The Greatest Migration of Humanity

Where did humanity originate? How did we end up where we live today? Starting as a group of hunter-gatherers in Africa, over 200,000 years later, more than 6.5 million of their descendants have spread all over the globe.

For a long time, scientists have believed that modern humans originated from the African continent as the oldest bone samples have been found there. Geneticists have drawn similar conclusions after conducting extensive studies on the genetic traits of African people.

However, many are still uncertain about the path our ancestors took to migrate out of Africa and disperse across this planet long ago. A skull dating back approximately 92,000 years found at the archaeological site of Qafzeh, Israel, proves that humans undertook early migrations, likely traveling northward along the Nile Valley to reach the Middle East.

Additionally, other migrations from Africa tens of thousands of years later may have occurred through another route: crossing the northern regions of the Red Sea. Many scientists suggest that these “wanderers” account for the approximately 5.5 million people currently living outside the African continent.

Genes Are the Key to All Secrets

To this day, many scientists still do not have answers to questions about who the first modern humans in Africa were and what compelled their descendants to leave their homeland about 50,000 years ago to expand into Eurasia. When and how did the first humans set foot in the Americas?

Other inhabitants of the Andaman Islands off the coast of Myanmar carry the oldest known genetic markers discovered outside Africa, providing evidence that modern humans (Homo sapiens) moved east from Africa around 70,000 years ago. Throughout their migration, they increased their offspring and created new ethnic groups.

For decades, the only evidence to answer these questions relied on the bone samples and artifacts left by our ancestors during their journeys. However, over the past 20 years, scientists have utilized DNA samples from present-day humans to re-establish the migrations of humanity. “Every drop of our blood contains a long history written in the language of evolutionary genes,” said Spencer Wells, a geneticist with National Geographic.

The human genetic code, or genome, accurately indicates 99.9% of the origins of people worldwide; the remaining percentage pertains to individual DNA differences such as eye color or disease susceptibility, along with some functions that are not clearly defined. By comparing markers across various ethnic groups, scientists can uncover correlations with their ancestors. In most genomes, these rapid changes are obscured by the genetic alterations that occur each time in the DNA of mothers and fathers during the formation of subsequent generations. A type of mitochondrial DNA (mtDNA) is passed intact from mother to child, while most Y chromosomes, the male chromosome, are transmitted from father to son.

Long-lasting mutations in your mtDNA and Y chromosome are just two threads linking in a vast tapestry of contributors to our genetics. However, by comparing the mtDNA and Y chromosomes of individuals from different ethnic groups, geneticists can determine when and where these groups diverged during their great migrations across the planet.

Exploring the Chromosomes of Adam and Eve

Klaas Kruiper, a hunter from the San people, waits for family members in the Kalahari Desert of South Africa. The common genetic traits among the San people may indicate a connection to modern humans. They communicate with clicks—a feature found in languages spoken by other African groups that carry DNA from ancient ancestors.

In the mid-1980s, the late Professor Allan Wilson and his colleagues at the University of California used mtDNA to trace the ancestry of humanity. They compared mtDNA from women around the world and found that women of African descent exhibited twice the diversity of their predecessors. From this, these distinct mutations appeared to occur at a stable rate, and modern humans likely lived in Africa twice as long as those in many other regions. Scientists now estimate that present-day humans are related to a solitary woman who lived about 150,000 years ago in Africa, referred to as “mitochondrial Eve.” This woman was not unique at the time; however, if geneticists’ calculations are correct, all of humanity today is connected to Eve through a chain of mothers!

Mitochondrial Eve is quickly linked with “Y-chromosomal Adam,” the common ancestor of us all, also originating from Africa. Subsequent careful studies of DNA have confirmed one undeniable fact: the origins of humanity on Earth today trace back to groups of hunter-gatherers in Africa.

The Greatest Migration in Human History

The diversity among different genetic groups (the colorful dots) indicates that Africa is the earliest home of modern humans. Groups carrying genetic patterns left Africa (in the middle) and over tens of thousands of years, they settled in various regions (on the right).

Between 50,000 and 70,000 years ago, a small “wave” of migrants from Africa reached the western shores of Asia. Archaeologists believe that the migration out of the African continent marked a revolution in behavior, including the development of complex tools, extensive social networks, and the first forms of jewelry and art created by humans. It is possible that some neurological mutations led to the development of spoken language, gradually civilizing our ancestors, with a small group beginning to seek their settlements throughout the world.

In Asia, scientists have uncovered evidence proving that the first migrants appeared here. In the Nile Valley, along the Sinai Peninsula, and to the north of the Levant, they utilized primitive underwater fishing tools. Genetic evidence in Asia indicates that the migrants split into various directions. One group settled briefly in the Middle East, while another traveled along the coastline across the Arabian Peninsula, India, and beyond. Each subsequent generation moved to locations farther than their forebears had settled.

Over thousands of years, the slow movements of humans eventually brought them to southern Australia. Here, archaeologists discovered the remains of a man buried at a site known as Lake Mungo, dating back approximately 45,000 years. The stone tools found beneath the grave may be as old as 50,000 years, representing the earliest evidence of modern humans migrating from Africa to this region. Some indigenous groups on the Andaman Islands near Myanmar, in Malaysia, Papua New Guinea, and throughout much of Aboriginal Australia show genetic markers tracing back to the first migrants.

Modern humans in Asia and Europe exhibit numerous differences, yet share common mtDNA and Y-chromosome genetics, indicating they descend from a common ancestry.

The First Footprints in the Americas

A man from the Onge tribe

Most scientists today agree that Native Americans (Indigenous peoples) descended from ancient Asians who crossed from Siberia to Alaska at the end of the Ice Age, when sea levels fell and gradually revealed the “land bridge” between the two continents. For decades, it has been thought that the first Americans arrived around 13,000 years ago, just before the end of the Ice Age, opening a pathway connected to present-day Canada. However, some archaeologists assert they have evidence that these people were present earlier, such as at the Meadowcroft Shelter site in Pennsylvania, which is 16,000 years old, and Monte Verde in southern Chile, which is over 14,000 years old.

DNA samples from living Native Americans may help resolve some of these questions. Most of these individuals carry genetic markers similar to those of Asians. Jody Hey, a geneticist at Rutgers University, states, “The genetic makeup of modern Indigenous peoples today speaks to their relationship with their ancient ancestors.”

Minh Tú

 (1) The Cradle of Africa

Most anthropologists and geneticists agree that modern humans emerged and developed around 200,000 years ago in Africa. The first fossils of modern humans were found in Omo Kibish, Ethiopia. Sites in Israel also contain significant evidence of modern humans outside Africa, but this group did not migrate far and became extinct around 90,000 years ago.

(2) Beyond the Dark Continent

Genetic data indicates that a small group of modern humans left Africa around 70,000 to 50,000 years ago, replacing other hominid species such as Neanderthals (which are now extinct). All non-African individuals are descendants of those migrants who crossed the Red Sea or the southern region of this area.

(3) The First Australians

Discoveries at two ancient sites – artifacts from Malakunanja and fossils from Lake Mungo – confirm that modern humans moved along the southern coastal regions of Asia and reached Australia nearly 50,000 years ago. Their descendants, the Aboriginal people of Australia, continue to inhabit these lands today.

(4) The First Europeans

For a long time, many anthropologists believed that settlers in Europe followed routes from North Africa through the Levant. However, genetic data shows that the DNA of present-day Western Eurasians actually traces back to Indigenous peoples. This potentially indicates a migration within the continent from Asia to Europe approximately 40,000 to 30,000 years ago.

(5) Asian Inhabitants

About 40,000 years ago, humans traversed Central Asia and reached the northern Himalayas. Around this time, they also moved throughout Southeast Asia and China, stepping onto Japanese and Siberian lands. Genetic evidence confirms that people in Northern Asia indeed migrated to the Americas.

(6) In the New World

The exact timing of when the first humans truly arrived in the Americas remains an unsolved puzzle, despite numerous published studies. Genetic evidence suggests this occurred around 20,000 to 15,000 years ago, when sea levels were low, and land connected Siberia and Alaska. Glaciers likely covered vast areas of North America, forcing newcomers to migrate down to the western coastal regions.