New genetic evidence tells the story of the decline of Neanderthals

The Neanderthal population declined during a cold period about 75,000 years ago, and the loss of genetic diversity may have contributed to their extinction.

A new analysis of Neanderthal DNA, recently in PNAShelped reconstruct the history of many millennia of difficult times that ultimately led to the disappearance of our ancient human relatives.

Faced with a cooling climate, their population declined and they ended up confined to what is now southwestern France.

Later, the climate warmed and Neanderthals began to move across a wider area. However, most of their genetic diversity had been lost, so even widely dispersed groups had very similar DNA.

This situation – small isolated groups with little genetic diversity – may have contributed to its extinction, new research confirms.

As , Neanderthals lived in Europe and Asia for hundreds of thousands of years, disappearing of the archaeological record about 40,000 years.

Previous studies of their DNA had shown that, close to their final years, they had a drastic change in your genetics.

Late Neanderthals, that is, those who lived after about 60,000 years ago, were genetically similar to each other and different from those who came before.

“There must have been a population replacement near the end of Neanderthal history”, theorized the leader of the investigation, Cosimo Posthfrom the University of Tübingen, Germany, to the same magazine.

But how?

To find out how this happened, the team obtained DNA from 10 Neanderthals from six locations in Belgium, France, Germany and Serbia.

In each case they sequenced the mitochondrial DNA, which is inherited only from the mother. They compared the new mitochondrial genomes with 49 that had already been read.

The Neanderthals who lived between 60,000 and 40,000 years ago almost all belonged to the same lineage, which originated about 65,000 years ago. Other lineages that were present in earlier periods were absent.

“This is a very strong indication that this is indeed population replacement,” Posth said.

The new strain appears to have emerged in southwestern France and subsequently expanded from there after 60,000 years ago, when the climate warmed again.

Although the new lineage became widespread, appearing as far east as the Caucasus, the population does not appear to have grown significantly.

The Neanderthals’ habit of living in small isolated groups may have put them at greater risk of extinction – researchers say.