In the video, a preposterously cute, gray squirrel monkey named Dalton bonks his head against a computer screen in front of him. Wide-eyed and muttonchopped, Dalton has quite the setup—the screen, wide in squirrel-monkey terms, displays dots of varying sizes and colors. Below that is a monkey-sized basin, like a sink in a dollhouse kitchen remodeled with stainless steel fixtures.

Dalton is doing science. Male squirrel monkeys don’t see color well; they have a kind of red-green color blindness. Dalton's eyes really only see medium and short wavelengths of light—blues and greens, and their overlap color, yellow. He's what vision scientists call a protanope. With no receptor for reddish hues, he sees reds as dark yellows and yellow-browns, and greens as mostly yellow—to the extent that human color words mean anything to a monkey.

He isn’t really bonking his head; Dalton is trained to indicate when he can see a color on the screen. “He’s actually fairly carefully touching his tongue to the screen,” says Jay Neitz, a color vision researcher at the University of Washington. Dalton sticks his tongue out, Jay says, because he knows that when he recognizes a color, a drop of grape juice will appear in the basin. Dalton really likes grape juice. And a little click will sound in the background, another bit of reinforcement. When he sees a color, he gives it a little kiss.

When Dalton can’t find a color, or kisses the wrong part of the screen, a less pleasant buzz replaces the click. Also: no grape juice. When that happens, Dalton sometimes takes a random guess. Or he just looks around the room, seemingly a little frantic.

“Is he angry?” I ask.

“It’s more like, what the hell?” Neitz says. “Sometimes they’ll grab ahold of the tray. It’s a frustration thing.” In clip after clip, shades of red scattered amid grays go unseen, unlicked. The buzzer buzzes, the grape juice does not appear. Dalton’s body assumes the posture of a primate who would very much like to speak to a manager, please.

Then there’s a discontinuity, a weeks-later time jump. Offscreen—this was in 2009—Dalton undergoes a delicate operation. A surgeon inserts a long needle into Dalton’s eye, all the way to the receptor-dense, light-sensing retina at the back. With this microliter syringe, the surgeon injects a tiny bleb of fluid. “It creates a retinal detachment that looks like a blister,” Neitz says. The surgeon does this in three places, each 120 degrees from the others, in both eyes.

This is where Dalton apparently gets superpowers. In this origin story, Neitz and his wife Maureen, a geneticist, are the scientists who create the super-monkey serum.

In the fluid is a virus, specifically an adenovirus, a common variety of pathogen that includes the common cold. This one has been scraped clean of the things that make it germy, repurposed to carry a carefully designed stretch of DNA wrapped inside a ball of protein.

Viruses are good at hijacking a cell’s genetic machinery. Usually they do it to trick cells into making more virus; that’s called infection. Here, in Dalton’s eyeball, the modified adenovirus is carrying instructions to teach the cone-shaped cells in the monkey’s retinas that normally sense medium-wavelength, greenish light to instead (or maybe also) sense longer, reddish wavelengths.

SIGN UP TODAY Sign up for the Backchannel newsletter and never miss the best of WIRED.

A lot has to go right. The virus has to stick to the cell and evade the monkey’s immune system. It has to get the new gene into the cell’s nucleus and integrate into the existing DNA. The gene has to actually get turned on and start making proteins. It rarely goes right. “We’ve been working on ways to improve the efficiency,” Neitz says. At the highest viral titer, just 30 percent of cells infected actually turn on the gene. But those that do will go on to express not just one photopigment but two. A once-middle-wavelength cone will also have a long-wavelength receptor. Nominally, it’ll see red, and Dalton will have a monkey superpower.