The latest research on ancient DNA has provided extremely important insights into the evolutionary history of humanity, offering a new timeline for interactions between Neanderthals and modern humans. The results show that these evolutionary cousins interbred during a period that began around 50,500 years ago and lasted for about 7,000 years. This period of interbreeding left an indelible mark on the genetic legacy of modern Eurasian populations.

Coexistence of two species in Eurasia

According to archaeological evidence, Homo sapiens and Neanderthals lived side by side in Eurasia for at least six millennia. During this coexistence, gene exchange occurred, shaping the genetic structure of today's populations. Neanderthal genes, which today make up between 1% and 2% of the genome of modern Europeans and Asians, played a crucial role in adapting our ancestors to the living conditions of the time.

When did modern humans leave Africa?

One of the key conclusions of this study is that the first wave of migration of modern humans from Africa to Eurasia ended around 43,500 years ago. This is important because it allows for a more precise understanding of the migration routes and the timing of Homo sapiens' spread beyond Africa. These data also help scientists better connect archaeological and genetic evidence.

Ancient genes in contemporary populations

Neanderthal genes are not just passive traces of the past. Studies have shown that some of these genes helped our ancestors in the fight against diseases, adapting to colder climates, and regulating skin pigmentation. For example, certain genes inherited from Neanderthals are linked to immune responses to specific pathogens, including viruses. Interestingly, one of these genes today plays a role in increasing resistance to certain variants of the coronavirus.

Genetic differences between regions

While the Neanderthal genetic contribution is present in all non-African populations, East Asian populations carry approximately 20% more Neanderthal DNA compared to European populations. This difference may be explained by a longer or more intense period of interbreeding in East Asia.

"Neanderthal deserts" in the human genome

One of the fascinating findings of the study concerns parts of the human genome that are completely devoid of Neanderthal genetic material. These so-called "Neanderthal deserts" suggest that certain Neanderthal variants were harmful to modern humans, leading to their rapid removal through natural selection. Interestingly, these parts of the genome were already present in the first modern humans 40,000 years ago.

The complexity of interbreeding

One of the key points of the study is that the process of interbreeding between Neanderthals and modern humans was not a one-time event. Instead, it appears to have been complex and prolonged. Over a period of 7,000 years, different groups of people may have repeatedly separated and interbred again, resulting in the genetic diversity we see today.

Advantages of inherited genes

While some genes were quickly eliminated due to their harmful effects, others became beneficial and provided evolutionary advantages. For example, genes related to immune function and adaptation to cold climates increased in frequency among modern humans. This suggests that some of these genes allowed our ancestors to better survive in the challenging conditions of the Ice Age.

Approach to contemporary research

This study was based on the analysis of 58 ancient human genomes and 275 modern genomes. More accurate models were used to date the periods of interbreeding and understand the impact of Neanderthal heritage on today's populations. Additionally, comparisons with parallel studies provided further confirmation of the timeframes and impact of this process.

Broader context

Although the study mainly focused on interactions with Neanderthals, scientists also examined the legacy of other ancient human species, such as Denisovans. This legacy further enriches our understanding of the evolutionary process and enables scientists to reconstruct the history of human adaptation to different ecological conditions.

Ultimately, the results of this study open up new questions about the dynamics of interbreeding between different human species and their impact on the evolutionary history and genetic future of Homo sapiens.