January 23, 2013
Genetic Profile Of Leg Bone Fossils Shows Important Human Evolutionary Transition
April Flowers for redOrbit.com - Your Universe Online
A multinational team of scientists led by the Max Planck Institute for Evolutionary Anthropology has sequenced nuclear and mitochondrial DNA extracted from the leg of an early modern human found in the Tianyuan Cave near Beijing, China. The Tianyuan human shared a common origin with the ancestor of many present-day Asians and Native Americans, the analysis showed. Moreover, the team found that the proportion of Neanderthal and Denisovan DNA in this early modern human is not higher than in people living in this region nowadays.
Many questions remain though about these early humans and their relationship to present-day Homo sapiens. The BBC News reports that some evidence hints at extensive migration into Europe following the last Ice Age, with fossil finds at Red Deer Cave (China) and Iwo Eluru (Ethiopia) pointing to a hitherto unappreciated diversity among Late Pleistocene humans.
Between 40,000 and 50,000 years ago across Eurasia, humans with morphology similar to present-day humans appear in the fossil record. The genetic relationships had not yet been established between these early modern humans and present-day human populations.
The scientific team extracted nuclear and mitochondrial DNA from a 40,000-year-old leg bone found in 2003 at the Tianyuan Cave site located outside Beijing. They used new techniques able to identify ancient genetic material from an archaeological find even when large quantities of DNA from soil bacteria are present. A genetic profile of the leg's owner was then developed.
"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 PÃ¤Ã¤bo of the Max Planck Institute for Evolutionary Anthropology.
This early modern human was related to the ancestors of many present-day Asians and Native Americans, the genetic profile revealed, but had already diverged genetically from the ancestors of present-day Europeans. The Tianyuan specimen also did not carry a larger proportion of Neanderthal or Denisovan DNA than present-day people in the region.
"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 PÃ¤Ã¤bo.
Results of the study were published in the PNAS Online Early Edition on January 21, 2013.
Image 2 (below): Researchers carrying out excavation works at the Tianyuan Cave from which the leg bones had been excavated in 2003. Credit: Institute of Vertebrate Paleontology and Paleoanthropology (IVPP), Beijing