If you look at a rainbow, the spectrum of light is continuous and seamless. One wavelength bleeds imperceptibly into the next. There are no black lines separating “green” from “blue.” Yet, when humans describe what they see, they slice this infinite spectrum into neat, labeled boxes. In English, we call them red, orange, yellow, green, blue, indigo, and violet.

For a long time, linguists and anthropologists believed these boxes were drawn arbitrarily. They thought that because culture shapes language, a remote tribe in the Amazon and a stockbroker in New York would categorize color in entirely different, random ways based solely on their cultural upbringing. This concept, loosely tied to the Sapir-Whorf hypothesis, suggests that language dictates how we perceive reality.

But in 1969, two researchers named Brent Berlin and Paul Kay dropped a bombshell on the linguistics world. After analyzing data from nearly 100 languages, they discovered that color naming isn’t random at all. It follows a strict, universal hierarchy. There is a predictable evolutionary path that almost every language on Earth follows as it gets more complex.

And rule number one of this hierarchy? “Red” always arrives before “Blue.”

The Berlin and Kay Experiment

To understand why red is the king of the color spectrum, we have to look at how Berlin and Kay conducted their research. They didn’t ask people to discuss philosophy; they showed native speakers of various languages a set of 329 standard color chips (the Munsell color chips). They asked the speakers to identify the “focal point” of their basic color terms.

They defined a “basic color term” as a word that is:

• Monomorphemic: One word (like “blue”, not “light blue”).
• Generally known: Used by everyone, not just artists or specialists (like “taupe” or “chartreuse”).
• Not contained within another color: “Scarlet” is a type of red, so it doesn’t count.

What they found was a stunning consistency. If a language had a word for “red”, the focal point (the “reddest” red) was almost identical across cultures. But even more fascinating was the mathematical pattern of how these names emerged.

The Seven Stages of Color Evolution

Berlin and Kay identified that languages acquire color terms in a specific chronological order. A language cannot invent a word for “brown” unless it already has a word for “blue.” It cannot have distinct words for “green” or “yellow” unless it has a word for “red.”

Here is the breakdown of the hierarchy:

Stage I: Dark and Light

If a language only has two color terms (which is true for the Dani people of New Guinea), those terms are always Black (or dark/cool) and White (or light/warm). This covers everything. “White” encompasses fire, the sun, and bright objects. “Black” encompasses the night, shadows, and often cool colors like murky water.

Stage II: Enter the Red

When a language evolves a third term, it is universally Red. It is never blue, never green, never orange. It is always red. At this stage, the world is divided into Dark, Light, and Red.

Stage III and IV: The Earth Tones

Next comes either Green or Yellow. Different languages pick one or the other first, but both usually arrive before anything else. This makes sense from an evolutionary standpoint, as these are the colors of vegetation, ripeness, and the earth.

Stage V: Finally, Blue

Only after a language has established black, white, red, green, and yellow does it usually develop a distinct word for Blue. This explains why ancient texts (like Homer’s The Odyssey) famously describe the “wine-dark sea” rather than a blue sea. Homer wasn’t colorblind; Ancient Greek just hadn’t lexicalized “blue” as a distinct category yet.

Stage VI and VII: The Specifics

Once blue is established, languages move on to Brown, and finally, meaningless order terms for Purple, Pink, Orange, and Grey.

Why Red Reigns Supreme

Why is red the first hue to break away from the black/white binary? Why does it beat blue every single time? Linguists and evolutionary biologists have a few compelling theories.

1. Biological Salience

The human eye is drawn to red. It has the longest wavelength in the visible spectrum and triggers a specific physiological response. More importantly, red is the color of blood. For our ancestors, spotting red was a matter of life and death. It signaled a wounded prey, a bleeding clan member, or the flush of anger or arousal in a face. It is the most “human” color.

2. Ecological Relevance

Beyond our bodies, red is distinct in nature. It is the color of fire and, crucially, the color of ripe fruit against green foliage. Primates (and humans) evolved trichromatic vision largely to spot ripe berries. If you need to communicate a vital resource to your tribe (“Eat this berry, not that leaf”), you need a word that distinguishes the fruit from the background.

The “Grue” Phenomenon and the Problem with Blue

If red is the loud, attention-seeking child of the color family, blue is the quiet introvert. In nature, blue is actually quite rare. There are very few blue animals, blue rocks, or blue foods. While the sky is blue, it is inaccessible—it is the “background” of the world rather than an object we interact with.

Because blue is often physically darker, many developing languages lump it in with other colors. In the Berlin and Kay hierarchy, before “blue” exists as a separate word, it is usually categorized as a shade of black (dark) or merged with green.

Linguists call this merged category “Grue.”

You can see remnants of “Grue” in languages today:

• Vietnamese: The word xanh can refer to both the blue of the sky and the green of the leaves. Context usually dictates the meaning.
• Japanese: The word ao is used for blue, but historically covered green as well. This is why Japanese traffic lights have a “green” signal that is officially called ao (blue).
• Welsh: The word glas translates to blue, but historically covered various shades of green and grey.

Because blue lacks the urgency of red (blood) or the utility of green/yellow (vegetation/earth), it simply doesn’t require a dedicated label until a culture creates dyes or artifacts that necessitate the distinction.

Evolution Continues: The Russian Blue

Is English done evolving? Not necessarily. The hierarchy suggests that as culture becomes more complex, so does our vocabulary. English has 11 basic color terms. However, Russian has 12.

In English, “light blue” and “dark blue” are just varieties of the same color. But in Russian, goluboy (light blue) and siniy (dark blue) are as distinct as “pink” and “red” are to an English speaker. If you show a Russian speaker a gradient of blues, they will perceive a boundary line that English speakers usually gloss over.

Recent studies suggest that because Russian speakers have these mandatory linguistic distinctions, their brains are actually faster at distinguishing between shades of blue than English speakers. The language has trained the brain.

The Takeaway for Language Learners

Berlin and Kay’s theory teaches us something profound about the human experience. While our cultures are vastly different—with unique foods, clothing, and customs—our brains are wired on the same biological chassis.

When you are learning a new language and struggling to memorize vocabulary, remember the hierarchy. You aren’t just memorizing arbitrary sounds; you are looking at a map of human consciousness. We all start with light and dark. We all notice the blood and the fire (Red) before we notice the sky (Blue).

So, the next time you see a “wine-dark sea” in a poem or get confused by a traffic light in Tokyo, remember: it’s not a translation error. It’s just a different stop on the evolutionary timeline of color.