Basic Color Terms: Their Universality and Evolution (1969) is a book by Brent Berlin and Paul Kay, who’s work proposed that the kinds of basic color terms a culture has, such as black, brown or red, are predictable by the number of color terms the culture has.
Berlin and Kay posit seven levels in which cultures fall, with Stage I languages having only the colors black (dark–cool) and white (light–warm). Languages in Stage VII have eight or more basic color terms. This includes English, which has eleven basic color terms.
The authors theorize that as languages evolve, they acquire new basic color terms in a strict chronological sequence; if a basic color term is found in a language, then the colors of all earlier stages should also be present. The sequence is as follows: Stage I: Dark-cool and light-warm (this covers a larger set of colors than English ‘black’ and ‘white’) / Stage II: Red / Stage III: Either green or yellow / Stage IV: Both green and yellow / Stage V: Blue / Stage VI: Brown / Stage VII: Purple, pink, orange, or grey
The work has achieved widespread influence. However, the constraints in color-term ordering have been substantially loosened, both by Berlin and Kay in later publications, and by various critics. Barbara Saunders questioned the methodologies of data collection and the cultural assumptions underpinning the research, as has Stephen C. Levinson.