For hundreds of thousands of years, Neanderthals lived across western Eurasia (Europe and parts of western Asia). This long period matters because it set the stage for later overlap and interbreeding when Homo sapiens expanded out of Africa into the same regions.
By the time Homo sapiens began spreading through the Near East and into Eurasia, humans and Neanderthals could meet in the same landscapes. This geographic overlap created repeated opportunities for interbreeding, which is the source of Neanderthal DNA found in most people outside Africa today.
Genomic studies indicate that most living non-Africans share Neanderthal ancestry from a single, broadly shared period of gene flow rather than many unrelated events. This is important because it ties much of Neanderthal introgression (DNA movement across groups through interbreeding) to an early phase of the Out-of-Africa story, before major non-African population splits were fully established.
A large analysis of ancient and present-day genomes attributes the vast majority of Neanderthal gene flow to an extended period roughly between 50.5 and 43.5 thousand years ago. This timeframe fits the idea that early Eurasian humans experienced sustained contact with Neanderthals over many generations, not just a single brief encounter.
Genome data from approximately 45,000-year-old human remains from Ranis (Germany), alongside analysis of Zlatý kůň, support a single admixture event shared with all sequenced non-Africans. That event is dated to about 45,000–49,000 years ago, helping narrow where the widely shared Neanderthal ancestry in modern non-Africans likely entered the human lineage.
The ~45,000-year-old Ust’-Ishim genome (western Siberia) contains Neanderthal DNA in long segments. Because recombination breaks segments into shorter pieces over time, these lengths imply Neanderthal gene flow into his ancestors about 7,000–13,000 years before he lived—often summarized as an admixture date around 50,000–60,000 years ago.
Around 44,000 years ago, individuals from Bacho Kiro Cave (Bulgaria) had Neanderthal ancestors within roughly the last 10–20 generations. This indicates that, alongside the broadly shared introgression event, some early modern human groups in Europe experienced additional, later local interbreeding with Neanderthals.
The Oase 1 individual (Peștera cu Oase, Romania), dated to roughly 37,000–42,000 years ago, carried an unusually high fraction of Neanderthal ancestry (about 6–9%). The large size of several Neanderthal-derived DNA segments indicates a Neanderthal ancestor only about 4–6 generations earlier, showing that interbreeding could be very recent in some European contexts near the end of Neanderthal history.
Neanderthals are generally thought to have disappeared in Europe around 39,000–41,000 years ago. By this point, interbreeding had already left a lasting genetic legacy in many modern human lineages, even as Neanderthals themselves ceased to exist as a separate group.
Comparisons among early modern humans show that some individuals carry evidence of later, additional Neanderthal admixture while others do not. For example, the Nature synthesis notes no evidence of additional admixture in the Tianyuan individual (China) or Zlatý kůň, contrasting with Oase and Bacho Kiro—supporting a picture of multiple human groups moving through Eurasia with different contact histories.
Over time, recombination broke Neanderthal DNA into smaller segments, and natural selection removed many harmful archaic variants while some persisted. Later ancient and present-day genomes show that most non-African populations retain a relatively consistent baseline of Neanderthal ancestry (often summarized as roughly 1–3%), even though specific segments differ among populations.
In 2010, the first draft Neanderthal genome provided strong genetic evidence that Neanderthals shared more derived variants with present-day Eurasians than with sub-Saharan Africans. This supported the conclusion that gene flow from Neanderthals occurred into the ancestors of non-African humans after the Out-of-Africa expansion, making introgression a central part of the modern human story.
Using very early modern human genomes, a 2024 Nature study dated the widely shared Neanderthal admixture event to about 45,000–49,000 years ago. This tighter window helps link introgression to specific phases of human dispersal across Eurasia and clarifies that some older fossils outside Africa may represent earlier migrations that did not leave descendants in most living non-Africans.
Timing and geography of Neanderthal introgression into modern human genomes (c. 60–40 ka)