HUMAN MIGRATION OUT OF AFRICA, widely accepted model regarding the geographic dispersal of the first anatomically modern humans (Homo sapiens). The Out of Africa (OoA) theory holds that humans in both the archaic and modern biological senses evolved first in Africa and then spread throughout the rest of the world. OoA theory comprises two primary migrations: “Out of Africa I,” involving the movement of archaic humans (i.e., non–Homo sapiens) from Africa to Eurasia as far back as 1.8 million years; and “Out of Africa II,” the migration of Homo sapiens out of Africa after their emergence between 200,000 to 300,000 years ago. The theory is supported by DNA and archaeological findings. These migrations established the dominance of Homo sapiens and ushered in the extinction of whichever competing hominids remained.
Homo sapiens are believed to have originated in the Horn of Africa, or Somali Peninsula, between 200,000 and 300,000 years ago. Though the precise cognitive and behavioral characteristics of these early humans is a subject of debate, the evidence suggests that humans exhibiting “modern human behavior” were present along the African coast by, at the latest, 100,000 years ago. The Herto Man fossil, discovered in Herto Bouri, Ethiopia, and estimated to be around 160,000 years old, further supports this timeline, reinforcing the notion that humans inhabited Africa tens of thousands of years before migrating out of the continent.
Changes to the climate, including drought and food shortages, eventually made life difficult on the African continent. As humans struggled to survive, the population split into small, isolated groups. On the brink of extinction, humans were forced to seek new habitats and resources beyond Africa.
Modern humans migrated first to Asia, likely settling there between 80,000 and 60,000 years ago. This initial migratory group is thought to have comprised anywhere from 1,000 to 50,000 people, and little evidence has been found to clarify the specific paths these migrants took. However, tools found in southern India from 70,000 years ago match those found in Africa from the same period, and there is further evidence to suggest that by around 50,000 years ago Homo sapiens had settled in what are now Indonesia, Papua New Guinea, and Australia. Modern humans likely entered Europe around 40,000 years ago, probably via two routes: from Turkey along the Danube corridor into eastern Europe, and along the Mediterranean coast. In Europe Homo sapiens would have encountered a robust existing population of Neanderthals, which likely resulted in thousands of years of interspecies warfare. It appears to have taken between 15,000 and 20,000 years for Europe to be entirely colonized; eventually the Neanderthals died out, signaling the elimination of Homo sapiens’ last hominid rival.
Around 16,000 to 20,000 years ago humans crossed from Asia to North America via a temporary land bridge and possibly also in boats. Once established in the northern parts of the continent, the population spread rapidly southward. By 12,000 to 14,000 years ago humans had occupied both North and South America.
In 2013 Pulitzer Prize–winning journalist Paul Salopek embarked on a 24,000-mile expedition known as the Out of Eden Walk, retracing the path of human migration from Africa to the Americas. Starting from Ethiopia, Salopek traveled through Central and Southeast Asia, crossed China, and eventually boarded a ship to cross the Pacific Ocean. Upon reaching the Americas, he walked along the West Coast of the United States into Mexico, traversed Central America, and continued into South America, concluding his journey at Tierra del Fuego, the southernmost point of the continent. In retracing humanity’s first steps Salopek sought to bring a novel perspective to contemporary issues such as migration, climate change, and human connection across cultures and landscapes. While the Out of Africa theory is by now commonly accepted, ongoing research and new scientific discoveries continue to refine our understanding of human-migration patterns and evolutionary history. In 2023, for example, a pair of human bones found in a cave in Laos were dated to between 68,000 and 86,000 years old, suggesting the possibility of a slightly earlier migration from Africa.