“Fisher’s Proof of Darwinism Has Been Flipped” paper is making waves – Twitter displeased

I just saw Bill B's post, which furthered anything I was going to say. PaV PaV

[This discussion has been given its own post: Fisher’s Proof of Darwinism Flipped: William Basener replies to Bob O’Hara - News] Bob O'H, RE 17: Your question regarding the mutation rate we used in the paper is pertinent. As you stated it has long been known that a high mutation rate can lead to decline in fitness while a low mutation rate allows for adaptation, observed in biological populations and mutation-selection models in the literature discussed in Section 2.2 (differential equations with an infinite-population). Thank you for the good question. The mutation rate used in the paper is 1 mutation per generation. As with all the parameters in the paper we chose this parameter so that if there is any bias, the parameter selection favors selection and increasing fitness. This is in the mathematics in the paper, but you are certainly correct that we did not state this as the mutation rate and that would have been helpful to readers. In the math, Equation 5.1 for $f_{i,j}$ is the probability distribution provided by Kimura to estimate the effect of a single mutation on fitness. We modify this distribution to add beneficial mutations (at a rate and magnitude that are greater than observed estimates), and this is used as the net effect of all mutations for $f_{i,j}$ in Equation 3.2. Anyone who wishes to explore parameters can use the JavaScript simulation I posted at my RIT web page (referenced in the paper): https://people.rit.edu/wfbsma/evolutionary%20dynamics/EvolutionaryModel.html This was used to create the figures in the paper, and thus provides full transparency and opportunity to validate/reproduce/modify our results. I agree with you that it would have been nice to go further with the math, and done an exploration of the parameters space. But the paper is at 34 pages, and we wanted to provide proper support for the model (hence the beefy literature review in Section 2) and give proper context with regards to Fisher. I think you and I agree that determining behavior for parameters spanning the space of realistic values is an important next step. I think it would beneficial to have multiple different groups explore results for varying parameters. Bill B

Bob, Thanks for the response. tribune7

tribune7 - It would only be significant if the mutation rate was in the region where the corollary broke down. The general point that high mutation rates are bad has been known for decades (see work on mutation-selection balance). FWIW, I don't think anyone would doubt that the modern synthesis can’t fully explain the development of life. If it could, evolutionary biology research would be a lot less interesting. Bob O'H

Bob, there are some regions of the parameter space where the mutations reduce fitness in the long term, and others where it increases fitness OK, I accept that and if they are using the corollary as a strawman it makes for an interesting thing to discuss during slow afternoons but if it has been disproved isn't that significant and doesn't it imply that the modern synthesis can't fully explain the development of life? tribune7

tribune7 - this is how they describe the corollary:

. Fisher only accounted for new mutations using informal thought experiments. In order to analyze Fisher’s Theorem we found it necessary to define the informal mutational element of his work as Fisher’s Corollary, which was never actually proven.

So the corollary is due to Basener & Sandford. Depending on how they define it, it might be falsified, or it might not: there are some regions of the parameter space where the mutations reduce fitness in the long term, and others where it increases fitness. Unfortunately, B & S don't explore the parameter space. Their corollary is a strawman (which is fine, as long as they use it as such), and had already been disproved. Bob O'H

In his informal corollary, Fisher essentially assumed that new mutations arose with a nearly normal distribution – with an equal proportion of good and bad mutations (so mutations would have a net fitness effect of zero). Is this true and is this true? We now know that the vast majority of mutations in the functional genome are harmful, and that beneficial mutations are vanishingly rare. If yes, why would someone argue that the corollary has not been falsified? tribune7

tjguy - The maths isn't troubling (except that I' sure they could have gone further). The simulation section shows that fitness can decrease, but we already knew this. Basener & Sanford don't say what mutation rate they use though. It's obvious, I think, that the paper will be used to claim that mutations mean that evolution can't work, so it's a shame they don't provide such an important parameter. Bob O'H

Further analysis indicates that realistic rates and distributions of mutations make sustained fitness gain [of a population] extremely problematic, while fitness decline becomes more probable.

Worth remembering that the definition of "fitness" is "differential reproductive success". The fitness of a population, therefore, is simply a measure of whether or not it's approaching extinction, rather than some measure of whether it's evolving in some interesting direction. So "fitness decline" means "declining population". Jon Garvey

An acquaintance of mine said this in response to this paper: "What this means for the science of evolution is clear if you read the original article. It takes the original model of Fisher (known to be unrealistic) and re-proves the result with more realistic assumptions and limitations." In essence, he is claiming it is no big deal for evolution. Does it really "re-prove" the result with more realistic assumptions and limitations? Any opinions? https://link.springer.com/article/10.1007/s00285-017-1190-x tjguy

Sanford speaks for himself: https://creation.com/genetic-entropy kairosfocus

https://hort.cals.cornell.edu/people/john-sanford kairosfocus

While you're waiting for an answer to your question, rvb8, I thought I'd pop by to remind you that we never did receive an answer from a question posed here multiple times to you. As an atheist without a Moral Lawgiver, isn't it completely reasonable and practical to process aborted fetuses into a nourishing and highly compatible protein food source that could be used to save the lives of millions of starving people in the world? Plus, why shouldn't they be used as a plentiful source for organ transplants and medical research? Just wondering. -Q Querius

I've just googled Sanford. Interesting chap. Was an atheist, tried theistic evolution, OEC, then YEC, before settling on ID. Good for him. Is he considered a feather in ID's cap? rvb8

Fisher’s Theorem proves only that selection improves a population’s fitness until selection exhausts the initial genetic variation, at which point selective progress ceases. Which makes perfect sense. tribune7

Is it fair to say John Sanford accomplished more with his invention of the gene gun than Bob O'Hara, Elizabeth Liddle, and their combined family trees have accomplished in their entire existence? I'd say it is. While they sit and bicker on the Internet, desperately defending an badly-outdated idea solely because their atheistic religion depends upon on it (spoiler: you're fooling no one), men like John Sanford have progressed humanity's knowledge. For that, I stand up and applaud Mr. Sanford. And for Bob and Liz? I fart in your general directions. Jammer

kf - Sorry, which comments page? Bob O'H

BO'H: I was remarking about the comments page out there (which reacted like that -- you didn't you spoke about links), I guess I was too compressed in my remark. KF kairosfocus

Does any of this matter in corporate-funded, post-modern 'science' ? They appear to have a very ancient, time-honoured watch-word : 'A little of what you fancy does you good.' Well, in their case, a lot that tickles their fancy. Axel

kf - I am well aware who Sanford is. Bob O'H

F/N: Key clip from the summary page, for comment:

The authors of the new paper realized that one of Fisher’s pivotal assumptions was clearly false, and in fact was falsified many decades ago. In his informal corollary, Fisher essentially assumed that new mutations arose with a nearly normal distribution – with an equal proportion of good and bad mutations (so mutations would have a net fitness effect of zero). We now know that the vast majority of mutations in the functional genome are harmful, and that beneficial mutations are vanishingly rare. The simple fact that Fisher’s premise was wrong, falsifies Fisher’s corollary. Without Fisher’s corollary – Fisher’s Theorem proves only that selection improves a population’s fitness until selection exhausts the initial genetic variation, at which point selective progress ceases. Apart from his corollary, Fisher’s Theorem only shows that within an initial population with variant genetic alleles, there is limited selective progress followed by terminal stasis. Since we now know that the vast majority of mutations are deleterious, therefore we can no longer assume that the mutations and natural selection will lead to increasing fitness. For example, if all mutations were deleterious, it should be obvious that fitness would always decline, and the rate of decline would be proportional to the severity and rate of the deleterious mutations. To correct Fisher’s Theorem, the authors of the new paper needed to reformulate Fisher’s mathematical model. The problems with Fisher’s theorem were that; 1) it was initially formulated in a way that did not allow for any type of dynamical analysis; 2) it did not account for new mutations; and 3) it consequently did not consider the net fitness effect of new mutations. The newly formulated version of Fisher’s theorem has now been mathematically proven. It is shown to yield identical results as the original formulation, when using the original formulation’s assumptions (no mutations). The new theorem incorporates two competing factors: a) the effect of natural selection, which consistently drives fitness upward); and b) the effect of new mutations, which consistently drive fitness downward). It is shown that the actual efficiency of natural selection and the actual rate and distribution of new mutations determines whether a population’s fitness will increase or decrease over time. Further analysis indicates that realistic rates and distributions of mutations make sustained fitness gain extremely problematic, while fitness decline becomes more probable. The authors observe that the more realistic the parameters, the more likely fitness decline becomes. The new paper seems to have turned Fisher’s Theorem upside down, and with it, the entire neo-Darwinian paradigm.

KF kairosfocus

The first resort -- dismiss "Creationists" as incompetent invaders. It evidently has not registered who Sanford is (or is it was?). kairosfocus

Thanks for the heads-up, Bob O'H, problem believed corrected. Anyway, link: https://springeropen.altmetric.com/details/28653916/twitter Good thing that wasn't the whole point of the post News

Um, the "Twitter doesn’t like the paper." link goes to Sandford's homepage. So you've borked the whole point of the post. :-( Bob O'H