The time scale of the bottleneck?

(Randy) #81

That’s interesting–maybe we can have a thread on Marcion sometime. Enns has an interesting posting about him and his nuances. There’s a trend among many Christians now to downplay the OT (and I have a gut sympathy with them too, though not necessarily agreeing in everything.).

(Mitchell W McKain) #82

I was simply using this term for the modern homo-sapiens subspecies as distinguished from the Neanderthal. I suppose science has now identified another subspecies called the idaltu, and may identify more in the future.

I should be clear that I personally don’t consider any of these genetic differences in subspecies to be significant in the distinction between human and non-human. It is just that I consider Adam and Eve to be much more recent than any of this, so I would assume that they are of whatever subspecies survived.

But I was also saying that we cannot exclude the idea that some people may have of a subspecies like the Cro-magnon being very small in numbers at one time among a population of composed of other subspecies since these others subspecies could still contributed to the gene pool of modern humans.


Please explain all the problems with my previous use of “Christians.”

(Mitchell W McKain) #84

Already did that here in a discussion with someone else.

Please reply in that thread if you must.


I said problems with MY previous use of “Christians.” So you should point to some previous post.

(Mitchell W McKain) #86

…sigh… I tried… The first paragraph remains applicable. Christianity is a spectrum of beliefs. I absolutely refute that you have any authority to restrict Christianity to what you believe.

previous post?

(George Brooks) #87


In reference to your first quote (above):
A “not so tight” bottleneck has long been discussed regarding homo sapiens… but still in the thousands of individuals, not in the population equals “2”, “3” or even “12” range. If you want to explore something, check out the papers that discuss a bottleneck of 15 or 20 individuals that survived the walk across the Bering Straight into the Americas… now that is interesting. But even here, there were still other migrations that are believed to have supplemented diversity in the Americas.

In reference to your 2nd quote … “that small”?:
There is no rule of biology that says: “… new species have to become as sparse as less than a dozen individuals before a new species is allowed to form.”

Over time, evolution affects entire populations, or sub-groups of populations. Though the smaller the population becomes during stressful environmental changes, the faster adaptations can eventually permeate an entire surviving population.

(Mitchell W McKain) #88

Nevertheless, you cannot get around the fact that mutations START with a single individual. And there is no rule saying that a single gene mutation has to have only a small effect.

However, I remind you that I am NOT arguing that this is the case with Adam. I do not believe this. I merely suggest that honesty should admit the scientific facts, regardless of what one may believe.

(George Brooks) #89


Admitting facts is one thing; but creating the impression that facts are impugned automatically seems counter-productive.

(Chris) #90

Is there genetic evidence that no-one has ever lived 930 years? What would that evidence look like? Can you look at a genome and predict lifespan from it? I don’t think there is genetic support either way and we don’t have genetic samples from any of the long lived patriarchs for comparison anyway.

However as has been noted by John Sanford among others the lifespans of the patriarchs follows a biological decay curve “so it doesn’t look like the authors of genesis just pulled out a bunch of random numbers here”.
(* Down - Not Up, from about the 9:30 mark)

(Matthew Pevarnik) #91

Got a plot handy? I’m also not aware ‘biological decay curves,’ can you provide an example of what you mean?

(Chris) #92

At about 10:20 in the link. That’s why I provided it.



You might want to take a look at this which points out several problems with the “biological decay curve”.

(Matthew Pevarnik) #95

I watched it. And he plots generations after Noah vs. lifespan and it follows an inverse 1.4322 power law. Why that much? Is there any Biological reason why that should be the case? There is no biology at all there or any explanation of why this particular graph other than later ‘mutations.’ Is there any such thing as a ‘biological decay law?’ My internet search mostly turned up Dr. Sanford’s own writings-meaning he made up the term unless I just didn’t dig far enough.

What actually would constitute a scientific explanation would be what? Being able to theoretically describe the graph we see - what mutations are occurring that lower the lifespan along a 1.4322 inverse power law? Why does the curve tend to level out at Jesus - and why does he put Jesus on there at all. Jesus was killed presumably much earlier than he would have lived otherwise so Jesus should not fit the plot all! Can you help me think through this better @aarceng as it seems rather void of any real substance.

(Chris) #96

@Bill_II, thanks for the link to Confounding the Patriarchs. It’s worthwhile tracking back to find“Genetic Entropy Recorded in the Bible?" (His link is broken so I have provided a new one). This explains the reasoning of Dr. John Sanford, Jim Pamplin & Christopher Rupe in more detail, including relative fitness calculated using Mendel’s Accountant.

However after reading it I think Sanford et al might have made a mistake by not including a change that occurred with Noah’s Flood where "Then the Lord said, “My spirit shall not abide in mortals forever, for they are flesh; their days shall be one hundred twenty years.” Genesis 6:3. So we see after the flood a marked decline in lifespans so that by 20 generations they are reduced to 120 years.

I think this also mostly answers the comment by @pevaquark


@aarceng Looking for the effects of natural selection after only 200 generations may not be allowing for enough time. Given humans populate the entire globe I doubt any single mutation could spread through the entire or even most of the human population in that amount of time. Interesting question for someone who does population studies of which there are a few around here. I have also always suspected that since humans support the sick and infirm members of the population that natural selection may not work in exactly the same manner as it does in other species.

Bottom line is it appears Dr. Sanford has cherry picked his data and then created a pretty chart which actually tells you nothing.

Edit to add: In looking around I found a youtube video on how to fit data to a power law curve. Using purely made up data a rather nice looking curve was generated so it is not a surprise that Dr. Sanford could create a curve that fit the ages in the Bible.

Here’s a link that points out the problems with Dr. Sanford’s Mendel’s Accountant software.

(George Brooks) #98


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.

(Chris) #99

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.

(Matthew Pevarnik) #100

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.

(George Brooks) #101


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”.