Researchers identify principles that shape kinship categories across languages

Different languages refer to family relationships in different ways. For example, English speakers use two terms -- grandmother and grandfather -- to refer to grandparents, while Mandarin Chinese uses four terms. Many possible kinship categories, however, are never observed, which raises the question of why some kinship categories appear in the languages of the world but others do not. 

A group portrait of a mother, son and daughter on glass, Ancient Rome, c. 250 AD [Credit: Wiki Commons]

A new study published in Science by Carnegie Mellon University's Charles Kemp and the University of California at Berkeley's Terry Regier shows that kinship categories across languages reflect general principles of communication. The same principles can potentially be applied to other kinds of categories, such as colors and spatial relationships. Ultimately, then, the work may lead to a general theory of how different languages carve the world up into categories. 

For the study, Kemp and Regier used data previously collected by anthropologists and linguists that specify kinship categories for 566 of the world's languages. Kemp and Regier used a computational analysis to explore why some patterns are found in the data set but others are not. In particular, they tested the idea that the world's kinship systems achieve a trade-off between the two competing principles of simplicity and informativeness. 

"A kinship system with one word referring to all relatives in a family tree would be very simple but not terribly useful for picking out specific individuals," said Kemp, assistant professor of psychology within CMU's Dietrich College of Humanities and Social Sciences and lead author of the study.