The Late Neanderthals of Europe Came from a Single Ice Age-Surviving Group

The last Neanderthals in Europe had a significant population turnover, according to a study using new DNA data and archaeological evidence. According to the research, late Neanderthals descended from a single localised group that endured the hard conditions of the Ice Age and shared a relatively homogeneous gene pool before their final extinction approximately 40,000 years ago.

Under the direction of Professor Cosimo Posth of the Senckenberg Centre for Human Evolution and Palaeoenvironment at the University of Tübingen, an international team of researchers examined the remarkable genetic history of European Neanderthals.

One localised population managed to survive the harsh climate by withdrawing to a glacier refugium in what is now southwestern France some 75,000 years ago, according to a recent study published in the journal PNAS. After 65,000 years, the offspring of these tenacious survivors dispersed throughout Europe.

Nearly all late Neanderthals were genetically descended from this one lineage.Professor Posth said, "Our data allowed us to reconstruct geographically that Neanderthals retreated to what is now southwestern France." A new population first appeared there around 65,000 years ago, and it subsequently expanded throughout all of Europe. This explains why nearly every Late Neanderthal that has been sequenced thus far—from the Caucasus to the Iberian Peninsula—belongs to the same line of inherited mitochondrial DNA.

The Severe Population Bottleneck of Neanderthals

The researchers concentrated on mitochondrial DNA, which is inherited separately from the primary DNA in the cell nucleus, in order to unravel this past. Ten new Neanderthal individuals from six archaeological sites in Belgium, France, Germany, and Serbia had their mitochondrial DNA sequenced by the team. These were examined in conjunction with 49 previously released Neanderthal mitochondrial DNA samples.

Charoula Fotiadou, the study's first author, stated that although mitochondrial DNA typically lasts longer and is easier to retrieve, it does not store nearly as much genetic information as the full human genome. The findings were integrated with information from the extensive archaeological database ROAD regarding Neanderthal presence in Europe.

The genetically diverse European Neanderthal populations were drastically reduced by the severe climate of the Ice Age, which occurred about 75,000 years ago. Archaeological sites became fewer and more concentrated throughout southwest Europe during this time. The Neanderthals were highly genetically similar when the climate warmed and the population recovered because of this severe genetic bottleneck.

A Quick Decline Prior to Ultimate Extinction

In order to determine if the genetic variations in mitochondrial DNA diversity across time were consistent with a population of constant size, the researchers also used a statistical tool. This was not the case, according to the results. The estimates show that between 45,000 and 42,000 years ago, the Neanderthal population swiftly and dramatically decreased.

Around 42,000 years ago, just before the Neanderthals completely went extinct and were replaced by modern humans, Homo sapiens, this sharp decline in population reached a minimum. Their extinction might have been significantly influenced by the absence of genetic diversity.The Late Neanderthals were a highly homogeneous group in terms of genetics, according to Professor Posth. "So it may be that the low genetic diversity- and possibly also the subsequent isolation of small groups - contributed to the disappearance of the Neanderthals."

Seldom Occurring Exceptions to the Rule

Although this single lineage accounted for the great majority of late Neanderthals, new findings have shown rare deviations. Thorin, a member of an ancient lineage that had been isolated for millennia, was discovered in Grotte Mandrin, France, around 50,000 years ago. For late European Neanderthals, Thorin is still the anomaly rather than the rule.

The results of this thorough DNA analysis paint a far more accurate picture of the evolutionary advancements that occurred prior to the Neanderthals' extinction. Scientists are finally deciphering the intricate and dramatic demographic history of our closest ancient relatives by fusing genetic evidence with archaeological data.