24,000 year old DNA reveals Native American origins
An international team of scientists have reported a breakthrough in the quest for Native American origins in this week’s Nature. Key to the puzzle are 24,000 year old bone remains from a child in Siberia which shine new light on their history, as well as connections between groups in Europe and Asia during the Stone Age.
The genome from the 24,000 year old individual in Siberia is very similar to that of today’s Native American population, but also shows a strong genetic similarity with today’s populations in western Asia and Europe, a surprising and exciting discovery according to the researchers.
“Our results show that the Native American population has complex origins with contributions from at least two prehistoric groups, which is very unexpected. The results have large consequences for our image of what the genetic map looked like in Europe and Asia around the time of the peak of the latest ice-age”, says Dr. Pontus Skoglund from the Evolutionary Biology Centre, Uppsala University, one of the lead authors of the study.
The Americas were the last of the major continents to be colonized and questions of the Native Americans’ origins have long been discussed. How, when and from where did they come to America? Genetics have shown present-day East Asians to be closely related; however, the identity of the Old World populations closest to modern Native Americans is yet to be discerned.
In late 2009, researchers from University of Copenhagen and Texas A&M University sampled the remains of a juvenile individual from Mal’ta in Siberia which have been dated to approximately 24,000 years ago. The analysis of the samples, which were partly conducted at Uppsala University, only show little resemblance with today’s population in that part of Siberia. The child was more closely related to today’s populations in Europe and western Asia. This is shown using both mitochondrial and nuclear DNA.
“Representing the oldest anatomically modern human genome reported thus far, the Mal’ta child has provided us with a unique window into the genetic landscape of Siberia some 24,000 years ago”, says Dr. Maanasa Raghavan at the University of Copenhagen, one of the lead authors of the study.
The international research team, led by Professor Eske Willerslev at the University of Copenhagen, concludes that the connection between groups in western and north-east Europe and Asia was closer at that time than it is today. However, the clearest result of the study was the connection between the Mal’ta juvenile and the Native American population. Surprisingly there was no close connection to modern-day East Asians, which today are considered to be the group most closely related to Native Americans.
“Most scientists have believed that Native American lineages go back about 14,000 years ago, when the first people crossed Beringia into the New World. Our results provide direct evidence that some of the ancestry that characterizes Native Americans is at least 10,000 years older than that, and was already present in Siberia before the last Ice Age”, says Dr. Pontus Skoglund.
The study concludes that two distinct Old World populations led to the formation of the First American gene pool: one related to modern-day East Asians, and the other a Siberian Upper Palaeolithic population (14–38%) related to modern-day western Eurasians.
The results are strengthened by the fact that bone remains from a second individual in roughly the same area in Siberia, but 17,000 years old, show very large similarities to those from the individual dated 24,000 year old.
“It is remarkable how much we can learn about human history from these Paleolithic Siberian remains”, says Dr. Mattias Jakobsson from Evolutionary Biology Centre, Uppsala University. “We can access genetic information on lost peoples that help us understand the peopling of the Americas much beyond what would be possible based on genetic variation in modern-day populations.”