Oldest human genomes reveal how a small group burst out of Africa

https://www.nytimes.com/2024/12/12/science/oldest-human-genomes-lrj-neanderthals.html

by diodorus • 2 years ago

99 70 2 years ago

nytimes.com

The-Old-Hacker• 2 years ago

https://archive.ph/WLcdD

eddyzh• 2 years ago

Makes a huge claim at the start.

"The huge gap between those ages could change our understanding about how humans spread across the world. If the ancestors of today’s non-Africans didn’t sweep across other continents until 47,000 years ago, then those older sites must have been occupied by earlier waves of humans who died off without passing down their DNA to the people now living in places like China and Australia."

But at the end gets a bit more balanced

"He Yu, a paleogeneticist at Peking University in Beijing who was not involved in either study, said that the mystery wouldn’t be solved until scientists find DNA in some of the ancient Asian fossils. “We still need early modern human genomes from Asia to really talk about Asia stories,” Dr. Yu said."

This puzzle is still missing key elements.

jl6• 2 years ago

It doesn’t seem like an outlandish claim that many waves of humans tried and failed to colonize the world, until one succeeded. I would find it harder to believe that the first to leave Africa got it right first time.

h0l0cube• 2 years ago

I think the claim is that earlier founders did colonize the world before the final group left and also colonized the world. Land bridges disappeared as the last ice age came to a close, making later attempts more difficult

defrost2• 2 years ago

One question raised by a researcher in the article:

    Dr. Skoglund also said it would be strange for non-African ancestors to have arisen about 47,000 years ago while modern humans in Asia and Australia dated back 100,000 years. The sites in question could have been incorrectly dated, he said, or people could have reached Asia and Australia that long ago, only to die out.

Doesn't mesh well with genetic studies from Australia that show a long history of relatively stable regionalism within Australia (with some still unresolved mixing from Denisovan ancestors.

see:

(2016) https://www.abc.net.au/news/science/2016-09-22/world-first-s...

(2017) https://www.nature.com/articles/nature21416

etc.

enkid3• 2 years ago

I don't think a group of people living somewhere for thousands of years would be "getting it wrong." You're embedding an assumption that evolution has been working toward an end goal of getting humans to spread globally, which isn't how evolution works.

shellfishgene• 2 years ago

I doubt it's correct to assume groups of humans in Africa one day decided to 'colonize' another place and walked thousands of kilometers to settle down elsewhere. It's probably more like a slow expansion (and reduction) of the settled area, no?

tetris11• 2 years ago

I think they just walked to other places as and when the climate changed. Some adapted and stayed, others moved the greener pastures. This slow and climate-driven process can hardly be described as colonization.

mapt• 2 years ago

It doesn't seem like an outlandish possibility.

That's distinct from making a claim, an assertion with supporting evidence.

To make a claim, we would want evidence, and the evidence here would be a genetic isolation (lack of chronological overlap, synonymous with lack of interbreeding) of ancient Asian humans from ancient African humans. This requires sequencing a lot of ancient Asian DNA, which seems not to have happened yet. We barely have a cohesive evidence supported grasp of Neanderthal interactions in Europe, but are gradually updating to support more and more absorption by interbreeding.

kspacewalk2• 2 years ago

And their failure doesn't mean they're completely absent from our genome.

miniwark3• 2 years ago

The view of the chinese researcher is in line with the Multiregional origin hypothesis of modern humans, where asian humans may partially come from asia. So his reply is not surprising.

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

Instead, the article follow the Out of Africa origin, and therefore did not explain the old chineses and autralian remains. The article try to explain this by saying than it's because this lines where extincts or than the dates are wrong, but this explanations are not very convincing.

bee_rider2• 2 years ago

What’s the most significant difference between the theories? The Wikipedia article says:

“The primary competing scientific hypothesis is currently recent African origin of modern humans, which proposes that modern humans arose as a new species in Africa around 100-200,000 years ago, moving out of Africa around 50-60,000 years ago to replace existing human species such as Homo erectus and the Neanderthals without interbreeding.[5][6][7][8] This differs from the multiregional hypothesis in that the multiregional model predicts interbreeding with preexisting local human populations in any such migration.”

But it is a somewhat weird quote in the Wikipedia article. They’ve got the whole thing in quotes with multiple citations (so it isn’t clear which citation the quote comes from), it isn’t attributed to anybody in particular, and it doesn’t seem to be a very accurate description of what I though the consensus was, at least. (It is widely believed that humans interbred with other hominids, right?)

PittleyDunkin8• 2 years ago

Am I missing something? Surely Europe is the same continent as Asia. Why wouldn't people just walk over? It seems reasonable to assume that if evidence exists on one side of the continent that it'd imply existence on the other side, too. If anything you'd need a theory why they failed to spread to formulate interesting discussion!

hackinthebochs3• 2 years ago

The Steppes are a natural barrier between East and West until the point where technology caught up to make it passable.

verisimi• 2 years ago

Such fictional assumptions...

Some 45,000 years ago, a tiny group of people — fewer than 1,000, all told — wandered the icy northern fringes of Europe.

Is it not possible that:

Some 45,000 years ago, a tiny group of people — fewer than 1,000, all told — wandered from sunny Australia into China, eventually reaching Africa and Europe?

It is impossible to tell the direction of travel.

pvg2• 2 years ago

Is it not possible that:

You'd be able to look for and find some evidence of their ancestors in Australia and you don't. But there's plenty of it in Africa.

Mountain_Skies2• 2 years ago

That assumes all evidence is equally easy to find and has been equally searched for.

pfannkuchen• 2 years ago

Africa is a static large site of habitation where the disappearance of 99% of evidence would still leave easily findable evidence. In GP’s scenario the habitation would be transient. Not really comparable.

reedf1• 2 years ago

It is not really up for debate. Haplogroups provide direct lineage and evidence for migration.

madaxe_again• 2 years ago

No. The genomes tell a pretty clear story. Should your hypothesis be correct, you would find haplogroups in the 45kya group descended from the 60kya austronesian group - but you do not. Rather, you find a most recent common ancestor before the 60kya group left Africa. As to why Africa - this is where ancestral hominids and the earliest known sapiens specimens have been found. While we have found cousins elsewhere, the evidence all points towards sapiens having emerged in Africa and spread elsewhere in successive waves.

When the hypothesis first appeared it was somewhat shocking to science, as the leading theory was some sort of parallel emergence of the races - but this was not grounded in the evidence being found in Africa at the time, and genetic evidence has since cemented this not as hypothesis, but well-established theory.

Cthulhu_• 2 years ago

I mean the fictional assumption is that it was a single group that wandered thousands of miles across continents; it was many generations that would settle somewhere, with subsequent generations migrating and spreading slowly, leaving behind traces like gravesites and settlements and the like; combine that with accurate dating and you can in fact tell the direction of travel.

vixen99• 2 years ago

Thank you!

dang• 2 years ago

We detached this comment from https://news.ycombinator.com/item?id=42430565 - your comment is just fine, there's nothing wrong with posting 'thank you'! But I wanted to pin the other link to the top, where real estate is expensive.

InfiniteLoup• 2 years ago

Would any evidence that contradicts the 'Out-of-Africa' dogma even get considered by Western scientists?

AndrewDucker• 2 years ago

Sure!

If you've encountered some then please share!

themgt• 2 years ago

The current "Out of Africa" is really not the same as what you might have learned 2-3 decades ago, despite the branding. David Reich is probably the leading researcher in this field and his description of our best guesses is highly nuanced and open to new data.

https://www.youtube.com/watch?v=Uj6skZIxPuI

https://www.razibkhan.com/p/out-of-africas-midlife-crisis

enkid3• 2 years ago

Out of Africa was fought by the majority of Western scientists during the early 20th century because of their pro-European biases. The reason its accepted is because the preponderance of evidence supports it.

Mountain_Skies2• 2 years ago

No doubt those biased Europeans felt their theory had the preponderance of evidence behind it. Funny how often the settled science is like that until the incumbent scientists die off rather than because better evidence was considered and adopted by science.

whimsicalism3• 2 years ago

there were also a lot of sociocultural changes coming out of the 60s/70s that changed the scientific conclusions we drew.

it used to be that we saw changes in ancient pottery and language and assumed that previous people had been replaced by new people with different techniques. then, in the 60s/70s it became popular that these changes didn’t mark population replacement but were more cultural spread and shift.

then genetics came around in the 90s and obliterated the cultural hypothesis and showed that in most of these cases it was largely population replacement.

there are lots of theories from the mid-20th that haven’t yet had their ‘genetics in the 90s’ moment.

drawkward• 2 years ago

Yes.

throw3288932• 2 years ago

from European fossils dating back 45,000 years

It is racist BS.

There were modern humans in Australia 60k years ago. Europe was also colonized way before that date. And some modern humans never left Africa.

PittleyDunkin8• 2 years ago

Would any evidence that contradicts the 'Out-of-Africa' dogma even get considered by Western scientists?

An easy example is that neanderthals, denisovans, h erectus, etc contribute via admixture to Homo Sapien Sapiens and well predate "out of africa" dates by hundreds of thousands of years. It's not a hard stretch to presume that other yet-unnamed branches of modern humans left earlier and admixed the same as the other named groups.

I don't think anyone is proposing an extant group of humans that don't have relatively recent roots in africa, though.

whimsicalism3• 2 years ago

yes, see david reich

zoombippy• 2 years ago

This doesn't account for shrinkage in the pool

erichocean• 2 years ago

It's amazing how out of date this conception is with the actual research.

I guess it's to be expected that pop-sci is 10-15 years behind…

robwwilliams4• 2 years ago

One error in this article by Zimmer that surprises me. He claims all modern humans have some admixture with Neaderthals but to the best of my knowledge this is not true of KhoiSan, Central African hunter gatherers, and several West African populations.

Does Zimmer know something that I do not? Or David Reich?

mmmrtl2• 2 years ago

Hasn't backmigration/Eurasian admixture post-introgression made that true? iirc reference bias artefactually made African genomes look like they had no Neanderthal segments.

https://www.cell.com/cell/fulltext/S0092-8674(20)30059-3 https://www.pnas.org/doi/full/10.1073/pnas.1313787111

robwwilliams4• 2 years ago

Lovely paper but their analysis did not include either KhoiSan or Central African hunter-gather Pygmy populations. They used the 1000 Genomes project.

Oldest human genomes reveal how a small group burst out of Africa

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