Ask Us Anything: Why can’t we see more colors?

Other animals see many more than we do.

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A glowing sunset. A field of wildflowers. A rainbow peeking out of the clouds. The world is teeming with colors we see everyday. But humans don’t see every color on the light spectrum. There is a whole world of color that we can’t recognize. 

Why can’t we spot these hues? We see colors thanks to our eyes and brains. Our eyes contain two types of cells called cone cells and rod cells. Rod cells enable us to see in grayscale, which comes in handy at night when hues are more subdued. Cone cells, on the other hand, enable us to see in color. Our two eyeballs contain a total of about six or seven million cone cells. Actually processing and seeing color also requires the use of our brains. When a certain wavelength of light passes through the cornea it hits one of those cone cells. The cells then send a signal through neurons up to the optic nerve which relays a message to the brain and processes that data.

These cone cells only pick up on a select range of colors. It’s likely we can only see this selection and nothing more because honestly, we’ve been able to survive and thrive just fine with just these hues. But it is true that detecting light with shorter wavelengths than we currently can now, for example, would allow us to see more purplish hues. On the other hand, seeing longer wavelengths, like in the infrared spectrum, would enable us to have the ultimate night vision. 

Hear more about the colors we can and can’t see and why on this week’s episode of Ask Us Anything.  

Claire Maldarelli

Claire Maldarelliis the Science Editor at Popular Science. She has a particular interest in brain science, the microbiome, and human physiology. In addition to Popular Science, her work has appeared in The New York Times, Scientific American, and Scholastic’s Science World and Super Science magazines, among others. She has a bachelor’s degree in neurobiology from the University of California, Davis and a master’s in science journalism from New York University's Science, Health, and Environmental Reporting Program. Contact the author here.