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What does DNA evidence show about interbreeding between Homo sapiens and Neanderthals?

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Illustration showing side-by-side reconstructions of five hominins in the human lineage: Australopithecus afarensis, Homo habilis, Homo erectus, Homo neanderthalensis, and Homo sapiens, with each figure labeled and depicted in a walking pose to highlight evolutionary changes in posture and body structure. A scale bar at the top right indicates relative height. — human evolution An artist's depiction of five species of the human lineage.

DNA evidence has fundamentally changed our understanding of the relationship between Homo sapiens and Neanderthals, confirming that limited interbreeding occurred between the two groups.123

Genetic analysis reveals that modern human populations outside of Africa carry approximately 1–4 percent Neanderthal nuclear DNA. This interbreeding likely took place between 80,000 and 50,000 years ago, as Homo sapiens migrated out of Africa and encountered Neanderthals in regions such as the Levant and across Eurasia.132

The legacy of this interbreeding persists in the modern human genome. Some inherited Neanderthal genes are associated with immune system responses, while others have been linked to skin complexion and an increased risk of certain health conditions, such as type 2 diabetes. While most classifications have historically treated them as distinct biological species, the evidence of successful interbreeding suggests a closer evolutionary relationship than previously assumed.123

It is important to note that while this genetic exchange occurred, Homo sapiens and Neanderthals maintained distinct lineages, and the Neanderthals were eventually replaced or assimilated by modern human populations.245