Monday, 2 April 2012

Sequencing of the Neanderthal Genome

Sequencing of the Neanderthal Genome

Are we family?

By Kayla Arabena-Byrnes, 42879037

Neanderthals were the first extinct human species to be distinguished by scientists as having an important significance concerning the evolution of humans. Their species represents an important step in discovering the origin of the human species, and by sequencing their genetic information into a readable format we are becoming ever closer to finding out exactly how closely we are related to them.
It was first thought that, as a species, we split with the Neanderthals to evolve into the human predecessor, Cro-Magnon man being the first and earliest modern humans. 
But evidence suggests that up to 30,000 years ago the Cro-Magnon and the Neanderthals cohabited in territories within Europe and Western Asia. However since then Cro-Magnon’s technological and anatomical superiority over the Neanderthals’ led them to dominance and this was the most likely cause of Neanderthals becoming endangered and finally extinct.
This separation into different species was thought to be the end of the Neanderthal line, but when looking at comparisons between Neanderthal DNA and the DNA of a modern human, similarities of 1% to 4% were noted. This suggests that interbreeding between Neanderthals and Cro-Magnons occurred, which ensured the continuation of some Neanderthal DNA, as present within the non-African population around the world today.

Who made this discovery?
This insight into the history of our genetic information was provided by the “Neanderthal Genome project”, which was founded in July of 2006 and has since then been committed to sequencing the 3.2 billion base pairs of DNA that constitute the Neanderthal genome. Their goal was to discover any similarities between modern humans and Neanderthals at a genetic level, which they successfully achieved.

Initially, simply finding a sample of intact Neanderthal DNA was difficult, as many samples were contaminated by bacteria or were simply damaged and unable to be tested. Finally researchers in Croatia found useable samples of DNA from the femur bones of three 38,000-year-old female Neanderthal specimens. More examinable DNA samples were also found in sites rich with Neanderthal remains located in Spain, Russia and parts of Germany.

During the experimentation involving the bone samples, many difficulties arose while extracting and testing the DNA. Some of these issues included the bacterial contamination of the bone samples as well as some research staff ruining the DNA samples during handling.
In late 2006, the DNA sequencing analysis had begun on a large supercomputer, but many copies of the DNA had to be analysed for accuracy. This DNA replication was done by a relatively new technique where the Neanderthal DNA was inserted into live bacteria which continuously copy their DNA during rapid growth. This resulted in multiple rounds of replication and therefore multiple strands of DNA were replicated to be cut, observed and compared to our modern DNA.

What did they find?
The final results of the Neanderthal Genome project revealed several noteworthy findings that modern human and Neanderthal DNA shared the same number of base pairs – being 3.2 billion. Also, according to the sequence analysis, humans and Neanderthal’s DNA are 99.7% identical, suggesting a close genetic tie between Neanderthals and non-African modern humans.
This new information provides a closer understanding of the history of our human genome, as well as delivering a deeper knowledge base of our Neanderthal predecessors and their origins.

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