Working with bones discovered in 2003, researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig were able to reconstruct portions of DNA from an individual who lived in China about 40,000 years ago. Earlier analysis of the bones suggested that this individual showed “archaic” features, somewhat like Neandertal bones.
Credit: A Photograph of China's Empress Dowager, taken in the 1890s by Xunling, the Imperial Court Photographer. In the public domain.
The Max Planck team, led by Svante Pääbo, is well-known for work in producing the virtually complete Neandertal genome. In addition, using just a tiny fragment of a finger bone, this team produced the genome of a previously unknown form of humanity, called the Denisovans.
In their earlier work, they discovered that Europeans and Asians are descended in part from Neandertals, who disappeared about 30,000 years ago. In addition, some Asians, especially those living on the islands south of Asia, are partly descended from the Denisovans.
One of the reasons why the team was interested in this new sample was to look more deeply into the relationship between Europeans and Asians and to ask what role Neandertal and Denisovan interbreeding might have played.
Comparing the newly-reconstructed DNA sequence from the 40,000 year old bones, they found they were looking at an individual who also was descended from Neandertals, pretty much the way Europeans and Asians are today. And they also learned that this individual showed no evidence of Denisovan interbreeding.
What this means, they suggest, is that 40,000 years ago, an early version of anatomically modern Eurasians lived in China, near Beijing. While this human community was very much like the humans moving into Europe at about the same time, these two lineages were beginning a process of divergence.
On the basis of additional comparisons, the team concluded that the early-modern human community in China 40,000 about years ago was closely related to today’s Native Americans.
The report is also significant because it shows the power of new approaches to DNA extraction and sequencing. In their raw form, the samples extracted from the bones contained mostly DNA from microorganisms. In fact the human DNA was less than one-tenth of one percent of the total DNA. Even so, researchers were able to establish reliable human sequences, suitable for comparison with other human genomes.
What does that mean? At the very least, it means that many more discoveries like this lie ahead. The new technology means that old findings take on new significance.
The research appears online January 22, 2013, in the Proceedings of National Academy of Sciences, as "DNA analysis of an early modern human from Tianyuan Cave, China."