Old DNA, New Tricks

Over the past decade, researchers have learned to reconstruct ancient DNA from fossils.  In December 2013, we were stunned to learn that refinements in techniques made it possible to restore human DNA from as far back as 400,000 years ago. 

Quickly on the heels of that advance, another new development has been announced in the 27-31 January online edition of PNAS.  Scientists at the University of Uppsala, in cooperation with the pioneering team in Leipzig, have developed a way to separate the old DNA sequences from contamination.

Photo Credit: Creative Commons, posted by Archaeogenetics, no restrictions.

Why is that important?  Because contamintion is a leading problem when it comes to reconstructing ancient DNA.  Literally thousands of fossils fill draws and shelves in museums around the world.  They contain DNA, too much of it, in fact, to be of any use.  Bits of ancient DNA are surrounded by more modern DNA from humans and from other organisms.  Now, researchers have learned to separate the old from the new. 
 
What makes the new breakthrough exciting is that now, at least some DNA information from many of these old fossils might be retreivable. 

"Many extremely interesting DNA data sets from ancient humans never see the light of day because of contamination. The idea behind this method was to change that," says Pontus Skoglund, a lead author at Uppsala University.
 
To test the new technique, the researchers used it to reconstruct the mitochondrial DNA from a previously unusuable Neandertal bone from the Altai Mountain region of Siberia.  The sample compared well with other known Neandertal DNA sequences in contrast to more modern humans.
 
It is hard to predict just where this new technology will lead.  At the very least, it seems to unlock the file boxes of museums throughout the world.  Previously discovered fossils, some of them very well dated, might be analyzed for the DNA.  Who knows what we will learn.

"There are many really interesting ancient human remains that we can rescue from severe contamination with this method. And the method is not limited to Neanderthals, even remains of anatomically modern humans that are contaminated by modern-day humans can be rescued," says co-investiagor Mattias Jakobsson in a press release from the University of Uppsala.
 
The new technique is described in a paper entitled "Separating endogenous ancient DNA from modern day contamination in a Siberian Neandertal." Skoglund, P.; Jakobsson, M.; Northoff, B.H.; Pääbo, S.; Krause, J.; Shunkov, M.V.; Derevianko, A.P; PNAS Online Early Edition the week of Jan 27-Jan31, 2014.