In a groundbreaking revelation, recent research suggests that Neanderthals and anatomically modern humans engaged in amorous encounters as early as 250,000 years ago, a far more ancient connection than previously believed. This fascinating exploration of our distant past unveils the complexities of our ancestry, migration, and the genetic footprints they left behind.
A Rewritten Prehistory
Traditionally, it was held that Neanderthals and anatomically modern Homo sapiens first intermingled around 75,000 years ago. However, a fresh analysis published in the Current Biology journal upends this narrative. It reveals that approximately 250,000 years ago, a group of Homo sapiens from Africa crossed paths with Neanderthals in Eurasia, initiating a profound intermingling that forever altered our genetic makeup.
The group of early humans who partook in these interactions ultimately vanished, but they left an indelible mark on Neanderthal DNA. This legacy was discerned in the genome of a Neanderthal discovered in Siberia, which contained 6% of human DNA. When the descendants of these human-Neanderthal liaisons returned to Africa, some sub-Saharan populations of anatomically modern humans inherited traces of Neanderthal DNA, enriching their genetic diversity.
Michael Dannemann, an associate professor in evolutionary and population genomics at the University of Tartu in Estonia, emphasizes the significance of these findings. He believes that this research will provide a more precise understanding of Neanderthal DNA in modern human genomes and shed light on the reciprocal process. It will empower scientists to better anticipate how these interbreeding events influenced the physical traits of both groups and enhanced our comprehension of migration patterns and interactions between modern humans and Neanderthals.
In 2020, the prevailing hypothesis suggested that most interbreeding between modern humans and Neanderthals took place in Eurasia, based on a study published in the journal Cell, which identified Neanderthal DNA in sub-Saharan African human genomes. However, the origin of this DNA remained a mystery, with the analysis predominantly focused on Niger-Congo-related populations.
In this recent study, researchers compared the 122,000-year-old genome of the “Altai Neanderthal” from Siberia with the genomes of 180 individuals from 12 modern sub-Saharan African populations. They then developed a statistical tool to trace the origins of Neanderthal DNA in the modern human genome.
Alexander Platt, a co-author of the study from the Department of Genetics at the University of Pennsylvania, explains that the statistical analysis scrutinized genes shared by both humans and Neanderthals. It aimed to determine whether specific alleles or genetic variants appeared to have Neanderthal origins and had been transmitted to modern humans, or if the flow of genetic information was in the opposite direction.
The researchers found that all the examined sub-Saharan genomes predominantly contained Neanderthal DNA from the interbreeding event that transpired 250,000 years ago. Some sub-Saharan populations carried up to 1.5% of Neanderthal DNA, inherited from the humans who migrated back to Africa.
Moreover, the scientists discovered that most of the human DNA within the Neanderthal genome resided in non-coding regions, indicating that human genes were selected during Neanderthal evolution. Conversely, the same genomic regions in modern humans lacked Neanderthal DNA.
Fernando Villanea, a population geneticist from the University of Colorado Boulder, underscores the significance of this finding. It implies that no particular region of the DNA was superior to the other; it was merely the overall genomic compatibility that mattered.
The authors of this study hope that these findings will contribute to answering other questions regarding human evolution. Sarah Tishkoff, a genetic and biology professor at the University of Pennsylvania, expresses excitement at the prospect of acquiring more knowledge about the genome of the population that existed 250,000 years ago and comparing it to the modern human genome. This could potentially unravel intriguing aspects of human evolution and adaptation.
This captivating journey into our prehistoric past reveals that the connections between Neanderthals and modern humans are far older and more intricate than previously thought. The genetic exchanges between these two groups have left an indelible mark on our DNA, shaping the course of human evolution. This newfound understanding not only sheds light on our shared history but also paves the way for further discoveries about our ancient ancestors.
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