The naming of colors has long been a topic of interest in the study of human culture and cognition -- revealing the link between perception, language, and the categorization of the natural world. A major question in the study of both anthropology and cognitive science is why the world's languages show recurrent similarities in color naming. Linguists at Yale tracked the evolution of color terms across a large language tree in Australia in order to trace the history of these systems.

The study's co-authors -- Claire Bowern, associate professor of linguistics at Yale, and former Yale postdoc Hannah J. Haynie -- utilized an evolutionary framework to study the color systems in the Pama-Nyungan language. The researchers analyzed the color systems of 189 languages in the Pama-Nyungan language family, which was chosen because of its history (it dates back 6,000 years) and its size (it spans about 90% of the Australian mainland).

"We need large numbers of languages to get a good sample size and a good variety of colors," says Bowern. "The Pama-Nyungan societies are also relatively similar in terms of material culture and the sorts of ways they make use of resources for color. We were able to reconstruct a number of different systems by testing two or three explicit hypotheses."

According to the researchers, the evolutionary process of color naming has seven distinct stages. The most basic of these stages centers on the development of names for the colors of black and white. In the next stage, terms for a color associated with red are added, followed by names for either yellow or green, then blue and brown. The final stage involves introducing designations for pink, purple, orange, and/or gray.

The results of the Yale study provide an detailed history of color terms across a large language sample, say the researchers, and show that there is broad support for the color terms defined by the Berlin and Kay theory, which maintains that the world's languages share all or part of a common group of color names, and that terms for these concepts evolve in a specific order.

The researchers also found that there is extensive evidence for the loss -- as well as gain -- of color terms. "We find alternative trajectories of color term evolution beyond those considered in the standard theories," says Bowern.

The work -- which Bowern says is of relevance to anthropologists, psychologists, and linguists -- was published in the Proceedings of the National Academy of Sciences.