Out of Africa I vs Out of Africa II: Two Great Migrations

Picture two travellers setting out from the same African doorway, but nearly two million years apart. The first was Homo erectus — small-brained, tool-carrying, walking on fully modern legs into a world that had never seen a human. The second was us, Homo sapiens, arriving long after the first traveller's descendants had already settled Asia. This is the heart of Out of Africa I vs Out of Africa II: not one migration, but at least two great waves separated by an almost unimaginable gulf of time.

The names sound like sequels, and in a sense they are. But they involve different species, different routes, different toolkits, and very different fates. Out of Africa I scattered the genus Homo across the Old World for the first time. Out of Africa II eventually peopled every habitable continent — and it is the journey from which nearly all living people outside Africa descend. Here is how the two compare, and why the second story turned out to be far messier than a single departure.

Out of Africa I: Homo erectus leaves

The first humans to step beyond Africa were not our species. They were Homo erectus — or, depending on how you split the names, the early African form some researchers call Homo ergaster. By around 1.8 million years ago, this tall, long-legged, striding hominin had walked clear out of the continent and into the grasslands of western Asia.

The single most important piece of evidence is Dmanisi, a hilltop site in the Republic of Georgia. Dated to roughly 1.8 million years, Dmanisi has produced five well-preserved skulls and other bones — the oldest securely dated hominins anywhere outside Africa. The Dmanisi people were small-brained (the famous Skull 5 holds only about 546 cc) and short, carrying simple Oldowan stone flakes rather than the more refined handaxes of later times. They show that you did not need a big brain or advanced technology to make the first great journey; you needed legs, adaptability, and time.

From that western foothold, Homo erectus kept going. In Southeast Asia, fossils from Sangiran and Trinil on the island of Java date to roughly 1.5–1.8 million years ago — the original "Java Man" discovered in the 1890s. Far to the north and east, the cave site of Zhoukoudian near Beijing ("Peking Man") records a later but long-lived erectus presence in China. Over hundreds of thousands of years, the species spread across a vast belt of Asia, evolving regional forms and, in places like the island of Flores, dwarfing into the tiny Homo floresiensis.

Out of Africa I was therefore not a single dash but a slow, deep colonisation. Its brains ranged from about 600 to 1,000 cc over time, its tools advanced from Oldowan choppers to early Acheulean handaxes, and its descendants endured in Asia until surprisingly late. Crucially, though, none of those Asian erectus lineages left direct descendants among living humans. Out of Africa I was the opening act — but a different cast finished the play.

Out of Africa II: Homo sapiens spreads

Almost two million years later, a second human stepped through the same doorway. Homo sapiens had evolved in Africa by at least 300,000 years ago, as fossils from Jebel Irhoud in Morocco show. For most of that history our species stayed on the continent. Then, in the latter part of the last ice age, modern humans poured outward in the dispersal we call Out of Africa II.

The demographically dominant wave — the one that matters most for the living world — happened roughly 60,000 to 70,000 years ago. Genetic studies of people alive today point to this relatively narrow window: nearly all non-African populations trace the bulk of their ancestry to a single major exit around that time. From the Near East, these people fanned out with startling speed. They reached Australia by perhaps 50,000–65,000 years ago, crossing open water to do so, and spread across Europe and Asia over the following tens of millennia. Much later, by around 15,000–20,000 years ago, their descendants crossed into the Americas.

What set this wave apart was not anatomy alone but behaviour. These were people with brains averaging around 1,350 cc, making finely worked blade tools, sewing fitted clothing, painting cave walls, carving figurines, and trading materials over long distances. That cultural toolkit let them survive environments — high latitudes, deserts, island chains — that earlier humans had never mastered. If you want to trace these routes visually, the interactive migration map lays out where and when modern humans spread across the globe.

Key differences

Set the two dispersals side by side and the contrasts are sharp.

• Who: Out of Africa I was Homo erectus; Out of Africa II was Homo sapiens. These are different species, not different generations of the same people.
• When: Nearly two million years separate them — about 1.8 million years ago versus a main wave around 60,000–70,000 years ago.
• Drivers: The first dispersal seems tied to a more carnivorous diet, longer legs, and the spread of grassland habitats that erectus could exploit. The second was powered by larger populations, flexible technology, and the cultural capacity to adapt fast.
• Technology: Oldowan and early Acheulean stone tools for erectus; blades, projectile weapons, art, and symbolism for sapiens.
• Fate: The Asian erectus lineages eventually died out, leaving no direct living descendants. The sapiens wave, by contrast, is the source of every person of non-African ancestry alive today.

Were there earlier sapiens excursions?

Here the tidy "two waves" story gets more complicated — and more interesting. The 60,000-year wave was the successful one, but it was not the first time Homo sapiens tried to leave Africa. Several fossils record earlier forays that appear to have left little or no surviving genetic legacy.

• Misliya Cave, Israel (~177,000–194,000 years ago): An upper jaw with teeth, the Misliya-1 fossil, is the oldest widely accepted modern human found outside Africa. It pushes the earliest known sapiens excursion back to nearly 200,000 years ago.
• Apidima Cave, Greece (~210,000 years ago): A partial skull, Apidima 1, has been argued to be an early modern human — which would make it the oldest Homo sapiens in Europe. The interpretation is genuinely contested, and some researchers read the fossil differently, but it hints at very early probes into Eurasia.
• Skhul and Qafzeh, Israel (~90,000–120,000 years ago): These caves preserve a population of early modern humans, including deliberate burials. They were in the Levant tens of thousands of years before the main exodus.

These early travellers seem to have been pioneers whose lines petered out — possibly pushed back by climate swings, by Neanderthals occupying the same region, or simply by small numbers. Their DNA does not survive in living people in any major way. That is why "Out of Africa II" usually refers to the later, successful dispersal. But the honest picture is one of multiple dispersals over a long span, not a single clean departure. Modern humans knocked on the door of Eurasia several times before the door finally opened for good.

What happened when they met other humans?

The second great migration had a twist the first did not: the continent was already occupied. When modern humans spread across Eurasia during Out of Africa II, they walked into lands held by other human species — and they interbred with them.

In western Eurasia they met the Neanderthals, and the encounter is written into our genomes: most people of non-African descent carry roughly 2% Neanderthal DNA. Further east, in Asia and out into Oceania, our ancestors met the Denisovans, whose genetic contribution peaks at several percent in Melanesians, Aboriginal Australians, and Papuans. Some of those inherited genes proved useful — a Denisovan high-altitude variant, for instance, helps modern Tibetans live in thin air.

Nothing comparable is known from Out of Africa I, partly because DNA does not survive from such deep time and partly because Homo erectus was moving into a world with few or no other large-brained hominins to meet. The second migration, by contrast, was a story of contact and mixture as much as of movement. You can see how these species branch and where they overlapped on the deep-time family tree timeline.

Why it matters

Out of Africa I and Out of Africa II together rewrite the old idea of a single human "exodus." Instead, leaving Africa was something hominins did more than once, in different bodies, with different tools, separated by the better part of two million years. The first wave proved that a small-brained biped could colonise half a planet. The second wave produced the global, interbred, culturally explosive species reading this sentence.

Seen this way, our deep history is less a straight line and more a series of departures, dead ends, and second chances. The Asian descendants of the first travellers eventually vanished. The descendants of the second are everywhere. Understanding the difference between the two — and the messy reality of multiple sapiens dispersals within the second — is essential to making sense of how one African primate came to inhabit the entire Earth.