The language of the creole-speaking population of Cape Verde, off the northwest coast of Africa, has been passed down over generations much the same way that genes are passed from parents to their children.
To explore the connections between genetic characteristics and linguistic traits, researchers collected DNA samples within the creole-speaking population of Santiago, the main island in Cape Verde. They also recorded speech data from the same people to study their idiolects—a person’s specific, unique way of speaking a language.
The language spoken in Cape Verde is Kriolu, a mixture of European and African languages that came into contact during the Portuguese transatlantic slave trade.
Linguists have long known that this creole still shows imprints of the African languages spoken by the slaves that populated the island of Santiago beginning in 1461. Further, geneticists have long known that relationships between populations and their languages have a lot in common.
The findings show genes and African-derived linguistic features have been transmitted in a similar way within families over generations, so that individual Cape Verdeans retain traces of their genetic ancestry in their idiolects.
By collecting DNA from native speakers of Kriolu born on Santiago and comparing their patterns of genetic variation with other African, European, and American populations, the researchers show that the genetic mix in Cape Verde reflects the known history of islands populated by Senegambian slaves from West Africa and Portuguese settlers between the 15th and 19th centuries.
For the study that appears in Current Biology, researchers recorded Kriolu speech data from the same subjects who contributed genetic data and identified words whose origins were either Portuguese or African, or a convergence of both. They then tabulated the frequencies of words in the speech patterns and compared the total frequency of words of African origin with the proportion of African genetic ancestry of each individual.
They found a significant correlation between the fraction of African genetic ancestry and the fraction of African-derived words used by an individual.
Further, the parents’ birthplace was a strong predictor of an individual’s word frequency patterns, regardless of their own birthplace.
“This result indicates that contact with other members of the community and with sources such as radio and television is insufficient to eradicate the speech patterns transmitted from parents to offspring in Cape Verde,” says Paul Verdu, a former postdoc at the University of Michigan and one of the study’s lead authors. He is now at the Centre National de Recherche Scientifique in Paris.
The observed genetic-linguistic correlations might also be explained by sociocultural factors and how individuals construct their own identity and way of speaking to reflect their perceived genetic origin, says coauthor Marlyse Baptista, a professor of linguistics at the University of Michigan.
Source: University of Michigan