Scientists explain why humans universally perceive four primary colors

For over a century, a quiet paradox sat at the heart of human perception: our eyes hold three kinds of color receptors, yet every culture on Earth organizes color experience around four primaries. Researchers at UC Berkeley have now offered a resolution, proposing that the brain does not simply relay what the eye detects but actively reshapes that signal to match the sparse, asymmetric palette of the natural world. In doing so, the mind achieves something elegant — encoding all of nature's color with the fewest possible moving parts, through two pairs of opposites that cannot coexist: red agai