April 2, 2016
Ancient DNA confirms European settlers wiped out Native Americans
The arrival of the first Europeans in the New World had a devastating impact on the indigenous American population, leading to the extinction of the genetic lineage of pre-Columbian men and women that originally called that part of the planet home, according to a new study.
Researchers from the University of Adelaide's Australian Centre for Ancient DNA (ACAD) and their colleagues reconstructed a genetic history of indigenous Americans by analyzing the genes of 92 pre-Columbian skeletons and mummies dated between 500 and 800 years old.As they reported in this week in the journal Science Advances, they found that not one of those early genetic lineages was present in modern indigenous Americans, indicating that the arrival of the Spaniards and other Europeans spelled the end of the line for these ancient populations.
“Surprisingly, none of the genetic lineages we found in almost 100 ancient humans were present, or showed evidence of descendants, in today's Indigenous populations,” Dr. Bastien Llamas, co-lead author of the study, said in a statement. He added that this separation appeared to take place “as early as 9,000 years ago” and was “completely unexpected” by the research team.
Study also provides more precise date for arrival of first Americans
According to Dr. Llamas, he and his colleagues “examined many demographic scenarios to try and explain the pattern” and were only able to come up with one scenario that fit the data: soon after the initial colonization of the New World, “populations were established that subsequently stayed geographically isolated from one another.”
A significant portion of these populations later became extinct following contact with travelers arriving from Europe, he added. This scenario matches closely with historical records indicating that there was a major demographic collapse in the late 1400s – a collapse which coincided with the arrival of the first Spaniards, the study authors explained.
Dr. Llamas and his colleagues then sequenced whole mitochondrial genomes that were extracted from bone and teeth samples belonging to 92 pre-Columbian mummies and skeletons. The goal was to trace the maternal genetic lineages of these primarily South American humans, while also establishing a more precise timeline for the arrival of the first humans in America via the former Beringian land bridge that once connected Asia to northwestern North America.
“Our genetic reconstruction confirms that the first Americans entered around 16,000 years ago via the Pacific coast, skirting around the massive ice sheets that blocked an inland corridor route which only opened much later,” said ACAD director and study co-author Professor Alan Cooper. “They spread southward remarkably swiftly, reaching southern Chile by 14,600 years ago.”
“Our study is the first real time genetic record of these key questions regarding the timing and process of the peopling of the Americas,” added Dr. Wolfgang Haak, a former ACAD researcher who is now with the Max Planck Institute for the Science of Human History. “To get an even fuller picture, however, we will need a concerted effort to build a comprehensive dataset from the DNA of people alive today and their pre-Columbian ancestors, to further compare ancient and modern diversity.”
Image credit: Huaca Pucllana research, conservation and valorisation project