There are two camps when it comes to imagining what aliens would look like. There are the people who think that aliens will be fundamentally humanoid, and then there are those who believe that life will have evolved very, very differently on other planets.
“I’m of the strong opinion that if humanoid aliens exist, they must have some genetic heritage in common with human beings,” says Mark A. Bullock with the Southwest Research Institute.
Plenty of people agree with him. In fact, the theory has a name! Panspermia is the idea that some long-ago alien race seeded its DNA throughout the galaxy–maybe even the universe–as it traveled the stars. Somehow, that leads to all intelligent life look basically like this guy, who is the first result on Shutterstock when I searched for “generic man.”
If you think about life on Earth, most of it looks… kind of the same. While we can obviously tell the difference between a mantis shrimp, a house cat, and a human being, all three creatures share similar aspects. A central torso, an even number of limbs on both sides, a mouth eating and eyes for seeing.
Even the most imaginative science fiction shows and movies, like Babylon 5 or Doctor Who, stick pretty close to the humanoid template for aliens.
Of course, those shows have to somehow depict the aliens onscreen, and practical effects and CGI are expensive. It’s a lot easier to just put a person into a makeup chair for a couple of hours than to use special effects.
Even H.R. Giger’s famous creation for the Alien franchise draws on earthly inspiration. It has a recognizable head, torso, and arms and legs. Sure, the tail and spines are a little weird. But even the iconic second jaw that juts out of the alien’s mouth is based on a creature from our planet: the moray eel.
In fact, one of the few examples of truly outside-the-box thinking in alien design comes from Douglas Adams’ iconic Hitchhiker’s Guide to the Galaxy. Although many of the aliens do share a similar look to Earthlings, Adams also described the alien race of the Hooloovoo as “a super-intelligent shade of the colour blue.”
The alien intelligence had to be refracted through a special prism in order to attend an event early on in the book. It’s a throwaway joke, but it remains one of the most creative examples of imagining intelligent life that doesn’t follow our fundamental body plan.
It’s no coincidence that Adams stuck with “mostly humanoid” for the main alien characters, such as Zaphod Beeblebrox. The more monstrous or strange the alien, the less sympathetic it is to the reader or viewer. The alien from Aliens? Not very human. Spock? Basically just a dude with pointy ears.
Doctor Who used that idea to great effect with the Ood, a race with heads that look like boiled Cthulu and which talked through glowing orbs attached to their necks. Originally depicted as scary, the Doctor and Donna eventually discovered that the Ood were actually gentle creatures while the humans were the true evil.
Other than the masks, the Ood are clearly just people in black suits. Hey, the Doctor Who budget isn’t unlimited, okay? But it does harken back to the idea of the body plan.
What is a body plan, you ask? In essence, it’s evolution’s way of testing different forms to see which ones work best. In the water, the sleek shape of fish like tuna, dolphins, and sharks emerged as the best one for large animals to move fast. Even though they aren’t closely related, all of these creatures share a similar body plan.
On land, we need legs instead of fins (as the Little Mermaid helpfully pointed out). And the number of legs correlates to the intelligence of the creature. The closer you get to humans, the fewer legs you get until it is winnowed down to just two. While you could have more, you don’t need more. Evolution tends to move us meatbags toward the most streamlined design.
Unless aliens have evolved way past the need for locomotion, sense organs, and physically manipulating objects, they’re gonna need legs, eyes and ears, and arms with something akin to fingers.
Now, it’s possible that these hypothetical aliens are that advanced and can use psychic powers to navigate the universe. Maybe they’ve evolved past the need for bodies at all.
Maybe they are just super-intelligent shades of blue.