Study reveals complex genetic history of Amazonian peoples in South America


Geneticists are working to understand the complex genetic history of Amazonian peoples in South America, and their effort is already revealing some interesting information.

Led by researchers from the Max Planck Institute for the Science of Human History, the study seeks to map out the genetic history and match it up to historical events such as migrations, invasions, or other forms of contact to find connections between cultures and even discover new cultures that have been overlooked.

“We wanted to bring attention to the fine-grained, complex events taking place during the pre-colonial and post-European contact times,” Max Plank Institute geneticist Chiara Barbieri said in a statement.

“We therefore visited diverse regions of South America, collecting new samples from rural populations with different cultural backgrounds. In our analysis, we focused on signals of contact and shared ancestry, trying to find exceptions to the current paradigm on the diversity of the continent.”

For instance, the results found genetic connection between the Incas in the Andes and smaller tribes of Amazonian peoples in more isolated areas, suggesting that they came into contact with each other, most likely through migration or trade.

 

The Incan city of Machu Picchu in Peru. Image via Wikimedia.

“This model builds on evidence for major complex societies in the Andes (culminating with the well-known but short-lived Inca Empire) which fostered population movements and connections, counterbalanced by the traditional view of the Amazon Basin as the homeland of small, isolated tribes,” the study says.

“On a continental scale, one of the major findings is the presence of a distinct ancestry component in Amazonia, present at high frequency in populations from Ecuador and Colombia, near the Eastern Andes slope,” Barbieri says.

“This genetic component, previously undetected, might have started to differentiate from other ancestry components (for example the one frequently found in Amazonia and the one found in the Coast and Andes) more than 4,000 years ago. This has implications for understanding the early migrations and structure of the continent, and suggests that human diversity in Amazonia is larger than we thought.”

The study also found Native American DNA.

“One major Native American ancestry component is shared by all populations…in line with results from other living populations and from ancient DNA, which support an early entry as a single major migration,” the study shows.

This means some Native Americans migrated south from North America thousands of years ago, mixing their DNA with that of the natives of South America. It could even be possible that some of these Native Americans came from the American Southwest and Midwest to escape droughts that collapsed their own cultures in the 12th century.

The Anasazi people who abandoned Chaco canyon scattered in many directions as their society entered a serious decline. What if some of them migrated further south and added their DNA to the gene pool in South America?

 

Chaco Canyon in the American Southwest, as abandoned by the Anasazi in the 12th century. Image via Wikimedia.

The team also matched genetic markers that came from contact with Europeans, who were searching for a shorter trade route to Asia only to find the New World instead. Many of the Europeans who sailed to South America never returned home, opting to start a family with a native instead, resulting in European genes being passed down over the centuries.

 

Spanish conquistadors conquered territory controlled by the Incas and the Aztecs after 1492. Image via Wikimedia.

As Europeans began to further exploit South America, they also brought Africans as slave laborers with them, which introduced African DNA into the gene pool as well.

“The results confirmed the impact of large, complex societies already known from archaeological evidence, but also revealed previously unknown migrations and connections across vast distances, including in Amazonia, an area that has not been as deeply studied archaeologically,” the Max Plank Institute reports.

Indeed, there are thousands of potential archaeological sites in Peru and Guatemala alone that have yet to be excavated.

They even found language connections in addition to genetic ones.

“Connections have been found between speakers of Quechua (a widely-spoken Andean language) through the Andes and part of Amazonia. Also, some populations of Loreto and San Martín (Amazonian regions) of Peru are genetically very close to the Cocama speakers (an Amazonian language) of Colombia. These genetic signatures suggest that here languages are diffused by movement of actual people instead of by cultural diffusion alone,” José Sandoval and Ricardo Fujita of the University of San Martín de Porres in Lima, Peru, explained.

It’s a massive study, but one that helps us better understand the history of the people in South America from a period of its history that we don’t know much about. Plus, it’s fun to see genetic markers corresponding to specific events in history that we do know about along with finding new events that we had no idea existed.

University of California biological anthropologist Lars Fehren-Schmitz certainly thinks so.

“Taken all together, these findings bring attention to the diversity and complexity of people from Amazonia and their interactions with neighboring regions of the Andes,” he said.

“The genetic inheritance of South American people still bears traces of the important events that took place before the historical record in colonial times.”

Future studies could very well reveal more hidden history, giving us more insight into the ancient cultures of pre-Columbian times and how all of this culminates into modern South America. Everyone should be able to understand their own history and where they came from. Genetic studies offer us that opportunity.


Featured Image: Wikimedia


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