Confirmed: The Hominins Found at Atapuerca are the Earliest Genetic Evidence of Neanderthals to Date
After decades of study and many assumptions, the analysis of nuclear DNA has finally confirmed the evolutionary lineage of the inhabitants of the Sierra de Atapuerca in Spain.
For some time, scientists and researchers of the site in Atapuerca have known that the 28 individuals who lived near the Sima de los Huesos “Pit of Bones” around 430,000 years ago were similar to modern humans in stature, though wider and more robust. In addition, their work has shown that the beings preferred to use their right hands, size differences between females and males were similar to today, and that they were probably able to talk like modern humans. Despite having all that information, clarification was still needed on one important issue: to which hominid species did they belong?
Until now, as Agencia SINC indicates, these origins were a mystery. On the one hand, the characteristics of the recovered skeletal remains were better related to Neanderthals. On the other, the analysis of mitochondrial DNA (DNA transmitted by the maternal line) of a femur sequenced in December 2013, associated the hominins with the extinct Denisovans - distant relatives of Neanderthals who lived in Siberia. That DNA analysis did not correspond with European Neanderthals.
Skull number 5 of the Sima de los Huesos of Atapuerca, as it was discovered in the excavations of 1992. The jaw of this skull appeared, almost intact, years later, very near the site of the initial discovery. (José-Manuel Benito Álvarez/CC-BY-SA 2.5)
That first result surprised the Atapuerca research team. But mitochondrial DNA only provides information from the matrilineal line, and therefore it is partial information. Since then, they have worked tirelessly to sequence nuclear DNA from remains found in the cave, as it is inherited by both sides: maternal and paternal.
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This was a task that can only be described as daunting - due to the age of the DNA in question, deterioration, and the fact that it was fragmented into very short segments. However, the painstaking effort of many years has earned a long-awaited reward thanks to the improvement in both the isolation of genome samples and sequencing technologies available at the Max Planck Institute for Evolutionary Anthropology in Leipzig (Germany). Thus, German, Canadian and Spanish researchers have finally managed to sequence nuclear DNA from a second femur and incisor.
The findings, published in Nature, confirm that the hominids from the Sima de los Huesos were actually primitive Neanderthals. "We have waited many years until paleogenetic techniques advanced enough for this little miracle to occur. We excavated with the utmost care and very slowly to avoid contaminating the remains with our own DNA,” says Juan Luis Arsuaga, scientific director of the Museum of Human Evolution in Burgos and co-author of the study.
Juan Luis Arsuaga, a member of the Research Team of Pleistocene sites in the Sierra de Atapuerca and scientific director of the Museum of Human Evolution in Burgos, Spain, with his team during excavations in the Sima de los Huesos. ( Javier Trueba-Madrid Scientific Films/Agencia SINC)
Specifically, the results of the analysis on the remains of the Pit of the Bones indicate that the separation between Neanderthals and Denisovans is older than 430,000 years ago. Moreover, according to Matthias Meyer, an author of the study and a researcher in the Department of Evolutionary Genetics, “ The separation of the line leading to Homo sapiens from the others -the lines of the 'archaic' humans (Sima de los Huesos, Denisovan, Neanderthals) - could have occurred between 550,000 and 800,000 years ago.”
With that time interval for separation between modern humans and Neanderthals, the remains of the Homo antecessor found at the site of Gran Dolina, also in the Sierra de Atapuerca, whose age is dated between 800,000 and a million years, could be the best candidate to fill the key position of our last ancestor, according to the experts.
Featured Image: Reproduction of Homo neanderthalensis. Museum of Human Evolution (MEH), Burgos, Spain. Source: Nachosan/CC BY-SA 3.0
By Mariló T. A.
This article was first published in Spanish at http://www.ancient-origins.es and has been translated with permission.