New research sheds light on the genetic interactions between Neanderthals and early Homo sapiens, revealing critical details about when and how these two species mixed. Neanderthals, known scientifically as “Homo neanderthalensis,” were robust hominins with distinctive physical traits who lived in Europe, Asia, and the Middle East from around 430,000 years ago until their extinction approximately 39,000 years ago. Homo sapiens, originating in Africa around 300,000 years ago, encountered Neanderthals during their migrations into Neanderthal-occupied regions. Two recent studies have provided a more accurate timeline for their interbreeding. One study, using the oldest sequenced Homo sapiens DNA from remains found in Germany and the Czech Republic determined that gene flow occurred between 49,000 and 45,000 years ago. Another study, analyzing ancient and modern genomes, suggested a similar range of 50,500 to 43,500 years ago. These interactions likely took place over generations, leaving a genetic legacy in modern humans.

The implications of this interbreeding are significant, both biologically and anthropologically. Genomic evidence indicates that some Neanderthal genes conferred survival advantages to Homo sapiens, particularly in areas like immune response, skin pigmentation, and metabolism. For example, an immune gene inherited from Neanderthals provides protection against coronaviruses. However, other Neanderthal genes were deleterious and were eventually lost. Despite this, around 1-2% of the DNA in non-African populations today originates from Neanderthals. The studies also revealed the harsh conditions faced by early humans in Europe, with genome data from Ranis and Zlatý kůň individuals showing no living descendants, suggesting their populations died out. These findings highlight the complex dynamics of early human history and the enduring impact of Neanderthal genes on modern human populations.