Researchers have used a new method to extract DNA of Neanderthals from the soil of caves they inhabited to reveal how they came back from near extinction at least twice before finally disappearing from the planet. A new study was published last week showing details of how an international team of researchers recovered fragments of Neanderthal genetic material that dated to between 200,000 and 50,000 years ago from cave sediments found in caves in Spain and Russia.
The data the scientists gathered show that there were two radical replacements of the Neanderthal population in Eurasia, with one occurring about 135,000 years ago and another occurring about 100,000 years ago. Researchers believe the events could indicate environmental pressures possibly caused by a cooling climate that temporarily decimated the local Neanderthal population. The data suggests that in both instances, conditions improved, and a surviving lineage of Neanderthals repopulated the continent.
The most exciting part of the discovery is that the finding doesn’t come from skeletons or archaeological remains, rather than information directly from the soil. The team was able to sequence Neanderthal DNA from sediments at a cave in northern Spain known as Galeria de las Estatuas. Some of the DNA was recovered from Denisova and Chagyrskaya in Siberia.
The site in Denisova is perhaps the most famous of all sites associated with Neanderthals. At that location, about ten years ago, scientists were able to sequence the DNA discovered in a single finger bone and identified it as belonging to a previously unknown hominin called the Denisovan. That particular cave housed Neanderthals and Denisovans as well as a hybrid individual during its history.
The causes of the two differences in the Neanderthal genetic tree aren’t clear this time. However, scientists believe it’s unlikely the differences were caused by one group of Neanderthals coming into the region and wiping out the original population.