50,000 Year Old DNA Sequenced In Breakthrough Technique

The field of human genome sequencing just received a fresh shot in the arm – after an international team of scientists used a breakthrough technology to sequence the genome of a girl who lived more than 50,000 years ago. The sequencing is said to be so thorough that amazing detail about the girls physical appearance has been discovered, such as the fact that she had brown eyes, brown hair and skin. The girl’s genome, called “archaic” because of its age, has been lauded for its quality – which scientists attribute as being the reason such a thorough sequencing was possible.

The girls is said to have lived in Siberia’s Denisova Cave more than 50,000 years ago. But, despite this early date, her genome has been able to be directly compared to the genome of people living today. Scientists have used these comparisons in an attempt to catalog which genetic mutations have occurred between the time of the Denisovans and modern people. The Denisovans were close relatives of the much better known Neandertals.

After this stunning breakthrough in genetic sequencing, the Denisovans, who used to be only known through a single, small, fossilized finger bone, are now better known than the Neandertals, at least from a genetic standpoint. This, desite the fact that there are hundreds of Neandertal specimins currently known to science.

One interesting finding is that the Denisovans did interbreed with the ancestors of modern man. The same has been said about the Neandertals as well, that there was at least limited interbreeding of that pre-modern species with the ancestors of modern man. In fact, Denisovan DNA can be found in those living today, especially in Paupa New Guinea.

The sequencing of the Denisovan girl’s genome was possible because of a breakthrough in genome sequencing itself. Usually, double strands of DNA were the starting points of the human genome sequencing process. But a technique developed by the team of Matthias Meyer, a postdoc at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, started with just single strands of DNA. The technique binds special molecules to the single strand, which holds the strand in place while they are copied. These copies then provide the scientists with additional material to sequence, allowing Myers’ team to sequence the DNA from the girl’s finger a whopping 31 times.

The information from the sequencing showed that, like humans, the Denisovans had 23 pairs of chromosomes. The findings also suggest that the Denisovan’s ancestors and those of modern humans split between 170,000 to 700,000 years ago. The Denisovans suffered from low genetic diversity, which continued to shrink. This may have been one of the contributing factors in the demise of the Denisovan people.

The sequencing of the Denisovan girl’s genome is a major breakthrough in DNA science related fields. Not only is it proof positive for a novel genome sequencing technology, using one DNA strand instead for the traditional two, but it also provides the beginnings of a road map with which to directly follow genetic mutations back from modern man to our ancestors.

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