Islands are not only hotspots of biodiversity, they also make a significant contribution to linguistic diversity. This is shown by a study in which a research team created and analyzed a database of languages from over 13,000 inhabited islands. Although islands make up less than one percent of the inhabited land mass, around ten percent of languages are spoken almost exclusively on islands. Due to this high proportion, islands play a special role in the preservation of endangered languages, according to the researchers.
In biology, islands are particularly important for biodiversity. Many islands offer special ecological niches and, thanks to their isolation from the mainland, are home to unique ecosystems. It was not for nothing that expeditions to the Galapagos Islands led Charles Darwin to his findings on the origin of species. For us humans, the geographical isolation of islands is no longer a barrier. Nevertheless, many of the world’s islands are still cultural refuges to this day.
13,100 islands and their languages at a glance
“We were curious why islands are home to such a large part of the world’s linguistic diversity,” says Lindell Bromham from the Australian National University in Canberra. To investigate this question, she and a team created a database of 1,197 languages spoken on 13,100 inhabited islands in the world. The researchers counted islands as land masses with an area of up to 11,000 square kilometers. That’s roughly the size of Jamaica.
“When we analyzed the global database, we found that islands play a similar role in the formation of language diversity as they do in species diversity,” says Bromham. “Our results provide quantitative evidence that islands are home to a much larger proportion of the world’s languages than would be expected based on land area.” While the area of the islands included only accounts for 0.71 percent of the inhabited land mass, 17 percent of the languages spoken worldwide are found on islands.
Endemic languages
Not all of these languages are exclusive to islands. “Many languages spoken on islands are practically extensions of the language area on the mainland,” the researchers explain. “For example, Swedish is spoken on four percent of the world’s inhabited islands, but most people who speak Swedish live on the European mainland.” However, around ten percent of the languages are endemic to islands, meaning they are spoken almost exclusively on islands.
Further analysis revealed that these island languages have different evolutionary patterns than languages that are usually spoken on the mainland. “Languages that are spoken predominantly on islands have significantly fewer phonemes, the basic sound units from which words are formed,” says Bromham. The reason for this could be that phonemes are gradually lost in small populations of speakers. Isolation from neighboring languages and other processes could also play a role, according to the researchers.
Preservation of linguistic diversity
The team also analyzed which factors favor language diversity on islands. According to their findings, the number of endemic languages increases with the size of the island and with its distance from the mainland. “But unlike biological diversity, isolation is not a consistent predictor of language richness,” the researchers write. “However, the more isolated an island is, the more likely it is to host endemic languages.” Bromham and her team identified the climate and topography of islands as other influencing factors, with more languages occurring on islands with a tropical climate and higher altitudes.
Since many of the world’s languages are now threatened with extinction, the team also looked at how threatened island languages are. “Our analysis shows that endemic languages on islands are not significantly more threatened than their mainland counterparts,” says Bromham. “But because islands account for such a disproportionate share of global language diversity, they will play a crucial role in maintaining linguistic diversity. Islands are not only cradles of linguistic diversity, but also arks that carry linguistic diversity into the future.”
Source: Lindell Bromham (Australian National University, Canberra) et al., Nature Ecology & Evolution, doi: 10.1038/s41559-024-02488-4