'Dune' Explained: Why the Fremen's Eyes Are So Blue

Frank Herbert created one of the strangest sci-fi universes ever committed to paper in his novel Dune—which is why it was long considered an extremely difficult story to adapt faithfully for the big screen. Director Denis Villeneuve was not deterred, though, and his film, streaming now on HBO Max, includes even the weirdest stuff from the book franchise.

One of the most noticeable details is that the Fremen—the race of desert dwellers that includes Chani, played by Zendaya, and Stilgar (Javier Bardem)—all have bright blue eyes.

This is briefly explained in the movie, but the books offer more far more information about this bizarre trait (which is still less weird than the fact that the Fremen wear suits that recycle their sweat into drinking water).

Why Zendaya's Eyes Are So Blue in 'Dune'

In the books and the film, the blue eyes are related to "spice," a psychedelic drug that plays a key role in Dune (not to be confused with the real-world synthetic cannabinoids often known as spice).

Spice, which is also called melange in Herbert's 1965 novel, is found among the sands of the desert planet Arrakis, the home of the Fremen.

The drug comes from the excretions of the younger form of the sandworms that are native to Arrakis, altered by heat and pressure (and the water that lies deep below the planet's surface) into melange.

Used as a psychedelic, the substance also has a second function that is crucial to the galactic economy—it gives its taker the ability to see a little into the future, which is called prescience.

After computers were outlawed in the world of Dune (it's a long story), spice became crucial to navigation through space. That is why the Harkkonens and then the Atreides were willing to harvest it despite the huge dangers of sandworm attack. Similar to oil-rich countries in the real world, the noble houses that have large amounts of spice also amass great wealth and international influence.

Spice, however, has some side effects. The navigators who have to take loads of it (and are surrounded by a spice gas while they work) actually mutate because of this, with their heads and limbs becoming longer.

Before that happens, however, the users' eyes turn blue. This is called in the books "the eyes of Ibad."

zendaya blue eyes
Zendaya in "Dune." Her character has bright blue eyes. Warner Bros.

Villeneuve's film removes some of the moral judgments about spice in the book. Herbert's novel states that blue eyes are a result of being addicted to spice. Perhaps not wanting to imply that an entire race is addicted to drugs, Villeneuve includes a scene explaining that the Fremen's eyes have turned blue simply because of their constant exposure to spice in the sands of Arrakis.

Dune is in theaters and on HBO Max now.