Ancient DNA Reveals Genetic History of Caribbean World

by johnsmith

In a new study of the genetic history of the pre-contact Caribbean, researchers analyzed genome-wide DNA data from 174 ancient individuals who lived in the Bahamas, Haiti and the Dominican Republic (collectively, Hispaniola), Puerto Rico, Curaçao and Venezuela, as well as the data from 89 previously sequenced ancient individuals.

Illustration of one of the early settlers in the Caribbean. Image credit: Tom Björklund.

Illustration of one of the early settlers in the Caribbean. Image credit: Tom Björklund.

Prior to European colonization, the Caribbean was a mosaic of distinct communities that were connected by networks of interaction since the first human occupations in Cuba, Hispaniola and Puerto Rico around 6,000 years ago.

The pre-contact Caribbean is divided into three archaeological ages, which denote shifts in material cultural complexes.

The Lithic and Archaic Ages are defined by distinct stone tool technologies, and the Ceramic Age — which began about 2,500-2,300 years ago — featured an agricultural economy and intensive pottery production.

Technological and stylistic changes in material culture across these periods reflect local developments by connected Caribbean people as well as migration from the American continents, although the geographical origins, trajectories and numbers of migratory waves remain under debate.

“The islands’ first inhabitants, a group of stone tool-users, boated to Cuba about 6,000 years ago, gradually expanding eastward to other islands during the region’s Archaic Age,” said Dr. William Keegan, an archaeologist in the Florida Museum of Natural History at the University of Florida.

“Where they came from remains unclear — while they are more closely related to Central and South Americans than to North Americans, their genetics do not match any particular Indigenous group.”

“However, similar artifacts found in Belize and Cuba may suggest a Central American origin.”

“About 2,500-3,000 years ago, farmers and potters related to the Arawak-speakers of northeast South America established a second pathway into the Caribbean.”

“Using the fingers of the Orinoco River Basin like highways, they traveled from the interior to coastal Venezuela and pushed north into the Caribbean Sea, settling Puerto Rico and eventually moving westward.”

“Their arrival ushered in the region’s Ceramic Age, marked by agriculture and the widespread production and use of pottery.”

“Over time, nearly all genetic traces of Archaic Age people vanished, except for a holdout community in western Cuba that persisted as late as European arrival.”

Intermarriage between the two groups was rare, with only three individuals in the study showing mixed ancestry.

Many present-day Cubans, Dominicans and Puerto Ricans are the descendants of Ceramic Age people, as well as European immigrants and enslaved Africans.

But Dr. Keegan and colleagues noted only marginal evidence of Archaic Age ancestry in modern individuals.

“That’s a big mystery. For Cuba, it’s especially curious that we don’t see more Archaic ancestry,” he said.

During the Ceramic Age, Caribbean pottery underwent at least five marked shifts in style over 2,000 years.

Ornate red pottery decorated with white painted designs gave way to simple, buff-colored vessels, while other pots were punctuated with tiny dots and incisions or bore sculpted animal faces that likely doubled as handles.

Some archaeologists pointed to these transitions as evidence for new migrations to the islands.

But DNA tells a different story, suggesting all of the styles were developed by descendants of the people who arrived in the Caribbean 2,500-3,000 years ago, though they may have interacted with and took inspiration from outsiders.

“We document this remarkable genetic continuity across changes in ceramic style. We talk about ‘pots vs. people,’ and to our knowledge, it’s just pots,” said Dr. Kendra Sirak, a postdoctoral researcher in the Department of Genetics at Harvard Medical School and the Department of Human Evolutionary Biology at Harvard University.

Highlighting the region’s interconnectivity, an analysis of male X chromosomes uncovered 19 pairs of genetic cousins living on different islands.

“Uncovering such a high proportion of genetic cousins in a sample of fewer than 100 men is another indicator that the region’s total population size was small,” said Professor David Reich, a researcher in the Blavatnik Institute at Harvard Medical School and the Department of Human Evolutionary Biology at Harvard University.

The scientists also found that about 10,000 to 50,000 people were living on two of the Caribbean’s largest islands, Hispaniola and Puerto Rico, shortly before European arrival.

“This falls far short of the million inhabitants Columbus described to his patrons, likely to impress them,” Dr. Keegan said.

Later, 16th-century historian Bartolomé de las Casas claimed the region had been home to 3 million people before being decimated by European enslavement and disease.

“While this, too, was an exaggeration, the number of people who died as a result of colonization remains an atrocity,” Professor Reich said.

“This was a systematic program of cultural erasure. The fact that the number was not 1 million or millions of people, but rather tens of thousands, does not make that erasure any less significant.”

The study was published online this week in the journal Nature.


D.M. Fernandes et al. A genetic history of the pre-contact Caribbean. Nature, published online December 23, 2020; doi: 10.1038/s41586-020-03053-2

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