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Author Topic:   New Type of Ancient Human FoundDescendants Live Today?
RAZD
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Message 166 of 209 (600295)
01-13-2011 7:35 PM
Reply to: Message 157 by Coyote
01-12-2011 8:58 PM


Re: New article
Interesting indeed Coyote,

In particular I find this interesting

quote:
Following the first Denisova results, I speculated that this mtDNA might be from a late-surviving heidelbergensis living in Siberia.

So, in Europe, H. heidelbergensis gave rise to Neanderthals, in Africa they gave rise to us (modern humans), and in Asia, perhaps to the Denisovans.


And one of the issues that comes to my mind in regard to:

quote:
If the populations were very small, that component [5% Denisovan genes] might represent as few as 50 Denisovans mixing with 1000 pre-Melanesians, but it was sufficient to give the present-day inhabitants of places like New Guinea and Bougainville as much as 8% archaic genes - a small Neanderthal component they acquired first, probably in western Asia, and an additional Denisovan component they acquired later, on their long journey towards Melanesia.

... is that what we could be seeing is the occasional fertility of hybrids as occurs with horses, mules and zebras.

Enjoy


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This message is a reply to:
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Coyote
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Posts: 4698
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Message 167 of 209 (600306)
01-13-2011 8:45 PM
Reply to: Message 166 by RAZD
01-13-2011 7:35 PM


Re: New article
Hi--

It is interesting indeed.

My guess is that there was a lot more interbreeding than we thought.

These different species represent geographic/temporal isolates, but that pertains to the fossils we have, and to the central tendencies of each of the species. Who knows how much fraternization there was at the fringes of each groups' ranges.

That's some of the fun part of paleontology!


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 Message 166 by RAZD, posted 01-13-2011 7:35 PM RAZD has acknowledged this reply

  
Jon
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Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 168 of 209 (600323)
01-13-2011 11:37 PM
Reply to: Message 165 by Taq
01-13-2011 5:52 PM


Re: Continuity of the Species
The genetic divergence of anatomically modern humans, neanderthals, and the Denisova species. This genetic divergence required 300,000 years of very limited to no gene flow.

Unfortunately the genetic evidence available cannot address this question, as the genetic difference between any modern and archaic population in the process of evolving will certainly be great.

Which I supplied with the Y-chromosome haplomap, the dominance of African DNA across the globe, and modern examples of the mechanism in action.

Interesting how the link between genetic flow and migration continues to be repeated ad nauseam without a single effort to support this extraordinary assumption.

The most diverse genetic groups are found in Africa, and they include the alleles found in human groups outside of Africa. Regional alleles are modifications of these African alleles (except for the tiny percentage of alleles from non-African, non-modern human populations). This means the source was Africa.

Never been disputed. Again, the issue for discussion is the validity of the assumed link between gene flow and migration.

These measurements are taken using molecular clock data using modern DNA. Since we are talking about the evolution of modern humans this seems to be a viable sample pool.

This is the first error: to believe we can discover truths about the past without ever needing look at it. Genetic samples are valuable, but they only make sense in light of a workable modelwe cannot use the present as a sole basis for a model of the past. Such fallacy is demonstrated by, for example, Alan Templeton, who's shown various analyses of the same genetic data to yield drastically different results. On top of this, higher selection pressures on the peripheries (where population numbers are low and thin) makes the termination of mtDNA lineages more prevalent in these regions, a possibility demonstrated as fact in Mungo Man. The factual possibility of these lost lineages shatters the presumed link between modern genetic diversity and population age.

I could go on, but...

Jon

Edited by Jon, : schpelling


Check out Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

This message is a reply to:
 Message 165 by Taq, posted 01-13-2011 5:52 PM Taq has responded

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Blue Jay
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Posts: 2615
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 169 of 209 (600378)
01-14-2011 10:08 AM
Reply to: Message 163 by Jon
01-13-2011 5:17 PM


Re: Continuity of the Species
Hi, Jon.

Jon writes:

Whatever the initial contribution, we cannot determine its size by only making measurements of the present population; all our measurements of present populations tell us is whether or not we have evidence of continuity and how much of that evidence remains.

As Kapyong explained beautifully here, a theory in science is an explanation for something. This can be extended to a hypothesis, as well.

So, what are OoA and MR supposed to explain?

You seem to be going down the path that MR is just the hypothesis that modern humans interbred with other groups of Homo. This is not accurate. The reason MR comes into conflict with OoA is because both are hypotheses that attempt to explain the ancestry of modern, living humans, not just claims about whether some particular event (migration or hybridization) happened in prehistory.

So, the amount of evidence that remains to the present day is precisely the thing that the hypothesis is meant to be explaining, and is thus a direct measure of the correctness and explanatory power of the two hypotheses.

If an out-of-Africa migration is demonstrated to have happened, but nobody today is descended from the migrants, then OoA is falsified.
If interbreeding among various groups of Homo is demonstrated to have happened, but nobody today is descended from the hybrids, then MR is falsified.

Because there is evidence demonstrating that both happened, and that people today are descended from both migrants and hybrids, we allow the predominant mechanism to dominate our paradigm. Thus, OoA remains the champion, with a minor contribution from MR.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


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 Message 163 by Jon, posted 01-13-2011 5:17 PM Jon has responded

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Taq
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Posts: 5215
Joined: 03-06-2009
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Message 170 of 209 (600407)
01-14-2011 11:39 AM
Reply to: Message 168 by Jon
01-13-2011 11:37 PM


Re: Continuity of the Species
Unfortunately the genetic evidence available cannot address this question, as the genetic difference between any modern and archaic population in the process of evolving will certainly be great.

Not if there is uninterrupted gene flow between the populations as the MR model proposes.

Interesting how the link between genetic flow and migration continues to be repeated ad nauseam without a single effort to support this extraordinary assumption.

What link? The genetic data points to very limited gene flow between the populations, not free genetic flow as the MR model proposes.

This is the first error: to believe we can discover truths about the past without ever needing look at it.

Our genomes are direct records of the past. They are the written genetic history of our ancestors passed down from one generation to the next.

Genetic samples are valuable, but they only make sense in light of a workable modelwe cannot use the present as a sole basis for a model of the past.

The workable model is OoA. MR fails to be a workable model, as we have been discussing.

Such fallacy is demonstrated by, for example, Alan Templeton, who's shown various analyses of the same genetic data to yield drastically different results.

Could you cite his work so we could all take a look? (apologies if you have already presented it in a previous post)

On top of this, higher selection pressures on the peripheries (where population numbers are low and thin) makes the termination of mtDNA lineages more prevalent in these regions, a possibility demonstrated as fact in Mungo Man.

So why is it that African lineages dominate for both mtDNA and Y-chromosome DNA? Why do the Y-chromosome haplotypes create a pattern of migration?


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 Message 168 by Jon, posted 01-13-2011 11:37 PM Jon has responded

Replies to this message:
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Jon
Member
Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 171 of 209 (600422)
01-14-2011 12:25 PM
Reply to: Message 169 by Blue Jay
01-14-2011 10:08 AM


Re: Continuity of the Species
You seem to be going down the path that MR is just the hypothesis that modern humans interbred with other groups of Homo. This is not accurate. The reason MR comes into conflict with OoA is because both are hypotheses that attempt to explain the ancestry of modern, living humans, not just claims about whether some particular event (migration or hybridization) happened in prehistory.

I'm well aware of the differences between the two models. Neither is concerned solely with 'ancestry', especially given the varied nuances of that term. Where they conflict is primarily in their models of population movements.

So, the amount of evidence that remains to the present day is precisely the thing that the hypothesis is meant to be explaining, and is thus a direct measure of the correctness and explanatory power of the two hypotheses.

I see that neither model is crippled in explaining the present evidence. It is precisely the fact that both models are capable of explaining the present evidence that tells us the answer does not lie with present analysis alone: we must look elsewhere, and the only place else to look is to the past.

Because there is evidence demonstrating that both happened, and that people today are descended from both migrants and hybrids, we allow the predominant mechanism to dominate our paradigm. Thus, OoA remains the champion, with a minor contribution from MR.

Again, this is the claim you are supposed to be supporting. So far, I've seen no evidence offered that can corroborate this definitively. Repeated assertions of genetic histories will not do.

Jon


Check out Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

This message is a reply to:
 Message 169 by Blue Jay, posted 01-14-2011 10:08 AM Blue Jay has responded

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 Message 177 by Blue Jay, posted 01-14-2011 11:04 PM Jon has responded

  
Jon
Member
Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 172 of 209 (600434)
01-14-2011 1:07 PM
Reply to: Message 170 by Taq
01-14-2011 11:39 AM


Re: Continuity of the Species
Not if there is uninterrupted gene flow between the populations as the MR model proposes.

But, of course, the MH model doesn't propose uninterupted gene flow between populations.

What link? The genetic data points to very limited gene flow between the populations, not free genetic flow as the MR model proposes.

Again, that is not what the genetic data show; they show that there is a small amount of surviving genetic continuity. They do not and cannot provide insight into the amount of initial regional contribution, aside from showing that it occurred.

Our genomes are direct records of the past.

Absolutely false. I've demonstrated already that this is not the case.

The workable model is OoA. MR fails to be a workable model, as we have been discussing.

The claim that has yet to be supported, despite repetition of it as though it were fact ad nauseam.

Could you cite his work so we could all take a look? (apologies if you have already presented it in a previous post)

Sure, let me give you some references (I haven't yet read a couple of these, but am working on them; the first is the most relevant):

     Templeton, A. (1993). "The 'Eve' Hypothesis: A Genetic Critique and Reanalysis". American Anthropologist Vol. 95, 1. pp. 5172.
     Templeton, A. (1994). "'Eve': Hypothesis Compatibility versus Hypothesis Testing". American Anthropologist Vol. 96, 1. pp.141147.
     Templeton, A. (1998). "Human Races: A Genetic and Evolutionary Perspective". American Anthropologist Vol. 100, 3. pp. 632650.

Those are just the ones I've got from Mr. Templeton. There are others, but he's quite prolific.

So why is it that African lineages dominate for both mtDNA and Y-chromosome DNA? Why do the Y-chromosome haplotypes create a pattern of migration?

If you're able to access those articles, give them a read. In short, the genetic evidence is not only ambiguous, but even if correct in the interpretation preferred for OOA, not evidence of population histories at all, but simply mtDNA histories:

quote:
Wolpoff & Caspari in Race and Human Evolution:

These genetic studies must be considered along with mtDNA and Y chromosome analyses indicating low levels of variation that might reflect a recent bottleneck. If these interpretations are correct, it means some genetic systems went through bottlenecks while others didn't. This would be an impossible finding if all human populations had gone through a recent bottleneck, but in fact all genetic systems do not have the same history, and therefore the history of the individual genetic systems is not population historyremember, if there was a common recent origin for all populations because a new species appeared, all of the genetic systems should reflect this and there could be none that did not pass through a bottleneck. But in fact this is what the genetic data, in aggregate, show did not happen. Some gene systems, for instance, mtDNA and certain segments of the Y chromosome, have gone through bottlenecks, but others have not. What this evidence means is that mitochondrial DNA evolution, indeed the evolution of other genetic systems, is not the same as population evolution. The "Eve" of mtDNA is just that, the last common ancestor of mtDNA lines, and not the last common ancestor of the humans who carry them. (1997, p. 308)


Let me know if you can't get those articles.

Jon
__________
Wolpoff, M. & R. Caspari. (1997) Race and Human Evolution. New York: Simon & Schuster.


Check out Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

This message is a reply to:
 Message 170 by Taq, posted 01-14-2011 11:39 AM Taq has responded

Replies to this message:
 Message 173 by Taq, posted 01-14-2011 1:42 PM Jon has responded

  
Taq
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Posts: 5215
Joined: 03-06-2009
Member Rating: 2.9


Message 173 of 209 (600445)
01-14-2011 1:42 PM
Reply to: Message 172 by Jon
01-14-2011 1:07 PM


Re: Continuity of the Species
Again, that is not what the genetic data show; they show that there is a small amount of surviving genetic continuity.

The data shows that there was discontinuity between the populations for 300,000 years. It wasn't until populations migrated out of Africa that these genomes came into contact again, and even then the interaction was very limited resulting in the 5% of non-African DNA in modern populations.

Also, why is there only a small amount of surviving non-African DNA? Shouldn't we find a lot more? As DNA moves through populations by genetic drift it has to be diluted by local variation. There is no way around it. What you seem to be pushing for is the genetic equivalent to homeopathy.

Absolutely false. I've demonstrated already that this is not the case.

So what part of our genome was not inherited from an ancestor?

The claim that has yet to be supported, despite repetition of it as though it were fact ad nauseam.

So what evidence, in your eyes, would support it? More importantly, what evidence would falsify the MR model as the major mechanism for the evolution of modern humans?

ABE: I will definitely take a look at those articles and any others that are cogent.

Edited by Taq, : No reason given.


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 Message 172 by Jon, posted 01-14-2011 1:07 PM Jon has responded

Replies to this message:
 Message 174 by Jon, posted 01-14-2011 3:32 PM Taq has responded

  
Jon
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Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 174 of 209 (600468)
01-14-2011 3:32 PM
Reply to: Message 173 by Taq
01-14-2011 1:42 PM


Re: Continuity of the Species
The data shows that there was discontinuity between the populations for 300,000 years.

Perhaps you can make references to the data you believe show this discontinuity, as well as how this discontinuity is relevant in the MH-OOA discussion?

It wasn't until populations migrated out of Africa that these genomes came into contact again, and even then the interaction was very limited resulting in the 5% of non-African DNA in modern populations.

The migration is yet to be supported. Furthermore, I've repeatedly addressed the error of using the percentage of modern, surviving regionally continuous traits to infer the percentages of initial contributions of these populations and the degree to which archaic populations can be considered physically ancestral to modern populations.

Also, why is there only a small amount of surviving non-African DNA? Shouldn't we find a lot more?

Also something I've addressed several times now. Given the size and density of African (central) populations compared to the peripheral populations (Europe, Asia), it is no surpriseeven with an MH modelto find a higher proportion of African genetic material in the world population. This, along with the continued bombardment of peripheral populations by African DNA and the higher selection pressures (driven by the population size and density differences, among other things) for 'modern' traits, makes a modern dominance of African DNA perfectly reasonable within either an OOA or MH model. The amount present we find of non-African DNA depends on how long these factors have been at play and the strength of their effect on selection processes.

Jon writes:

Taq writes:

Our genomes are direct records of the past.

Absolutely false. I've demonstrated already that this is not the case.


So what part of our genome was not inherited from an ancestor?

I don't believe I ever implied that the case was otherwise. Your statement appeared to be a claim that genetic evidence is direct evidence of population histories. I've demonstrated that genetic evidence is partially evidence of the genetic histories of a species, not evidence of the population histories. We cannot use present genetic distributions to infer past population movements/histories. At some time, our model for the past must make some reference to substantial evidence from that past. You can't be a laboratory historian.

So what evidence, in your eyes, would support it? More importantly, what evidence would falsify the MR model as the major mechanism for the evolution of modern humans?

Glad you asked! One possible method, especially regarding regional continuity, would involve examining skeletal/genetic remains in various regions of the world.

Assuming an migration+interbreeding model: any halflings that result from interbreeding will be 50/50 carriers of sapiens and pre-sapiens genetic material and should be the oldest hybrids found in a region. If our model is mostly migration with limited interbreeding, then we should find these locations of 'halflings first' to be spotted around the Old World following the lines of migration.

Assuming a mostly gene-flow model with little migration: the earliest hybrids in the region will not be 'halflings', per se, but will be characterized by a higher proportion of pre-sapiens traits and a lower proportion of sapiens traits, with each later generation showing a higher proportion of sapiens characteristics than the generation(s) previous. If our model is mostly gene flow, then we should find 'halflings first' only at the genetic contact point between the non-originator populations and originator-of-the-DNA populations, and the further out we go from this point of contact, the lower the proportion of sapiens traits in the oldest hybrids will be.

I will definitely take a look at those articles and any others that are cogent.

Do enjoy!

Jon


Check out Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

This message is a reply to:
 Message 173 by Taq, posted 01-14-2011 1:42 PM Taq has responded

Replies to this message:
 Message 175 by Taq, posted 01-14-2011 4:05 PM Jon has responded

  
Taq
Member
Posts: 5215
Joined: 03-06-2009
Member Rating: 2.9


Message 175 of 209 (600477)
01-14-2011 4:05 PM
Reply to: Message 174 by Jon
01-14-2011 3:32 PM


Re: Continuity of the Species
Perhaps you can make references to the data you believe show this discontinuity, as well as how this discontinuity is relevant in the MH-OOA discussion?

From the article in the OP:

"The team estimates Denisovans split from the parent group of Neanderthals about 350,000 years ago."
http://news.nationalgeographic.com/...volution-fossil-finger

Likewise, neanderthals split from the modern human lineage at about this time. There were at least 3 human populations with highly restrictive to no gene flow for 300,000 years prior to the proposed migration of Africans into Asia and Europe.

Given the size and density of African (central) populations compared to the peripheral populations (Europe, Asia), it is no surpriseeven with an MH modelto find a higher proportion of African genetic material in the world population. This, along with the continued bombardment of peripheral populations by African DNA and the higher selection pressures (driven by the population size and density differences, among other things) for 'modern' traits, makes a modern dominance of African DNA perfectly reasonable within either an OOA or MH model.

So what would the population differences need to be in order for this to work with an MH model?

Also, why would African alleles that are specialized for the open savannas of Africa be selected for in Asia? On top of that, why would selectively neutral traits such as the protruding chin be selected for? That doesn't seem to jive.

Assuming an migration+interbreeding model: any halflings that result from interbreeding will be 50/50 carriers of sapiens and pre-sapiens genetic material and should be the oldest hybrids found in a region. If our model is mostly migration with limited interbreeding, then we should find these locations of 'halflings first' to be spotted around the Old World following the lines of migration.

What about 30,000 year old neanderthal DNA from Europe that remain distinct from 30,000 year old anatomically modern human DNA? How does that fit in?

Also, if MH is true then we shouldn't have divergent genomes to begin with, but we do.

We cannot use present genetic distributions to infer past population movements/histories.

I think we will have to agree to disagree on this one.

Assuming a mostly gene-flow model with little migration: the earliest hybrids in the region will not be 'halflings', per se, but will be characterized by a higher proportion of pre-sapiens traits and a lower proportion of sapiens traits, with each later generation showing a higher proportion of sapiens characteristics than the generation(s) previous.

The way I see it . . .

If there was open gene flow then alleles should be evenly spread throughout the population to begin with. We should also see encroachment of Asian genes into Africa.


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 Message 174 by Jon, posted 01-14-2011 3:32 PM Jon has responded

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Jon
Member
Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 176 of 209 (600503)
01-14-2011 8:36 PM
Reply to: Message 175 by Taq
01-14-2011 4:05 PM


Re: Continuity of the Species
Also, if MH is true then we shouldn't have divergent genomes to begin with, but we do.

I've repeatedly mentioned why divergence of the type we have isn't a problem for MH.

Likewise, neanderthals split from the modern human lineage at about this time. There were at least 3 human populations with highly restrictive to no gene flow for 300,000 years prior to the proposed migration of Africans into Asia and Europe.

The article doesn't mention how this figure is derived.

So what would the population differences need to be in order for this to work with an MH model?

About what we would expect them to be given the time period and environmental conditions:

quote:
Wolpoff & Caspari in Race and Human Evolution:

Prehistoric population sizes were dramatically larger in Africa (the center) than in the rest of the world, possibly by as much as an order of magnitude. (1997, p. 302)


Also, why would African alleles that are specialized for the open savannas of Africa be selected for in Asia?

Were they?

On top of that, why would selectively neutral traits such as the protruding chin be selected for? That doesn't seem to jive.

I'm not sure the protruding chin feature is the same for all modern humans, or that it's not just a simple architectural compensation/tag-along trait for other skull changes related to brain size. Comparisons of early erectus, late erectus, and Neanderthal varieties all show a steady progression toward a more pronounced chin.

Jon writes:

We cannot use present genetic distributions to infer past population movements/histories.


I think we will have to agree to disagree on this one.

Perhaps we will, but the entire OOA argument rests on the assumption that we can. Thus, I think it important to be discussed further than an agreement for disagreement. Though, I'm willing to let this rest if you'd like to discuss other things of interest related to the two models, such as skeletal morphology, behavioral evidence, etc.

Jon
__________
Wolpoff, M. & R. Caspari. (1997) Race and Human Evolution. New York: Simon & Schuster.


Check out Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

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Blue Jay
Member (Idle past 30 days)
Posts: 2615
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 177 of 209 (600524)
01-14-2011 11:04 PM
Reply to: Message 171 by Jon
01-14-2011 12:25 PM


Re: Continuity of the Species
Hi, Jon.

Jon writes:

Neither is concerned solely with 'ancestry', especially given the varied nuances of that term.

  1. Then please illustrate for me what else these two hypotheses are meant to explain, other than the ancestry of modern humans.

  2. There are no nuances to the term "ancestry"; and, even if there were, none of them is relevant to this debate.

-----

Jon writes:

I see that neither model is crippled in explaining the present evidence.

You see this because you think any model that is "technically not impossible" is equally capable of explaining the evidence as any other model. Therefore, when you see some farfetched idea about population genetics that can accommodate the data, you automatically assign it the same value and explanatory power as a more realistic and straightforward model.

It's official: this discussion has turned me into Straggler. That is my cue to get out while I can. I deem you hopeless anyway. Unorthodoxy seems to be a hobby with you, and there is nothing to be gained by trying to get you to accept the orthodox view of anything.

-----

Jon writes:

Again, this is the claim you are supposed to be supporting. So far, I've seen no evidence offered that can corroborate this definitively.

The person who wants to believe his theory will never see any evidence that can definitively corroborate the opposing theory.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


This message is a reply to:
 Message 171 by Jon, posted 01-14-2011 12:25 PM Jon has responded

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Jon
Member
Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 178 of 209 (600644)
01-15-2011 11:18 PM
Reply to: Message 177 by Blue Jay
01-14-2011 11:04 PM


Re: Continuity of the Species
It's official: this discussion has turned me into Straggler. That is my cue to get out while I can. I deem you hopeless anyway. Unorthodoxy seems to be a hobby with you, and there is nothing to be gained by trying to get you to accept the orthodox view of anything.

I assure you, you've a long ways to go till you turn into Straggler!

I'm glad you stuck around while you could stand it. I think it best to avoid any discussion once it's been labeled as a battle of orthodoxies, so I'm more than pleased to set our disagreement to rest.

All the best!

Jon


Check out Apollo's Temple!
Ignorance is temporary; you should be able to overcome it. - nwr

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Blue Jay
Member (Idle past 30 days)
Posts: 2615
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 179 of 209 (624692)
07-19-2011 12:49 PM


New evidence
It's been several months since Jon and I ruined this perfectly decent thread about human ancestry. I have not intention of resurrecting it just to ruin it again, but a new paper has emerged with some new genetic information that provides new insights into the controversy.

Here is a link to the abstract. The authors of this study have uncovered a segment of DNA from the human X-chromosome that is present as a minority in all modern populations outside of Africa. This segment can apparently be traced to a Neanderthal origin, and is present in about 9% of the sample of over 6000 multinational humans tested.

These researchers explain this data as evidence for an early admixture between African humans and European Neanderthals, prior to the spread of the predominantly African group across Asia.

This data, combined with the earlier discoveries of minority Neanderthal and Denisovan haplotypes in various populations around the world, provide support for the Multiregional Hypothesis of human origins. It is seeming more and more likely now that early African Homo sapiens did interbreed with various other populations of hominids in different parts of the world.

My personal view remains that the Out of Africa model explains the majority of modern human ancestry, and should not be regarded as falsified by this information; however, I also accept that the strict OoA model is insufficient to explain human ancestry. A hybrid view involving both an out-of-Africa migration and significant regional interbreeding is currently the best explanation for human ancestry.


-Bluejay (a.k.a. Mantis, Thylacosmilus)

Darwin loves you.


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 Message 180 by Jon, posted 07-19-2011 1:28 PM Blue Jay has responded

  
Jon
Member
Posts: 3999
From: Minnesota, U.S.A.
Joined: 12-29-2005
Member Rating: 1.3


Message 180 of 209 (624702)
07-19-2011 1:28 PM
Reply to: Message 179 by Blue Jay
07-19-2011 12:49 PM


Re: New evidence
Thank you for the link!

quote:
Yotova, et al. in X-Linked Haplotype (abstract):

Our analysis of 6,092 X-chromosomes from all inhabited continents supports earlier contentions that a mosaic of lineages of different time depths and different geographic provenance could have contributed to the genetic constitution of modern humans. (emphasis added)


This part seems central. It is difficult to say more without looking at the article itself, but it would appear that their conclusion of an 'early admixture between expanding African migrants and Neandertals prior to or very early on the route of the out-of-Africa expansion' is not properly supported by this evidence.

The authors apparently want to interpret the findings as pointing to an early one-off admixture consistent with a single migration event. However, it is difficult to understand how this can be reconciled with 'a mosaic of lineages of different time depths and different geographic provenance'.

On top of this, these findings verify a prediction of the MH model and are supported by the OOA model only through the introduction of further ad hoc explanation.

Anyone still attempting to hold to anything even resembling a strict OOA model is no longer doing science.

Jon
__________
Yotova, V., et al. (2011) "An X-Linked Haplotype of Neandertal Origin Is Present Among All Non-African Populations" Molecular Biology and Evolution. Vol. 28, pp. 19571962. Abstract.

Edited by Jon, : Emphasis added


Love your enemies!
This message is a reply to:
 Message 179 by Blue Jay, posted 07-19-2011 12:49 PM Blue Jay has responded

Replies to this message:
 Message 181 by Mr Jack, posted 07-20-2011 6:40 AM Jon has not yet responded
 Message 182 by Blue Jay, posted 07-20-2011 1:36 PM Jon has responded

  
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