicated to speculative evolution art (using ideas submitted by fans on Patreon) with weekly intermissions discussing the history of spec-evo as a genre. Several of their entries have included flying frilled lizards, carnivorous ceratopsians, and terrestrial cetaceans inspired by the below-mentioned Delphinus Archipelago, to name a few.
  • Illustrated_Menagerie has a project known as Tales of Kaimere, a low-fantasy universe where prehistoric animals from different time periods come to coexist in a fantasy world. Derived theropod dinosaurs called megaraptorans take the role of "dragons", large derived giraffids are "unicorns", and a wide variety of other fauna, such as hyena-like entelodonts, flightless ape-like pterosaurs, and manatee-like aquatic dicynodonts, to name a few.
  • DeviantArt artist (and Troper) ElSquibbonator gives us The Neozoic, a long-form project revolving around the evolution of life on Earth over the next 100 million years.
  • The Wiki Rule even applies here. Speculative Evolution Wiki lists works about speculative biology, amongst other things.
  • The Youtuber TREY The Explainer usually focuses on actual paleontology; however, he has dabbled with this:
    • He once did a video on what he thinks aliens would actually look like. He is very much against the prevalence of Humanoid Aliens and The Greys in media.
    • In his videos on debunking cryptids, he discusses near the end what he believes they hypothetically would realistically be. For example, in his video on the Loch Ness Monster he speculated that it wouldn't be a plesiosaur but instead would be a giant leech.
    • Likewise, his video on The Flatwoods Monster ends with the theory that it would be a giant salamander, rather than an alien.
  • Natural history Youtuber Ben G. Thomas does an excellent three-part history on speculative zoology that can be viewed here.
  • The Speculative Dinosaur Project is a modern-day Spiritual Successor to the 1980s book The New Dinosaurs: An Alternative Evolution. It's a speculative biology project on how dinosaurs could have evolved if the K/PG mass extinction had not occured.
  • Sagan 4 is a web project about creating an entire alien ecosystem that evolved from a single unicellular life form, inspired by discussions of the game Spore which was then in production.
  • Green Antarctica includes a whole ecosystem evolved from penguins, marsupials, sloths, monkeys, and other Gondwanan animals. However, many of the details are informed by Rule of Scary, and/or are inspired by H. P. Lovecraft.
  • Serina, by Dylan "Sheather" Bajda, is a web project that takes place over 250 million years on Serina, a fictional terraformed moon where a number of plants, algae, microscopic organisms and invertebrates were introduced, but only 8 vertebrates: 7 tiny fish (guppies, mollies, swordtails and platies) and only one tetrapod: the domestic canary. Over millions of generations, the canaries produce a bizarre array of species, resembling dinosaurs, mammals, reptiles and eventually even resembling insects and fish, while the guppies colonize the land and become analogues of amphibians, reptiles and mammals.
    • Sheather also has another project known as Sheatheria, a bizarre alien planet that defies the laws of physics: it has an equatorial ice cap separating the north and south hemispheres, and is three times bigger than Earth but is less dense and thus has the same gravity. On the planet, various Earth lifeforms, from different geological eras from the Cambrian to the Permian to the Mesozoic to the Cenozoic, are introduced at intervals, and evolve alongside other creatures they never coexisted with during their time period.
    • Another Sheather project, Pluvimundus, focuses on the titular alien planet where the alien animals have evolved to be rather convergent with Earthly tetrapod life...but not quite. Most notably, the "birds" are most closely related to the "mammals", with beaked feline predators and handstanding "pterosaurs", as well as a sapient species resembling small, green-furred lemurs.
    • In his most bizarre project yet, there is the tongue-in-cheek An Ordovician Tomato, where a time traveling accident sends a tomato back 479 million years, before there were even any land plants, and starts a parallel timeline that resets the history of all life on Earth. Sadly, the project appears to have been deleted from the internet completely.
  • Snaiad is a project by C.M. Kosemen, author of All Tomorrows, envisioning "vertebrate" life on an alien planet. All of these creatures have two heads, neither of which contains the brain - that's located in their chests.
  • Amphiterra by Javier Valdez, is an experiment dealing with an alternate timeline where frogs, instead of mammals and reptiles, colonized the earth at the beginning of the Triassic period from the ancestral amphibian, Triadobatrachus. While the early descendants resemble frogs of today, they quickly become a wide array of forms, such as barnacle-like sessile filter-feeders, arctic grazers with an insulating coat of secreted foam, or giant T. Rex-sized apex predators, as well as two sapient species that evolve 65 million years apart from each other.
  • Alien Biospheres is a series of videos by Biblaridion dedicated to detailing the evolution of life on an alien planet. The two predominant groups of lifeforms in the series are the shelled cephalopod-like tentaclostomes and the spider-like sarcopods.
  • The Delphinus Archipelago, a Tumblr project about the evolution of land dolphins that started with a criticism of the hideously inaccurate Titan Dolphin from the cancelled The Future Is Wild virtual reality game by Tumblr user Alphynix and was expanded on by various others. It features the evolution of dolphins that become terrestrial, modifying their tails and foreflippers into three hoofed legs, and evolve into a wide variety of forms, ranging from mostly-conservative seal-like forms, to truly absurd forms such as giraffe-like browsers, furry squirrel-like rodent-analogues, and a unicorn-like apex predator that chops its prey apart with its horn (even having a scientific nomenclature named after Guiron.)
    • The project was later added upon by Alphynix, adding long-necked brontolphins and herbivorous dolphalopes, and a further installment introduced the beaked dolphins with bird-like bills, which included mole-like burrowers, azdarchid-like ground hunters and even a gliding arboreal species.
  • Planet of the Pseudosnakes, a project by Reddit user Tribbetherium, which features a parallel evolution on Earth in which the land ended up being conquered not by lobe-finned fish, but by an unspecified eel-like bony fish lacking paired fins entirely. These become a group of terrestrial, limbless snake-like forms, which diversify into clades such as the snogs (monopedal frog-like hoppers), theriodontophidians (serpentine analogues of mammalian carnivores), and the arboreal twintrunks, among which is a sapient species that makes homes out of living trees.


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