Mostly, Mad Max: Fury Road is two hours of driving across colorful wastelands peppered with moments of grunt-heavy dialogue. There are explosions, there’s some gunfire, and there are a whole lot of cars and trucks covered in spikes. The main resources the central city needs are bullets and gasoline. With the inhospitable and sandy backdrop, and the near-continuous vehicular action in front of it, Fury Road appears to be a film about the crunch and grind of engines and less so the unfortunate souls whose bodies are thrown under the wheels of war parties and left forgotten in the wastes.

But this would be missing a central element. Fury Road’s violent animosity between man and machine is, upon closer examination, a description of a precarious alliance between meat and metal, centered on those body parts most primal and most delicate: our hands and our mouths.

Theron’s Furiosa rocks a prosthetic arm with a two-fingered hand, made of pistons and wrenches and recycled car parts. It clanks against the steering wheel or the guns she holds, but the audience is watching her use the metal arm differently: not as a tool, but as a body part. When she removes it early on, its absence is striking because of the limb’s unexpected detachability; because she was using it so “naturally.” It’s only a weakness when she isn’t wearing it, and even then she’s more than able to hold her own in a fight.

When one of Max’s flesh-and-bone hands is crushed against the door of the truck cab, its being flesh raises the stakes: it is threatened with mutilation or outright destruction. The same is true when he reflexively puts his hand to his head to stop a crossbow bolt, and ends up with it pinned to his forehead—having saved his brain, his being, his core self, but having sacrificed, in part, the most efficient way he has of manipulating his environment.

The film’s preoccupation with the body isn’t limited to hands, either. The mouth, in Fury Road, becomes a reflection of the self—Immortan Joe’s is grotesque and constructed, Max’s spends much of the first third of the film trapped behind a garden hoe muzzle. The War Boys spray their mouths with chrome paint to prepare themselves as an offering to some unnamed god of gasoline, that they might enter Valhalla with the best warriors of legend.

But like the hand, the mouth is equally a tool and a weakness—in the climax of one chase, Max and a War Boy are lying face down on trucks neck and neck with each other, both sucking gasoline into their mouths and spitting it into the front of their respective vehicles to try to outpace the other. At the very end of the film (spoilers, obviously), Immortan Joe is killed when his mask is attached to a grappling hook and his face is ripped off, and Max repeats the gasoline-sucking action to pump his blood into Furiosa to keep her alive.

In the barely inhabitable wastelands of the future, where people are reduced to supplies of blood or breeding material, our bodies will be in constant turmoil—as Furiosa says, “out here, everything is pain. ”But, according to Fury Road, they will also be the last frontier of our humanity, and how we choose to use them—for glory, for others, for control—will determine our nature going forward.