Humanity Came From Space

"Life out here began out there."
Commander Adama, Battlestar Galactica (2003)

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 Precursors were 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).

Examples:

Anime and Manga

Film

Literature
  • 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.
  • 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.
  • In 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.
  • In the Paratime multiverse timelines are assigned to "levels" based on whether the inhabitants remember humanity originally came from Mars.
  • 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.
  • 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.

Live Action TV
  • 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 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 worshiped.
  • In The Twilight Zone 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.
  • In the final episode of Space1999 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.

Webcomics
  • 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.

http://tvtropes.org/pmwiki/pmwiki.php/Main/HumanityCameFromSpace