Where did life on Earth come from, exactly? It’s one of the most fundamental questions that scientists have yet to fully explain, and it offers a tantalizing premise for Hollywood screenwriters and directors to explore through science fiction — albeit not always accurately.
One film that tackled this topic head-on was Ridley Scott’s Prometheus, the 2012 sci-fi movie that served as a prequel of sorts to the Alien franchise.
From ancient cave art, archaeologists in the movie surmise that aliens from a far-off solar system, known as “Engineers,” seeded life on Earth through their DNA. It seems like a hokey premise invented for cinematic entertainment, but is it more plausible than you think? Well, kind of.
Seth Shostak, a senior astronomer at the SETI Institute, says “it's definitely possible” that life originated on another planet, but probably not how Prometheus explains. Inverse spoke with Shostak and other experts in astronomy and archaeology to explain the weird and problematic science behind this strange alien horror flick. Let’s dive in.
But if you want to watch the movie, don’t wait too long — Prometheus is leaving Amazon Prime at the beginning of June.
Reel Science is an Inverse series that reveals the real (and fake) science behind your favorite movies and TV.
What is panspermia?
As it turns out, Prometheus’s bizarre sci-fi premise has roots in a real-life scientific theory known as panspermia, which argues that life can be seeded from elsewhere onto a planet — whether as a passenger on a comet or asteroid or through a transfer between planets.
“It’s just used to refer to the idea that life might have a single origin, but end up in multiple places in the Solar System or even in the universe,” Jason Wright tells Inverse. Wright is a professor of astronomy and director of the Penn State Extraterrestrial Intelligence Center.
One possible example of panspermia would be if life originated on a planet like Mars, but then an asteroid impact dislodged a rock, which then carried ancient microbes to Earth.
“In that sense, it's possible that life is not indigenous to Earth,” Shostak says.
The idea that comets and asteroids could carry life between planets is well-known, and astrobiologists refer to this theory as lithopanspermia. It’s also partly why astronauts are so interested in searching for signs of microbial life on Mars. If we could find evidence of life on Mars that resembled our own, it could help explain the origins of life on Earth.
But Wright says there’s also the idea that “life could have been spread deliberately by a spacefaring species.” Like humans. Or, yes, extraterrestrial beings.
In the 1970s, researchers Francis Crick and Leslie Orgel proposed the idea of directed panspermia, which they described as “the theory that organisms were deliberately transmitted to the Earth by intelligent beings on another planet.”
Yet Wright says that both panspermia theories are “highly speculative” and have never been proven, so Prometheus’ proposal that extraterrestrial beings are the origin of life on Earth is firmly in the realm of science fiction — for now.
Is Prometheus possible?
But could life on Earth have originated from aliens from a planet in another system?
After all, it’s not implausible that there is another habitable planetary system in the galaxy like the one in Prometheus. NASA has even found several Earth-sized planets in a potentially habitable zone in the TRAPPIST-1 solar system, and they’re on the hunt for more.
“It's all very possible that such a system could exist,” Wright says, but states that it’s unlikely we could find any evidence of aliens bringing life to Earth.
“Remember: the origin of life on Earth goes back over 4 billion years. So any alien technology that might have brought it to the Solar System was billions and billions of years ago,” Wright adds.
Shostak says the idea that life transferred between two planets in the same planetary system — such as Mars and Earth — is pretty plausible, but it’s an entirely different ballgame between planetary systems. To find our supposed alien ancestors in Prometheus, the movie’s scientists travel to a system so far away that they have to hibernate for years to survive the journey.
Wright adds, “the big implausibility is that the aliens could come all the way here from their own planet, but it's not impossible.”
But the science becomes implausible if you read deeper into the movie, which suggests that the alien engineers seeded the DNA origins of just human beings — not all life. When the movie’s Dr. Shaw says, “They engineered us,” she seems to imply that “us” means specifically “humans,” though it’s left somewhat ambiguous. Neither Shostak nor Wright finds this idea plausible.
“It's a nice way of making ourselves sound important, but I don't think there's any possibility of supporting that as science,” Shostak says.
So, the science in Prometheus is a mixed bag, to say the least. But Wright says, “I wouldn't try too hard to make it make sense.”
“You're not supposed to take it too seriously in terms of science,” he adds.
Is Prometheus’ alien theory problematic?
Prometheus plot may be rooted in real scientific theory, but it’s also based on problematic and often racist theories of ancient peoples and aliens, known as “ancient aliens.”
The History Channel popularized the concept of ancient aliens, but it’s essentially the idea that aliens influenced and may have even engineered the art and civilization of ancient peoples. It’s a racist idea because it suggests that ancient peoples were not sophisticated enough to create complex societies and art, requiring the aid of aliens to build structures like the pyramids.
“Certainly, we can argue it’s racist to suggest that ancient societies of people who weren’t white needed the help of aliens to come up with their amazing inventions,” Denning adds.
Prometheus’ explanation of the Engineers creating humanity and the depiction of alien creatures in ancient cave art can be read as an elaborate version of the “ancient aliens” theory. The movie’s Dr. Holloway even leans into the racism, arguing “there’s no way these primitive, ancient civilizations could have possibly known about” the planetary system where the Engineers came from.
Many archaeologists deride the “ancient aliens” theory because of the lack of evidence and its problematic implications.
“It’s not taken seriously by any anthropologists that I know,” Denning says.
But Denning says that the ancient alien theory fascinates us because it offers something archaeology does not: “the promise of an exciting return visit — and maybe even help — from extraterrestrials.” Though in Prometheus, the scientists get anything but help from the Engineers.
Ultimately, experts say the movie’s more impactful meaning may lie in its questions about humanity’s aims rather than our scientific origins.
“Perhaps Prometheus is most usefully read as a mythical exploration of what we ourselves, as humans, create and destroy,” Denning says.
Prometheus is streaming now on Amazon Prime.