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Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

sciencemag.org

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Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#61

Post by bryanrasmussen »

mytailorisrich wrote: post #57
IIAOPSW wrote: post #53

Earlier quoted context omitted.

I'm not so sure. Even with modern transportation technologies, the price of moving is still high enough that the number of single ethnicity births will generally outpace multi-ethnicity births. I don't think we have nearly enough airplanes and jet fuel to homogenize the genetics of ~8 billion people. But I also haven't run those numbers so feel free to change my mind.

A few instances of "new blood" in a population can be enough because it will then spread over generations. In many countries the proportion of foreign-born is >10%, so the mixing is quite intense in terms of evolutionary time scales. If that continues for a few hundreds of years, diversity will have significantly reduced. Indeed, some suggest that e.g. skin colour may largely homogenise within a thousand years. A tho…

So Science Fiction Story time, immortal finds it difficult to blend into future less diverse population because their personal characteristics are no longer widely enough found that they can just wander off and go live somewhere else.

The last X is an easy target.

on edit: for anyone unfamiliar with this trope, see https://en.wikipedia.org/wiki/Requiem_for_Methuselah or https://en.wikipedia.org/wiki/The_Man_from_Earth (both written by Jerome Bixby, but many other examples by Neil Gaiman, etc. available) for easy clarification. One of the common ideas of the trope is that an immortal sooner or later becomes problematic to have in one place, they must wander of people will attempt to experiment on them to figure out the secret of immortality. Of course the second bit of the trope is the wandering immortal leave traces, and more intense searchers after immortality will follow them and attempt capture. If diversity decreases in the future based on present trends the story then becomes that it becomes increasingly difficult for the wandering immortal to wander without everyone being aware of them.

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#62

Post by hobby-coder-guy »

bryanrasmussen wrote: post #61
mytailorisrich wrote: post #57

Earlier quoted context omitted.

A few instances of "new blood" in a population can be enough because it will then spread over generations. In many countries the proportion of foreign-born is >10%, so the mixing is quite intense in terms of evolutionary time scales. If that continues for a few hundreds of years, diversity will have significantly reduced. Indeed, some suggest that e.g. skin colour may largely homogenise within a thousand years. A tho…

So Science Fiction Story time, immortal finds it difficult to blend into future less diverse population because their personal characteristics are no longer widely enough found that they can just wander off and go live somewhere else. The last X is an easy target. on edit: for anyone unfamiliar with this trope, see https://en.wikipedia.org/wiki/Requiem_for_Methuselah or https://en.wikipedia.org/wiki/The_Man_from_Eart…

?

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#63

Post by [deleted] »

chmod775 wrote: post #17
thaumasiotes wrote: post #9

Earlier quoted context omitted.

> but for Homo sapiens that "other group" would be of a different species and we thus we shouldn't be able to produce fertile offspring with them. That's one definition of "species" (specifically, it's "the biological species concept"), but like all the other definitions, it doesn't work and does not correspond to most usage of the term. You can read modern genetic work discussing how homo sapiens interbred with homi…

>You can also observe how easily different species interbreed today, like wolves (canis lupus, obligatory pack animals) and coyotes (canis latrans, solitary). Their taxonomy predates the more modern biological classification systems though. Things have been reclassified before and I expect they will be again. [A bit of a rant:] Any classification system that can't tell you something about the objects it classifies is…

[deleted]

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#64

Post by sradman »

The paper Neanderthal-Denisovan ancestors interbred with a distantly related hominin [1] suggests a simple model of hominid population movement

> ...which involves only three expansions of humans from Africa into Eurasia: an expansion of early Homo at about 1.9 Ma ago, an expansion of neandersovans at about 700 ka ago, and an expansion of modern humans at about 50 ka ago.

The “early Homo” or “superarchaics” are H. erectus and their DNA contribution is inferred since no sequences have yet been extracted. “Neandersovans” is the common ancestor of European Neanderthals and Asian Denisovans.

Interbreeding occurred in Eurasia after the second and third expansion.

[1] https://advances.sciencemag.org/content/6/8/eaay5483

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#65

Post by tsimionescu »

Ygg2 wrote: post #59
tsimionescu wrote: post #47

Earlier quoted context omitted.

Given that we have absolutely no idea what other biological systems could look like, what you're saying seems extremely likely, but not an absolute certainty.

It's near certainty. I mean it's not absolutely certain that your nearest pencil won't transform into Jesus and tell you the message that will unite all of humanity. I kinda doubt you would entertain it though.

Yes, true.

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#66

Post by beowulfey »

chmod775 wrote: post #5
dfischer wrote: post #3

Interesting in the limelight of pandemics in regards to the closing paragraph: > Today, H. sapiens doesn’t have the possibility of quickly grabbing a load of diversity by mating with another group: For perhaps the first time in our history, we’re the only humans on the planet. It’s another reason to miss our extinct cousins, says population geneticist Carina Schlebusch of Uppsala University. “To have such a large den…

This sentence doesn't make any sense: "H. sapiens doesn’t have the possibility of quickly grabbing a load of diversity by mating with another group". It would make sense if she specifically referred to Homo sapiens sapiens, but for Homo sapiens that "other group" would be of a different species and we thus we shouldn't be able to produce fertile offspring with them. Also Homo sapiens sapiens have plenty of genetic di…

So the definition of species being “can’t interbreed” is correct, but it doesn’t have to be a physical or biological inability to interbreed—-species can arise by being geographically separated, and merge into a new species if they eventually meet. In the same vein, two species can split from a single one if something happens to isolate a subset of a single species.

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#67

Post by enkid »

mytailorisrich wrote: post #49
dfischer wrote: post #3

Interesting in the limelight of pandemics in regards to the closing paragraph: > Today, H. sapiens doesn’t have the possibility of quickly grabbing a load of diversity by mating with another group: For perhaps the first time in our history, we’re the only humans on the planet. It’s another reason to miss our extinct cousins, says population geneticist Carina Schlebusch of Uppsala University. “To have such a large den…

Even as the single human species we used to be spread into isolated groups, that's why different populations have specificities (e.g. skin colour, but also other adaptations). Now that we have such a huge and interconnected population diversity will fade and adaptation will slow.

I don't think that genetic diversity will necessarily slow under those conditions. Genetic differences between people are already dominated by individual genetic differences over group genetic differences. Our diversity is more about us as individuals than as a collection of groups. Why, then, would the mixing of groups decrease diversity? I would think it would increase it.

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#68

Post by sdfqasdghj2 »

autokad wrote: post #25
dragonwriter wrote: post #16

Earlier quoted context omitted.

> Covid is comparable to flu with a higher mortality rate. So, like 1918 pandemic flu?

the 1918 spanish flu death rate was around 20%. It was only in March 2020 after covid19 was mainstream news it got edited in Wikipedia to show 2% (not sure if that's changed by now), you can check the edit history. But in short, in 1918, there were coffin shortages, compared to the toilet paper shortages with covid19. covid19 and the Spanish flu are not even in the same weight class, not even a little bit, whereas ye…

The big problem with comparing with flu is that many people think that their colds are "flu". This means they think of flu as being 3 days feeling a bit rubbish. In reality influenza is quite nasty and involves at least a week of being very sick.

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#69

Post by enkid »

Ygg2 wrote: post #29
chmod775 wrote: post #5

Earlier quoted context omitted.

This sentence doesn't make any sense: "H. sapiens doesn’t have the possibility of quickly grabbing a load of diversity by mating with another group". It would make sense if she specifically referred to Homo sapiens sapiens, but for Homo sapiens that "other group" would be of a different species and we thus we shouldn't be able to produce fertile offspring with them. Also Homo sapiens sapiens have plenty of genetic di…

You're overlooking the fact that even if easily breedable pool of foreign species existed along H. sapiens, given enough time they would either be purged or become common ancestors to everyone by now. Since they were purged and exist as remnants in individuals' DNA.

If they are remanants in people's DNA, they did become common ancestors, no? Everyone's family tree collapses to the same individuals at 5500 BC, after the other humans went extinct.(1) That means we are all descended from non Homo Sapiens humans. What I'm trying to say is that they were not "purged," we are their descendants. We got most of our genetic material from the Homo Sapiens side, but there is continuity with the other species as well.

(1) https://www.scientificamerican.com/article/humans-are-all-mo...

Re: Mysterious ‘super-archaic’ populations had multiple trysts with human ancestors

#70

Post by Metacelsus »

dfischer wrote: post #3

Interesting in the limelight of pandemics in regards to the closing paragraph: > Today, H. sapiens doesn’t have the possibility of quickly grabbing a load of diversity by mating with another group: For perhaps the first time in our history, we’re the only humans on the planet. It’s another reason to miss our extinct cousins, says population geneticist Carina Schlebusch of Uppsala University. “To have such a large den…

This is why we need to do large-scale human gene editing.
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