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Interbreeding with Neanderthals & Denisovans
main pulse c. 50,000–45,000 years ago; other episodes earlier and later· Event· Human ancestors & us
Well establishedStrong fossil, genetic or geological evidence.
Modern humans had children with Neanderthals and Denisovans, so most people alive today carry some of their DNA.
See it on the Life map →What happened
As modern humans left Africa they met Neanderthals in western Asia and Europe, and Denisovans farther east. People outside Africa carry about 1–2% Neanderthal DNA; Papuans, Aboriginal Australians and some Filipino groups also carry a few percent Denisovan DNA. Mixing happened several times, including about 250,000–200,000 years ago, when early sapiens genes flowed into Neanderthals. A Siberian girl nicknamed Denny, about 90,000 years old, had a Neanderthal mother and a Denisovan father.
Why it matters
The human family looks less like a neatly branching tree and more like a braided stream; inherited variants still affect immunity, skin, altitude tolerance and disease risk.
Think of it like
Like a merger where the acquired company's name disappears but some of its staff, systems and habits live on inside the new firm.
The evidence (fossils, genes, rocks)
Genomes from Neanderthal and Denisovan bones since 2010, compared with living people's DNA; 2024 genomes from Ranis, Germany, and Zlatý kůň, Czechia, date the main mixing to about 49,000–45,000 years ago.
Still debated
How often groups met, whether hybrids were less fertile (some chromosome stretches lack Neanderthal DNA), and whether still-unknown 'ghost' populations also contributed.
Connections (4)
▸Neanderthals passed genes to us through Interbreeding with Neanderthals & DenisovansWell established
The connection
When modern humans entered western Asia and Europe, they met Neanderthals and sometimes had children together. Those hybrids' descendants carried Neanderthal DNA forward. As a result, people outside Africa today carry about 1–2% Neanderthal DNA, including variants affecting immunity, skin and hair, and some disease risks, such as severe COVID-19.
When and how
Mainly, probably in western Asia, about 50,000–45,000 years ago; also earlier contact, including a modern-human gene flow into Neanderthals about 250,000–200,000 years ago.
The evidence
Neanderthal genomes sequenced from bones since 2010, compared with modern genomes; Romania's Oase man, about 40,000 years old, had a Neanderthal ancestor four to six generations back.
Debates and open questions
Why some chromosome stretches have almost no Neanderthal DNA (perhaps reduced hybrid fertility), and whether mixing happened mostly in one region or many.
▸Denisovans also took part in Interbreeding with Neanderthals & DenisovansWell established
The connection
Denisovans, known mostly from DNA, also mixed with modern humans spreading through Asia. Papuans, Aboriginal Australians and some Filipino groups carry the most Denisovan DNA, a few percent, while East and South Asians carry traces. The DNA suggests several distinct Denisovan populations were involved. A Denisovan version of the EPAS1 gene helps Tibetans cope with thin air.
When and how
Across Asia and island Southeast Asia, roughly 50,000–30,000 years ago (estimates vary); first detected in 2010 from a finger bone in Denisova Cave, Siberia.
The evidence
The Denisovan genome (2010, high quality 2012) compared with modern populations; distinct patterns of DNA segments point to at least two or three Denisovan sources.
Debates and open questions
Where the mixing happened, given how few Denisovan fossils exist, and whether Denisovans themselves crossed the sea gaps of the Wallace Line toward New Guinea.
▸Out of Africa: Homo sapiens spreads worldwide brought encounters and Interbreeding with Neanderthals & DenisovansWell established
The connection
Interbreeding required meeting. As modern humans spread out of Africa, they entered lands where Neanderthals and Denisovans already lived. Early in the expansion, probably in western Asia, small groups mixed with Neanderthals; this one early pulse explains why all non-Africans carry similar Neanderthal DNA. Farther east, travelers met Denisovans.
When and how
Western Asia, about 50,000–45,000 years ago for the main Neanderthal pulse; South and Southeast Asia, somewhat later, for Denisovans.
The evidence
Neanderthal DNA is spread similarly across Europeans, Asians and Native Americans, pointing to one shared early mixing event before these populations split.
Debates and open questions
Whether earlier waves out of Africa, before 70,000 years ago, also mixed, and how Africans came to carry small amounts of Neanderthal DNA (likely via back-migration).
▸Svante Pääbo proved Interbreeding with Neanderthals & DenisovansWell established
The connection
Svante Pääbo's lab developed ways to recover and read fragile, contaminated ancient DNA. In 2010 it published a draft Neanderthal genome showing that non-Africans share extra DNA with Neanderthals, proving interbreeding. The same year it identified the Denisovans from a finger bone's DNA. He won the 2022 Nobel Prize in Physiology or Medicine.
When and how
Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany; both genomes published in 2010, with Richard E. Green, David Reich and many colleagues.
The evidence
Published in Science and Nature in 2010 and confirmed by many later high-quality genomes; the Nobel committee cited his discoveries on extinct hominins.
Debates and open questions
His 1997 Neanderthal mitochondrial DNA had suggested no mixing, a view nuclear genomes reversed. Open questions now involve DNA from cave sediments and still-unknown 'ghost' groups.