Genetic uniformity of late Neanderthals may have led to their extinction, reveals study by Greek researcher

Combining genetic and archaeological data, researchers from the University of Tübingen and the Senckenberg Nature Research Society have reconstructed the dramatic population changes during the last millennia of the Neanderthal presence in Europe. As they found, almost all of the late Neanderthals in Europe descended from a single population.

The researchers analyzed mitochondrial DNA from ten Neanderthal bones and teeth found at six archaeological sites in Belgium, France, Germany and Serbia, which yield genetic material for the first time and which date from 110,000 years ago to 42,000 years ago.

As the first author of the study, doctoral student at the University of Tübingen, Charoula Fotiadou, explains to APE-MPE, mitochondrial DNA, which is inherited from mother to child, as it has multiple copies, usually survives longer and is therefore a valuable tool for the study of evolutionary history.

These samples were then compared with 49 previously published samples of Neanderthal mitochondrial DNA and, as Ms. Fotiadou describes, the researchers created a “phylogenetic tree,” which represents in tree form how related the genetic sequences are to each other and how they evolved over time, leading back to their common ancestor. It was then determined that all late Neanderthals come from one population.

The genetic analysis was also combined with data on the presence of Neanderthals in Europe, which came from the large-scale archaeological database ROAD, which has been developed by the interdisciplinary ROCEEH project of the Heidelberg Academy of Sciences, based at the University of Tübingen and the Senckenberg Nature Research Society and the Natural History Museum in Frankfurt.

The results of the study, published in the journal PNAS, show that around 75,000 years ago, the harsh climate of the Ice Age led to a drastic decline in Neanderthal populations in Europe. A small population survived, moving to a climate refuge in what is now southwestern France.

The descendants of this small population spread across Europe again ten thousand years later. However, this common ancestry resulted in limited genetic diversity. Almost all of the late Neanderthals studied, from the Iberian Peninsula to the Caucasus, belong to the same mitochondrial lineage.

Genetic uniformity of late Neanderthals may have led to their extinction, study by Greek researcher reveals

In addition, the study found evidence of a sharp decline in the Neanderthal population around 45,000 years ago. Their numbers reached a minimum around 42,000 years ago - just a few thousand years before their final extinction.

As the head of the study, professor at the University of Tübingen, Cosimo Posth, explains to ΑΕΝ-ΜΕΝ, this population movement in the final phase of Neanderthal history "significantly reduced the genetic diversity of European Neanderthals and could have had significant consequences for their extinction."

The researchers point out that the loss of genetic diversity may have played a crucial role in the extinction of Neanderthals. While modern humans, Homo sapiens, replaced Neanderthals in Europe about 40,000 years ago, the study suggests that the decline of the latter may have begun much earlier. A genetically homogeneous population is often more vulnerable to environmental changes, disease and other pressures.

Link to the scientific publication:

https://www.pnas.org/cgi/doi/10.1073/pnas.2520565123