Migration out of Africa may have been driven by first glaciation of Pleistocene

https://phys.org/news/2024-03-migration-hominins-africa-driven-major.html

by wglb • 2 years ago

63 51 2 years ago

phys.org

alcover2• 2 years ago

I wonder which routes were opened by this. Gibraltar ? Tunisia -> Sicilly -> Italy ?

In any case the Levant was always an out.

mikhailfranco8• 2 years ago

You might like this YT video about the refilling of the Med...

The MEGAFLOOD that brutally filled the Mediterranean in months

https://www.youtube.com/watch?v=_RSPgIcnRN0

The Med was created by long-term tectonic forces, which closed the sea at Gibraltar, about 7 million years ago. The whole thing dried out, leaving salt deposits on the lowest dusty plains (like Great Salt Lake, Dead Sea, Aral Sea today). Enough dust, dirt and seasonal river inflow, covered the salt in sedimentary layers.....

About 6 million years ago, Gibraltar was breached by rising sea levels, and flooded the Balearic (W. Med) basin, up to the line Italy-Sicily-Tunisia.

Very shortly afterwards (months < 2 years) the water breached the high ground immediately south of Sicily, creating the subsea Noto Canyon, and filling the eastern Med.

P.S. Interesting final comment - the Black Sea was probably not filled by a similar dramatic flood through the Bosphorus. Alluvial structures and fans in the Black Sea floor, show that it silted up from the north, and almost certainly overflowed the Bosphorus from the north, which is why the Bosphorus is relatively narrow - not the whole Med carving wide straits, but a freshwater trickle out from the silted Black Sea.

P.P.S. Also note this contradicts some imagined historical basis for the Gilgamesh and Biblical floods being in the Black Sea (in the direction of what is now called Mt. Ararat). Those tales are much more likely to refer to Mesopotamian floods of the Tigris or Euphrates, perhaps triggered by breaching of earthquake-induced rockslides that temporarily blocked one of the rivers. We can now date and locate a specific episode like this in ancient China 4,000 years ago:

https://www.nationalgeographic.com/science/article/china-yel...

blueflow6• 2 years ago

Avoid using clickbaity YT videos as source, they are entertainment and not reliable.

alcover2• 2 years ago

Thank you. I fail to grasp your P.S. in relation to the Levant passage ?

qwertyuiop_• 2 years ago

Are there popular competing theories like https://www.researchgate.net/publication/21589761_The_Multir... ?

CSMastermind3• 2 years ago

This paper seems to be referencing the migration of Homo Erectus which occurred earlier and is generally agreed upon (though the specifics are still widely debated, thus the paper).

Multiregional Evolution posits that modern Humans evolved directly from these distributed pockets of Homo Erectus, while the competing Out of Africa theory suggests that anatomically modern humans evolved once in Africa and then spread to the rest of the world, outcompeting the prior hominoid species as they went.

My understanding is that the MRE hypothesis was largely discarded in favor of Out of Africa based on genetic data in the early 00s. Studies show that all humans share mitochondrial DNA (mtDNA), Y-chromosome DNA, and autosomal DNA ancestors which is not what you'd expect if humans evolved separately multiple times.

The big compromise of the model which has emerged in recent years is Out of Africa with Admixture. Basically saying that Homo Sapiens didn't just outcompete other local hominoid branches but interbred with them to a meaningful extent. This was originally not well supported but there's a growing body of work to support it and I believe the academic community is coming around. You see this most strongly with Neanderthals in Europe, for instance.

AlotOfReading• 2 years ago

There's no compromise model. Admixture with archaic hominins is widely accepted these days, but it's simply a small asterisk on top of OOA for essentially everyone outside China (where MRE remains popular).

CSMastermind3• 2 years ago

My understanding is that there were multiple waves of migration out of Africa, the first being around 2 million years ago.

The first waves were not of anatomically modern humans but Homo erectus and its contemporaries up into modern Georgia, then East into China, then eventually into Indonesia.

Then around 1 million years later, there was another migration of Homo erectus out into Southeast Asia along the coast through India and eventually into Vietnam and Malaysia.

This second migration seems to be what the paper is referencing and definitely the one that, at least 10 years ago, the anthropology community had the least confidence in. My understanding, again dated by a decade now, is that it was uncertain if hominoids entered Europe at that point or not.

Neanderthals left Africa 500,000 years later into Europe while Denisovans left at the same time into Asia ending up concentrated in Serbia.

Modern Humans don't show up until another 400,000 years after that (around 100,000 years ago) and don't leave Africa until 70,000 years ago. They also left Africa in multiple waves with 5 main ones spreading out across the globe.

KoftaBob• 2 years ago

They also left Africa in multiple waves with 5 main ones spreading out across the globe.

Where can I learn more about these 5 waves?

defrost3• 2 years ago

The number of waves and the granulation of waves isn't set in stone as such; there's a pretty decent broad view from afar regarding early human, and a great deal of finer detail still up for debate.

Reading through

https://en.wikipedia.org/wiki/Early_human_migrations

top to bottom will give a good enough first overview and an idea of where uncertainly lies and references to chase for further debate.

Eg: Currently there's some hot debate on whether parts of the "coastal migration" to Australasia took place over inland routes within South East Asia - that's a matter of old coast lines at the time, inland cave shelters with datable bones, and a sparse game of chronological joind the estimated dots in space and time - it gets technical.

mihaic• 2 years ago

Who We Are and How We Got Here by David Reich is I think a great book if you're interested in human migrations.

prawn• 2 years ago

I always liked this map that helped convey the possible pathways that spread humans from the main wave: https://en.wikipedia.org/wiki/File:World_map_of_prehistoric_...

verisimi• 2 years ago

Where can I learn more about these 5 waves?

You simply go back 2 million years and verify it yourself.

Alternatively, read it on wikipedia.

smnc• 2 years ago

while Denisovans left at the same time into Asia ending up concentrated in Serbia.

You probably meant to write Siberia.

CSMastermind3• 2 years ago

I did! Thank you.

lkrubner• 2 years ago

"Neanderthals left Africa 500,000 years later into Europe while Denisovans left at the same time"

For most of the past 25 years there was a theory that Neanderthals and Denisovans were descended from Homo Heidelbergensis, in which case Neanderthals and Denisovans probably evolved in Europe or the Middle East. The oldest known Homo Heidelbergensis is maybe 1 millions years old and most of the early Homo Heidelbergensis were found in Europe, so it is assumed that Homo Heidelbergensis evolved in Europe.

Recently, many have argued that Neanderthals and Denisovans were not descended from Homo Heidelbergensis, but instead from some other species of humans that has not yet been discovered. But it remains likely that Neanderthals and Denisovans evolved outside of Africa.

dghughes• 2 years ago

I can understand why ancient people would migrate west or east since the sun movement; rise or set would draw them there. What would spur people to move north or south other than hunting animals? If animals I'd expect north for a bit then south again (or vice versa below the equator).

mikhailfranco8• 2 years ago

I think my favorite strange factoid of human migration, is that Madagascar was (majority) settled from Borneo, not from Africa.

https://theconversation.com/how-the-banjar-people-of-borneo-...

https://en.wikipedia.org/wiki/History_of_Madagascar

includes the nice map:

https://en.wikipedia.org/wiki/History_of_Madagascar#/media/F...

BSOhealth• 2 years ago

Another interesting way to headline this is, Madagascar was the last place on earth to be settled, despite being right next to the first

dagoodnews• 2 years ago

Madagascar was the last place on earth to be settled

I believe that honor belongs to antarctica.

https://en.wikipedia.org/wiki/Colonization_of_Antarctica

mikhailfranco8• 2 years ago

Apart from Antarctica - New Zealand seems to be the last large landmass to be settled in 1200 AD (see map linked above).

But even in NZ, there are some inconclusive claims of previous civilization. The gov has banned access and excavations to verify or refute the claims. One example:

https://www.ancient-origins.net/ancient-places-oceania/kaima...

willmadden• 2 years ago

The honest interpretation of DNA evidence is that Cro-Magnon man mixed with the Neanderthals and Denisovans and then likely migrated into Africa, not out of it.

lebean• 2 years ago

And today it's driven by bad policy. Heyoo!

hnbad3• 2 years ago

Well, exploiting their resources for hundreds of years, then granting them "independence" while keeping a financial and economic stranglehold along with ill-fated financial "aid" projects offering cheap loans to build an export-focused penny economy and bringing in foreign companies rather than focusing on local sustainability and then bombing them or assassinating their leaders (or installing dictators) when you don't like the direction they're headed is a bit more complex than "bad policy".

Though to be fair, a lot of that also applies to South America and the Middle East.

misja111• 2 years ago

If temperatures dropped during the onset of the Pleistocene. Then why would humans have migrated away from Africa to Europe? It seems to me that in Europe it would be even more cold.

raffraffraff• 2 years ago

No idea, wild guesses incoming...

Early humans (or proto humans) might not know that it was warmer in the south or colder in the north, across vast areas. Some days are colder than others, even if you stand still. Add to this the effect of changing seasons through a year, some years being colder than others anyway. You could migrate North slowly as Winter turned to Summer. Then camp for the winter and migrate back. And their migrations might have moved slightly further north year by year. They would have to track temperatures from winter to winter, without a calendar, thermometer, notebook, pen, map, compass and perhaps even an enquiring mind.

I don't think that humans decided to move to a colder place or even realised that their movement was taking them somewhere cooler.

Ultimately, they would have followed their food wherever it went. You might be better off asking why a caribou herd migrated further North. Who knows? Better grass? Less competition? Fewer predators? Lower sea level opening a path to new grassland?

hnbad3• 2 years ago

The article suggests that this may have in part been due to the falling sea levels. Europe extended much further to the North to the point that Great Britain was surrounded by land. The gap between Europe and Africa was also close enough to allow for much easier crossings.

Early humans were likely always somewhat migratory animals as there was no way to preserve food for longer periods - grain agriculture was what allowed for permanent settlements and bureaucracy (i.e. long-term planning and resource allocation). They may have tended to the local vegetation because they would likely return in the future but it seems obvious that they'd also be on the lookout for new places while keeping track of known good spots in the past - even elephants travel between distant "watering holes".

In other words: it wasn't the cold that was the problem, it was the availability of resources, i.e. food. If the accessible parts of Europe had sufficient food to make them attractive for foraging and hunting, humans would eventually make the crossing and decide to stay and eventually move further into the continent. Note that we're not talking about events that happened over human lifetimes - the North Sea didn't drain overnight.

Maybe a visual aid helps. Try to find Europe on this map. Hint: look for mountains that look like familiar coastlines: https://en.wikipedia.org/wiki/File:Global_sea_levels_during_...

photochemsyn• 2 years ago

If human populations expanded at a slow rate of 20 miles per 100 years, then from 1.1 million to 0.9 million years ago (200,000 years) they would have travelled 40,000 miles.

This is indeed migration, but not as we think of it today. Such migrations could have been blocked by oceans or high mountains, and were essentially like animal migrations.

pfdietz3• 2 years ago

The notion that bad environment caused migration seems very dubious.

What causes migration is the ability to migrate: that is, that new areas have environments in which the organisms can survive and reproduce. Decline in habitability of previously occupied regions is neither necessary nor useful for this to happen.

defrost3• 2 years ago

The assertion is not that (all) migration is caused by environmental changes.

The claim is that environmental changes can drive migration (causing it to start, or to accelerate migration already happening for other reasons).

Specifically that a particular wave of migration out of part of Africa was pushed along by glaciation 9,000 years ago.

This is not a dubious notion; it seems certain that either environment changes drove migration out of Doggerland or that humans in Doggerland drowned.

Decline in habitability of previously occupied regions is

barely half the full picture; glaciation can open land bridges allowing increased access to new destinations which are more habitable.

pfdietz3• 2 years ago

I'm not disputing glaciation had an effect, it's just that a decline in habitability of where the hominids were living was not an effect that can be pointed to as a cause of migration. If anything, there should be more outmigration from highly habitable areas than from less habitable ones. That's because any area quickly fills up to the limit of its carrying capacity, and the highly habitable area will then have more inhabitants to diffuse out.

Migration out of Africa may have been driven by first glaciation of Pleistocene

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