Why Did Early Humans Leave Africa and Spread Across the World? — Here’s What Researchers Say Drove Them

Scientists believe that modern humans all lived in Africa before migrating to the rest of the world. If this is the environment where we evolved and thrived, then why did the early humans leave?

Because around 50,000 to 70,000 years ago, fossils and DNA evidence suggest they finally ventured out of Africa after staying there for their whole existence. To Europe, Asia, then the rest of the world. Is it about conquering the lands, or was it to survive? Let’s discuss several theories that could explain it.

Climate Shifts and Drought Pushed People Out

One of the most significant reasons why early humans left Africa was the changes in the climate. The continent, 50,000 to 70,000 years ago, was starting to dry, and droughts could be felt in everyday life. Both the food sources and water are becoming scarce, which means that the only way to survive is to move.

However, how do they know where to move? Did they specifically aim to go outside of Africa? Well, researchers think that between these dry and colder climates was a period of increased rainfall. These phenomena created something called “green corridors”.

Across the normally dangerous and dry Sahara, the wet and green corridors created a route that made it possible for early humans to cross safely into new regions. These very same harsh climate changes that mainly drove them away from Africa also helped open paths into the Middle East, Asia, Europe, and beyond.

Read more: National Geographic

People Learned to Live in Many Kinds of Places

When Did Hominins First Leave Africa?

Another reason why early humans left Africa was not because of an extinction threat. This time, it was because they learned how to live in different kinds of environments and became ecologically flexible.

Inside the vast continent of Africa, the early humans lived in various habitats, including open savannas, grasslands, forest areas, deserts, and mountain regions. This ability to survive in almost any type of environment allowed them to travel to new, unfamiliar lands and even dominate the competition there.

Because soon, after they left Africa, they would meet the Neanderthals and other types of hominins. Experts also think that this is the skill that helped them outcompete all the other human species. Humans were already far superior in culture and their adaptability to different types of environments before moving out of Africa. To know more about how modern humans won this ancient competition, you can head on to this specific article instead: How Did Homo Sapiens Outcompete Every Other Human Species, and Are We Special? — Here’s Why We’re the Last Humans Standing

A Successful Group Carried Our Genes Everywhere

Evidence suggests that over 100,000 years ago was the first time early humans tried to migrate out of Africa. However, this initial migration failed for a variety of reasons, and the proof is in its remains. They are not genetically related to any of the current modern humans, because scientists think that they failed to survive and reproduce during this attempt.

But, 50,000 to 70,000 years ago, early humans became more adaptable and ecologically flexible. This time, they are more equipped to survive and outcompete the already present hominins in the new environments. However, most people do not know that only a small group has successfully migrated out of Africa, and all humans outside this continent are their descendants. So, earlier migration may have happened, but only this attempt was successful.

Read more: Live Science

Routes and Other Human Species Helped the Journey

Out of Africa (Archeological Evidence of Human Migration)

The routes the early humans may have chosen or led to by the climate also affected their chances of success. Experts think that it was also around this time that the modern human species met the Neanderthals after they migrated out of Africa. The primary location of the interbreeding and mixing was thought to have happened in the Middle East.

Until this age, most of the humans from outside of Africa still carry 1% to 4% of their DNA from Neanderthals. These ancient humans may have given us the necessary traits to survive in their environment, but soon, even they perished about 40,000 years ago for a variety of reasons.

Early humans used several routes to get out of Africa. One popular path could have been the land bridge through the Sinai Peninsula and Arabian Peninsula, where they could walk to cross Africa to Asia. However, it was also estimated that modern humans arrived in Australia around 50,000 years ago, so it is more likely that the successful group used another path instead.

So, this led the experts to believe that even without boats or evidence of them being found from that era, early humans may have primarily used watercraft to cross the seas. This journey would have been supported by an abundance of marine food sources.

The ability to cross the seas or coastal routes was the most significant factor for humans migrating out of Africa into new islands and continents. Because without this maritime capability, they would not have reached Oceania and the rest of the Pacific at around the same time.

Author's Final Thoughts

So, why did early humans migrate out of Africa if we evolved in that continent? The answer is a combination of various factors and theories. From climate change and droughts to green corridors and adaptability, the modern human species was driven to migrate out of Africa.

Soon, a small group was able to successfully arrive in the new continents, armed with their culture, ecological flexibility, use of fire, tools, and drive to make the journey that shaped all of human history.

Read next: Humans Are the Only Species With Complex Language, Researchers Say — And Here’s What Stopped Other Animals From Developing It

References & Further Reading

Beyer, R. M., Krapp, M., Eriksson, A., & Manica, A. (2021). Climatic windows for human migration out of Africa in the past 300,000 years. Nature Communications. https://www.nature.com/articles/s41467-021-24779-1

López, S., van Dorp, L., & Hellenthal, G. (2016). Human dispersal out of Africa: A lasting debate. Evolutionary Bioinformatics. https://pmc.ncbi.nlm.nih.gov/articles/PMC4844272/

Beyin, A. (2011). Upper Pleistocene human dispersals out of Africa: A review of the archaeological, fossil, and genetic evidence. International Journal of Evolutionary Biology / PLOS ONE. https://pmc.ncbi.nlm.nih.gov/articles/PMC3119552/