The world’s interest with meeting and coexisting with alien life has been around for the last hundred years or so.  When most people think of aliens, they believe that they look like little green men, or some other form similar to our own. But in recent decades there have been more complex ideas about what alien life would look like to us humans on Earth. We are unique to our own planet, and have physically evolved precisely because of the planet’s gravity and position in the solar system, so it’s biased for us to believe that alien visitors from planets completely different from our own would look anything like us.

Some of our most popular pieces of entertainment have been those that take place in a space setting, where humans coexist with hundreds of diverse alien species. This is most notable with Star Wars, whom millions just went and watched The Last Jedi, the latest installation in the series. But while watching these space fantasies on the big screen, there was always a question nagging in the back of my mind: Why do mostly all the alien beings in the Star Wars galaxy seem to look the same?

At first glance, many of the aliens in Star Wars don’t look human at all or like each other. Some have blue skin with red eyes. Others have bug eyes with green scales. Some just look like muppets, such as whatever this jazz-keyboard monstrosity is supposed to be…

Take Chewbacca for example. He stands at 7 feet tall, is covered in thick dog hair, and only speaks like a bear. But Chewbacca fits the same humanoid pattern we see in many races in Star Wars: two legs, two arms, and a head with two eyes and a mouth. Most aliens in Star Wars, despite coming from various planets billions of miles apart, all seem to share basic physical qualities that we do as humans.

Sure there are plenty of wild deviations from this pattern. Jabba the Hutt is more slug like in his physicality as he has no legs, but he still has other recognizable humanoid features like a face and arms. But why do we not see truly out-of-this-world looking aliens in the galaxy? Why doesn’t Han Solo talk smuggling tricks with a floating cloud of sentient gas?

And of course I will concede that the practical reasoning for this choice is that it’s a movie made by humans, and thus by having human actors play your alien creatures, you’re most likely going to have humanoid beings inhabit your world. And because it’s science fantasy versus actually science fiction, it’s less entertaining if Luke Skywalker learns about the force from the tall, silent Monolith from 2001: A Space Odyssey.

But what if there’s a conceptual reasoning to the similarity? What if all the species in the Star Wars universe were somehow connected by a singular origin? This would explain their shared features, and ability to coexist in the same physical space with relative ease.

Back in the 1800’s, Charles Darwin used finches on the Galapagos Islands as a basis for his Theory of Evolution. The birds, originating from a singular form, split off and developed various physical features that suited their environment.

Apply this theory to Star Wars. Millions of years ago there was a singular, human-like species that was able to travel and spread out far and wide through the galaxy. Over time, each group that split off developed into their own unique species, depending on the planet that they lived on. Cut to modern day Star Wars galaxy, and now you have hundreds, if not thousands, of diverse alien races that share common humanoid traits: generally walk on two legs, use two arms, breath with lungs, see with generally two eyes, and communicate with a single mouth.

Since there is very little explanation as the ancient origins of the alien races that exist in Star Wars canon, I’d like to believe this is the most reasonable explanation as to why all the aliens in Star Wars appear to look the same.