The genetic history of modern humans in Europe remains a fascinating area of study, especially when considering the complex interactions between early Homo sapiens and Neanderthals. It is widely accepted that after modern humans left Africa, they came into contact with Neanderthals, resulting in the interbreeding that has left a lasting genetic legacy. Today, about 2–3% of the DNA of people outside Africa is of Neanderthal origin. However, many questions remain about the specific timing of these interactions and the genetic makeup of the first human pioneers in Europe.
A particularly important site in Europe for understanding this early history is Zlatý kůň, located in the Czech Republic. This site yielded the remains of a complete skull from an individual who lived approximately 45,000 years ago. This skull, along with other findings from the site, has been genetically analyzed, revealing crucial insights into the genetic makeup of early humans. However, despite these discoveries, a major challenge has been the inability to link the individual to any specific cultural or archaeological group due to the lack of contextual evidence.
A nearby site, Ilsenhöhle in Ranis, Germany, located about 230 km away from Zlatý kůň, has also been central to the study of early human populations in Europe. Known for its association with the Lincombian-Ranisian-Jerzmanowician (LRJ) archaeological culture, which dates to approximately 45,000 years ago, this site has been the subject of much debate. There has been considerable uncertainty over whether the LRJ culture was created by Neanderthals or early modern humans, given the mix of tools and cultural artifacts found there.
Most of the remains found at Ranis are fragments of bones, which initially presented difficulties in determining whether the remains belonged to Neanderthals or early humans. However, previous studies that analyzed mitochondrial DNA from 13 bone fragments at Ranis confirmed that the remains were from modern humans rather than Neanderthals. Although mitochondrial DNA represents only a small part of the genome, these results confirmed that the specimens were genetically aligned with Homo sapiens, but they left the broader genetic relationships and the context of their interactions with Neanderthals still unclear.
In a breakthrough study published in Nature, researchers set out to address this gap by analyzing the nuclear genomes of the 13 individuals from Ranis. Their findings revealed that the remains represented at least six distinct individuals, two of whom were infants. Genetically, three were male and three female. The study also identified familial relationships among these individuals, including a mother and daughter. In a surprising turn of events, the research team discovered a fifth- or sixth-degree genetic relationship between one of the individuals from Zlatý kůň and two individuals from Ranis, indicating that the two sites were not just geographically close but likely part of the same extended family group. This connection suggests that the early humans in these regions shared both genetic and cultural ties.
The DNA analysis also provided a glimpse into the physical characteristics of these early human populations. The genomes from Ranis and Zlatý kůň revealed genetic variants associated with dark skin, dark hair, and brown eyes, characteristics that reflect their relatively recent African origins. These findings are significant as they give us a picture of the appearance and genetic makeup of the first modern humans to settle in Europe, demonstrating how they were still genetically connected to their African ancestors. The research team’s ability to analyze these genomes marks the sequencing of some of the oldest high-quality human genomes ever retrieved from the Pleistocene era.
Moreover, the study found no evidence of Neanderthal ancestry in the genomes of these early European pioneers. This was a key finding, as it raised questions about the timing and geographical context of the Neanderthal admixture. Previous studies have established that later modern human populations carried evidence of Neanderthal DNA, but the lack of Neanderthal ancestry in the Ranis and Zlatý kůň individuals suggests that they might have arrived in Europe via a different route or did not come into contact with Neanderthals as extensively as other groups did.
The absence of Neanderthal ancestry in the Zlatý kůň and Ranis populations also challenges earlier assumptions about the timing of human migrations and interactions with Neanderthals. Since all present-day non-African populations share a common Neanderthal ancestry, researchers used the genomes of Zlatý kůň and Ranis to estimate that the shared Neanderthal admixture likely occurred between 45,000 and 49,000 years ago, much later than the time when these early European humans first arrived in the continent. The findings suggest that these first settlers may have entered Europe via a different route or perhaps had a different history of interaction with Neanderthals than those who arrived later.
The shared Neanderthal ancestry that is seen in all non-African populations today is believed to have resulted from an admixture event that occurred when modern humans and Neanderthals interacted. This event occurred around 45,000 to 49,000 years ago, and it highlights the complexity of early human migrations. The genetic traces of this interaction are now part of the DNA of all non-African populations, but the timing of these interactions and their exact mechanisms remain topics of ongoing research. It is likely that the Neanderthal ancestry seen in modern humans today was inherited through a mixture of populations that crossed paths and intermixed, although the extent and frequency of these interactions are still debated among scientists.
The research on Zlatý kůň and Ranis provides a clearer understanding of the timeline of human migrations and the early interactions between modern humans and Neanderthals. It suggests that there was no single, uniform route of migration into Europe, and that different populations of early humans may have taken distinct paths across the continent. The discovery of the genetic links between the two sites, as well as the lack of Neanderthal admixture in these early populations, challenges previous models and offers a more nuanced picture of human prehistory.
The results also underscore the importance of DNA analysis in reconstructing ancient human history. By sequencing the genomes of early modern humans, scientists are able to gain insights into the genetic diversity of populations that lived tens of thousands of years ago. In doing so, they are able to uncover the genetic legacies that continue to shape the human genome today.
The study also suggests that the early European populations that settled in places like Ranis and Zlatý kůň may have been much smaller and more isolated than previously believed. Based on genetic data, the researchers estimate that the population likely consisted of only a few hundred individuals, who would have been dispersed over a large territory. Despite their small numbers, these groups laid the genetic foundations for the future populations of Europe and the rest of the world. These early pioneers represent a unique branch of human ancestry, offering new clues into how our ancestors adapted to life outside Africa and their relationships with the Neanderthals who had already lived in Europe for thousands of years.
More information: Arev Sümer, Earliest modern human genomes constrain timing of Neanderthal admixture, Nature (2024). DOI: 10.1038/s41586-024-08420-x. www.nature.com/articles/s41586-024-08420-x