Scientists have extracted DNA from 7,000
year old “caveman” bones found in Spain and genetically matched them to modern northern
European populations.
Previously, the oldest modern human genomes
yet recovered yet came from Ötzi the Iceman, a 5,300-year-old mummy found in
the Alps in 1991.
Researchers have salvaged DNA from even older human cells,
but this comes from the mitochondria that generate energy for our bodies, and
not from the nucleus where our chromosomes are housed. (Mitochondrial DNA is
passed down only by mothers.)
Now researchers have rescued fragments of
genomes from the remains of two cavemen unearthed in northern Spain.
"These are the oldest partial genomes
from modern human prehistory," researcher Carles Lalueza-Fox, a
paleogeneticist at the Spanish National Research Council, was quoted as saying.
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.
The scientists recovered 1.34 percent and
0.5 percent of the human genomes from the bones of these two cave men. Analyses
revealed that current populations of the Iberian Peninsula, which includes
Spain, Portugal and Andorra, are not genetically linked with these ancient
hunter-gatherers. Instead, these cavemen were closer genetically to the current
populations of northern Europe.
"There are many works that claim the
Basques [of the Iberian Peninsula] could be descendants from Mesolithics that
became isolated in the Basque country," Lalueza-Fox said. "We found
the modern Basques are genetically not related to these two individuals."
The scientists also recovered the complete
mitochondrial DNA of one of these cavemen. This revealed that European
populations during the Mesolithic were very uniform genetically.
"Despite their geographical distance,
individuals from the regions corresponding to the current England, Germany,
Lithuania, Poland and Spain shared the same mitochondrial lineage,"
Lalueza-Fox said. "These hunters-gatherers shared nomadic habits and had a
common origin."
The researchers now aim to complete the
genomes of both cavemen. Such data could help "explore genes that have
been modified with the arrival of the Neolithic in the European
populations," Lalueza-Fox said.
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