Comments on "Heliocentric Certainty Against a Bottleneck of Two"?


#21

They were not considering the type of bottleneck that Buggs is proposing: very brief, very sharp, and followed by rapid exponential expansion.

And I agree. There is no evidence for it. The question, however, is if there is evidence against it. It is possible there is no evidence for or against a bottleneck with exponential expansion.

I’ve never aimed to demonstrate a bottleneck. If what we are uncovering here is valid, such an attempt would be impossible. We would not expected evidence one way or another (except maybe Ayala’s…).


#22

I thought that’s exactly what was being tested by the paper which said “There is no evidence for an exponential expansion out of a bottlenecked founding population, and an effective population size of approximately 10,000 has been maintained.”

If that is the case then we should not be basing theological arguments on it, but that’s exactly what people are doing.


#23

Bottleneck in that sentence is a different type of bottleneck than proposed by Buggs. It’s a subtle distinction, which is why I missed it at first. But it could be a valid distinction. That’s what we are hashing out.

That’s a different conversation. Theological concerns don’t change the math. At least they shouldn’t.


#24

What kind of bottleneck is it?

Let’s remember that the entire aim of this investigation is actually theological. This was not a scientifically motivated study.


#25

That is a lot of very impressive material to digest. As you may remember, I don’t think there was ever a bottleneck of two, but I ask what is next out of curiosity. Many if not most scientists in what I guess I should call genetic anthropology believe that there was limited but detectable admixture with non-humans around 55,000 years ago. For example my genetic testing identified 1.5% of my genome as “Neanderthal”. East Asians tend to have marginally higher amounts. Sub-Saharan Africans much lower. And a few isolated groups have even higher contributions from another hominid. In each case, apparently the percentages were higher in the past, and mostly somewhat deleterious as evolution is weeding out most of the non-human “contribution” to Homo Sapiens over time.

My question is this, wouldn’t this set of genes, which are different enough from the human versions to show a result of much greater than 495K years for a “common ancestor” gene, skew the results of your calculations older? I mean if it measured a group of 50 genes and 48 of them were calculated to have a MRCA of 150K ago but the other two - which were introgressed from non-humans- had a MRCA of 1.5 Million years ago then wouldn’t the average be driven upward in a misleading fashion by the limited contribution of the archaic material?


#26

In general, yes. That is why we used a median estimate of TMR4A instead of (for example) the max or mean. The median estimate is only going to minimally affected by this. If 10% of the genome is subject to interbreeding artifacts, for example, we’d only expect that would increase the estimate by about 20 kya. So no this ends up not being a large source of error.


#27

At the moment, there are edits being privately proposed to this statement.

How do you think it should be written?


#28

I’d write it mostly the way you wrote it since that appears to be what the numbers say. I would change this sentence

Is the assumption “that humans share common ancestry with apes,” even strictly necessary to determine your numbers since you are comparing diversity in humans with the rate of mutation in humans? Even if it was a part of the calculations of some of the research which you drew data from, I see it as superfluous and a potential distraction from your actual findings. I don’t see where it is essential that your team assume that in order to get the numbers that you did.

Regarding the phrase “God has not intervened with physical miracles” I think I would be way more specific. Something like “We assume God has not intervened in a super-natural way so as to give a false appearance of age to the genetic data.” I think your results are going to be dismissed as based on invalid assumptions by those who believe in miracles unless you phrase it in such a way that you are only assuming He won’t do any miracles which are outside His character.

The only thing else I might suggest, and maybe this is the next study and not this one, is that you address the idea that a flood wiped out all Y-chromosomes except for one sometime long after Adam. If your MRCA for just Y-chromosomes also shows a date in the distant past, it might be worthwhile to point that out. There is not just the question of the nature of Adam to consider, but the flood and Noah as well.


#29

Hi Joshua,

By and large, I’m pretty happy with the statement. Regarding the controverted sentence, “We have assumed that humans share common ancestry with apes, and that God has not intervened with physical miracles,” I’d write: “We have assumed that humans share common ancestry with apes, and we assume by default that God has not supernaturally altered our DNA since the time when the line leading to humans diverged from the line leading to the apes that are most closely related to us.” How does that sound?