Researchers sequence fragments of the oldest human genome on Earth

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An international team of researchers has sequenced fragments of DNA from a pair 7,000-year-old human skeletons. In an intriguing twist, the remains, while recovered from a cave in northeastern Spain, bear little genetic resemblance to people living in the region today.

If the remains have been dated accurately, their genetic information predates that of the previous recordholder — Ötzi the Iceman — by 1,700 years, and could hold valuable clues to the link between prehistoric humans and moden European populations.


Writes LiveScience's Charles Choi:

The skeletons of two young adult males were discovered by chance in 2006 by cave explorers in a cavern high in the Cantabrian mountain range, whose main entrance is found at 4,920 feet (1,500 meters) altitude. Winters there are notably cold, which helped preserve the DNA in the bones.


These bones date back to the Mesolithic period, before agriculture spread to the Iberian Peninsula with Neolithic settlers from the Middle East. These cavemen were hunter-gatherers, judging by the ornament that one was found with of red-deer canines embroidered onto a cloth.


Paleogeneticist Carles Lalueza-Fox and his team were able to rescue the complete mitochondrial DNA from the skeleton pictured up top, which was recovered in almost perfect condition and belonged to a human the researchers have since named "Braña1." Mitochondrial DNA is the genetic information housed in sub-cellular structures called mitochondria. It is inherited only from the mother, and is incredibly useful for tracing common ancestry.


"Despite their geographical distance, individuals from the regions corresponding to the current England, Germany, Lithuania, Poland and Spain shared the same mitochondrial lineage," said Lalueza-Fox in a statement. "These hunters-gatherers shared nomadic habits and had a common origin.


The researchers went on to acquire fragments of the genetic information housed within the nuclei of the skeletons' remarkably well preserved cells. Using a technique known as shotgun sequencing, Lalueza-Fox and his colleagues were able to recover 1.34% and 0.5% of the individuals' total genomes. Their findings reveal that Braña1 and Braña2 are more closely related to contemporary populations of northern Europe than they are to modern populations of Spain and Portugal.

"Until now... the genetic affinities of the Mesolithic populations to the modern Europeans were largely unknown," write the researchers in the latest issue of Current Biology. They continue:

Our partial La Braña 1 and 2 genomic data show that modern Iberian populations are not descendants of the local hunter-gatherers inhabiting the same region prior to the arrival of farmers and thus support a genetic shift in that region between the Meso- lithic and modern populations.


[Current Biology via LiveScience]

All images via Lalueza-Fox et al.