New Type of Ancient Human Found—Descendants Live Today?

Hi, Jon. I would argue that it does contradict the MH model.The multiregional model focuses on local sources of genetic diversity, while the available DNA evidence indicates a very minor role for local sources in human genetic diversity.Since nobody expects either hypothesis to be the absolute truth of the matter, it would be unscrupulous to afford out-of-Africa no error in the amount of interbreeding that may have occurred. So, OOA should not be treated as denying that any interbreeding took place.The proper way to evaluate competing hypotheses is to determine which is closer to the truth. Since DNA from African populations is overwhelmingly the majority of modern H. sapiens DNA in nearly all modern populations, and local sources of genetic diversity are rare; then, rather than argue for the success of the MH model---which is only required to explain a tiny portion of the data, while being totally superfluous to nearly all of it---it would seem appropriate to grant victory to the out-of-Africa side, while acknowledging the few exceptions with footnotes.Likewise, if it was discovered that God actually created millipedes, but everything else evolved, then the divine origin of millipedes would just be a footnote in a textbook that otherwise discusses only the Theory of Evolution.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. What's the difference, exactly?How do genes move without the people that carry them?----- The out-of-Africa hypothesis also makes predictions. It predicts that human gene pools across the planet will be dominated by genetic signatures from African lineages.So, to compare the predictions:MH predicted a variety of regional populations of humans with diverse origins. We see a little bit of that.
OOA predicted predominance of African genetic lines in populations around the globe. We see a whole frickin' lot of that.Furthermore, MH predicted that the traits that are common across all populations would be traits that are useful in all environments. I have no idea what the status of this prediction is.Meanwhile, OOA predicted that the traits that are common across all populations would be traits that arose in Africa. This prediction is upheld very strongly by the genetic evidence.So, how does OOA not win the prediction game?----- You can't have genetic flow without population flow.How could a population whose gene pool is 95% of African origin not be an "out-of-Africa" population? Those African genes had to have come from an African population. Whether the "genetic takeover" involved killing off the locals or simply swamping their genes out through interbreeding, the population is still an "out-of-Africa" population.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. This is wrong. Modern refinements of the theory can be traced to the information gathered from population genetics studies in the last two decades, but the idea that H. sapiens originated in Africa and migrated out from there is many decades older than that, and it has been essentially the consensus view for most of that time.----- What does this have to do with anything?Language is not strictly hereditary. Genetics are. If your parents are genetically English (let's pretend that's possible for now), then you are also genetically English. If you are born to parents who are H. sapiens, then you are also H. sapiens, regardless of whether or not there used to be H. erectus in your population.----- What is the difference?At some point, some African, or somebody with African genes, has to leave Africa in order to get African genes into Asian gene pools. Surely this is not controversial.And, at some point, the H. sapiens in a population have to outnumber the H. erectus in the same population in order for the population's gene pool to be dominated by H. sapiens genes. Surely this is also not controversial.And, at some point, the H. erectus in a population have to go extinct and be replaced by H. sapiens in order for the population to become entirely H. sapiens. Surely this is also not controversial.Whether by conquering, by outcompeting, or by outbreeding, H. sapiens replaced H. erectus in Asian gene pools. Replacement is replacement. And replacement is the out-of-Africa hypothesis.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. What else could it possibly indicate?If population A and B interbreed, and population B eventually becomes saturated with immigrant genotypes from A, such that the genetic signature of B is essentially extinct, isn't this the same thing as population A "flowing" into the region occupied by population B and taking over?This is the scenario the population genetics evidence is showing us: takeover by H. sapiens, with the possibility that some H. erectus integrated and interbred with the immigrants.How is this not "population flow"?----- Well, you're right of course. But, neither is your comment relevant to my claim that elephants can be trained to play mancala.I mentioned the status of the model to point out that OOA did indeed predict the discoveries of population genetics, rather than simply emerge as a result of them.To that point---and only that point---it is extremely relevant. I don't see why it should have to be relevant to any other point we were discussing.----- Nonsense. There is no evolutionary significance to distinguishing between migratory and reproductive replacement: both still result in population replacement, and both likely contributed to the final result to some extent.OOA is a population model, not an individual model. It doesn't talk about what happens to individuals, but only to populations. It is equally compatible with conquest, disease, ecological competition and saturating gene pools. In fact, I think its likely that every proponent of OOA thinks all four of these mechanisms were probably involved in the H. sapiens takeover to some extent. I find it equally likely that very few researchers think only one of these mechanisms accounts for the takeover entirely by itself, and that very few researchers would be willing to state the any one of these mechanisms did not play a role.If we find a handful of populations in which interbreeding occurred, and in which some H. erectus genetic signatures remain to the present, this is equally devastating to OOA as the discovery of a H. erectus tribe that was murdered by a H. sapiens tribe is to MH---that is to say, not at all.Conquerors rape and lovers murder. We shouldn't be surprised to see a little of either happening when the other is the dominant trend, nor should we discredit the dominant trend just because we see a little bit of the subordinate trend alongside it.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. Because population A used to only inhabit one location. Now, after swamping out population B, it inhabits two locations.If that's not "population flow," what is?----- Jon, any time a gene moves from one population to another, it's because an actual person moved.Do you disagree with any part of that?----- You're not making any sense, Jon!Movement of genes requires movement of people.It does not require any individual person to walk from population A to population C.It does however, at the very least, require somebody of population-A origin to move from population A to population B, and somebody of population-A origin to subsequently move from population B to population C.This is what the out-of-Africa hypothesis is: a gradual migration of people from Africa into and across Asia over several generations, interacting with and replacing whatever populations of H. erectus they encountered.Now, replacement of population B by population A requires something more. It either requires immigrants from A to outnumber natives from B, or requires that all of A's genes are superior to all of B's, such that natural selection causes A's genes to be the only ones that survive. That second option is obviously farfetched, so let's just assume that the first is correct. What the new data shows is that the replacement of former types of humans by modern humans proposed by OOA was imperfect in one case. And, by "imperfect," I mean, "individuals in one population retain 5% of the pre-sapiens gene pool."So, instead of "all humans are descended entirely from African sources," we have, "all humans are descended entirely from African sources, with the exception of a few traces of Neanderthal and Denisovan sprinkled in."I don't see that as a major change to the theory.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. How else do you propose population A got its genes into population X? Teleporting gametes?It's a simple fact of heredity that the only people who can transmit my genes to somewhere else are myself and my descendants. Therefore, if I'm African, and my genes somehow end up saturating the gene pool of Malaysia, this means that either I or my descendants went to Malaysia and hosed the placed down with our African gametes. There is literally no other way for my genes to get there (ignoring artificial insemination and sperm banks, which presumably don't apply here).And remember that we're not just talking about a few African genes being moved into Asia: we're talking about essentially entire African genomes saturating every population in Asia! How does this happen? By slow diffusion of genes from Africa through hundreds of hybrid populations until they reach the extremities of Asia?Realistically, hybridization can't explain such a lopsided result, unless the Africans were contributing substantially more to the Asian gene pools than the Denisovans were, which shouldn't be happening if Africans are staying in Africa.Realistically, Africans actually being in Asia---indeed, Africans outnumbering Denisovans in Asia---explains the lopsided result much better.But, if Africans live in Africa, how do they end up in Asia?Why... migration, of course.----- Ignoring the fact that somebody still has to leave the family farm in order for the next generation to not end up on the family farm, let me show you why this is absurd.In order for this scenario you've proposed to explain the data, there would have to be an endless network of interconnected populations spanning all of Asia, no one of which was so far from the neighboring populations that any of the locals actually had to walk farther to get there than they would have walked that day anyway.I haven't done the math, but I'm pretty sure even modern Asia doesn't have a population density high enough for that to be feasible. Paleolithic Asia certainly didn't.Furthermore, you're still stuck with the evidence that shows that these populations were once isolated enough for them to have diverged morphologically; but you're proposing that, later, they were interconnected enough for the African gene pool to sweep through all these populations and eliminate all but a few traces of the other gene pools, all without anybody having to do a little extra walking.Are you really going to take it this far?Why is it so hard for you to admit that somebody had to hoof it out of Africa?

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. ...but not without a corresponding travel of some body.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. There's only one way to define it that's meaningful in an evolutionary context: i.e. as a hereditary lineage, in this case a lineage of humans that began in Africa, as opposed to the separate lineages from Europe (Neanderthal) and Asia (Denisovan).----- How did you determine how likely this is?I say that the evidence does not bear this out.The evidence seems to suggest that, up until the point of the alleged "super-exodus" (about 70,000 years ago), the three lineages had distinct morphologies and distinct genetic markers. Then, at about 70,000 years ago, the isolation was broken, and now everybody alive belongs to the African lineage.This evidence suggests a shift from isolated populations to an invasion of Africans that swamped out and/or exterminated the other lineages. This shift indicates that something changed in the movement patterns of the Africans.----- I'm not sure what "pre-sapiens" has to do with this, because it was the Denisovans and Neanderthals who inhabited the areas into which H. sapiens allegedly migrated (all the other groups of hominins from the region were apparently extinct by 70,000 years ago, when the migration is thought to have happened); and, since the new evidence shows that humans interbred with Neanderthals and Denisovans, I think we can go ahead and say that they coexisted.----- I like that you said "little need" instead of "no need."

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. Yes.----- How do you gather this? My ancestors and yours came from across a frickin' ocean, for crying out loud!Everything we know about the way people live, grow up, leave the nest, and start their own families suggests that people may go pretty much any-damn-where after "leaving the nest." Nomads doubly so.----- But it is inconsistent with your model of no migration.----- I'm addressing the movement of a whole frickin' lot of genetic material over a long distance, and the concomitant disappearance of virtually all other genetic material.You don't get that by having everybody stay where they have always stayed and allowing some gametes to percolate through hybrid populations. You get that by having somebody uproot and invade.This is how North America came to be populated by Native Americans in the first place, and how its gene pool later came to be dominated by white people from Europe.A few pockets of Native American genome survive.
A very few pockets of Denisovan and Neanderthal genome survive.
Most of North America's population is from Old World sources.
Almost all of Eurasia' population is from Paleolithic African sources.Do you see the parallels? Why do these parallels not point to similar causative events?

Hi, Jon. It doesn't really have that specific a meaning: directional movements, cyclical movements, movements of whole populations, etc., are all included. Any movement that results in an entity (individual, population, colony, haplotype, etc.) inhabiting an area that it didn't previously inhabit is properly called a "migration."----- "'Rush' characteristics"? Who said anything about "rushing"? What does the speed of movement have to do with anything? Can migrations not be slow? Do you define "migration" by speed? OOA proponents, and evolution biologists in general, don't.Okay. Let's forget the colonization of America. Let's instead focus on the westward expansion of the Europeans and their derivative peoples (that's us) after we arrived in North America. We started in the east, then slowly "spread out" westward into new areas, displacing or killing the natives. Some of us tolerated and even intermarried with the natives, but they were mostly just swamped out or pushed aside. In the end, we have a gene pool that's almost entirely immigrant, with only a few pockets of native populations remaining.We also see the same thing happening with the European colonization of Australia and the Bantu expansion across sub-Saharan Africa.Aside from the technological differences, do you have any reason to think that the migration event proposed by OOA is any different from these?Call it "spreading out," if you want. But, it's still the same thing that OOA proposes.----- But, it is the only way that has been documented to effect the wholesale takeover of gene pools by genomes from other populations, so we should be in the habit of assuming it until something else comes along.----- This isn't how Ockham's razor works. Yes, it favors the "simplest" explanation, but "simplest" isn't chosen based only on the evidence you have in your hands: it's chosen by the context provided by the entire scientific literature. So, when two models are possible (e.g., hybridization with migration vs. migration with or without hybridization), you pick the one that has been successful in explaining other similar situations.The evidence we have from population ecology and population genetics with a variety of species tells us that migration often results in the wholesale takeover of gene pools by immigrant populations and species.In contrast, as far as I'm aware, there are no documented cases of hybridization without migration causing the same result, so there is no precedent for it. And, a hypothesis without precedent doesn't earn the favor of Ockham's razor, regardless of how simple it seems to be.This means that Ockham's razor favors a migration model over a hybridization model.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. Have you not been reading my last several posts? I think I've done a good job showing you that the types of evidence we would expect to see from a migration event are exactly the types of evidence that we do see.And, your response to that is a vague reference to an undefined "specific type of evidence" which you claim is lacking. This is highly rude and disingenuous debate style, Jon. Please put some effort into it. Until you start defining these vague things you're referring to, I don't see any reason to put any stock in any argument you've made.----- We do if that one population consists of about 1 million people spread out over a landmass that covers 1/6th of the planet's surface.----- We're not talking about novel genes, Jon! We're talking about entire genomes! Please assimilate this important detail!A single allele can easily become fixed in a population through simple admixture if natural selection favors it over all competing alleles. But, we're not talking about a single advantageous allele or an arbitrary number of advantageous alleles percolating through a vast, hybrid population: we're talking about entire genomes---non-coding DNA that is irrelevant to fitness included---saturating the global gene pool.For this, the evidence says that we do need migration.Genetic admixture is a wonderful explanation for why a handful of alleles from Neanderthals and Denisovans can be found in modern human populations. But, it is a very lousy explanation for why Paleo-African alleles dominate every modern human genome that has ever been studied.----- Here you go again. What specific types of movements? I have challenged your assertion that OOA is formulated around a specific type of movement, and you just keep re-asserting it.And, I can't resist pointing out that the "expected behavior" of nomadic peoples is migration. That's pretty much the definition of "nomad."

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon.I just noticed that I have apparently once again set off Coyote's "pedantic" alarm. Obviously, I should back out now so Coyote can feel like he can participate in a topic about his area of expertise.It's been fun: I hope I didn't offend you too badly.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Nuggin.I promised to leave, but I can't stay away. We're talking about something like 5% of the mutations in one insular population of modern humans being Denisovan, though (along with 1-4% of most of the world's mutations being Neanderthal). How small does the contribution of non-sapiens have to be before we consider MR effectively refuted?It doesn't seem all that meaningful to acknowledge a theory that only explains such a tiny percentage of the data. It's like calling a sports game a draw because both teams scored points.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. Oh, so, when you said "pre-sapiens," you were referring to Neanderthals and Denisovans? I didn't realize that before. That's not strictly accurate, since H. sapiens didn't evolve from either one.And, let me repeat myself: evidence that H. sapiens and Denisovans interbred is evidence that they existed in geographical proximity. And, evidence that Denisovans are extinct in Siberia, where H. sapiens can now be found, is evidence that the latter replaced the former, isn't it?----- I'm still amazed that you think migration is an extraordinary claim.----- What is so special about this one period is that, before this one period, we see divergence in regional populations, and [i]after this one period, we see divergence in regional populations. But, during this one period, we see convergence between regional populations.This implies that something was happening at this time period that was different from what was happening in the prior and later periods. Yet, your model proposes that one mechanism (genetic flow) explains all three periods of time.----- Theoretically, sure. But, let me repeat my earlier comment: total saturation of a population with "irrelevant" traits by genetic flow alone has never been observed in the real world.On the other hand, total saturation of a population with "irrelevant" traits by genetic flow with migration has been observed many times in the real world, with multiple species.Migration is at least the null model here.----- Many groups of nomads and hunter-gatherers have been seen to move unidirectionally. Consider the Hyksos and the Jurchens. Read a little about the Colonial and pre-Colonial history of Native Americans: they were constantly moving around in a decidedly non-cyclical manner, combining and splitting with each other in complex patterns.Nothing is as clean-cut as you seem to want to make it: population dynamics, ecological dynamics and evolutionary dynamics are messy. No hunter-gatherers are strictly cyclical, because they have to follow the food, and animals populations and food resources vary from year-to-year. Sometimes, they abandon some places and don't come back. This is fairly normal thing that hunter-gatherers do.It seems reasonable to expect that enough of this pattern of population movement will eventually result in some tribe or another leaving Africa. It really isn't that extraordinary an expectation.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Jon. I've never heard the term "selective sweep" before. Thanks for the new education!Still, this isn't a genome full of "irrelevant" alleles spreading through a population by hybridization: this is a single advantageous allele, plus a few "irrelevant" alleles neighboring it on a chromosome, being spread with the help of natural selection.You can't seriously say that genetic linkage accounts for 95%+ homology. The Wikipedia article you linked to says there is evidence for selective sweeps on 6 out of 23 human chromosomes. And these don't include an entire chromosome, but just small regions of chromosomes associated with single genes.You have a mechanism, but you still have no evidence that this mechanism can be expected to account for a 95% takeover by an external populationOoA has a mechanism, and there is evidence that this mechanism can, and has in the past, accounted for a 95% takeover by an external population.----- An "occasional great escape" is exactly what OoA proposes. If you want to propose that MR can absorb a "great escape" from Africa, you're just being silly.

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-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.