Testing Jeanson's Model: Y Chromosome Mutation Rates

Yeah, but that is bacteria. This level of per-generation mutation in humans (or any large mammal) is unheard of at this time.


For the between-species comparison, you also have to include the coalescence time within the ancestral population, which is a large effect.


Sure, but there doesn’t seem to be any reason why such an increased rate couldn’t evolve in principle.

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It is hard to imagine a complex organism that wouldn’t be at a mutation catastrophe with such high mutation rates. In principle, I do see prohibitive negative selection against hypermutators.


Yes that would increase their mutational load quickly, and thus would explain why such high mutation rates don’t persist for any extended period of time(either the species goes extinct, or selection manages to bring the rate back down). It is my understanding that the mutation rate of any given species reflects some balance between historical population size(and thus variance in the balance between selection and drift) and mutation load. Larry Moran had a good post about this on his sandwalk blog: https://sandwalk.blogspot.com/2016/12/learning-about-modern-evolutionary.html

Curiously(or, accordingly), even in the LTEE the hypermutator lineages are actually evolving reductions in their elevated mutation rates(*). But my only point was really that, biochemically speaking, the causes of hypermutability could happen in large multicellular eukaryotes such as humans, too.

(*) See https://www.pnas.org/content/110/1/222.short


Isn’t that actually the contention of the “genetic entropy” clowns? Sanford, and that lot? I recall it being pointed out that if they were right, lineages with shorter generation times ought to have gone extinct a long while ago, so that we would be living in a rat-free world, among other things.


It’s also being done because sequencing is so much less expensive and easier these days… It’s kinda like picking the low hanging fruit.

It works out all the time in the Marvel Universe. They frequently get superpowers plus side effects that make it difficult to get dates for a Friday evening. So, predominantly adverse mutations but with interesting phenotypes.


This review paper from 2016 alone has 11 pedigree studies. We can certainly be sure that many more studies have been done since then. Notice that the date on Jeanson’s study is 2019, which means there is just no excuse for not including the 11 papers in this review.

These are whole genome studies, which will also include Y-Chromosome. Even if they don’t state the Y-Chromosome rates directly, the supplementary information or a simple email to the authors will usually be enough to get that subset of the results/data.


It would also be impossible to reconcile with pretty much everything else we know from those fields.

Which just further shows the degree of Jeanson’s hubris (great word choice, @thoughtful!) in claiming that he has demonstrated this thru his study that he published on a creationists website. This finding would be almost Einsteinian in its importance, in the sense that we would have to rethink almost everything we think we know about biology to accommodate this finding.

Of course, the real answer is simple. Jeason is wrong.

BTW, I am usually skeptical of the utility of the “Peaceful Science” approach, but this discussion is a model example of the form. If all sides of the discussion participate with a genuine attitude of openmindedness and objectivity, then this is what can happen. So my thanks to you, @thoughtful.


Because males have a higher mutation rate than females, because there are more cell replications for male gametes than female gametes. Y chromosome spends all its time in males, and X chromosome spends most it’s time in females. Autosomes are 50/50 between the two. That explains the divergence patterns between human/chimp Y vs. X vs. autosome chromosomes and the difference in mutation rates too.


Thank you, that makes sense. I was confused by the wording. I interpreted “the Y chromosome has a higher mutation rate” to mean “compared to autosomal chromosomes in men,” which I’m guessing is not the case. Rather, all chromosomes in men have a higher mutation rate than all chromosomes in women, but the average autosomal mutation rate (which represents the rate for chromosomes from both men and women) is lower. Is that correct?
I didn’t know this and will add it to my lectures. In my Human Biology class we discuss autosomal vs sex linked chromosome disorders.


Check out how I used it in this presentation: Livestream: How I Changed My Mind on Evolution.

Approximately. As always, the real story is more complex.

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One interesting consequence @stlyankeefan is that about 95% of the variation of de novo mutation rates between individuals is related to paternal age, but not maternal age. That’s a pretty cool result, that follows directly from understanding the mechanism.


Happy to start conversations even though I understand very little of what people are talking about, since I’m not a scientist. It’s still interesting :slight_smile:


Sometimes this graphic helps to get the point across:


You get your mitochondria from just one of your great grandparents. Does this mean you only had one great grandparent? Obviously not. There were 8 people (4 women) who contributed* to your genome, and they were all contemporaries.

*ghost ancestors are a real thing, just using a generalization


I did not explain in this thread that Jeanson claims his mutation rate fits accepted historical population growth rates, and it fits far better than what’s considered to be true about mutation right now. I was curious if anyone had actually delved into the argument to notice that, or had just dismissed it out of hand and not gotten that far. I was playing devil’s advocate a bit. Just checking back here, it doesn’t look like anyone had gotten that far.

Yes, it would be extremely important to medicine.

Jeanson’s claims about the mutation rate have been analyzed in detail and rejected. @Evograd posted up earlier about reviewing Jeanson’s claims.


I’m puzzled: what do mutation rates have to do with population growth rates?

Jeanson’s mutation rates are inconsistent with almost all estimates. He has cherry-picked a few sources, and he has inappropriately applied the rate in one part of the mitochondrial genome to the entire genome. That’s all been mentioned above.


That’s just false. Totally false. He even agrees this is false, because he uses a mutation rate around 50x more than the currently accepted rate.

Yes, we’ve covered it in depth serveral times on this forum, including this thread.