Human waves populated the Caribbean islands

Pirates or no pirates, the islands of the Caribbean were settled and resettled by at least three successive waves of colonists from the American mainland, according to a new study.

The examination of ancient DNA from 93 islanders who lived between 400 and 3200 years ago reveals a complex population history and ties to broader, inter-continental human expansions in both North and South America, according to an international research team.

“The DNA evidence adds to the archaeological data and enables us to test specific hypotheses as to how the Caribbean was first settled,” says Hannes Schroeder from Denmark’s University of Copenhagen, a senior author on a paper in the journal Science.

The Caribbean was one of the last regions in the Americas to be settled. Archaeological evidence suggests the first residents arrived about 8000 years ago, and that 3000 years later humans were widely dispersed.

However, much of the settlement history has relied on interpretations from archaeological findings, such as the stylistic comparison of artefact collections between Caribbean sites and those from the surrounding mainland.

While these approaches have illuminated broad-scale population movements, many of the more nuanced aspects of Caribbean population history remain unknown.

To try to fill these gaps, a team led by Kathrin Nägele from Germany’s Max Planck Institute for the Science of Human History analysed the genomes of the 93 islanders using bone fragments excavated from 16 archaeological sites in Cuba, the Bahamas, Puerto Rico and Guadeloupe.

Due to the region’s warm climate, the DNA were not very well preserved, but targeted enrichment techniques allow the researchers to extract new information.

This leads them to believe that there were at least three different population dispersals into the region: two earlier dispersals into the western Caribbean, one of which seems to be linked to earlier population dispersals in North America, and a third, more recent wave, which originated in South America.

And rather than a hinderance, it seems that the Caribbean Sea served as something of an “aquatic motorway”.

“Big bodies of water are traditionally considered barriers for humans and ancient fisher hunter-gatherer communities are usually not perceived as great seafarers,” says Nägele.

“Our results continue to challenge that view, as they suggest there was repeated interaction between the islands and the mainland.”

The researchers also report genetic differences between early settlers and newcomers from South America who, according to archaeological evidence, entered the region around 2800 years ago.

“Although the different groups were present in the Caribbean at the same time, we found surprisingly little evidence of admixture between them,” says Cosimo Posth, from the Max Planck Institute.