The first humans began to settle on the Caribbean islands around 6,000 years ago. Genetic analyzes now show that the colonization occurred in two waves. The archaic population was largely displaced by settlers from South America around 1,700 years ago. After that, there was no relevant genetic exchange with the mainland for a long time. In return, the genetic and cultural relationships between the islands were more intensive than previously assumed. This can be seen both in shared genetic material and in archaeological artifacts such as pottery. When Columbus discovered the islands in 1492, the new analyzes show that they were more sparsely populated than historical reports suggest.
Settlement of the Caribbean islands began around 6,000 years ago. But where did the people come from who settled in the regions we know today as the Bahamas, Cuba, the Dominican Republic, Haiti, Puerto Rico, Guadeloupe, St. Lucia, Curacao or Venezuela? What was the relationship between them? How many people were living in the Caribbean when the Spanish got there? And can genetic traces of the indigenous groups still be discovered in the genome of the Caribbean population?
Ancient aboriginal DNA
An international team headed by Daniel Fernandes from the University of Vienna has dealt with these questions. The researchers analyzed the genetic makeup of 174 individuals who lived in the Caribbean between 3,100 and 400 years ago. In addition, they included earlier genetic analyzes of 89 other individuals and made use of archaeological findings which, for example, provide information about the pottery art of the people of that time. “Our aim was not only to examine the origins of the people who lived in the Caribbean before their first contact with Europeans, but also to shed light on their regional interaction networks,” explains Fernandes.
According to the analyzes, the original, archaic population of the Caribbean probably came from a single population group from northern South America or Central America. However, a direct genetic relationship with known indigenous groups from these areas could not be proven, so the exact origin remains unclear. Contrary to what previous studies suggested, the researchers consider it unlikely, based on their data, that the first humans in the Caribbean came from North America.
Exchange between the islands
At least 1,700 years ago, a new population group came to the region. Originating in northeastern South America, these people spread from the islands of the Lesser Antilles over the entire Caribbean. These people, who brought the pottery with them, gradually displaced the archaic population who used stone tools. However, there was hardly any genetic exchange between the two population groups: Of the more than 200 analyzed individuals who have lived in the Caribbean since that time, only three people had proportions of both groups in their genome.
Over the following centuries, the gene pool of the Caribbean population remained largely unchanged, as the analyzes suggest. The archaeological relics of pottery from that period, however, show considerable changes in style. Previous research saw it as evidence of an exchange with the mainland. “We’re seeing remarkable genetic continuity here while the ceramic style is changing at the same time,” explains co-author Kendra Sirak of Harvard Medical School. “The question is: did the exchange only concern vessels or also people? As far as we know, it was only the vessels. “
Even if a cultural exchange with the mainland might have played a role, the researchers assume that the contact between the peoples of the different islands in particular has led to innovations. “Our results support the theory that the peoples of the Ceramic Age were well connected, which could have acted as a catalyst for the spread of new ceramic styles across the region,” says Fernandes.
Population smaller than expected
The genetic data also confirm the close links between the populations of the individual islands. The researchers discovered 19 pairs of individuals who were second or third degree cousins and lived on different islands. “The fact that we were able to demonstrate family relationships across several islands is an amazing step forward,” says co-author William Keegan of the Florida Museum of Natural History. Given that the winds and currents between the islands have made crossings difficult, the result is surprising.
The researchers can also draw conclusions about the population density from the family relationships. The genetic data suggests that the Caribbean aborigines avoided ties between close relatives. Nevertheless, a relatively high proportion of the individuals examined were related over just a few corners. “That indicates a low population density,” the authors say. The region of Puerto Rico, Haiti and Dominican Republic is estimated to have only a few tens of thousands of people living when Europeans arrive. This contradicts historical accounts that report hundreds of thousands or even millions of inhabitants. According to Keegan, these reports could possibly have been deliberate exaggerations, which Columbus, for example, used to impress his clients.
Genetic traces to this day
Traces of the indigenous genome from the time before the first contact with Europeans can still be found in the genome of the Caribbean population. Depending on the region, the researchers come up with values between four and 14 percent. Other parts of the genome come from Europeans (up to 70 percent) and from people from Africa who were brought to the Caribbean as slaves. “The analysis of the ancient DNA brings our understanding of the Caribbean a big step forward,” says Keegan. “The methods that were used in this study provided answers to questions that I would never have thought could be answered at all.”
Source: Daniel Fernandes (University of Vienna) et al., Nature, doi: 10.1038 / s41586-020-03053-2