Friday, July 11, 2014

NATIVE AMERICAN CONNECTION TO 40,000 YEAR OLD HUMAN IN NORTHWEST CHINA



Detailed examination of samples of ancient DNA has revealed the genetic makeup of humans living circa 40,000 years ago in an area near what is now Beijing in China.
International research

An international team of researchers including Svante Pääbo and Qiaomei Fu of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have sequenced nuclear and mitochondrial DNA extracted from the leg of an early modern human from Tianyuan Cave near Beijing.

Analyses of DNA recovered from the leg bones showed that the Tianyuan human shared a common origin with present-day Asians and Native Americans. In addition, the researchers found the proportion of Neanderthal and Denisovan-DNA in this early modern human is no higher than in current populations living in this region today.

Humans who looked broadly like present-day people started to appear in the fossil record of Eurasia between 40,000 and 50,000 years ago, however many questions remain about the relationship between these early modern humans and present-day Homo sapiens populations.



The leg bone of the early modern human from Tianyuan Cave was used for the genetic analysis as well as for carbon dating.
© MPI for Evolutionary Anthropology
Oldest DNA recovered from early humans

The researchers were using new techniques that could identify ancient genetic material from an archaeological find even when large quantities of DNA from soil bacteria are present.

They then reconstructed a genetic profile. “This individual lived during an important evolutionary transition when early modern humans, who shared certain features with earlier forms such as Neanderthals, were replacing Neanderthals and Denisovans, who later became extinct”, says Svante Pääbo of the Max Planck Institute, who led the study.

The genetic profile showed this early modern human was related to the ancestors of many present-day Asians and Native Americans but had already diverged genetically from the ancestors of present-day Europeans.

“More analyses of additional early modern humans across Eurasia will further refine our understanding of when and how modern humans spread across Europe and Asia”, says Svante Pääbo.


Researchers carrying out excavation works at the Tianyuan Cave from which the leg bones had been excavated in 2003.
© Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Beijing

Dienekes Pontikos, who runs the influential Dienekes blog on human population genetics comments that “This is an important finding because some published demographic models had Europeans and East Eurasians diverging as recently as 20 thousand years ago.”

He adds, “It now appears that they did so already at around the time of the Upper Palaeolithic revolution, when unambiguous evidence of modern humans across Eurasia exists.”

Around 40,000 years ago, Neanderthals and Denisovans were being replaced by Homo sapiens and it is these genetic studies of people living at the important crossover period that could help scientists understand when and how this interbreeding took place as well as answering the question of how and when modern humans began their colonisation of the globe.

Parts of the work was carried out in a new laboratory jointly run by the Max Planck Society and the Chinese Academy of Sciences in Beijing.

Source: PNAS/Max-Planck-Gesellschaft, München