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."
2 comments:
When I addressed the increasing evidence that seemed to demonstrate our ties with neanderthals on Sunday, one of my congregants seemed unconvinced.
His objection was that the similarities between one individual's DNA with another for simply being human was already greater than 98%. In addition, to prove that any individual was descended from the ancient primate remains would be difficult due to the difficulty in mapping genetic material that was incomplete even if we happened to have a series of complete skeletons. There is no way to necessarily know that these were all subsequent skeletons of generations of a human being. Without even that much evidence, he found the current theories to be rather incredible.
I was not sure how to respond. His way of coming to terms with the biblical narrative with anthropological findings was to dismiss them offhand as possible creatures related to us who became extinct. These were contemporaries of humans at the time of their existence, but humans were much the same then as they are now. I simply informed this individual, that it was alright to have such a perspective. I also cautioned him, on the risk of assuming this was the way it is, as that would be making the same 'mistake' as those who theorize that we are descended from hominids.
I wonder if there was a better way to answer these objections. My personal inclination is to believe in the process of natural selection, but I am open to any new discoveries that may contradict my views. After all, the search for truth is more important than being right.
There are two important advances in the study of the DNA of ancient humans,and one of which is the establishment of the sequencing method of the focal phosphoric acid method, which lays the foundation for the nuclear DNA sequencing.
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