“Why should humans all choose roughly the same places to identify transitions, when color is just photons, irreducible quanta of light on a continuous spectrum of wavelengths? Linguists might say it’s because language creates cultural norms. Anthropologists might say it’s because some colors have more cultural relevance than others. Neuroscientists and physiologists might say it’s because of the specific light-sensitive cells in the primate eye tuned to pick up red, green, and blue wavelengths and send signals to the visual cortex—trichromatic vision.”