Spanning a million square miles and dotted with more than 700 islands, the Caribbean Sea was one of the last places colonized by Native Americans as they explored and settled North and South America. Archaeologists have long struggled to pinpoint the origins and movements of those intrepid seafarers. Now, thanks to genetic material gleaned from the bones of ancient Caribbean residents, the invisible history of this tropical archipelago is coming to light.
Among the surprising findings is that most of the Caribbean’s original inhabitants may have been wiped out by South American newcomers a thousand years before the Spanish invasion that began in 1492. Moreover, indigenous populations of islands like Puerto Rico and Hispaniola were likely far smaller at the time of the Spanish arrival than previously thought.
Extracting DNA from bones in warm, wet places like the Caribbean was impossible until a few years ago. But thanks to recent advances in genetic technology, a Harvard University lab run by geneticist David Reich was able to recover DNA from 174 individuals excavated at sites from Venezuela to the Bahamas.
The results, published December 23 in the journal Nature, follow on the heels of a July paper in Science that analyzed the genomes of 93 ancient Caribbean individuals at a University of Copenhagen lab. Because of the breakthrough, “we are able to paint a very detailed picture of the early migration history of the Caribbean,” said Johannes Krause, director of the Max Planck Institute for the Science of Human History and a co-author of the Science paper.
Both studies confirm that a wave of pottery-making farmers—known as Ceramic Age people—set out in canoes from the northeastern coast of South America starting some 2,500 years ago and island-hopped across the Caribbean. They were not, however, the first colonizers. On many islands they encountered a foraging people who arrived some 6,000 or 7,000 years ago from the coasts of Central America and northern South America.
The foragers—known as Archaic Age people—seem to have largely vanished soon after the newcomers appeared. There are only limited genetic traces of Archaic individuals in the Ceramic Age people, a sign that the two groups rarely mixed. The ceramicists, who are related to today’s Arawak-speaking peoples, supplanted the earlier foraging inhabitants—presumably through disease or violence—as they settled new islands.
But there are intriguing exceptions that paint a more complex picture of the interactions between these two distinct peoples.
“The remarkable thing is that the Archaic way of life seems to survive in western Cuba until about 900 C.E.,” said William Keegan, an archaeologist at the Florida Museum of Natural History and a co-author of the Nature study. “They apparently lived unmolested and with little mixing.”
One of the most provocative findings of the Harvard study is that the indigenous populations of large islands like Puerto Rico and Hispaniola were far smaller at the time of the Spanish arrival than Spanish records suggested.
A decade after Columbus arrived, a Spanish friar estimated that there were as many as 3.5 million people on Hispaniola, today’s Haiti and Dominican Republic. But extrapolations from the genetic data, based on new mathematical models, point to only tens of thousands of inhabitants. That calls into question the old assumption that hundreds of thousands, if not millions, of indigenous people died from disease and other impacts of the European invasion.
“This new approach of estimating past population sizes has the potential to revolutionize our view of past migration and cultural changes,” said Krause.
While large numbers of indigenous people died after the arrival of the Spanish, genetic studies show that their DNA survives in modern-day islanders, mixed with genes from later European colonizers and enslaved Africans.
Many indigenous groups have alleged that geneticists—often white Europeans and Americans—don’t consult with them, or show proper respect for their traditions, while investigating their origins. In this case, however, the Nature authors said they collaborated with descendant communities as well as local Caribbean scholars in gathering and analyzing their data. The research was supported in part by a grant from the National Geographic Society.
One mystery yet to be resolved is how relatively small island populations avoided inbreeding over so many centuries. There is no sign of any subsequent major migrations from the mainland. But archaeologists say the new evidence points to extensive island-to-island contacts that likely helped ensure genetic diversity.
The research published in Nature “highlighted the connectivity of peoples in the region,” said Jada Benn Torres, a Vanderbilt University genetic anthropologist who was not directly involved in the study. Torres and her colleagues say a next step is to understand the links among islands in what remained a relatively closed system until the Spanish arrived in 1492.
“This was a dynamic and interconnected region of the world,” said Miguel Vilar, a University of Maryland anthropologist. The history of the Caribbean, he said, “is finally being understood through DNA in ways that archaeology alone hasn't been able to do before.”