Two recent studies have shed new light on the interbreeding between Neandertals and modern humans that occurred around 45,000 to 49,000 years ago. This period of genetic exchange has left a lasting impact on non-African populations today, with individuals outside of Africa carrying 2 to 3 percent Neandertal DNA in their genomes.
The first study, published in Science, was led by Leonardo Iasi from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. According to Iasi, the peak of Neandertal-human interaction occurred around 47,000 years ago, coinciding with an out-of-Africa migration event. This suggests that the influx of Neandertal genes into the human genome was a result of a single surge of interbreeding between Neandertals in Europe and newly arrived humans.
The second study, published in Nature, focused on sequencing genomes from ancient human remains in Germany and the Czech Republic. These individuals lived between 49,000 and 42,000 years ago and exhibited 2.9 percent Neandertal ancestry. By analyzing the length of Neandertal gene segments in these genomes, researchers were able to determine that the interbreeding event occurred approximately 1,500 to 1,000 years ago, spanning about 80 generations.
In a larger dataset of 59 ancient human genomes and 275 present-day humans, researchers found evidence of a single pulse of Neandertal genetics entering the human genome between 50,500 and 43,500 years ago. This genetic exchange also showed signs of natural selection, with certain segments of the genome retaining more Neandertal genes than others.
Despite the connection to the out-of-Africa population, the individuals from the ancient sites in Germany and the Czech Republic did not leave any descendants behind. This raises questions about the dispersion of modern humans and the gradual replacement of Neandertals as the dominant species in Europe.
Overall, these studies highlight the complex interactions between Neandertals and modern humans and the lasting impact of interbreeding events on human genetic diversity. The findings also underscore the importance of integrating genetic data with archaeological and cultural evidence to gain a deeper understanding of our evolutionary history.
