Despite the considerable evidence that Homo sapiens evolved here on Earth, it is tempting to hypothesize that our ancestors could have come from somewhere else. Not only were ancient humans incredibly advanced, they also had a star-spanning empire. And Earth is a Lost Colony of that empire, if not the last remnant of it.
Contrast Transplanted Humans (humanity did originate from Earth, but some ancient humans were taken away by aliens to settle another planet) and Ultraterrestrials (supposedly "extraterrestrial" nonhumans are actually natives to Earth). Usually involves Advanced Ancient Humans, which is any case where the supposed Precursors were indeed human, regardless of their spatial origin. Compare Panspermia, where all life on Earth originated from space (and thus may or may not overlap with this trope) as well as Original Man, where the older form of humanity is noticeably distinct from the newer.
Anime and Manga
- In Neon Genesis Evangelion, all life on Earth (humans included) traces its origins to Sufficiently Advanced Aliens who were apparently "human" as well. See NGE's entry on Panspermia for further details.
- Earth is a colony of the Jurai Empire in Tenchi Muyo!. They enforce an Alien Non-Interference Clause and have some contact with the Japanese government. Though most of the population isn't even aware of this.
- Macross plays with this; it's revealed in the first series that humanity was created by a Precursor race known as the Protoculture, who inserted their own genetic material into Earth's native wildlife to create a new species that would evolve to be similar to their creators. The Protoculture actually did this with a number of planets across the Milky Way, but their ultimate plans are still largely shrouded in mystery, as they seem to have gone completely extinct around 10,000 years before the start of the series.
- Jupiter Ascending is one of the few examples where humanity's ancient star-faring empire is still around, and Earth is one of their People Farms for Longevity Treatment ingredients. They also killed the (sapient) dinosaurs.
- Outlander mentions that Earth is an "abandoned seed colony" of Kainan's species.
- In the made-for-TV movie Roswell: The Aliens Attack, John reveals to Katie that Earth was settled by the crash-landed survivors of an interstellar prison transport. It escaped notice for a long time, being just another Lost Colony, until some interstellar rich guy bought rights to the planet and hired John and Eve to "exterminate the vermin" crawling all over it. It's heavily implied that this is what they do for a living. John infiltrates the Walker Air Force Base as a nuclear physicist from the Pentagon and uses his advanced tech to supercharge the atom bomb stored on the base to irradiate the entire surface of the planet. Then he falls for Katie and changes his mind. Side note: John and Eve are Human Aliens; The Greys found at the crash site were their genetically-engineered pilots.
- Empire from the Ashes: Earth was colonized 50,000 years ago by the mutinous crew of the Fourth Imperium warship Dahak, which has been acting as the Moon ever since.
- It's also believed Earth was seeded by an the Third Imperium, after the 5th planet was destroyed in an attack against the Second Imperium, causing the Asteroid that killed the Dinosaurs.
- The plot of Edmond Hamilton's The Haunted Stars revolves around the discovery that humanity is descended from the vast interstellar empire. A true homeworld of humanity was Ryn, the third planet of Altair. That empire was destroyed by unknown powerful alien enemies.
- In The Hitchhiker's Guide to the Galaxy, it is revealed that humans are descended from the most useless third of the Golgafrinchan population, who were kicked out for having silly jobs like disinfecting pay phones. The remaining two-thirds of the Golgafrinchans were later wiped out by a plague contracted from a pay phone. Despite being nearly completely hopeless at survival (they're more preoccupied with sorting out things like currency than food and shelter), the Golgafrinchans managed to out-compete and replace Earth's native hominids and survived long enough to start some form of civilization.
- In Larry Niven's Known Space universe, Homo habilis were actually Pak breeders, from a planet closer to the galactic core. In the "breeder" phase of their life they are about as smart as chimps (who also evolved from Paks, apparently) but in middle age they become able to eat a root called "The Tree of Life" that contains a virus which transforms them into superintelligent armored Protectors single-mindedly obsessed with preserving their genes. When they colonized Earth it turned out that the soil couldn't support the Tree of Life and the Protectors died off, without them and their instinctive culling of mutants the Pak colony evolved into Earth's great apes.
- The Ringworld was also built by Pak Protectors, whose descendants evolved into hundreds, if not thousands of different humanoid species.
- The punchline of Frank Herbert's short story Occupation Force is that the aliens who just landed in Washington DC are just checking up on a colony they founded... roughly seven thousand years ago.
- In the Paratime multiverse, timelines are assigned to "levels" based on whether the inhabitants remember humanity originally came from Mars.
- In The Stars Are Cold Toys, it's eventually revealed that both Earth and the Geometers' homeworld are Lost Colonies of the original humans from the galactic core. It's heavily implied that most life started in the Core and spread out, which includes the majority of the Conclave races. Partly subverted is that there's no great ancient empire at the Core. Just a whole bunch of worlds connected by a unique Portal Network that sends people to a place matching their innermost desires.
- In one series of novels (can't recall the name), the main characters eventually figure out that the Solar System used to be colonized by a race of native Martians, who mastered Casual Interplanetary Travel and had some nifty tech but never figured out interstellar travel. Eventually, they were soundly defeated by an interstellar race, who allowed a few Martians to start over on Earth without any tech, while rendering Mars itself uninhabitable.
- Downplayed in The Giants Series, and the arguments about whether this is possible make up much of the plot of the first book, Inherit The Stars. Humans from Earth were taken to Minerva millions of years ago, and returned 50,000 years ago when Minerva was destroyed.
- Area 51: It's revealed that humanity isn't native to Earth. They were created elsewhere by the Airlia, an alien species, to be their soldiers.
- The novels about Northwest Smith repeatedly inform us that Man has conquered space before, you may be sure of that.
- Survey Team by Philip K. Dick has an expedition sent to Mars during a nuclear war to see if the survivors can settle there. They find the entire planet has been mined or harvested of anything useful, so even the soil is no longer any good. They find records indicating that the Martians evacuated their population to a pristine world, but their society descended into barbarism. Facing extinction, the desperate humans decide to find this planet and seize it from the Martians, until they discover it's actually Earth.
- Part of the background of H. Beam Piper's Paratime stories is that Earth was originally settled by Martians; in most timelines, the colony regressed to primitivism, with the survivors losing all knowledge of their history and gradually developing a new civilization which believes itself to be native to Earth.
- The short-short story "Reunion" by Arthur C. Clarke consists of a message from interstellar visitors explaining that Earth is one of their lost colonies, which collapsed in mass panic when much of the population developed a disfiguring (though not debilitating) genetic condition. The message ends in the Wham Line "If any of you are still white, we can cure you."
- In Babylon 5, the Centauri tried to pull a fast one by claiming that Earth is their Lost Colony. It didn't take long for human scientists to get a sample of Centauri DNA and expose the hoax-at which point the Centauri explained it away by stating that, given the nature of hyperspace travel and that they used to rule the space around Earth, they mistook Earth for a lost colony that was in the area.
- The premise of both versions of Battlestar Galactica is that humanity evolved on Kobol and Earth is one of thirteen colonies, the other twelve of which have maintained contact. Though in Battlestar Galactica (2003) it eventually turns out that the audience lives on the second planet to be called Earth, the first one suffered the same fate as the other twelve colonies. "We" are apparently descended from a mix of refugees from all thirteen colonies and Earth II's native hominids.
- In the final episode of Space: 1999 the Alphans come across a planet called Arkadia that hosts the ruins of a 25,000-year old human civilization, and they gradually figure out that it was humanity's original homeworld.
- In season 9 of Stargate SG-1 it turns out that the Ancients weren't originally from Earth but came from a different galaxy altogether, and that they were fleeing a war with religious fanatics who have since then Ascended to a Higher Plane of Existence like them, but unlike the Ancients they want to be worshipped.
- In The Twilight Zone (1959) episode "Probe 7 - Over and Out" an astronaut crash-lands on an uninhabited planet after his homeworld has a nuclear war, and shortly after meets a woman in a similar situation. Their names turn out to be Adam and Eve.
- The Unarians believe that Chinese people came from Mars.
- The later Halo games revealed that humanity once had a large space empire thousands of years ago but we're beaten back to the caveman level on Earth after a war with the Forerunners. However, not even the scientist from that empire could tell for sure whether or not Earth was where humans came from.
- Doom 3 implies that we're the last survivors of a martian civilization that came to Earth to escape the demons that were wiping them out.
- In Afrikaans webcomic Verlore Geleentheid humans, or "Om-Ankh", invaded Earth and drove off the original inhabitants, a canine species called "Khanites", ten thousand years ago. Until it turned out the Om-Ankh were created by a Khanite cult that believed the world government's peace was making their society stagnant.
- The South Park episode "Cancelled", all life on Earth is one big intergalactic Reality Show, in which different species from other planets had been brought together for the amusement of the viewing public. Notably, each human ethnicity (for instance Jews, Asians and Hispanics) is said to be from a different planet.