Oldest human genomes reveal how a small group burst out of Africa(nytimes.com)
nytimes.com
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
96 comments
https://archive.ph/WLcdD
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.
>"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.
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.
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?
Humans were nomadic before agriculture so they would have been moving all the time anyway. There would have been no settling down.
It’s more likely competitive pressure forced them to expand out further because to a small group, even a small conflict with a neighboring tribe that costs them a few of their fittest members would be particularly traumatic and risky. It’s just easier and safer to migrate.
Archaic humans made it out to South East Asia over a million years ago back when the sea hadn’t even risen to form the major islands like Indonesia. Migration is in our DNA.
It’s more likely competitive pressure forced them to expand out further because to a small group, even a small conflict with a neighboring tribe that costs them a few of their fittest members would be particularly traumatic and risky. It’s just easier and safer to migrate.
Archaic humans made it out to South East Asia over a million years ago back when the sea hadn’t even risen to form the major islands like Indonesia. Migration is in our DNA.
Both processes could coexist, right? I could see myself waking up one day and saying "what's the farthest we can get to? maybe there are amazing things at the end of the journey"
I’m not 100% clear on what the two processes are. In particular, early humans already were pretty mobile. So they’d be going from place to place, hunting as they go. Maybe following some migratory animals. If you got wanderlust, I guess you’d only make it a couple days before you ran out of food, so maybe some dozens of miles, and then you are back to doing typical human stuff, right?
it can also be stupid politics/religion: "your village is the reason for our famine, your entire village is banned from here. you will walk until you see the mountains and until you no longer see them behind you" ... next thing you know, you're in europe or asia.
They where all nomadics, so the concept of a village did not exist yet. It was more like family related moving groups, or maybe "clans". That said, at an individual level there was probably a concept of people exchange when meeting another group, or banning of an individual.
yeah, can replace "village" with "group of people" like families or clans. Basically just 'we blame you for our problems so you need to leave' type of situation.
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.
It doesn't seem all that improbable that humans or close ancestors had colonized other parts of the world for thousands of years only to die off due to climate change/disease/other factors about 40,000 years ago when they had to start all over again. Or maybe the ancestors colonized it and the extinction event was Homo Sapiens out of Africa, although in this case you would expect more DNA mixing. It seems more likely that the ancestors died out for whatever reason and the humans moved into their habitats to refill that ecological niche.
I don't see how you could say that's more likely without evidence, lack significant gaps in archaelogical finds between eras of human presence in a region.
And their failure doesn't mean they're completely absent from our genome.
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
One question raised by a researcher in the article:
see:
(2016) https://www.abc.net.au/news/science/2016-09-22/world-first-s...
(2017) https://www.nature.com/articles/nature21416
etc.
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.
see:
(2016) https://www.abc.net.au/news/science/2016-09-22/world-first-s...
(2017) https://www.nature.com/articles/nature21416
etc.
The actual results in papers like these (both the paper in question and the ones you refer to) are typically of the form: "We sequenced these genomes. Then we took the noisy data, made a lot of assumptions, and applied statistical magic to estimate that the populations split approximately X generations ago. We interpret that as Y years ago." Everything beyond that is interpretation, not the result.
Such results are inherently noisy and subject to assumptions. The further back in history you go, the less accurate and reliable the results will be. Ancient DNA comes with its own issues and assumptions, but it helps with the accuracy of the results. Instead of trying to infer something that happened thousands of generations ago, you may now be only hundreds or even tens of generations from the split.
The clearest way forward would be sequencing Aboriginal Australian DNA from tens of thousands of years ago. Then you could get a more accurate estimate for the split between that population and other sequenced ancient populations.
Such results are inherently noisy and subject to assumptions. The further back in history you go, the less accurate and reliable the results will be. Ancient DNA comes with its own issues and assumptions, but it helps with the accuracy of the results. Instead of trying to infer something that happened thousands of generations ago, you may now be only hundreds or even tens of generations from the split.
The clearest way forward would be sequencing Aboriginal Australian DNA from tens of thousands of years ago. Then you could get a more accurate estimate for the split between that population and other sequenced ancient populations.
my own theory. Depending on cyclical geography limitations, humans have been forever moving out of Africa sporadically, going way back to Neanderthals and possibly even before. It wasn't just one wave, it was multiple waves from time to time.
The people that ended up in Australia were some of the earliest anatomically modern humans that successfully made the trip out and for some reason or the other were not really able to colonize Europe/Asia and kept venturing south until they ended up in Australia
Other later waves probably made it to the middle east and went back. Some made it a bit into Europe and some of asia. But it wasn't until relatively recent times, that we got waves that finally got a foothold in Europe/Asia and eventually outlasted other homo species that had dominated those areas for a 100,000 years.
I am not an anthropologist. I can't prove anything I wrote. I am just using my own common sense and the evidence that has so far been published.
The people that ended up in Australia were some of the earliest anatomically modern humans that successfully made the trip out and for some reason or the other were not really able to colonize Europe/Asia and kept venturing south until they ended up in Australia
Other later waves probably made it to the middle east and went back. Some made it a bit into Europe and some of asia. But it wasn't until relatively recent times, that we got waves that finally got a foothold in Europe/Asia and eventually outlasted other homo species that had dominated those areas for a 100,000 years.
I am not an anthropologist. I can't prove anything I wrote. I am just using my own common sense and the evidence that has so far been published.
> and for some reason or the other were not really able to colonize Europe/Asia and kept venturing south until they ended up in Australia
Any people that did settle in Europe to the north during that first pass through further south some 70K years ago very likely were pushed back by the worsening conditions preceding the advance of the Last Glacial Maximum (dry very dusty air, poor vegetation .. and later ice everywhere).
Following the path of best land with least resistance led to following the tropics mostly by land, consistent year round conditions, no winters to store food for, etc.
Any people that did settle in Europe to the north during that first pass through further south some 70K years ago very likely were pushed back by the worsening conditions preceding the advance of the Last Glacial Maximum (dry very dusty air, poor vegetation .. and later ice everywhere).
Following the path of best land with least resistance led to following the tropics mostly by land, consistent year round conditions, no winters to store food for, etc.
I wonder if this migrate-and-survive is a "great filter" that organisms must do in order to grow. The same thing will likely happen to space colonists, many will go, but only a few will survive.
The dating of the fossils is quite secure. So in this dimension all is good. The DNA sequence is as good given the number of closely related individuals.
Your comments do not apply with any force to this particular study.
Your comments do not apply with any force to this particular study.
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.
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.
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.
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.
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.
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?)
> “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?)
With recent genetics proofs than early human, did have interbreed with at last Neanderthals and Denisovans, this is now indeed more "true" than the "Only from Africa" hypothesis.
Thad said:
- as the time of the emergence of both theories there where no genetics evidences yet in one way or another
- the interbreeding with this two other species is still very small, (less than 5% of the actual genes). There is still no evidences for other important species like Homo erectus (or hedelbergensis, or florensis, etc.)
The truth maybe in between: a major pool of gene from Africa, but with small local parts from all over the ancient world.
The big remaining question is:
- Did sapiens and erectus had babies? And if yes, then, what was the results (Denisova or something else ?).
Thad said:
- as the time of the emergence of both theories there where no genetics evidences yet in one way or another
- the interbreeding with this two other species is still very small, (less than 5% of the actual genes). There is still no evidences for other important species like Homo erectus (or hedelbergensis, or florensis, etc.)
The truth maybe in between: a major pool of gene from Africa, but with small local parts from all over the ancient world.
The big remaining question is:
- Did sapiens and erectus had babies? And if yes, then, what was the results (Denisova or something else ?).
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!
The Steppes are a natural barrier between East and West until the point where technology caught up to make it passable.
Well we have human ancestors on both sides of that barrier, so clearly it's not insurmountable in absolute terms, either from taking the souther route or migrating with herds or some other thing I haven't thought about (I'm not sure waterways would get you the whole way, but it'd get you from the urals to either side). The question is why this would pose a barrier to some populations and not others.
EDIT: also, I forgot that a lot of the steppe is forested. Surely that would make it significantly less of a barrier.
EDIT: also, I forgot that a lot of the steppe is forested. Surely that would make it significantly less of a barrier.
No terrain is insurmountable considering chance and a hundred thousand years. The question is how likely will any given group be able to pass through and flourish on the other side? We have many examples of isolated human populations on islands or across inhospitable barriers that it shouldn't be surprising to find isolated populations on either side of the Eurasian continent. Off the top of my head, Australian aboriginals, the Andamanese and New Guinea islanders are examples of isolated populations with essentially no gene flow between larger populations over 10s of thousands of years. Even the fact that we talk about how many populations ultimately left Africa in prehistory implies there must have been some barrier to overcome.
> also, I forgot that a lot of the steppe is forested. Surely that would make it significantly less of a barrier.
Also consider the ice age and how that affected the degree to which Eurasia was hospitable.
> also, I forgot that a lot of the steppe is forested. Surely that would make it significantly less of a barrier.
Also consider the ice age and how that affected the degree to which Eurasia was hospitable.
What exactly do you mean by the Steppes? I thought this referred to a grassland region so can't see how it would constitute a barrier.
Yes, its a continent-spanning grassland. But humans don't eat grass. Sourcing water is also a problem. It's inhospitable to humans without some reliable means of turning grass into nutrition. If we're talking about early humans it would be a significant barrier.
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?
Does Zimmer know something that I do not? Or David Reich?
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
https://www.cell.com/cell/fulltext/S0092-8674(20)30059-3 https://www.pnas.org/doi/full/10.1073/pnas.1313787111
Lovely paper but their analysis did not include either KhoiSan or Central African hunter-gather Pygmy populations. They used the 1000 Genomes project.
I read a bit more. There definitely was introgression of West Eurasian populations into East Africa and Sudan than percolated into West Africans to the tune of about 15 million base-pairs of sequence tagged as Neanderthal. Not sure we have values for how much Yoruban ancestry is now embedded in Mbuti genomes, but it is small. So the flow of Neanderthal genomes into Central African hunter-gathers will sub-decimal dust.
But having said all that, maybe the key point Zimmer is making IS a good generalization.
But having said all that, maybe the key point Zimmer is making IS a good generalization.
I think it is a fair generalization at this point. Mbuti also have a ~6% West Eurasian admixture signal using an ancient (4.5kya) Ethiopian individual as reference, though Pickrell 2014 did not see it. Decimal dust, perhaps?
https://www.science.org/doi/10.1126/science.aad2879
The ghost admixture story(s) will turn out to be much more localized, I imagine.
The ghost admixture story(s) will turn out to be much more localized, I imagine.
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…
I guess it's to be expected that pop-sci is 10-15 years behind…
This doesn't account for shrinkage in the pool
Thank you!
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.
Would any evidence that contradicts the 'Out-of-Africa' dogma even get considered by Western scientists?
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
https://www.youtube.com/watch?v=Uj6skZIxPuI
https://www.razibkhan.com/p/out-of-africas-midlife-crisis
> 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.
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.
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.
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.
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.
> 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.
I think the current consensus is a fusion of the two stances, particularly as some of the changes have appeared to be too rapid to reflect population displacement, and genetics clearly indicate genetic admixture with varying distinguishing characteristics relevant to the region and timeperiod as opposed to straight displacement.
Unsatisfying, I know, but basically any firm position on either side has equally firm arguments against it.
I think the current consensus is a fusion of the two stances, particularly as some of the changes have appeared to be too rapid to reflect population displacement, and genetics clearly indicate genetic admixture with varying distinguishing characteristics relevant to the region and timeperiod as opposed to straight displacement.
Unsatisfying, I know, but basically any firm position on either side has equally firm arguments against it.
I had a recent discussion about this, will try to pull up the sources, but my understanding is displacement is the majoritarian current and cultural shift with same population very much a secondary that only applies in a minority of the cases
a lot of these admixture events show near total displacement of the y chromosome also
a lot of these admixture events show near total displacement of the y chromosome also
I'm not disbelieving your source entirely, but it seems a little ridiculous to assume population displacement across all pre-history (or undocumented history if you'd prefer that term). Particularly when modern populations are so genetically diverse.
For one example, the idea a single "sea people" were responsible for the shift from bronze age to iron age in the eastern mediterranean is nearly universally rejected at this point. The populations of the mediterranean seem to descend at least in part from the bronze-age populations of the area. However the economic and cultural impact of the same period undeniably transfused rapidly through the region as heavily demonstrated with the archaeological record.
Even in the case of neanderthals we didn't fully displace so much as mostly displace but also admixed. Same with denisovans, cro magnons, etc. Genetic testing of cro-magnons shows modern-day descendants, and not just in the matrilineal or patrilineal line (i.e. presumably indicating either descendants of rape or partial infertility, as is presumed in the case of neanderthals).
With the spread of agriculture (seed cultivation, husbandry, plow, etc) we also see a mixture of genetic and cultural transfusion. Ditto with the horse, except much more rapidly, and horse-based technology much slower. This is partially why there's a gradient of genetic similarity across europe rather than a "european" set of genes—and with the horse technology, we have the benefit of an archeological and in certain cases textual evidence of trade between northern europe and the rest of the world.
Now, some of this is a matter of quibbling over semantics—is it displacement or is it admixture? Understandable. But the cultural diffusion in the material record is undeniable regardless of which term you pick. I'm not so sure it's worth picking a primary cause rather than accepting the inherent messiness of the archeological and genetic record where, as in the case of neanderthals, there isn't very solid evidence of infertility demonstrating firmly that the migration was mostly, if not entirely, displacement, as presumably non-hss-mixed neanderthals are extinct.
For one example, the idea a single "sea people" were responsible for the shift from bronze age to iron age in the eastern mediterranean is nearly universally rejected at this point. The populations of the mediterranean seem to descend at least in part from the bronze-age populations of the area. However the economic and cultural impact of the same period undeniably transfused rapidly through the region as heavily demonstrated with the archaeological record.
Even in the case of neanderthals we didn't fully displace so much as mostly displace but also admixed. Same with denisovans, cro magnons, etc. Genetic testing of cro-magnons shows modern-day descendants, and not just in the matrilineal or patrilineal line (i.e. presumably indicating either descendants of rape or partial infertility, as is presumed in the case of neanderthals).
With the spread of agriculture (seed cultivation, husbandry, plow, etc) we also see a mixture of genetic and cultural transfusion. Ditto with the horse, except much more rapidly, and horse-based technology much slower. This is partially why there's a gradient of genetic similarity across europe rather than a "european" set of genes—and with the horse technology, we have the benefit of an archeological and in certain cases textual evidence of trade between northern europe and the rest of the world.
Now, some of this is a matter of quibbling over semantics—is it displacement or is it admixture? Understandable. But the cultural diffusion in the material record is undeniable regardless of which term you pick. I'm not so sure it's worth picking a primary cause rather than accepting the inherent messiness of the archeological and genetic record where, as in the case of neanderthals, there isn't very solid evidence of infertility demonstrating firmly that the migration was mostly, if not entirely, displacement, as presumably non-hss-mixed neanderthals are extinct.
>when modern populations are so genetically diverse.
Are they? Are there any studies that confirm that hypothesis?
My understanding[0][1][2][3][4][5][6] (there are plenty more references, but I assume you get the point) is that modern human populations are incredibly similar, and not very diverse at all. In fact, all humans are more genetically similar to each other than many other species are, including chimpanzees and wheat.
[0] https://www.science.org/content/article/how-we-lost-our-dive...
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC7115999/
[2] https://www.ashg.org/wp-content/uploads/2019/09/genetic-vari...
[3] https://www.scientificamerican.com/article/humans-are-doomed...
[4] https://bigthink.com/life/humans-are-less-genetically-divers...
[5] https://www.jstor.org/stable/41466860
[6] https://www.kqed.org/quest/474/explosive-hypothesis-about-hu...
Are they? Are there any studies that confirm that hypothesis?
My understanding[0][1][2][3][4][5][6] (there are plenty more references, but I assume you get the point) is that modern human populations are incredibly similar, and not very diverse at all. In fact, all humans are more genetically similar to each other than many other species are, including chimpanzees and wheat.
[0] https://www.science.org/content/article/how-we-lost-our-dive...
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC7115999/
[2] https://www.ashg.org/wp-content/uploads/2019/09/genetic-vari...
[3] https://www.scientificamerican.com/article/humans-are-doomed...
[4] https://bigthink.com/life/humans-are-less-genetically-divers...
[5] https://www.jstor.org/stable/41466860
[6] https://www.kqed.org/quest/474/explosive-hypothesis-about-hu...
> Are they? Are there any studies that confirm that hypothesis?
??? what is there to confirm? Why are you trying to spin an internal comparison as external? Indigenous populations tend to be more related to physically close indigenous populations than physically far apart indigenous populations. This is what I was referring to with the "genetic gradient". Comparing us to chimpanzees makes zero sense, let alone wheat, as we aren't trying to have sex with either, let alone "displace" them. I mean, hopefully not.
It's true that our diversity has lessened over time but this is "I don't see color" levels of delusion.
??? what is there to confirm? Why are you trying to spin an internal comparison as external? Indigenous populations tend to be more related to physically close indigenous populations than physically far apart indigenous populations. This is what I was referring to with the "genetic gradient". Comparing us to chimpanzees makes zero sense, let alone wheat, as we aren't trying to have sex with either, let alone "displace" them. I mean, hopefully not.
It's true that our diversity has lessened over time but this is "I don't see color" levels of delusion.
You said:
And I provided documentation to support that assertion.
I didn't even get into the genetic evidence that variation within human population groups is greater than the variation between such groups.
That you made some sort of assumption as to the reason for my assertion, is on you and not me.
I merely pointed out that your assertion is not supported by the genetic evidence. Full stop.
when modern populations are so genetically diverse.
And I provided documentation to support that assertion.
I didn't even get into the genetic evidence that variation within human population groups is greater than the variation between such groups.
That you made some sort of assumption as to the reason for my assertion, is on you and not me.
I merely pointed out that your assertion is not supported by the genetic evidence. Full stop.
I don't understand why you're using diversity in this comparative manner when I was clearly not. I was just pointing out there's a lot of genetically distinct humans and this genetic distinction follows geographic trends. It's your choice to interpret it as a comparison to other species and frankly I'm bewildered why you decided to take the conversation there.
>I don't understand why you're using diversity in this comparative manner when I was clearly not.
Clear to whom? You? I'm sure it was. To anyone else? Not so much.
I read your words "I'm not disbelieving your source entirely, but it seems a little ridiculous to assume population displacement across all pre-history (or undocumented history if you'd prefer that term). Particularly when modern populations are so genetically diverse."
And you made the claim that "modern populations are so genetically diverse." Did someone commandeer your account or force you to write that at gunpoint?
If not, it was you who referenced genetic diversity.
Or does "modern populations are so genetically diverse" mean something other than "modern populations are so genetically diverse?"
As for my response, my apologies. Clearly I did not communicate my thoughts effectively. I will attempt to do so again.
>I was just pointing out there's a lot of genetically distinct humans and this genetic distinction follows geographic trends.
And your assertion is flat wrong. In fact, modern humans have very little genetic diversity, measured any way you'd like.
What's more, the human populations with the most genetic diversity are those native to Southern and Eastern Africa.
Populations everywhere else in the world are incredibly genetically similar to each other.
So much so that the differences within geographical population groups are greater than those between such groups.
As to my references to chimpanzees and wheat, that was just to point up that humans -- regardless of geographical population -- are not genetically diverse at all.
And that's it. Humans, regardless of geographic population, are remarkably similar in genetic make up. Humans are not, as you asserted, "so genetically diverse." Exactly the opposite.
Do you understand now? If not, I obviously need to learn to write more clearly.
Clear to whom? You? I'm sure it was. To anyone else? Not so much.
I read your words "I'm not disbelieving your source entirely, but it seems a little ridiculous to assume population displacement across all pre-history (or undocumented history if you'd prefer that term). Particularly when modern populations are so genetically diverse."
And you made the claim that "modern populations are so genetically diverse." Did someone commandeer your account or force you to write that at gunpoint?
If not, it was you who referenced genetic diversity.
Or does "modern populations are so genetically diverse" mean something other than "modern populations are so genetically diverse?"
As for my response, my apologies. Clearly I did not communicate my thoughts effectively. I will attempt to do so again.
>I was just pointing out there's a lot of genetically distinct humans and this genetic distinction follows geographic trends.
And your assertion is flat wrong. In fact, modern humans have very little genetic diversity, measured any way you'd like.
What's more, the human populations with the most genetic diversity are those native to Southern and Eastern Africa.
Populations everywhere else in the world are incredibly genetically similar to each other.
So much so that the differences within geographical population groups are greater than those between such groups.
As to my references to chimpanzees and wheat, that was just to point up that humans -- regardless of geographical population -- are not genetically diverse at all.
And that's it. Humans, regardless of geographic population, are remarkably similar in genetic make up. Humans are not, as you asserted, "so genetically diverse." Exactly the opposite.
Do you understand now? If not, I obviously need to learn to write more clearly.
Diversity does not imply comparison to other species. I'm still struggling to figure out how that entered the conversation. We are either diverse or not, and we are not clones, so we are diverse.
This is one of the most unpleasant conversations in recent memory. Haven't you ever heard of good faith conversation? Jesus. Absolutely rank vibes.
This is one of the most unpleasant conversations in recent memory. Haven't you ever heard of good faith conversation? Jesus. Absolutely rank vibes.
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.
I don't think it's some sort of conspiracy among scientists. A lot of the genetic sequencing techniques simply weren't possible until recently.
> 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.
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.
[deleted]
yes, see david reich
Yes.
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.
> 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.
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.
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.
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.
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.
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.
That assumes all evidence is equally easy to find and has been equally searched for.
Sort of but we're not talking about apes and monkeys here, it's placental mammals in general. So the evidence is overwhelming https://en.wikipedia.org/wiki/Mammals_of_Australia#Evolution...
If we got this wrong, most of paleontology is unreliable.
If we got this wrong, most of paleontology is unreliable.
It is not really up for debate. Haplogroups provide direct lineage and evidence for migration.
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.