According to this paper, the mean time is sqrt(N/s) for recessive beneficial alleles (conditional on fixation). Maybe 10,000 years for strong selection. The probability of fixation is sqrt(2s/πN) – maybe 0.2% for s=.1 and N=15,000.
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Is that assuming panmixis?
That doesn’t look right - if nothing else, it suggests that in small populations very slightly beneficial mutations take longer to fix than neutral ones.
Undoubtedly.
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That kind of approximation is typically only valid for some range of s and N.
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I am making changes as I go along to see if these are needed to make this model work and to take into account the problems you and others raise. As I’ve said before, I’m posting in this forum in order to receive this kind of feedback and to make the changes that are needed. But the basic model remains the same. I have also sometimes added alternate scenarios to point out that if one approach I take does not work, others will. If you find this objectionable, I do not see why. This produces the problem that you critique a particular scenario I offer and act as though that destroys the whole model. I’ll try to be clearer about this in the next post. I don’t see any justification for calling these modifications ad hoc. One allele does not confer greater intelligence with spiritual and moral consciousness. You haven’t been paying attention to what I’ve said.
I won’t be able to comment for a few weeks unless I get a time break in the next couple of weeks. For now the only thing more I can say is that I am assuming that Adam was homozygous with the last gene in the complex producing humanness. That means some predecessors had the last mutation but were not human because they did not have both. This allows us to more easily produce a scenario in which Eve is not Adam’s daughter, as I pointed out in the essay.
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What if it was dominant?
On the contrary. I’ve been paying close attention to what you say; perhaps what you say isn’t quite what you mean.
In that case Adam is not special; he’s just the first person in a population containing the recessive allele to become a homozygote. There would in that case be other independent events later. And of course not all Adam’s children or other descendants would be human. He would have to mate with a heterozygote in order for even half to be human. Are you saying that either Cain or Abel was probably not human?
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I’m assuming there was some point in making the allele recessive. But I don’t know what that point would be. I don’t think he’s said.
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I’m not sure about fully dominant, and I don’t have time to look much right now. If it’s additive (each allele contributes equally), then the mean time is 2ln(2N)/s, or 5000 years with the same parameters I’ve been using. Fully dominant will take longer. (Maybe as long as recessive – generally the time is symmetric as you go from additive toward either recessive or dominant.)
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Fully dominant should take longer, as the recessive allele can hang around in the population for a long, long time, only being selected against when by chance a homozygote arises. The lower the frequency, the lower the chance of encountering selection.
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Being the first to be homozygous with the recessive allele would be special. This would be the first person to be human and to have the human characteristics we’ve discussed. There could be a few others around in his or a previous generation who are heterozygous with the allele and thus it would not be expressed. Thus Eve could be descended from a couple of heterozygotes, she would be the first woman in the population with this allele to be a homozygote, and she wouldn’t have to be Adam’s daughter, sister, or mother; she could be more distantly related to Adam. This way Eve is truly human as well. As for everyone else in the population not descended from Adam who is heterozygous with the allele, those linages could die out without having anyone of those lines produce another homozygous individual. This of course, would require a bit of divine intervention or an extremely great amount of luck. Since this is a theistic model, I very greatly doubt God relied on luck. So here again, John, this model must resort to some degree of divine intervention.
Now A&E’s descendants could mate with the non-humans heterozygous with the human allele and those homozygous with the non-human allele. They would have human and non-human children (those humans who mate with non-humans having no copy of the human allele will have no human children). Since both A&E were homozygous, all of their children would be homozygous.
More about why recessive genes, the possibility of a first human, and the origin of monotheism when I get back. In my last post I said it would be a few weeks before I can post again. This is definitely my last post for a while. Enjoy the break from my comments.
Not special enough, because other people would be equally special.
Doesn’t that disagree with the Genesis story? I thought your purpose was to maintain the story.
They could, but it would take another miracle. How many miracles are you going for? Get enough miracles, and you might as well just postulate special creation. What is the advantage of your scheme vs. plain creationism?
What are you talking about? Figure 1B shows that ~55% of chimp alternatively spliced exons are the same as human AS exons, but this divergence is the smallest of the 10 vertebrates examines. This isn’t surprising, as humans and chimps are the closest relatives in the dataset. Indeed, the percentage of shared AS exons decreases with phylogenetic distance, just as I’d expect from evolution.
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We can quibble over this but there is quite a biochemical change here. My point is this needs an explanation eventually as we get more detailed understanding into what caused this change.
It’s not a “quibble” to point out that your claim that the divergence in AS exons between humans and chimps was the largest out of any 2 species in the dataset is blatantly wrong.
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What I meant to say is that the divergence is the largest of all the vertebrates if you look at adjacent neighbors. It is much greater than the change from frogs to chickens for instance. The reason I used “quibble” is that the real issue is explaining the magnitude of the change.
That’s still not right, because the divergence with all the other 8 species was greater. The graph shows the divergence from humans, you can’t compare the frog bar and the chicken bar as though that is indicative of the divergence between frogs and chickens.
Are you trying to say that the AS exon divergence was the greatest relative to divergence time? At least that would be accurate.
I am good with this. Thanks for the correction. I also think this data is tentative and we will learn more as time goes on.