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Out of Africa: Homo sapiens spreads worldwide
main dispersal c. 70,000–50,000 years ago· Event· Human ancestors & us
Strong evidenceGood evidence; dates or details still being refined.
The spread of Homo sapiens from Africa across the rest of the world, mainly about 70,000–50,000 years ago.
See it on the Life map →What happened
Small groups crossed into Asia via Sinai or across the narrow southern mouth of the Red Sea into Arabia, then spread rapidly: to South Asia, to Australia by about 50,000 years ago or earlier, and to Europe and Siberia by about 45,000. Earlier groups reached Israel, and perhaps Greece, between about 200,000 and 90,000 years ago but left little lasting ancestry. Along the way migrants interbred with Neanderthals and Denisovans. The rival 'multiregional' model has largely given way.
Why it matters
Almost everyone outside Africa descends mainly from this one expansion, which carried our species to every habitable continent and coincided with the disappearance of other human species.
The evidence (fossils, genes, rocks)
Genetic diversity that falls with distance from Africa; mitochondrial and Y-chromosome family trees rooted in Africa; dated fossils and tools; and ancient genomes such as 45,000-year-old Ust'-Ishim from Siberia.
Still debated
The exact timing and routes, whether earlier waves left any trace in living people, and why this expansion succeeded where earlier ones faded.
Inside this (2)
Connections (7)
▸Dmanisi skulls (Georgia) record a far earlier exit than Out of Africa: Homo sapiens spreads worldwideWell established
The connection
Dmanisi shows hominins reached Eurasia by about 1.8 million years ago, more than 1.7 million years before Homo sapiens' main dispersal. 'Out of Africa' happened more than once: erectus-grade humans spread to Georgia, China and Java long before our species existed.
When and how
Dmanisi, Georgia, about 1.8 million years ago; stone tools at Shangchen, China, about 2.1 million years ago; Homo sapiens' main exit about 70,000–50,000 years ago.
The evidence
Securely dated fossils and tools outside Africa, far older than any Homo sapiens, show separate dispersals. Genes show today's non-Africans descend from the much later exit.
Debates and open questions
Who made the earliest tools outside Africa, and whether some early Eurasian groups evolved locally or even moved back into Africa, is debated.
▸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).
▸Jebel Irhoud (Morocco) is about 250,000 years older than Out of Africa: Homo sapiens spreads worldwideStrong evidence
The connection
Jebel Irhoud shows Homo sapiens existed by about 315,000 years ago, roughly 250,000 years before the main dispersal from Africa. For most of its history, our species lived only in Africa, evolving and mixing across the continent before a lasting expansion beyond it.
When and how
Morocco, about 315,000 years ago; the main exit, likely through the Middle East or Arabia, about 70,000–50,000 years ago.
How sure are we?
Fossil dates in Africa and genetic estimates of when non-Africans branched off agree on a long African prehistory.
Debates and open questions
Why a lasting expansion took so long, and why earlier forays into Israel and perhaps Greece left little lasting trace, are debated.
▸Homo sapiens left Africa in Out of Africa: Homo sapiens spreads worldwideStrong evidence
The connection
After a few earlier forays, a small population of Homo sapiens left Africa about 70,000–50,000 years ago and spread across Asia, Australia and Europe. Nearly all people outside Africa descend from this group, which met and interbred with Neanderthals and Denisovans along the way.
When and how
From northeast Africa into Arabia or the Levant, about 70,000–50,000 years ago; earlier forays at Misliya and Skhul–Qafzeh, Israel, about 190,000–90,000 years ago.
How sure are we?
Genetic diversity falls with distance from Africa; mitochondrial and Y-chromosome family trees root in Africa; ancient genomes and Neanderthal DNA segments help date the expansion.
Debates and open questions
Which route was used, and whether an earlier wave around 100,000 years ago left lasting ancestry. Some scholars put the main exit closer to 50,000 years ago.
▸Out of Africa: Homo sapiens spreads worldwide led to Humans reach AustraliaStrong evidence
The connection
Moving east along South Asian coasts and through the Indonesian islands, modern humans reached Sahul, the single landmass of Australia and New Guinea at low sea level. Even then they needed several open-sea crossings, the longest likely tens of kilometers: among the earliest evidence of deliberate seafaring.
When and how
Island Southeast Asia to northern Australia and New Guinea, about 65,000–50,000 years ago; Madjedbebe rock shelter in northern Australia holds the oldest claimed artifacts.
How sure are we?
Archaeological dates, plus genomes showing Aboriginal Australians and Papuans descend from the same out-of-Africa expansion as other non-Africans.
Debates and open questions
The date is contested, and so is the route: a northern path via Sulawesi to New Guinea, or a southern one via Timor to Australia.
▸Out of Africa: Homo sapiens spreads worldwide eventually led to Peopling of the AmericasStrong evidence
The connection
The Out of Africa expansion carried people across Asia by about 60,000–45,000 years ago. Some reached the far northeast; by about 32,000 years ago people lived at Yana, above the Arctic Circle in Siberia. Their descendants, mixing with an East Asian population, became the ancestors of Native Americans and crossed into the Americas, the last continents settled before Antarctica.
When and how
Northeast Asia and Beringia, roughly 30,000–15,000 years ago, well after the main Out of Africa dispersal of about 70,000–50,000 years ago.
How sure are we?
Ancient genomes, such as the 24,000-year-old Mal'ta boy from Siberia, show Native Americans descend from a mix of ancient North Eurasians and East Asians.
Debates and open questions
Exactly where the ancestral population lived during the ice-age peak, possibly in Beringia (the 'standstill' idea), and when it split from East Asians.
▸Toba supereruption may have affected Out of Africa: Homo sapiens spreads worldwideDebated
The connection
In 1998, anthropologist Stanley Ambrose proposed that Toba's 'volcanic winter' cut human numbers to a few thousand, explaining our low genetic diversity and setting up the later dispersal. Newer evidence shows people in Africa and India came through the eruption, and may even have spread out afterward along seasonal rivers.
When and how
Sumatra, Indonesia, about 74,000 years ago; ash studied at Jwalapuram (India), Pinnacle Point (South Africa) and Shinfa-Metema 1 (Ethiopia).
How sure are we?
Tiny Toba glass shards at African and Indian sites show people living through the eruption; Lake Malawi cores show no severe cooling there.
Debates and open questions
Whether Toba affected the timing of dispersals at all is unclear. Genetic bottlenecks are now usually explained by the founder effect of small migrating groups.