Global Densovans?

Econintersect:  Archeologists recovered remains of a branch of humanoid development known as Denisovans from a cave in Denisova, Siberia in 2010.  It has now been determined that the oldest ancient humanoid DNA yet recovered (about 400,000 years old) is Denisovan and not Neanderthal or Homo Sapiens.  And, as opposed to the 40,000 year old Denisovan DNA obtained from Siberia, this sample came from a cave in Spain.

From The New York Times:

Based on the anatomy of the fossils, Dr. Arsuaga has argued that they belonged to ancestors of Neanderthals, which lived in western Asia and Europe from about 200,000 to 30,000 years ago.

When Dr. Meyer and his colleagues drilled into the femur, they found ancient human DNA inside, just as they had hoped.

“Our expectation was that it would be a very early Neanderthal,” Dr. Meyer said.

But the DNA did not match that of Neanderthals. Dr. Meyer then compared it to the DNA of the Denisovans, the ancient human lineage that he and his colleagues had discovered in Siberia in 2010. He was shocked to find that it was similar.

Further research confirmed that the DNA was Denisovan.

This throws open the entire question of relationships between Denisovans, Neanderthals and modern humans.  Could Denisovans have been ancestors to Neanderthals who descended from some genetic variation or mutation of an older line, some of which continued unchanged for more than 300,000 years?

And if the Denisovan line survived for that long, how come there is no evidence of their genome in most modern humans?  The Denisovan DNA has only been found in the genome of some eastern Asians, and especially in the Melanesians with a population centered on Papua New Guinea. They certainly are not likely to have faded away elsewhere because their genome was fragile – it survived for hundreds of thousands of years.

Or was it fragile?  Did it only survive in Siberia in pure form because of isolation?

The new findings are changing the way scientists think about the potential for interactions among early hominid lineages.  Robert Lee Hotz, in The Wall Street Journal, suggests the new findings indicate that early humanoid interbreeding may have been more widespread than previously thought.

Earlier GEI News articles presented the following “family trees” for hominids:

There are now more interbreeding “connections” possible for the “family tree” and the timeline will need to be extended backward by hundreds of thousands of years.  According to an article in Wikipedia there is now evidence that early hominids may have been living in Spanish caves more than a million years ago in the Atapuerca Mountain region where the 400,000 year-old DNA was recovered.

John Lounsbury

Hat tip to Roger Erickson.

Sources:

• Baffling 400,000-Year-Old Clue to Human Origins (Carl Zimmer, The New York Times, 04 December 2013)

• Early Human Interbreeding More Widespread Than Thought, Study Suggests (Robert Lee Hotz, The Wall Street Journal, 04 December 2013)

• Why am I Denisovan? (The Genographic Project, National Geographic, not dated)

• Denisova hominin (Wikipedia)

• 50,000 Year Old Humanoid Genome Sequenced (GEI News, 03 September 2013)

• New DNA Analysis Shows Ancient Humans Interbred with Denisovans (Katherine Harmon, Scientific American, 30 August 2012)

• Atapuerca Mountains (Wikipedia)