The sandworms might be the most iconic inhabitants of Arrakis from “Dune,” but they aren’t the most important natives on the planet. The Fremen are the human tribes who live in the desert and ride the worms through the sand. Thanks to generations of survival in the harsh climate, the Fremen became some of the fiercest warriors in the entire galaxy.
Fremen are easy to spot because every single one of them has blue eyes. They aren’t born this way, but continuous exposure to the desert’s Spice eventually changes the color of their eyes. In all of Frank Herbert’s “Dune” books, we meet a number of characters who’ve had their eyes changed by the Spice, and sometimes even the whites of their eyes and their irises have turned blue.
Changing eye color is one of the many side effects of Spice consumption, and it’s not exclusive to the Fremen. Anyone who eats or drinks enough Spice will eventually have their eyes turn blue. In the lore of “Dune,” the changing color is a relatively unimportant side effect of Spice consumption, but there’s a reason Frank Herbert worked it into the story.
What’s really happening with the spice?
“Dune” has been around since 1965, and in that time the book’s fans have put a lot of thought into why so many of the novel’s characters have blue eyes. There’s no denying that the Spice’s effect on eye color has some serious thematic weight in “Dune.” Many view the story as being about imperialism, with the Fremen rising up from subjugation to eventually become militaristic dominators of the galaxy. They think that Frank Herbert chose to highlight the eye color of the Fremen to reference racist rhetoric used by real-world imperial regimes.
Someone else has a very different idea of why Herbert chose to make so many characters in his book have blue eyes. Herbert’s friend Paul Stamets has said that the sci-fi author based most of the lore surrounding the Spice on one of his favorite pastimes: taking psychedelic mushrooms. Herbert was apparently a big fan of magic mushrooms, and the Fremen’s blue eyes are meant to reflect the blue tinge that some mushrooms have.
Eyes aren’t the only thing Spice can change
When people ingest the Spice from Arrakis, it changes them on a physiological level, and the eyes aren’t the only part of the body it touches. The most dramatic effects of Spice are on the brain. Spice allows some people a limited ability to see the future. That’s why Guild Navigators – characters cut from Denis Villeneuve’s “Dune” – need Spice to safely travel the incredibly long distances between planets in the Imperium. Some people, like Paul Atreides, are especially affected by the Spice and can see the future on a level no other human can.
Spice also slows down the aging process, which is another reason why it’s the single most valuable substance on the entire planet. With enough Spice, people can extend their lives by decades or more. In most cases, that prolonged lifespan doesn’t come with any bizarre physical effects. In at least one famous instance, though, it did.
Paul and Chani’s son, Leto Atreides II, had a unique encounter with sand trout, infant sand worms that are also responsible for creating the Spice, during the events of “Children of Dune.” The sand trout fused to Leto’s skin and began transforming him into a human-worm hybrid. Thanks to that, Leto was able to live and rule over the empire for 3,500 years as God Emperor. Of course, Leto’s transformation wasn’t purely due to Spice, and it’s not something other users of the substance could realistically hope to replicate.