Why did our prehistoric ancestors migrate out of Africa?

THis, of course, is what I was thinking about. Human nature developed at some time, and the incipient impulses and instincts that became human nature were no doubt present in our Pleistocene forebears. The qualities that we call curiosity and initiative and adventuresomeness all had to be emergent at the time of these population dispersals. To some degree, I think they must have been part of the reason that people moved from one place to another, particularly places that were very different from what they were used to.

Humans and their ancestors, like many other animals, are very good at depleting local resources, and then traveling to find new environments to deplete. There were no signs that said ‘Now leaving Africa’ or ‘Welcome to Asia’. Humans just spread everywhere they could. This, like so many questions of this type don’t have an answer anyway. All of these responses are guesses, usually employing Occam’s Razor, but there is a lack of information that would provide anything more specific.

Related thread from a few years back.

It needn’t be part of human nature at all, since most animals seem to spread out as much as they can.

You’ve never heard of White Flight?

But seriously folks-

On one documentary I was watching they used computer graphics to demonstrate the formation of the Sahara, which was of course once grasslands and plains. As the land dried up and turned to desert, the groups at the north of it- per theory and some archaeological evidence- tended to go further north while those to the south retreated further south, and of course when the area became an ever increasing desert it cut off most contact twixt the southern and northern groups. Add a few thousand years and you ultimately have Bantu and Lapps and lots of folks in between.

Something that I thought was interesting is the evidence that early agricultural communities had a much poorer rather than much richer diet than hunter-gatherers. This could have something to do with it as well- people branching off to return to h&g lifestyle and leaving the farmers behind.

Addendum to above:

At the same time people were migrating out of Africa they were also migrating from central Africa into southern Africa. It wasn’t just a northward expansion.

I suspect so too. Its probably very hard to come to any firm conclusions about them.

Thanks for clearing that up.

The Journey of Man: A Genetic Odyssey is a National Geographic documentary (and book by Spencer Wells) which details how modern geneticists use the genes of geographically isolated populations to re-trace how humans spread throughout the globe.

Here are a few informative websites on the same.
http://www.bradshawfoundation.com/journey/
https://genographic.nationalgeographic.com/genographic/lan/en/atlas.html

Is that the one where they take DNA samples from people at a street fair in Astoria? Either way, that was an interesting NatGeo episode; Astoria’s one of the most ethnically diverse neighborhoods in the world and the DNA samples literally spanned every inhabited continent including Australia.

I live in Astoria ! Should I be carrying a cheek swab with me just in case I come upon someone executing this study?

Astoria is more ethnically diverse than it was years ago when I lived here. Odd that I’m back. When I was near 31st St and Ditmars Blvd from 1986-1992, the area was heavily Greek, heavily Italian, moderately Latino of all flavors, a smidgen of Jewish and virtually zero Muslim / Middle Eastern.

I now live a bit south of that area. The neighborhood is truly a potpourri. Judging by ear and eye and clothing, there’s Greek, Italian, Latino, Muslim and non-Muslim Middle Eastern ( when you have a man identify himself as Egyptian yet is dressed as a westerner, I’ve no clue if he’s Muslim or not. When a man and his son walk past me wearing traditional head coverings, I ID them as Muslim without doubt. And so on… ) I walk by folks speaking dialects from Africa, French, Spanish, Eastern European languages ( there’s a restaurant a block away that only sells food from Kosovo ).

It’s beautiful.

No, that was a different deal. The Journey of Man is actually a bit outdated now, and his newer book, Deep Ancestry, is probably a better read.

Alternatively, you can participate in the National Genographic Program, and have your own DNA analyzed. I did it a few years ago.

Sorry to disabuse all of you.

Do any of you have kids ?

have you ever tried to take your three-year old anywhere ?

The reason the human race spread out from the Tigris-Euphratese valley (or wherever it was) is that we were following our kids.

Jon

Not sure if you’re serious or not, but given that this is GQ, I’m calling bullshit on that. Firstly, the Tigris/Euphrates reference is Biblical, not scientific. Secondly, I know of no evidence that modern h/g follow their kids around, and so I see no reason to think our ancestral h/gs did either.

I really don’t understand the confusion about Humans leaving Africa. What would be remarkable is if we didn’t leave Africa, given our ability to adapt to different environments.

What about the Sahara Desert? I read about how the expansion and contraction of the Sahara allowed hominids to migrate out of Africa, but I only have a vague recollection of the timing. Anyone more knowledgeable than I am able to elaborate on this?

Ok, I’ll confess to having learned that one of the earliest civilizations was Mesopotamia - in between and around the Tigris and the Euphrates. Is that not so? Were our history books only informed by biblical texts?

It was one of the earliest civilizations, in the sense of societies with cities that we can find the remains of. That doesn’t mean it was early in the history of the human race. The human race goes back around 200,000 years ago in Africa and spread out from there. (Undoubtedly now someone is going to post with other estimates than 200,000 years for the beginning of the human race.)

“Civilization” refers to the formation of sedentary communities (i.e cities…the word “civilization” is based on the Latin word civis, meaning “city”) after the agricultural evolution. Modern humans (homo sapiens sapiens) existed for about 200,000 years as hunter gatherers before they discovered agriculture, started forming permanent settlements and invented “civilization.”

There were already modern humans right at the Southernmost point of Africa (Blombos Cave etc.) thousands of years before the Out of Africa migration.

Genetically, there’s not that much difference here - your average Jew has a lot more European ancestry, your Muslim, more African and Turkic, but if you have Jews, then you *have *Middle Eastern.