Where is the current RTB model articulated?
Out of scope on this thread. We’ll address it another day. I promise.
Agree, what you’ve written is entirely appropriate. Were it not for the fact that BioLogos is a “Christian advocacy group” founded by Francis Collins, I might have said just forget about it. But what they’ve done is straightforwardly unethical, and undermines their credentials from the standpoint of faith as well as science. It must be called out.
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It’s hardly out of scope since you brought it up. If RTB’s model tolerates a bottleneck of 2, even without requiring one, then it’s incompatible with the cross-species polymorphism evidence.
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Their proposal is pretty simple, actually:
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AE live about 185 kya, and there is a Noahic bottleneck at about 180 kya.
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Eve has a different genome in each egg (perhaps even pull from the surrounding population at her creation).
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At any point along this scenario interbreeding with other populations of hominins is possible. They officially believe Neanderthals did not arise before Adam and Eve, but have no reason to exclude other sorts of interbreeding.
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AE are our sole-genetic progenitors. They mean, by this term, that all the DNA that makes us fully human we receive by direct genetic descent from them. This a “unique” position that they “soley” hold.
If #4 sounds strange, it shouldn’t. That is how almost everyone in the conversation, it turns out, has understood sole-genetic progenitorship. The idea that sole-genetic progenitorship rules out interbreeding (#3) is a use of the term is highly idiosyncratic.
It should be pretty obvious that there is no strong evidence against this position. To the point, this scenario does not require a genetic bottleneck of 4 alleles.
Is it “plausible”? That is fudge term. I can certainly sympathize with the sentiment that this does not seem theologically necessary or plausible in some subjective senses. But this is an article about scientific evidence, and what is and is not compatible with the evidence. Shifting the terms of the debate away form the genetic evidence is not fair play.
Agree to disagree. “Sole” is a word that has a meaning, and so is “genetic”. This understanding does violence to both meanings.
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That’s not the issue.
The point is that people will point to evidence against sole-progenitor (by your definition) as demonstrating sole-progenitor (by their definition) is false.
Disagree with them if you like, but still engage what they are saying appropriately.
OK, I have to ask who is it using “sole-genetic progenitor” in this odd, counter-intuitive, and nevertheless vague sense?
And does it not require that you inherit considerable genetic material from A&E? If that doesn’t arise from a bottleneck of two, then how else could it happen? Strong selection, perhaps? Or a miracle? I don’t see a fourth option.
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Reasons To Believe and Ann Gauger are using it this way. That’s two independent groups.
Disagree with it if you must, but it’s just a fact.
Welcome to the mosh pit, @Robert_West! 
For those who don’t know, Robert is one of the moderators from the FB group.
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Hate to belabor this, but the definition is still quite vague. Are RTB and Gauger using it in exactly the same way? Do they each have the same understanding of “all the DNA that makes us human”? And either way, what is that understanding?
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Is this a recent change? I thought it was closer to 70kya in their model, but it’s been a while since I’ve looked at it. (I know this is tangential to the thread.)
Early 2020, about the time of our workshop with them. AJ laid it out in a series of 3 or 4 articles.
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Would you be so kind as to provide references when you mention things?
I’ll have to look that up later. We discussed them when it came out. They call it “Mosaic Eve”
This?:
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And here again:
Either you misremembered or AJ Roberts is consistently wrong about the RTB model.
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OK, I see this quote from the article as contradicting your idea of what “sole progenitor” means to AJ Roberts:
The linking of “no other source” and “because ours is a sole-progenitor pair model” seems to leave no room at all for anything other than a bottleneck of two and a meaning of “sole” in line with my expectations, not yours. Or did she misspeak?
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This in the context of developing a model that doesn’t allow neandertha-sapien interbreeding. Later on she relaxes that constraint. You can’t take that quote out of the larger context.
Clearly the meaning of “sole progenitor” at the time of the quoted bits was the one I would assume, not the one you’re talking about. Perhaps it changed later, but I haven’t seen the evidence. Surely this must call into question at least the idea that the term is generally understood the way you prefer.
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