A new genome strand was discovered in 2015 in the Rhône River Valley, France, showing an isolation of Neanderthal DNA, according to a study published in Cell Genomics Volume 4 Issue 9, on September 11th.
This study has not been peer-reviewed.
The excavation team at the Grotte Mandrin Cave in the Rhône River Valley, France, was directed by archaeologist Ludovik Slimak, a graduate of the University of Toulouse, as well as researcher Laure Metz. In 2015, the team uncovered the partial remains of Neanderthal DNA, which they nicknamed ‘Thorin.’ Thorin is currently still under excavation.
“Thorin is the most complete Neanderthal individual found in France since 1979 and falls among a group of other Neanderthals dating to the last millennia of their existence in Western Europe,” according to the new study.
Most of the research until now has focused on teeth and jaw analysis of Neanderthal fossils. Using dental dating methods such as teeth and jaw X-ray scans, the research shows that Thorin’s DNA dates back to approximately 50–42 thousand years ago.
Thorin “is one of the last representatives of these populations in Eurasia,” the study stated. Few discoveries of Neanderthals date back to a later period in time. This is consistent with the extinction dates of Neanderthals, which occurred at a similar time period 50,000 years ago.
Though Thorin dates back to the late Neanderthal period, his genetics split 50,000 years prior, during the early Neanderthal period 105,000 years ago.
The study suggested that there are no genetic connections between Thorin and the other lineages. The researchers further commented on their findings, stating that Thorin represents a lineage that possibly stayed isolated for approximately 50,000 years.
The study explored Neanderthal lineage lines in Europe. The results suggested that there are suspected “two, but possibly three, distinct Neanderthal lineages present in Europe during the late Neanderthal period.” The third lineage identified is Thorin’s detached from the other lines.
One notable difference between the lineage is the levels of homozygosity. Homozygosity is the presence of identical genes. High measures of homozygosity indicate higher levels of inbreeding. Compared with other Neanderthal DNA, the level of homozygosity had “low coverage [in] Neanderthal genomes.” Thorin lineage has "increased levels of homozygosity" compared to other late Neanderthals, indicating more inbreeding. This research adds to the isolation of Thorin's genetics compared to other Neanderthals.
The study ruled out the implications of homosapien and Neanderthal breeding in the early Neanderthal period. It identified that Thorin does not show genetics shared with modern humans compared to all other Western Eurasian Neanderthals. This is significant as the interbreeding between Neanderthals and modern humans occurred after the Thorin lineage was isolated 50,000 years earlier. This also rules out the possibility of recent interbreeding with early modern humans at the Grotte Mandrin Cave.
The discovery of the isolated line potentially furthers extinction research
The study highlights the significance of recognizing the separate lineage of Neanderthals. The researchers believe this could play a role in the reasoning behind the Neanderthal extinction. The study summarized that “these results have important implications for resolving competing hypotheses about causes of the disappearance of the Neanderthals.”
The study further expands on this topic by stating the following.
The study emphasizes that discovering a newly isolated lineage of Neanderthals, both culturally and genetically, in the late Neanderthal period raises "new lines of questions." The article stated that exploring the Neanderthals' social and behavioral practices could be beneficial, as this may have contributed to their extinction.