No, Sanford is showing that the trend must be down, not up. When extinction happens is a totally different question.
You mean after all the information in the genome has been totally changed by mutations? Okay… extinction will obviously happen long before that point.
The shape of the curve physically cannot remain constant. As you go lower, the effects of mutations increase in magnitude, and the distribution moves more mutations into the beneficial category. This has to happen at the physical and biochemical level.
Diminishing returns epistasis, a demonstrably real empirical phenomenon, means that adding one more gene copy when you have few will matter a lot more than if you already have many. Increasing the catalytic rate by some X amount will matter much more as a proportion of total when the rate is low, than if the rate is high. Etc. etc.
Simultaneously, as you move closer to a fitness peak, you get closer to having exhausted the total pool of beneficial mutations, which lowers their subsequent probability of occurrence, which means more mutations shift from beneficial to deleterious. Conversely as you accumulate deleterious mutations and move further down in absolute fitness, now more mutations shift back into the beneficial category.
The scenario that GE entails is physically impossible. It cannot occur in reality. It is based on imagining a fixed spectrum of mutations under all circumstances. It is an imaginary mathematical abstraction that does not reflect the real physical reality we inhabit.
Even if one grants that the current DFE of mutations for most organisms look like you describe it, that would only tell us that most organisms are highly adapted, it would not follow from this that inevitable and indefinite fitness decline is the fate of any form of life, as the demonstrable reality of the physical phenomena I described would come into play.
Here are some references for the reality of these effects:
https://science.sciencemag.org/content/332/6034/1190.abstract
https://science.sciencemag.org/content/332/6034/1193.abstract
For the sake of the moderators, and as requested, I’m replying to you here from the other thread.
I don’t think I’ve read @Rumraket as saying we know specifically what the DFE for neutral mutations is. Just that more mutations (of all sorts) are deleterious than beneficial. This is clearly true, but doesn’t imply anything about the detailed DFE for neutrality.
For neutrality. Not for non-neutral mutations.
Neutrality just means drift is the dominant force, not that they are invisible to selection. Neutral mutations will accumulate, the question is the DFE for those mutations. Which we don’t know.
Humans, especially our ancestors, have had fairly low effective population sizes compared to, for instance, mice. This means that a greater percentage of mutations will be effectively neutral, as detailed by Keightley. As our effective population size increases, selection becomes more efficient and is able to remove what had previously accumulated as neutral mutations.
I don’t think he and I disagree on anything of note.
There are only so many non-selectable mutations possible in a genome. There is a lower limit to that trend.
No, after all the non-selectable mutations have occurred. The selectable deleterious mutations will be removed.
What often happens when a human blastocyst splits in two?
Whether extinctions happen, in this model, depends on whether the trend reaches equilibrium before the problem is serious enough to cause extinction.
No, that was a little bit of bait and switch on your part. The question isn’t regarding all the information in the genome, only the nearly neutral bits. Are there enough of them with a negative enough selection coefficient, to cause extinction before the system reaches equilibrium? You can’t say. On the other hand, the evidence that life has existed for billions of years says that the answer is “no”.
Thanks for responding to me here.
Ok. I guess I’ll let him answer that.
Looks like he did.
I haven’t seen these arguments supported by empirical evidence, or missed them, so please link me.
No what I meant. I meant missing the forest for a tree.
So since only the most modern data show a difference, we only have relaxed selective pressure now in the era we live in?
I’ll read it.
It is this sort of “spiritual blindness drives scientific study” thinking that is dispensed in churches on the creationist speaking circuit. This stands as a good example of why sanctimony and self-righteousness have never produced legitimate progress in the history of science.
In the case of the human genome, it seems that « there actually is a “wild-type” human genome—one in which most genes exist in an evolutionarily optimized form. There just are no “wild-type” humans: We each fall short of this Platonic ideal in our own distinctive ways ».
https://science.sciencemag.org/content/331/6019/872.3.full
Um, yeah. That’s talking about detectable, functional, selectable differences in genes. There is no question that humans are highly adapted, and that most individuals have largely optimal (or at least locally optimal) versions of those genes.
GE isn’t about that. It’s about undetectable, non-selectable differences in DNA. What GE doesn’t explain is why those mutations of that kind should consistently be deleterious.
In the absence of supporting data, right?
And how does Sanford know the trend must be downwards? I expect published papers showing this as your response.
Right. Either a theoretical argument, based on what we know about evolution and biochemistry, say, about what we should expect from nearly neutral mutations, or (better) evidence about the actual distribution of fitness effects, is required.
The claim that the trend would reach an equilibrium was exhaustively rebutted in the joint article.
Near-neutral is not a descriptor for the genome, or for the information therein. It is a descriptor for mutations.
Thought I’d repost these questions here since you “accidentally” forgot to give your answers in the other thread.
Please explain how you determined the information content in the genome is progressively declining. How did you measure the information content so you can tell if mutations make the content increase, decline, or stay the same?
Forgive me for getting a little off-topic here, but I have to take a moment to complement @PDPrice for not responding to Timothy_Horton’s continual prodding with such a glaring fallacy.
@Timothy_Horton, I’m certainly not an expert in this field, but even a layman like myself can spot the obvious here. I’m reminded of the quote from evolutionary geneticist Alexey Kondrashov regarding the contamination of the genome: “Why aren’t we dead 100 times over?”.
Here’s the point: If GE is true, then your 700,000 horse genome is a problem for you. As you’ve said yourself: " Why haven’t horses gone extinct from GE in 700,000 years?". GE causes you to question those 700,000 years. Which is one reason why this is such a debated topic! And why evolutionists will never stop fighting against GE.
I don’t want to speak for him, but I have a feeling PDPrice is not replying to you because he’d rather spend his time engaging elsewhere…
I long ago availed myself of the “mute” feature to deal with his continual trolling. You won’t escape it either unless you do the same.
No it doesn’t. We have literally millions of pieces of evidence Earth and life on it are way older than 6000 years. The sciences supporting radiometric dating are as well confirmed and validated as anything in science can be. Price and Sanford and Carter and the rest of the Creationists continually dodge and ignore such evidence because it kills their silly GE claims deader than fried chicken.
PD has a long history of dodging all scientific evidence he can’t explain. He does it to everyone who posts such evidence, I’m not special in that regard. He’s basically an intellectual coward.
Hand-waves aren’t rebuttals. If you compare genomes between distantly related species you will find a lot of differences in junk DNA. The chances of a human mutation reverting a base to the ancestral sequence is very probable.