The time scale of the bottleneck?

@pevaquark

I’m not sure I’m following your point.

Do you think you could convince @agauger or @RichardBuggs that “… the idea of TMR4A is rather ridiculous from a purely scientific perspective. Not that the idea itself is not scientifically sound, it very much is and can be calculated, but you would never have two individuals that have two alleles at every loci that are different from their spouse…” ?

First, there is the phrasing you use: “… ridiculous from a purely scientific perspective…” I assume you mean that it is as ridiculous as the idea of Mary, the mother of Jesus, giving birth to a God? Or that it is ridiculous as the idea that Jesus was resurrected from his execution, and rose into the heavens on a cloud? This kind of ridiculousness?

Isn’t it really more to the point that the creation of Eve would be perceived as intentionally complimentary to the creation of Adam? If I were a Creationist, that’s what I would assume happened.

But let’s not get fixated on what is or isn’t ridiculous from a “purely scientific perspective”. Giving the assumption on alleles as you describe, we still get a 500 kya (looking at TMR4A) … which is virtually useless to any Young Earth Creationist or Old Earth Creationist that I know.

In any case, I certainly agree with your earlier comment (above) that “there is no evidence of any serious Homo sapien bottleneck [i.e., 1 mated pair]” … [with the addition of one little qualifying phrase] … any time within the last 500,000 years, which extends the timeline back before the rise of Homo sapiens.

I’ve read through the attached link. It seems that the claims of “problems” with Mendel’s Accountant have been answered in the discussion. Some of the anti comments were ridiculous even from a casual reading; like the following;

“He makes assumptions like the beneficial mutation rate and the selection rate–both of which are arbitrarily drawn up by him.” From /u/arthurpaliden:

Well, duh, of course they’re input variables. How else can you test the effect of a range of assumptions? As Sanford has shown even where assumptions favourable to evolution are used genetic entropy still results unless you push those initial parameters to completely unrealistic values.

There are certainly limitations to MA, but that can be said for any simulation. MA was written to overcome some of the limitations of earlier programs, and Carter and Powell wrote a program to overcome some of the limitations in MA as detailed in

and as they point out their program still has limitations, including the computational resources required which limits the detail they go to in their models.

Yes, both are equally ‘ridiculous’ from a scientific perspective. And the resurrection is ‘ridiculous’ from a purely scientific perspective too.

You wouldn’t naturally assume that this means they have maximum genetic diversity with 4 different alleles at every single one of the 20,000 genes. This is a ridiculous scenario from a ‘purely scientific perspective’ for multiple reasons, the first simply being that you would never expect that to happen in a bottleneck of two. And bottlenecks of two are entirely possible but extremely dangerous for the future of a population group. From a ‘purely scientific’ perspective, evolution is generally best thought of as a population level effect and so one wouldn’t naturally assume or expect that any species ever began with two individuals.

But if we do have the supernatural creation of such, I don’t see why we need to even bother with a mutation rate constraint like the TMR4A calculations. To squeeze all the genetic diversity of humans alive today some just say ‘hey the mutation rate was much higher in the past’ which is also fine if we’re allowing various miracles in our scientific models.

Perhaps we could rephrase: there is strong evidence against a bottleneck before 500 kya and a lack of evidence to support or reject a bottleneck beyond that.

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@pevaquark

If the difference between the “ridiculous” and the “not ridiculous” created a scenario where a bottleneck could fit the existing evidence, I think you know which of the two would be the logical position to take if God is omnipotent.

Genesis just got through making Adam from molecules of dust … it is certainly within that skill set for God to arrange alleles any which way he wants to.

Fortunately, you and I agree that even with the maximum diversity set for an Adam and Eve, it is still not enough diversity to defend a bottleneck of 2 any time before 500,000 years… and so we are able to reject the entire un-workable scenario!

Adam and Eve may have been created by God… but not as the first man and woman. Their role does not require being “the first”.

Sure, but to make God’s de novo creation a scientific model is a no go.

If evidence pops up that there is way too much genetic diversity amongst humans for any Adam and Eve before 100 kya no problem- the mutation rate was just higher and the original pair got a boost is genetic diversity.

Shared ancestry evidence beyond all reasonable doubt- God put homologous ERVs, Alu Elements and such there for a reason in shared locations with other closet related species. What reason, nobody can say but He did it, not ‘natural mechanisms’ that He made and upholds. Of course when it turns out some of these have a positive benefit, they were put there on purpose. But when some of these have a negative benefit, its because of the fall and evidence of genetic entropy.

Are we too closely related to chimpanzees genetically? Make the number lower, low enough that people feel happy. But what does that number mean? What number should we expect? Nobody knows when you include CNV (copy number variation)/gene duplication (full or partial)/etc. However we do know the point mutation rate very well and can compare that. That was highlighted multiple times (with the BL blog post) and just above by @glipsnort. Remarkably this number matches quite well with when we shared a common ancestor and looking at single point differences reveals the same mechanisms behind such diversity between humans today is what explains the differences between us and chimpanzees.

Unless you include supernatural mutation rates and other such things. Since you are already including supernatural intervention into your model that impacts such a crowd literally zero. Maybe some people will feel a bit challenged by it, but it’s no big deal for God to have mutation rates 5-80x what they were in the past for every year on average and in the modern era its slowed down. Because when you include God in scientific models, you can literally make Him do anything you need Him to for your model to be right!

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@pevaquark

The “target audience” are those Creationists frustrated by friends, family and so forth who deny the value of the mountain of scientific evidence that supports something as simple as Evolution.

Evolution can and should be embraced by modern Christians, especially if it can be shown how comfortable a fit it is to allow for de novo creation of a single pair of humans… anywhere from 6000 years ago to 12,000 years ago.

Sure … there could be some who “jump the fences” with God performing genetic back-flips … but that isn’t the target audience.

Good. I’m tracking with you here.

Ahhh! So people won’t accept it unless you tell them they can keep certain interpretations of the Bible? There are already lots of people that basically reject evolution by faith. And this isn’t exactly helpful for a YEC who already has a problem with virtually every other branch of modern science in some way shape or form.

I still don’t get it. If I’m going miraculous with regards to human origins, I care not what mutation rates are.

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@pevaquark,

Let me try to explain this scenario using different words.

I definitely understand that you think “Genealogical Adam” (“Geneal.Adam”) is supposed to convince skeptical Creationists that they can trust science. But this is not actually how @Swamidass or I present his scenarios.

The scenarios are designed to to “provide relief” to those who are caught up in the dynamic tension between those who see too much Biblical investment in a historical Adam to ignore the idea of an historical Adam - - but, who also see that there is so much scientific evidence supporting an ancient Earth, or the common descent of humans from the primate branch of the animal kingdom, that they struggle with anxiety or indecision regarding the possibility that they are misinterpreting what they see in the Bible vs. what they see in the scientific record.

So, right away, @pevaquark, we don’t expect every Creationist to find the “Geneal.Adam” scenario as answering a need.

But the scenario does do two things:

[1] In years past, I would attempt to dissuade a Creationist from accepting the notion of Original Sin. I would try to persuade my audience that if millions of Eastern Orthodox Christians can thrive without any reference to Original Sin, they could too! The problem, of course, is that Western Creationists are very keen on Original Sin - - and they can’t imagine letting it go. [Frankly, it’s like Western Christianity is an entirely different religion!]

So now I don’t even have to struggle with a Creationist who adheres to Original Sin. It is no longer a point of contention between us (this is part of the “Peaceful” thing of PeacefulScience.Org). If they want Original Sin, they can have it!

[2] And the other thing that “Geneal.Adam” does is provide an intermediate point in the Creation/Evolution spectrum which is much closer to conventional Creationist views. Let’s suppose a Creationist has a choice between attending two different “coffee cake” sessions, sponsored by Christians in the science professions, on how to interpret the Bible regarding Creationism versus Evolution:

(a) one session will focus on how Adam and Eve can be seen as “figurative” or “allegorical figures”;

(b) and the other session starts with the idea that God used special creation to create just one man and one woman (in the midst of a pre-existing population of evolved humans)! In relative terms, this is such a tiny episode of God’s miraculous power there is really no way for science to definitively say it could never have happened.

This is quite analogous to the millions of modern Christians who don’t let Mary’s birth of Jesus (or His resurrection) interfere with their reliance on, and confidence in, Science. Adding one more amazing, but still tiny, miracle of God creating just 2 humans, is not nearly the same as the usual Creationist who throws the entire corpus of physics, chemistry and biology out the window… because he thinks he has to oppose any idea that animals evolved in order to justify Original Sin.

Conclusion?:

Peva, you know plenty of Creationists personally, right? Even hard-core Creationists, right? Do you think that even the most militant of Creationists would prefer to go to the gathering where the starting point is “Adam is really just an allegory!” Or do you think they would be rather intrigued by the opportunity to speak with Christians who already accept the idea that at least Adam and Eve were specially created?

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This is a false dichotomy. There are a lot of different options and issues, which include…

  1. Adam and Eve are just an allegory or metaphor.
  2. Adam and Eve were actual people who lived at some time.
  3. The story of Adam and Eve is one of events which happened but rather than being a literal account of these events is told with considerable symbolism
  4. The story of Adam and Eve happened exactly as told with magical fruit giving knowledge and eternal life.
  5. Adam and Eve were golems of dust and flesh created by magical powers.
  6. Adam and Eve are the sole genetic progenitors of the human race.
  7. Adam and Eve existed exactly when the Bible says about 6000 years ago.

Even an evolutionist may not be too thrilled about number 1 if they are a Christian. I am in favor of 2 and 3, opposed to 4 and 5, think 6 is inconsistent with the evidence and therefore unreasonable, while I see no problem with the possibility that 7 is correct.

@mitchellmckain,

I see that Quibilation is still one of your favorite art forms.

My point was not that there are only two choices. My point was that the two choices represent the more common points of congregation.

As to your gradations of the full spectrum … I’m sure we could spend time developing even more nuanced distinctions:

[1]====||====||====||====||====||====||====||====||====||====[10]
1 . . . . . . . . . 3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 . . .4|6|7
Alleg.Figur. Historical

As for your “5”, you are seriously suggesting that Adam and Eve is actually not magical
enough, and that the Eden story is a veiled reference to magical (but historical!) Golems?

The problem with your typologies is that you are assigning just one feature to each of your
scenarios. For example, “6” is Adam/Eve are the sole genetic progenitors of the human
race… while “7” represents perfect historicity (I guess). While some would say “6” would be
part of “7” (if they don’t think Genesis is convincing that Adam was the first human ever.

But I am an example of someone who embraces 2,3, and 7 but not the others. Other combinations are possible and I am not sure I can list all the combinations possible. 1 is probably standalone, and 2 goes along with all the others, but just about any combination of 3, 4, and 5 looks possible. It seems that those who like 6 will discard 7 because the objective evidence cannot agree with both, and it is precisely because I reject 6 that I see no reason why 7 cannot be correct.

The evidence I see in both science and the Bible is that Adam and Eve were never the only homo-sapiens on the planet. And rather than being the product of a magic or design shaping them from dust or bone, Adam and Eve are a product of self-organization also known as evolution.

@mitchellmckain,

And you have every right to all these schemes.

As I was explaining earlier, “Geneal.Adam” addresses a certain need… a need, put at the simplest of all levels, is that Adam/Eve can be specially created by God without requiring a massive wholesale rejection of scientific evidence for the evolution of humans from the primate branch of the Animal kingdom.

With this minimal stance, you can fit many different scenarios to “Geneal.Adam”.

The only thing that won’t make much sense is to attempt to get Geneal.Adam to embrace the rejection of some well structured or coherent area of science.

But no doubt there will be some who want to do just that…

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Kind of like the revival of the mitochondrial barcode hype…

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I’m still not quite sure how one even goes from genetic entropy to fitness and correlates such fitness to the length of life and gets some kind of decay to -1.4322 power as a theoretical model.

Of course! It explains how the many species we have today came from the much smaller number of kinds from Noah’s Ark. That’s the origin of species by means of natural selection and is quite in keeping with observed science. Just don’t extrapolate beyond the evidence to infer that everything is descended from a single (or only a few) common ancestor(s).

@aarceng

If I promise not to extrapolate to the idea that everything is descended from a single common ancestor, will you accept the idea that humans evolved from the primate branch of the Animal Kingdom?

There is a MOUNTAIN of evidence for that … and you can still hold that Adam and Eve were made by special creation !!!

Ah George, you know that as a YEC I have a prior commitment to a separate creation for Adam & Eve distinct from the primates.

@aarceng,

But you have a problem; actually, a couple of them:

  1. You have to jettison a huge amount of naturally evident demonstrations not only of the antiquity of the Earth, but that whole groups of animals have genetic legacies that can only be interpreted as common descent.

  2. You don’t have a very good explanation for who mated with the offspring of Adam & Eve - - intertwined with who thought Cain was in danger from, for whom he built a city, and how did humans get all their genetic diversity if there was a single mated pair any time within the last 500,000 years!

  3. All you need is Adam/Eve, just 2 humans, specially created by God.

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