This is a genetic process that has led to the extinction of numerous human groups and can be observed today as being in the end stages with several large groups.
This is a melting pot archetype because it recurs over and over wherever two or more competing melting pots meet.
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"No evidence of Neanderthal mitochondrial DNA has been found in modern humans. This suggests that successful Neanderthal admixture happened in pairings with Neanderthal males and modern human females. Possible hypotheses are that Neanderthal mitochondrial DNA had detrimental mutations that led to the extinction of carriers, that the hybrid offspring of Neanderthal mothers were raised in Neanderthal groups and became extinct with them, or that female Neanderthals and male Sapiens did not produce fertile offspring."
https://en.m.wikipedia.org/wiki/Archaic_human_admixture_with_modern_humans.
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This archetypal process will be described as it pertained to Neanderthals, but modern parallels are clear.
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There are many theories about how and where modern humans originated. Most are variations of an early human migration from Africa, which is largely accurate but misleading.
https://en.m.wikipedia.org/wiki/Early_expansions_of_hominins_out_of_Africa
https://en.m.wikipedia.org/wiki/Recent_African_origin_of_modern_humans
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Current theories about Neanderthal extinction make a common mistake that often derails 'new' sciences.
Specifically they overuse new technologies at a speed that distracts from background common sense.
If a person has just purchased an expensive new car they might use it to drive places that are only a short walk away. Eventually they could see traveling as an extension of their car, rather than vice versa. Likewise if a scientist can hyper analyze a mountain of data it may further validate some conclusion, but ignores the fact that more data results in more opportunities to selectively interpret that data i.e., to follow an agenda. The scientist realizes he or she can 'go anywhere' with their data and they make the data follow them, instead of proceeding properly.
An example of the fruit of such misguided effort is the concept of 'clades', which at first seems to be a master tool to decipher various histories, but is missing an element of common sense.
"The common ancestor may be an individual, a population, a species (extinct or extant), and so on right up to a kingdom and further."
https://en.m.wikipedia.org/wiki/Clade
What makes the mistake hazardous is that it contains a visible 'truth' and an ignored 'contradictory truth' which are equal in weight, zero sum, but which cannot both be built upon. The initial 'payoff' of the theory leads a mass of 'aspiring scientists' into vesting in the 'truth' part of the equation. Like a seesaw whose movement is delayed, a person should anticipate that overweighting one side will have an effect.
Anybody falling victim to this fallacy will leave footprints of their mistakes in any science they touch.
There is a mountain of evidence indicating this sort of mistake has been made with respect to understanding many early human branches, and also enough evidence indicating that the popular version or continuation of this mistake will be much more costly than in the past.
Ultimately actual facts in this regard do not favor or disfavor any group, race, ethnicity etc. In terms of modern paradigms the most survivable human groups are currently a few African populations which are more isolated genetically from all other groups, but an equally valid competing, but not popular, not common, paradigm, would make those populations not the strongest, but the weakest. It all depends on whether a person prefers tribal survival or global homogeneity. The evidence seems to point to homogenization efforts being a mistake on a massive scale with costs which cannot be guessed.
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TLDR
The idea will be expanded below, but the TLDR version is that certain patterns of expansion or colonization create a sort of time bomb in the genetics of both the colonized and the colonizer. This leads to a problem which accelerates until one of the two has disappeared.
The issue overlaps with instincts, including intuition, and has a much more solid foundation than local politics.
In modern times people might imagine that there is some new progressive value that will limit the carnage, but any such 'new' progressiveness would have to be in the context of the problem, and there is no genuine progressiveness there. Instead there are social confusions that masquerade as solutions but in fact will make modern versions of the problem more severe.
In this context, the 'progressiveness' is actually a polarization into two camps, both primitive. One camp aligns behind one side, the other behind the other side. The modern 'controls' which some people fantasize might limit carnage i.e., nationalist political authority, will only be throwing gasoline on the fire.
Because many modern human groups have so much overlap amongst tribes, once the show starts there will be no way to limit its progression geographically. Actions and loyalties will shift based not on any conscious rational considerations, but on tribal 'awarenesses' that resonate with an individual based on his or her ancestral background. This is a massive blind spot in terms of global politics. As groups become aware of it they will coalesce and become more instinctively militant, again, without regard for geography in certain places.
The only solution, the same solution that has been used in the past and which failed the Neanderthals, is the proper type of reconsolidation within 'new' boundaries. In the case of modern variants of this archetype the proper consolidation has not happened.
Interestingly, the motives which would enable a solution are all 'higher' motives e.g. values etc, and the process seems to be a natural validation of some trusted philosophical principles.
So, again, the failure or success of any tribe in this situation today will boil down to military factors, as it has in the past, but almost all of the relevant 'military' factors are not generally considered as such. They are 'new' military factors that are not considered military variables in conventional war. For example a tribe that has become too diluted will lack certain senses that more stable tribes have, but will have corresponding overdevelopment of a past skill which will be of little use except as a crutch.
In practical terms, the current scenario favors Africa and Asia, and will be catastrophic for Western Europe.
The 'intelligent' solution would be a rapid retreat of the European colonial footprint in the furthest east reaches of initial human migrations i.e., the Americas. The more likely scenario is a 'digging in' of European investment in foreign areas, e.g. North America, followed by the natural processes that will be described.
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Below will be some relevant copy / pastes from Wikipedia along with excessive over explanation.
In Progress
"Neanderthal extinction began around 40,000 years ago in the Paleolithic Europe, after anatomically modern humans had reached the continent. This date, which is based on research published in Nature in 2014, is much earlier than previous estimates, and it was established through improved radio carbon dating methods analyzing 40 sites from Spain to Russia. The survey did not include sites in Asia, where Neanderthals may have survived longer. Evidence for continued Neanderthal presence in the Iberian Peninsula at 37,000 years ago was published in 2017. Hypotheses on the fate of the Neanderthals include violence from encroaching anatomically modern humans, parasites and pathogens, competitive replacement, competitive exclusion, extinction by interbreeding with early modern human populations, natural catastrophes, and failure or inability to adapt to climate change. It is unlikely that any one of these hypotheses is sufficient on its own; rather, multiple factors probably contributed to the demise of an already widely-dispersed population."
"In research published in Nature in 2014, an analysis of radiocarbon dates from forty Neanderthal sites from Spain to Russia found that the Neanderthals disappeared in Europe between 41,000 and 39,000 years ago with 95% probability. The study also found with the same probability that modern humans and Neanderthals overlapped in Europe for between 2,600 and 5,400 years. Modern humans reached Europe between 45,000 and 43,000 years ago. Improved radiocarbon dating published in 2015 indicates that Neanderthals disappeared around 40,000 years ago, which overturns older carbon dating which indicated that Neanderthals may have lived as recently as 24,000 years ago, including in refugia on the south coast of the Iberian peninsula such as Gorham's Cave. Zilhão et al. (2017) argue for pushing this date forward by some 3,000 years, to 37,000 years ago. Inter-stratification of Neanderthal and modern human remains has been suggested, but is disputed. Stone tools that have been proposed to be linked to Neanderthals have been found at Byzovya in the polar Urals, and dated to 31,000 to 34,000 years ago"
https://en.m.wikipedia.org/wiki/Neanderthal_extinction
"Studying the high-coverage female Vindija Neanderthal genome, Prüfer et al. (2017) identified several Neanderthal-derived gene variants, including those that affect levels of LDL cholesterol and vitamin D, and has influence on eating disorders, visceral fat accumulation, rheumatoid arthritis, schizophrenia, as well as the response to antipsychotic drugs."
"The early Upper Paleolithic burial remains of a modern human child from Abrigo do Lagar Velho (Portugal) features traits that indicate Neanderthal interbreeding with modern humans dispersing into Iberia. Considering the dating of the burial remains (24,500 years BP) and the persistence of Neanderthal traits long after the transitional period from a Neanderthal to a modern human population in Iberia (28,000–30,000 years BP), the child may have been a descendant of an already heavily admixed population."
"Manot 1, a partial calvarium of a modern human that was recently discovered at the Manot Cave (Western Galilee, Israel) and dated to 54.7±5.5 kyr BP, represents the first fossil evidence from the period when modern humans successfully migrated out of Africa and colonized Eurasia. It also provides the first fossil evidence that modern humans inhabited the southern Levant during the Middle to Upper Palaeolithic interface, contemporaneously with the Neanderthals and close to the probable interbreeding event. The morphological features suggest that the Manot population may be closely related to or given rise to the first modern humans who later successfully colonized Europe to establish early Upper Palaeolithic populations."
"By the early 2000s, the majority of scholars supported the Out of Africa hypothesis, according to which anatomically modern humans left Africa about 50,000 years ago and replaced Neanderthals with little or no interbreeding. Yet some scholars still argued for hybridisation with Neanderthals."
"The skeletal remains of an early modern human from the Tianyuan cave (near Zhoukoudian, China) of 40,000 years BP showed a Neanderthal contribution within the range of today's Eurasian modern humans, but it had no discernible Denisovan contribution. It is a distant relative to the ancestors of many Asian and Native American populations, but post-dated the divergence between Asians and Europeans. The lack of a Denisovan component in the Tianyuan individual suggests that the genetic contribution had been always scarce in the mainland."
"There are large genomic regions devoid of Denisovan-derived ancestry, partly explained by infertility of male hybrids, as suggested by the lower proportion of Denisovan-derived ancestry on X chromosomes and in genes that are expressed in the testes of modern humans."
"There is a presence of large genomic regions with strongly reduced Neanderthal contribution in modern humans due to negative selection, partly caused by hybrid male infertility. These large regions of low Neanderthal contribution were most-pronounced on the X chromosome—with fivefold lower Neanderthal ancestry compared to autosomes. They also contained relatively high numbers of genes specific to testes. This means that modern humans have relatively few Neanderthal genes that are located on the X chromosome or expressed in the testes, suggesting male infertility as a probable cause. It may be partly affected by hemizygosity of X chromosome genes in males."
"Tibetan people received an advantageous EGLN1 and EPAS1 gene variant, associated with hemoglobin concentration and response to hypoxia, for life at high altitudes from the Denisovans."
"From three candidate regions with introgression found by searching for unusual patterns of variations (showing deep haplotype divergence, unusual patterns of linkage disequilibrium, and small basal clade size) in 61 non-coding regions from two hunter-gatherer groups (Biaka Pygmies and San who have significant admixture) and one West African agricultural group (Mandinka, who don't have significant admixture), it is concluded that roughly 2% of the genetic material found in the Biaka Pygmies and San was inserted into the human genome approximately 35,000 years ago from archaic hominins that separated from the ancestors of the modern human lineage around 700,000 years ago. A survey for the introgressive haplotypes across many Sub-Saharan populations suggest that this admixture event happened with archaic hominins who once inhabited Central Africa."
"Researching high-coverage whole-genome sequences of fifteen Sub-Saharan hunter-gatherer males from three groups—five Pygmies (three Baka, a Bedzan, and a Bakola) from Cameroon, five Hadza from Tanzania, and five Sandawe from Tanzania—there are signs that the ancestors of the hunter-gatherers interbred with one or more archaic human populations, probably over 40,000 years ago. Analysis of putative introgressive haplotypes in the fifteen hunter-gatherer samples suggests that the archaic African population and modern humans diverged around 1.2 to 1.3 million years ago. Xu et al. (2017) analyzed the evolution of the Mucin 7 protein in the saliva of modern humans and found evidence that an unidentified ghost population of archaic African humans may have contributed DNA, with an estimated coalescence time to modern humans of about 4.5 million years BP, into the gene pool of modern Africans (e.g. African-American, African-Caribbean, Esan, Gambian, Luhya, Mende, and Yoruba people)."
"In February 2019, scientists discovered evidence, based on genetics studies using artificial intelligence (AI), that suggest the existence of an unknown human ancestor species, not Neanderthal, Denisovan or human hybrid (like Denny), in the genome of modern humans."
https://en.m.wikipedia.org/wiki/Archaic_human_admixture_with_modern_humans
"The multiregional hypothesis was first proposed in 1984, and then revised in 2003. In its revised form, it is similar to the Assimilation Model, which holds that modern humans originated in Africa and today share a predominant recent African origin, but have also absorbed small, geographically variable, degrees of admixture from other regional (archaic) hominin species."
"The finding that "Mitochondrial Eve" was relatively recent and African seemed to give the upper hand to the proponents of the Out of Africa hypothesis. But in 2002, Alan Templeton published a genetic analysis involving other loci in the genome as well, and this showed that some variants that are present in modern populations existed already in Asia hundreds of thousands of years ago. This meant that even if our male line (Y chromosome) and our female line (mitochondrial DNA) came out of Africa in the last 100,000 years or so, we have inherited other genes from populations that were already outside of Africa. Since this study other studies have been done using much more data (see Phylogeography)."
"More recent claims regarding continuity in skeletal morphology in Europe focus on fossils with both Neanderthal and modern anatomical traits, to provide evidence of interbreeding rather than replacement. Examples include the Lapedo child found in Portugal and the Oase 1 mandible from Peștera cu Oase, Romania, though the Lapedo child is disputed by some. Fossil remains of Graecopithecus found in Bulgaria and Greece have been dated to 7.2 million years ago, "several hundred thousand years older than the oldest known African hominid.""
"Initial analysis of Y chromosome DNA, which like mitochondrial DNA, is inherited from only one parent, was consistent with a recent African replacement model. However, the mitochondrial and Y chromosome data could not be explained by the same modern human expansion out of Africa; the Y chromosome expansion would have involved genetic mixing that retained regionally local mitochondrial lines. In addition, the Y chromosome data indicated a later expansion back into Africa from Asia, demonstrating that gene flow between regions was not unidirectional."
"An early analysis of 15 noncoding sites on the X chromosome found additional inconsistencies with the recent African replacement hypothesis. The analysis found a multimodal distribution of coalescence times to the most recent common ancestor for those sites, contrary to the predictions for recent African replacement; in particular, there were more coalescence times near 2 million years ago (mya) than expected, suggesting an ancient population split around the time humans first emerged from Africa as Homo erectus, rather than more recently as suggested by the mitochondrial data. While most of these X chromosome sites showed greater diversity in Africa, consistent with African origins, a few of the sites showed greater diversity in Asia rather than Africa. For four of the 15 gene sites that did show greater diversity in Africa, the sites' varying diversity by region could not be explained by simple expansion from Africa, as would be required by the recent African replacement hypothesis."
"Later analyses of X chromosome and autosomal DNA continued to find sites with deep coalescence times inconsistent with a single origin of modern humans, diversity patterns inconsistent with a recent expansion from Africa, or both. For example, analyses of a region of RRM2P4 (ribonucleotide reductase M2 subunit pseudogene 4) showed a coalescence time of about 2 Mya, with a clear root in Asia, while the MAPT locus at 17q21.31 is split into two deep genetic lineages, one of which is common in and largely confined to the present European population, suggesting inheritance from Neanderthals. In the case of the Microcephalin D allele, evidence for rapid recent expansion indicated introgression from an archaic population."
https://en.m.wikipedia.org/wiki/Multiregional_origin_of_modern_humans
https://en.m.wikipedia.org/wiki/Ghost_population
https://en.m.wikipedia.org/wiki/Neanderthal_extinction
https://en.m.wikipedia.org/wiki/Phylogeography
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"No evidence of Neanderthal mitochondrial DNA has been found in modern humans. This suggests that successful Neanderthal admixture happened in pairings with Neanderthal males and modern human females. Possible hypotheses are that Neanderthal mitochondrial DNA had detrimental mutations that led to the extinction of carriers, that the hybrid offspring of Neanderthal mothers were raised in Neanderthal groups and became extinct with them, or that female Neanderthals and male Sapiens did not produce fertile offspring."
https://en.m.wikipedia.org/wiki/Archaic_human_admixture_with_modern_humans.
"Analyzing chromosome 21 of the Altai (Siberia), El Sidrón (Spain), and Vindija (Croatia) Neanderthals, it is determined that—of these three lineages—only the El Sidrón and Vindija Neanderthals display significant rates of gene flow (0.3–2.6%) into modern humans, suggesting that the El Sidrón and Vindija Neanderthals are more closely related than the Altai Neanderthal to the Neanderthals that interbred with modern humans about 47,000–65,000 years ago. Conversely, it is also determined that significant rates of modern human gene flow into Neanderthals occurred—of the three examined lineages—for only the Altai Neanderthal (0.1–2.1%), suggesting that modern human gene flow into Neanderthals mainly took place after the separation of the Altai Neanderthals from the El Sidrón and Vindija Neanderthals that occurred roughly 110,000 years ago. The findings show that the source of modern human gene flow into Neanderthals originated from a population of early modern humans from about 100,000 years ago, predating the out-of-Africa migration of the modern human ancestors of present-day non-Africans."
https://en.m.wikipedia.org/wiki/Refugium_(population_biology)
https://en.m.wikipedia.org/wiki/Competitive_exclusion_principle
https://en.m.wikipedia.org/wiki/Pseudogene
https://en.m.wikipedia.org/wiki/X_chromosome
https://en.m.wikipedia.org/wiki/Ribonucleotide_reductase
https://www.nature.com/articles/ncomms16046
https://www.cell.com/cell/fulltext/S0092-8674(20)30059-3
https://en.m.wikipedia.org/wiki/Neanderthal_genetics
https://www.sciencemag.org/news/2017/07/neandertals-and-modern-humans-started-mating-early
Humans evolved the same way a lot of other species did, by expanding as separate groups, consolidating as separate groups, then reconsolidating as one group following some depopulation event, lather rinse repeat. First in Africa and Asia, many times, then globally, once so far.
https://phys.org/news/2021-05-human-stories-compatible-fossils.html