Why Did Early Humans Leave Africa?

[Judi Lynn]

Homo sapiens have always been on the move. But the traditional out-of-Africa story explains that H. sapiens evolved in Africa and then migrated in a wave to colonize the rest of the world. What sparked this exodus?
By Jesse HawleyJanuary 21, 2021 2:20 PM


Whichever way you look at it, the story of our species’ birthplace in Africa and dispersal across the planet is incredibly complicated. The conventional out-of-Africa story that took root in the 1980s describes a group (or groups) of Homo sapiens, some 150 to 1,000 people, crossing through the Middle East from northeast Africa before spreading throughout Eurasia around 60,000 years ago. They were not the first to make the journey, but they appear to have become the forbearers that populated the rest of the world.

This story, or model, is built from robust evidence from DNA and fossil analyses. But there is a lingering question that hasn't been answered: Why did they pick up and leave?

Before laying out a few of the major theories, we might add some cautionary notes and other considerations. Perhaps most importantly, H. sapiens didn’t just leave once; they were leaving all the time. An impermanent population made an excursion 180,000 years ago, as evidenced by fossil finds of a jawbone and teeth belonging to an anatomically modern human at a site in Israel. There's even evidence of humans making it all the way to the Arabian interior 20,000 years before the eventual out-of-Africa event.

And if you disregard anatomically modern humans, the journey began far earlier — far, far earlier, like a mind-numbing 2 million years ago. Homo erectus, an ancient upright ape, had found itself out of Africa and into China, Indonesia, and Europe before H. sapiens had even evolved. The H. erectus populations that remained in Africa likely gave rise to both H. sapiens and Homo neanderthalensis.

Of the who, what, when, where and how questions surrounding the migration, it is why that is often the most impenetrable to science. Why, exactly, did our ancestors leave their homeland? Short of catching a time machine back some 60,000 years and witnessing our ancestors on the plains of Africa, we may never know for sure. As a result, we must find satisfaction in the answers that circumstantial evidence can provide.

More:
https://www.discovermagazine.com/planet-earth/why-did-early-humans-leave-africa?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+discovercrux+%28The+Crux%29

[LuvNewcastle]

1. I think plain curiosity was another reason for leaving Africa.

People love to travel and explore; at least a lot of them do. We see it today with all of the people going on trips to exotic locations and new attempts at space travel. There's something fascinating about the land beyond the horizon and taking risks. I think that's as big a factor as any in answer to why we left Africa.

[stopdiggin]

2. another great link

Love this stuff. Thanks, Judi.

If I can attempt to answer, without really answering ...
1) homo sapiens never truly did leave Africa (as in there was always a population that remained behind)
2) Without knowing the exact trigger (if in fact there was one) it seems very likely that our species expanded their range for largely the same reasons that others do. Some combination of scarcity of resources, combined with newly discovered (or newly discovered ways to exploit) resources over the horizon. But the short answer is, populations that are having their needs met tend to stay with the familiar -- and populations that are under stress try new behaviors and territory in an effort to adapt.

(and then there is the fondness for theories that suggest some kind of 'cognitive' evolutionary leap -- that led to radically different behavior and abilities -- which are, again, pretty interesting but also pretty speculative at this point.)

[WheelWalker]

3. Humans are an invasive species.

[Thekaspervote]

4. My partner is such a fan of prehistory. He and I both thru reading, docs and visits to various sites

Find experts saying they didn’t leave just to explore, rather for a given reason..most likely climate change.

[no_hypocrisy]

5. The Sahara Desert used to be green, lush farmland millennia ago.

Look at it now.

That could be the reason for the migration.

[Chainfire]

6. Greener pastures.

We may try to overcomplicate the issue. It is probably that simple, the same reason people move today.

Looking at my own family history since the early 1700s, they moved in sequence; Scotland, Ireland, Pennsylvania, Georgia, Alabama and Florida. Always looking for greener pastures. Forgetting the overseas distance, they moved thousands of miles in a relatively short period of time. Of course I realize our miles are shorter than people who traveled on foot, but the principle is the same.

I think that people tend to forget that Homo Sapiens, even 50,000 years ago would have been very much like us with just less experiences to draw on. They would have wanted easier working conditions, more food, better weather, less crowding, and prettier partners.

[csziggy]

7. My family has much of the same history

Ireland, Pennsylvania, North Carolina, South Carolina, Alabama.

What's really interesting is that groups of families tended to move together even if they were not (yet) connected by marriage. The Crows, the Garys, and the Newmans moved from New Jersey to Pennsylvania to Virginia to South Carolina to Alabama. Some members of the families married in South Carolina, but my direct ancestors did not marry until they reached Alabama.

Same for the German families that moved to South Carolina early along, then to Tennessee then to Alabama - they moved as a group until they all settled in that one spot in Alabama between 1819 and 1825 where they settled and stayed.

It seems while people want to see new territory, they also want to take along people they were familiar with.

[PoindexterOglethorpe]

8. Some humans are ready, willing, and eager to move on.

Others prefer to stay in the same place. To me, that covers it. The ones who left were the first kind. Those who stayed, were the second.