Black Americans’ genes reflect the hardships and realities of slavery


The graph shows 23andMe’s top three search results.23andMe

The genes of 50,000 descendants of slaves reveal the effects of the global slave trade generations later, according to a study published Thursday in the American Journal of Human Genetics. Researchers analyzed data provided by thousands of 23andMe clients who agreed to share their genetic information to better understand the impact of forced migration on the genealogy of descendants of enslaved Africans in the Americas.

They found that slaves brought from an African region to a particular region of the Americas usually ended up sharing a genetic link with that African region generations later, said Steven Micheletti, a population geneticist at 23andMe and the first author of study.

But, in some cases, the results did not match historical data. For example, while African Americans, based on migration records, are expected to show genetic roots closely related to present-day Angola and the Democratic Republic of the Congo, many actually show closer genetic links to Nigeria. .

The high percentages of Nigerian ancestry among African Americans in the United States may be related to the number of slaves who were transferred from the British Caribbean to the United States. This was supported by historians who cited an “intra-American slave trade database, which made it clear that slaves had been brought from the Caribbean to the United States,” said Joanna Mountain, senior director of the United States. 23andMe research. “When you look at the model of the slaves brought to the Caribbean, especially the British Caribbean, you see that it often came from Nigeria.”

Dr Bernard Powers, historian and director of the Center for the Study of Slavery in Charleston, part of the College of Charleston in South Carolina, suggests that the origin of slaves shipped from the Caribbean to the United States may be difficult to trace. But he said the genetic gap could be the result of migrations of people from what is now southeastern Nigeria to parts of Angola and Congo which were later captured and sent to America.

There could have been “internal developments on the African continent, which shaped the export” of slaves, Powers said. “Each of these regions has its own political and economic history, as well as climatic, and variations could contribute to the export of people to the coast.”

Powers and researchers agree that once slaves from Angola and the Democratic Republic of the Congo arrived in the United States, they suffered high death rates on rice plantations where malaria and conditions of horrible work was common. “Rice was really the most labor intensive crop produced in colonial America, for sure,” Powers said. “It would have been the bringing together of the continent with the cultivation of sugar in the Caribbean.”

Mountain has suggested that the high death rates may have helped reduce the genetic representation of enslaved people from Angola and the Democratic Republic of the Congo among African Americans.

Despite the differences in the practice of slavery between countries and colonies across the Americas, researchers also found a global sexual bias that arose across continents.

“Sexual prejudice is essentially the ratio of African women reproducing to African men,” Micheletti said. “African women reproduce much more than African men. This indicates rape and exploitation which has been documented in diaries and other historical works.

The researchers recognize that their data is not representative of global populations due to 23andMe’s predominantly American customer base. Still, they say looking at genetics through the prism of historical data could raise awareness of new truths about ancestry.

“We don’t want these historic details swept under the rug,” Micheletti said. “We really want them discussed today, and adding genetic confirmation to these details could be a powerful tool. “


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