In 1969, two Berkeley researchers, Paul Kay and Brent Berlin, published a book on a pretty groundbreaking idea: that every culture in history, when they developed their languages, invented words for colors in the exact same order. They claimed to know this based off of a simple color identification test, where 20 respondents identified 330 colored chips by name. If a language had six words, they were always black, white, red, green, yellow, and blue. If it had four terms, they were always black, white, red, and then either green or yellow. If it had only three, they were always black, white, and red , and so on. The theory was revolutionary — and it shaped our understanding of how color terminologies emerge.