Monday, March 12, 2012

The Human Genome Holds Many Secrets

Ever since the extraordinary breakthrough that involved the complete sequencing of the human genome, many intriguing and heretofore unknown aspects of human genetic history have been uncovered.   One of the most exciting and interesting discoveries is that members of the human species may well have interbred with so-called archaic peoples of the past.

The picture of human evolution has proven to be not quite that simple.  Previous to recent findings, it was believed that about 100,000 years ago, early human migrated from their home in Africa to Europe and Asia displacing and ultimately replacing archaic peoples such as Neanderthals.  Evidence derived from an examination of the fossil evidence and supported by mitochondrial DNA studies seemed to support the view that there was no interbreeding between these divergent peoples.

Due to recent discoveries, however, this conclusion has proven to be fallacious.  As a result of genetic sequencing of Neanderthal nuclear DNA derived from fossil evidence and the subsequent comparison of this data with modern human nuclear DNA, Europeans and Asians have apparently inherited from 2% to 6% of their nuclear DNA from Neanderthals. 

In addition, by the end of 2010, a Russian led team found a 30,000 year old fossil finger bone of a young girl, and a tooth fragment from Denisova Cave in Siberia and reported the entire genomic sequence of a new archaic human species.  Studies of the DNA of scattered peoples throughout Southeast Asia demonstrate that they inherited approximately 5% of their DNA from the so-called "Denisovans" and 4% to 6% from Neanderthals. 

It is now evident that early humans interbred with archaic humans on at least three different occasions during their migration to other parts of the world.  These findings are of importance, for they help elucidate the complex nature and subtleties of human evolution. 

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