December 5, 2013

THERE'S NO SUCH THING AS SPECIES:

Oldest Known Early Human DNA Recovered (Ross Pomeroy, December 4, 2013, Real Clear Science)

The most famous site at Atapuerca, Sima de los Huesos -- "The Pit of Bones" -- is precisely that. Located at the bottom of a 43-foot chimney in the winding cave system of Cueva Mayor, it contains approximately 5,500 ancient human bones dated at over 350,000 years old! Now, drawing upon this piled wealth of history, Matthias Meyer, a lead researcher at the Max Planck Institute for Evolutionary Anthropology, and a team of colleagues have recovered and analyzed the earliest known human DNA. [...]

After sequencing 98% of the mitochondrial DNA genome, Meyer and his colleagues estimated the specimen's age using the length of the DNA branch as a proxy. The femur clocked in at around 400,000 years old, placing its former owner in the Middle Pleistocene and making the DNA by far and away oldest human DNA ever collected. The previous record belonged to 100,000-year-old Neanderthal DNA.

The team then attempted to determine the specimen's position in the ancient human family tree and were surprised to find that the owner did not share a common ancestor with Neanderthals, but instead with Denisovans, a mysterious subspecies of human discovered in 2008 that last shared an ancestor with Neanderthals and Homo sapiens about one million years ago. Indeed, the more scientists discover about our prehistoric ancestors, the further they seem to fall down Alice's Rabbit Hole. Things just get curiouser and curiouser.

Meyer presented three possibilities that could account for the team's unexpected findings.*

"First, the Sima de los Huesos hominins may be closely related to the ancestors of Denisovans."

"Second, it is possible that the Sima de los Huesos hominins represent a group distinct from both Neanderthals and Denisovans that later perhaps contributed the mtDNA to Denisovans."

"Third, the Sima de los Huesos hominins may be related to the population ancestral to both Neanderthals and Denisovans."
Posted by at December 5, 2013 4:14 PM
  
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