The Instigator
Pro (for)
5 Points
The Contender
Con (against)
9 Points

Mutations would eventually lead to the extinction of a species

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Voting Style: Open Point System: 7 Point
Started: 12/27/2012 Category: Science
Updated: 5 years ago Status: Post Voting Period
Viewed: 4,746 times Debate No: 28674
Debate Rounds (5)
Comments (10)
Votes (4)




This debate was conceived of before my starting the thread in the forum.

The full resolution is: "Mutations (along with Natural Selection) would eventually lead to the extinction of a species as opposed to it evolving or retaining population size."

The debate rounds shall be in this manner:
R1: Acceptance
R2: Opening arguments, No direct rebuttals, Rebuttals can be made in the form of creating one"s own arguments.
R3-4: Arguments
R5: No new arguments. Solely rebuttals.

Debate Rules:
1. Words shall be taken in their most contextual definition as defined by
2. Arguments that are not refuted/dropped (In a particular round) will not be counted as concessions. If the argument is not picked up again or refuted by the end of the debate, it will be counted as a concession. It is the burden of the debater to ensure that a dropped argument remains dropped.
3. Common conduct rules will apply.
4. Sources should preferably be posted into the 8000 character limit. TinyUrl or a direction to the comment section is allowed, but discouraged.

Debate format:
8000 characters
2 weeks voting
5 rounds
72 hours to reply
Voters will be required to comment


Challenge accepted.

I wish the best to my opponent and look forward to a truly fascinating debat.
Debate Round No. 1


I would like to thank Citrakayah for accepting this debate. I hope it will be intellectually stimulating.

Before we go anywhere, I will need to clarify two terms that are of great importance to this debate. Specifically, we are referring to the decline of the human species, since the human genome is the most studied, and even similar phenotypical organisms like most apes have not been sequenced to any practical extent.
Genetic Information does not refer to shannon information.
Mutations are changes in the nucleotide bases of a genetic sequence causing a distortion of the original genetic information. By definition, any mutation causes “new information” in that it has created a new allele. There are several types of mutations which I will not go into.

There are three main categories in which mutations can be classified in relation to their distortion of the genetic information:

The mutations at 1 of these categories of site are assumed to be neutral, whereas mutations at the other sites are assumed to be strongly deleterious, neutral, or advantageous...”[1]

This quote is partially wrong in that in the section of neutral, there are actually very few neutral mutations. Most mutations are nearly neutral, either in a deleterious or beneficial way. (See Kondrashov [2]) Mutations are regarded as “contaminations” in that they distort the “pure” information of the genome.

Mutations are known to cause most of the diseases humans experience [3], besides already being degenerational to the genetic information.

The Cost of Mutation is too High
It is widely held that the genome encodes information. Hence, any mutation, by definition, is “new information.” Is this mutation beneficial? Or is it deleterious? Mutations rarely are beneficial.
In the overwhelming percentages [4] of cases, mutations causes a loss of fitness, in that it is deleterious, sometimes to the point of lethality, to the organism’s genetic information [1].

In every human individual (The most widely studied genome), there are about 100-200 new mutations,[5] besides any mutations they might already have inherited.

In fact, populations face a risk of extinction simply due to fixation of reverse as well as deleterious mutations.

“For a given effective population size, the selection coefficient that maximizes the rate of erosion of mean Malthusian fitness, obtained from delta(sR)=deltas = 0, is the solution of 2Nes + e-2Nes = 1 ors = 0:797=(2Ne). Thus, nearly neutral mutations, with s slightly less than 1/(2Ne), do the most damage to the population...

Nearly neutral mutations that maximize the rate of erosion of mean Malthusian fitness also minimize the expected time to extinction. For 2Nes> 1, the expected time to extinction increases almost exponentially with Ne with a constant selection coefficient...

[T]he required number of loci fixed for mildly deleterious mutations to cause extinction is only a small fraction of the total number of loci...

[M]any mutations, such as large deletions of unique DNA sequence, are not reversible...” [6]

The amount of large deletions is surprisingly large. Quite a few examples have been discovered, and each of these deletions are of the order of hundreds to thousands of base pairs. [7] These deletions of beneficial information usually leads to the extinction of the organism and occurs not too infrequently. It is estimated that deletions occur in 1/7000 live births, which is a stunningly large number.

Taking into account deleterious mutations alone (Not natural selection or drifts, or any other degradational mutations), Kondrashov A.S. has estimated that humans would have died out 100 times over within just the time evolution allows for humans to have been around. [2] This forces us to consider two explanations.

I. The humans will go extinct within the next five millennia. (Based on a variety of estimates that I will not source here)
II. There is a reversing agent to deleterious mutations that will not allow for the extinction of the population.

It is obvious that there is experimental support for (I) but not for (II). It is thus logical to assume that I must occur. (Bacterial populations are far more resistant to deleterious mutations than humans due to their fast reproductive rate, but that does not mean that they will not eventually die out. See [4])

As such, experiments support the idea that mutations will be the death of organisms.

The Cost of Selection too high
It has been suggested that selection via a variety of means could counteract the relentless degradation by mutation. In fact, one of the major explanations is known as recombination. It is thought that by having a large enough population which can have their sequences recombined by reproduction would reduce and maybe even nullify the harmful nett effect of mutation.

Recombination has several problems which I will go into. Any beneficial mutations which would have overridden the effects from the dozens of slightly degradational mutations would not be capable of being selected for. This phenomena is known as genetic linkage, where chunks of DNA is inherited while retaining the status quo in the offspring. Genes tend to clump together in linkage blocks. This means simply that the beneficial and deleterious mutations are banded together and as such deleterious mutations cancel out the beneficial mutations. Even if these clumps can be split up, each individual gene and its accompanying regulatory DNA would have the same problem, thus this problem is insurmountable. (See citations, and ENCODE papers, too many to source)

Loewe L. has estimated from mutations just from within the mtDNA (Which has remained mostly intact)would have caused humans to go extinct within 20 million years.[8] However, if all known genetic data is taken into account, ie. the fact that deleterious mutations occur in all other regions besides the mtDNA, the time t becomes vanishingly small.

I am not saying here that some degradational mutations cannot be counteracted, but that the total amount cannot be counteracted, leading to extinction.

There has been some notion that these only occur in small populations. This is not so. In fact, Loewe and Kondrashov has shown that it applies to the fairly large human population. Even worse is the fact that the time to extinction is much shorter in small populations. The human population is not a homogeneous population in that it has many smaller sub-populations that each have their own new set of mutations that cause the independent genetic decay of these sub-population leading to the overall extinction of the greater human population. This is an irreversible fact of science.

I will not in this debate go into the "fudging" effect of noise on the genome. With that, I eagerly await to see Con's no doubt fascinating opening. I hope to learn even more of the genome from this debate.

1. (Mol Biol Evol (2008) 25 (6): 1007-1015.)
2. (J Theor Biol. 1995 Aug 21;175(4):583-94.)
3. (Genetics February 1, 2012 vol. 190no. 2 295-304)
4. (PNAS June 1, 2004 vol. 101 no. 228396-8401)
5. (Genetics September 1, 2000 vol. 156 no. 1 297-304)
6. (Genetica 102/103: 21–27, 1998.)
7. (Clancy, S. & Shaw, K. (2008) DNA deletion and duplication and the associated genetic disorders. Nature Education 1(1))
8. (Genetical Research / Volume 87 / Issue 02 / April 2006, pp 133-159)


A note: I shall abbreviate my points C1, C2, C3, etc, and shall abbreviate Muted’s points P1, P2, P3, etc. Though not in this round for the latter. I would also note that I believe my opponent is describing Muller’s ratchet.

C1: Many mutations are only ‘harmful’ or ‘beneficial’ in regards to the environment. For instance, a variation in the CCR5 receptor increases the risk of a nasty case of malaria, but decreases the risk of various other diseases—for instance, AIDS (in fact, a significant percentage of the Caucasian population is immune to AIDS as a result of the Black Death)[1]. If mutation X confers vulnerability to disease Y but resistance to disease Z, it will be selected against in areas with disease Y and without disease Z, selected for in areas with disease Z but not disease Y, and either selected for or selected against (depending on which disease is more predominant/severe/affected by the mutation) in areas with both disease Y and disease Z.

Now, deliberately moving to a place with fewer harmful diseases might be evidence of planning and intelligence, but deliberately moving isn’t necessary. If a species has a large population and a large range, different phenotypes or genotypes may ‘migrate’ over generations to areas where they are more suited.

C2. Relatively few mutations are deleterious. Nachman and Crowell estimated about three deleterious mutations out of one hundred seventy-five in each generation of humans[2].

C3: Labs have bred many, many generations of various species, ranging from bacteria to fruit flies. Many of these organisms have extremely short reproductive cycles. In the lack of conscious effort to prevent such populations from going extinct, we face the question of why they haven’t. If we can expect humans to go extinct within the next five thousand years due to mutations and natural selection, why do we not see fruit fly cultures regularly dropping dead because of mutations and natural selection? Why do we not see cricket cultures, or flour beetle cultures, or guppy populations, dropping dead?

Now, one might argue that all these populations have one thing in common: They are captive, and humans interfere with their evolution. However, this objection misses two points. Firstly, humans are perfectly willing to interfere in their own evolution. If we are to going extinct, we are probably going to put up quite a fight—far more of a fight than we would put up to save a fruit fly culture. Secondly, there are wild populations of fruit flies, and flour beetles, and guppies, and crickets, and we do not see them going extinct for these reasons.

A second objection would be that fast reproduction rates allow this to be avoided. I would like more detail on how this would work.

C4: Not all of the genome is actually used—junk DNA is famous here. A mutation here would, indeed, be a mutation, but would be truly neutral, since the DNA is not ‘useful’. Various hypotheses have been put forth that would have ‘junk DNA’ be of some use, but since .1% of the mouse genome was deleted without apparent effect on the phenotype, we can safely say that enough is useless[3].

C5: Recombination. Sexual reproduction and horizontal gene transfer allows Muller’s ratchet to be avoided. For such a deletion mutation to be carried into the offspring, both parents would have to have the same deletion mutation. Otherwise recombination would deal with the problem[4].

Indeed, this has been demonstrated using experimental evidence. A population of ciliates decreased due to Muller’s ratchet. When they were allowed to have sex, the ratchet stopped[5].



3. M.A. Nobrega, Y. Zhu, I. Plajzer-Frick, V. Afzal and E.M. Rubin (2004). "Megabase deletions of gene deserts result in viable mice". Nature 431 (7011): 988–993. Bibcode 2004Natur.431..988N. doi:10.1038/nature03022. PMID 15496924.



Debate Round No. 2


Thanks to Con for a concise opening. I will begin by clarifying that Loewe was using Muller’s ratchet, which is a theory of recombination. I will endeavour to use the same format as him.

Addressing Con's arguments (Which does not prohibit extinction)
C1: This contention has nothing at all to do with my argument. In fact, in regards to fitness in relation to environmental conditions, Con is correct. However, my argument is based on the fact that the genome codes for specific information, and that any mutation would degenerate the information within. This is widely accepted and thought everywhere. I will await a rebuttal of this before strengthening it. Also see my point regarding population size.

C2: The source cited by Con was from 2000, my earlier source 4 is from 2004. From [R2: 4], it can be clearly seen that almost 40% of mutations (Including deleterious, but mostly just degradational) are lethal. Also, it is a known fact that slightly deleterious mutations accumulate in the genome, because they cannot be selected against, and are correlated strongly with large mammal extinction.[1] (VSDM only, not other types of mutations which I described in the previous round)

I will put this point to rest. There are several categories of mutations. Very slightly degradational/deleterious/beneficial mutations cannot be selected for/against. Only that which is strongly effective can be selected. As such, small effect mutations (relatively few mutations have no effect) have the ability to contaminate the whole population before attaining sufficient power to cause a species to go extinct. (See [1] and sources of previous round, all of which expound on this) Con’s source actually talks about lethally and highly effective mutations, but ignore VSDM. (Let D stand for deleterious or degradational, depending on circumstances)

C3: This has no source. Nonetheless, I will address it. The first objection is actually a strawman of normal objections. This objection only works for objective breeding, which has serious ethical considerations in terms of humans. To keep the human population from degenerating further than it already has, scientists have estimated the need to terminate (kill) one-third of the population. This is just to retain information, not to increase it in any way. (See R2 citations)

For example, in plant breeding, a truncation line is drawn at a certain level in the list of plants, in terms of their fitness [2]. This obviously cannot be done for humans without serious ethical considerations. However, some have already written about the termination of humans. [3 for a discussion on the ethicality of genetic manipulation]

The second objection has been thoroughly dealt with in [1]. Inside, it is shown that sexual recombination, or “shuffling” in the genome, delay the extinction in fast reproducing populations, but not in humans. Also, consider that in smaller genomes, or rather simpler genomes, a change in a single bp is more likely to be affected by natural selection than is those in a more complex genome (like that of humans). Hence, VSDM have lesser impact (Not to say there is none, see R1:4) on simpler organisms.

C4: Con has brought up the infamous “junk DNA” argument. This argument has thoroughly been debunked by the ENCODE project, which has shown that the so called “junk DNA” is actually 50 times more active than coding DNA. It has since been renamed “regulatory DNA.”[4] This is not in any way a “hypothesis,” since it has been experimentally verified.

Note that Con’s example in no way overturns this internationally collaborated research. Furthermore, it in no way overturns my arguments, which state that it usually is lethal.

One more thing to note. Con’s source actually describes a case of deletion of redundant genes, or genes which have had a knockdown before. In fact, in the majority of cases, enough to cause extinction, deletions of this kind is known to be deadly. (See previous round)

Con may object that by this “falsification” example, the theory of genetic extinction is bogus. In fact, this is not so. Let us suppose that if there are 15 hypothetical cases of unique deletions, and one of them is non-lethal, does this mean that the other 14 organisms will survive? Experimental evidence points to the contrary. (See previous round citations)

C5: Con’s point does not at all address the problem of linkage blocks. In fact, Loewe L. (who did his paper in 2006, as opposed to Choi’s 1990) found that Muller’s ratchet is devastating to humans, which reproduce sexually. It is thus evident that Muller’s ratchet does not “cease” to work in terms of sexual reproduction. In fact, sexual reproduction only serves to slow down the process. Con must show that extinction is impossible in terms of mutation and genetics.

Strengthening Pro Arguments
There has been vast experimental support for the fact that mutations will lead to extinction. In fact, even if we assume that 98% of the genome is “junk,” which it is not, Loewe L has shown that extinction will occur via Muller’s ratchet acting on just the mtDNA, which is a coding region of the DNA. In fact, it is the smallest of all the chromosomes, coding for the fewest genes and having the least base pairs. If we took the same mutation rates, which does not differ by much, and include all the other coding regions, (not to include the regulatory DNA, which Con considers, despite vast evidence to the contrary, junk DNA,) it would still lead to species extinction.

Con’s points do not in any way address the fact that species on Earth will meet death by mutation. In fact, even if all of his current points are correct, it will still leave me with the Loewe L, Kondrashov, etc. papers which all work within the limits of his objections to show that mutations do indeed lead to extinction. Con must provide counters which are relevant to my arguments.

Back to Con. I hope he will think outside of TalkOrigins and for the intellectually stimulating part!

1. (PNAS August 14, 2007 vol. 104 no. 33)
2. (doi:10.2135/cropsci2007.04.0191Vol. 48 No. 2, p. 391-407) (See other crop breeding sources as well)
3. (Annu. Rev. Genet. 2001. 35:785–800)
4. (ENCODE website)


A Note: I have, indeed, not replied to the Kondrashov paper, which I do believe is the crux of Pro’s argument. This is in large part because so far ly been able to access the abstract, and thus do not know if Kondrashov answers his own question.

C1: This point is of utmost importance. Firstly, if a mutation is beneficial or deleterious in regards to environment, and environment can change, that introduces a new variable into the question of whether or not a population will go extinct.

Secondly, and as an addendum, there is a difference between recessive and dominant genes. For example, sickle-cell anemia is caused by two copies of a recessive allele. With this in mind, we might ask why it hasn’t been completely removed, or at the very least is far less common. The reason is simple—a single copy confers resistance to malaria[1].

The point to all this is that mutations are not nearly as clear-cut as Pro’s argument makes them out to be. The same mutation can be negative in one situation and positive in another, or it can be positive in conjunction with another mutation and negative without that mutation.

There’s another point, too. In a population, (at the risk of simplifying) traits are selected against for two reasons: they do not replicate as well as their peers (examples, in species, can be seen in native species of frog in Australia, or some species of rat on an island in the middle of nowhere that I forget the name of), or they are so drastically unsuited for the area that they simply cannot survive (dinosaurs after the KT extinction). If everybody really is getting weaker, then one of the primary sources of selection isn’t going to affect the population.

C2: Correction: 40% of mutations in a specific population of viruses were lethal (see Con’s source). These are also, for that matter, RNA viruses rather than DNA viruses, and humans have DNA rather than RNA. In lieu of another measurement regarding the percentage of harmful mutations in humans (since we are talking about humans, not RNA viruses), my study trumps.

I might also add that while more recent studies are generally better, a true comparison should take into account things like sample size, sampling techniques, et cetera.

C3: False. They could also be sterilized. Given the choice between total extinction (with severe suffering along the way) and sterilizing one third of the population, the latter choice seems like a valid alternative.

In any event, not all captive populations are objectively bred. Namely, experimental populations are not (often) objectively bred. The same, to the best of my knowledge, applies to cricket/mealworm/fruit fly cultures bred for food (in the case of herptiles). This inevitably raises the question of why we don’t see such extinctions—even counting the delaying effect Pro mentions, given the vastly sped up breeding cycle, we would still expect to see Muller’s ratchet.

C4: And yet about 20% of that DNA is still not known to serve any function, even with ENCODE’s data[2]. If mutations are randomly distributed, that means about 20% of the time a mutation has neither a beneficial or harmful effect. Another estimate puts it at 40% being useful, which means there is a 3/5 chance that a mutation has no significant effect[3].

C5: Speaking of Loewe, he also did another paper on Amazonian mollies. His analysis, using a simple model of Muller’s ratchet, found that Amazonian mollies, should, by all rights, have died out within the time period they are believed to have evolved[4]. Given that they very clearly haven’t, there are several explanations:

  1. The paleontological record is very, very, very wrong.

  2. Muller’s ratchet is incomplete, or at least the simple model is.

  3. There is something else avoiding Muller’s ratchet.

Loewe hypothesizes the existence of the third. For instance, incorporation of DNA from sexual sister species and compensatory mutations could help to explain this.

This is a common thread among papers discussing the concept. For instance, Michael Lynch, when discussing mutational meltdowns (a similar phenomenon)[5], noted that while mutational meltdowns (basically the same thing as Muller’s ratchet, really, at least for our purposes) that it is a serious risk for asexual populations—this is because ignoring back mutations, a parent experiencing no recombination of segregation can never produce offspring with fewer deleterious mutations than it carries. Recombination avoids this, by allowing two parents with deleterious mutations the possibility to produce offspring with fewer deleterious mutations. This is vitally important, because of the ‘best class’ of individuals in a population, there is always the chance that some will not reproduce or will produce progeny with new mutations, thus causing the class to be lost eventually. Erosion, if you will.

P1: Recent data displays a germline bottleneck[6] in mitochondria, which has a net effect of resisting genetic decay. At the very least this can slow down Muller’s ratchet, but it could also potentially slow it down enough for beneficial mutations to keep mitochondria viable indefinitely.







Debate Round No. 3


While it is true that I am arguing based on Kondrashov’s abstract, it is not true that it is the crux of my arguments. Although to answer Con’s question, no, Kondrashov did not conclusively answer his question. In the abstract, he clearly gives a short description of several possible reasons, none of which were followed up on, or have experimental support.

“This paradox cannot be resolved by invoking beneficial mutations or environmental fluctuations. Several possible resolutions are considered, including soft selection and synergistic epistasis among very slightly deleterious mutations.” (Kondrashov)

Neither explanation has experimental support in the real world. For one, Kondrashov was criticised heavily for not sticking to real world parameters for his epistasis argument by MacCarthy and Bergman [1]. The former explanation, soft selection, fails in real-world terms as well because a supervising agent is needed to “soft select” for a particular trait. [2] Hence both explanations were termed “possible” by Kondrashov.

Con graces my argument with only one point when in fact, it is much more than one point. He has made a far too hasty rebuttal of my points. His arguments against me are speculative at best, and not within real-world parameters either. I have given strong experimental support for my arguments, with which he deems a hypothetical, un-real-world like parameter-ed, with no experimental support, explanation is sufficient to refute. As such, I have to extend my arguments here.

C1: This point is talking about phenotypical fitness and not genetical fitness. In fact, even if a population were to successfully breed, the combined effects of degradational mutations will lead to a phenomena known as “mutational meltdown,” about which my argument is all about. As such, this point is a mute point and should remain so. Phenotypical fitness=/=genetic fitness.

The point about relative benefit is actually false in terms of genetics, but true in turns of phenotype for reasons I have already stated in the preceding rounds and in the following. (The problems with recombination have all been addressed in the earlier rounds) Even Kondrashov acknowledges the fact that environmental arguments will not do.

C2: My opponent makes a grave mistake of logic and facts here. RNA is a nucleic acid, just like DNA. [3] In fact, this is such a well recognized fact that even Wikipedia has an entry on it. I will make this clear. Humans have RNA as well as DNA. As can be easily seen from my source, the two studies can correlate easily. I will not go into the calculations. Why would DNA viruses be accepted while RNA viruses are not?

Going back to the TO entry. The entry’s logic is in the fact that since beneficial mutations are of a higher percentage than previously thought, then beneficial mutations outweigh degradational mutations. This in fact contradicts the Nachman study, which I will cite. [4] It clearly gives no space to that idea. Now, from Con’s study, it is clear that degradational mutations outweigh beneficial mutations by factors of magnitude. Don’t talk about environment. That has been refuted thoroughly earlier.

C3: I cited three different new sources for this point alone. All Con has to offer is a hypothetical and unethical objection. Stating the word “False” prominently does not indicate the falsity of my objections. It merely states Con’s opinions on the matter. It is illogical for him to state that a faster reproductive cycle would reduce the delaying effect when the faster reproductive cycle is cited as the cause of the delaying effect. In the next round, I would request that Con actually provide a source for this point, or else I will drop it as it is purely hypothetical.

C4: Actually, my opponent’s argument in no way contradicts my own! In fact, this is what I have been arguing for all along. Most mutations having no significant effect, but being an accumulative phenomena, this is widely held and experimentally supported even by Con’s sources. As such, I would like to know why Con is still arguing this point.

C5: There are several things that I would like to point out that would mean that I have to extend my arguments here.

I: There is no experimental support for (3). This is as obvious as the sun.
II: Con has entirely ignored the fact that humans reproduce sexually. Going off-tangent to something about mutational meltdown does not at all prevent Muller’s ratchet from happening. In Loewe’s paper, he clearly states that he calculated the extinction time for humans. He calculated the date solely from mutation/recombination rates in the mtDNA, the smallest chromosome. Humans definitely exhibit recombination, but that is not enough to stop extinction, which I explained in tedious detail in the previous rounds. Pushing back the date of extinction does not lead to no-extinction, which Con is supposed to be arguing for. It still will lead to extinction. I am imposing no time frame to the time of extinction here. If indeed extinction can be experimentally argued against, then I most certainly welcome such an argument.

Summary of Con Points
1/5 of Con’s points does not at all work in terms of genetics. 3/5 of Con points actually are hypothetical, and the remaining point agrees with my own arguments.

I find it of worth to note that Con has brought up arguments which in no way refutes the argument that species will eventually go extinct. At best, his arguments will work against a 6000 years old world. However, that is not what I am arguing for/against. My argument centers solely on the fact that genetic degradation will lead to extinction, against which he has not provided an argument showing it indeed is not so either of his own making, or through a study. At best he has merely shown that extinction can be delayed. Well, so what? Still death will find us.

I hope Con will not be offended by my somewhat feisty arguments. I mean no disrespect.

1. (Proc Natl Acad Sci U S A. 2007 July 31; 104(31): 12801–12806.)

2. (Genetics August 2009 vol. 182 no. 41387-1389)

3. (Wikipedia Entry on RNA)

4. (Genetics September 1, 2000 vol. 156 no. 1 297-304)



If Pro does not have the full text of the article, then it is impossible to know whether or not Kondrashov actually did answer his own question. For that matter, it may also be that someone else has answered Kondrashov's question. And, of course, humans are a special case, given that we put a great deal of effort into making sure as many members of our species survive if at all possible, even if they ordinarily wouldn't.

C1: The two are quite related. Negative mutations, even if they have no effect on the organism itself, can have an effect on the offspring. For instance, if I develop a mutation that leads to trait X, but it does not manifest because it is recessive, my offspring are at risk for having trait X.

Now, Pro says that any mutation 'degrades the information'. False. Whether or not the information is degraded depends on the mutation. If it is beneficial, it is 'upgraded'. If it is neutral/environment-dependent, it is simply 'replaced' with something that works in different circumstances or is little different. If it is harmful, it is 'downgraded'.

Pro's argument that linkage blocks prohibit selection against harmful traits is mistaken. Firstly, any given linkage block has a probability of forming, rather than being a certainty. Therefore, the presence of a specific block can be selected against. Two adjacent loci are very likely to be inherited together, but since it isn’t certain, members of the species with the beneficial mutation but not the negative one would be selected for.

Secondly, Pro’s argument assumes that positive mutations will necessarily form linkage blocks with negative ones with a high enough frequency to cause such an accumulation of negative mutations as to render the population unviable.

C2: Yes, but the information is conserved in DNA for humans. Furthermore, RNA viruses mutate very quickly: they evolve six times faster than human DNA[1]. In any event, I didn’t say that DNA viruses would be acceptable but RNA viruses would not. I said that the fact that 40% of mutations in RNA viruses in a single experiment were lethal does not tell us very much about the frequency of lethal mutations in humans.

C3: Hey, sterilization’s a lot better than termination or dooming millions to live with severe congenital illnesses. I would, by the way, like both a source and an explanation by Pro for how, exactly, a fast reproductive cycle is supposed to delay this, rather than simply speeding it up. Pro’s source talks about body mass, and the resultant effects on population size—namely, species with large body mass have fewer members, thus leading to increased risk of mutational meltdown.

C4: Because you can’t add zero and zero and get one. If a mutation affects part of the genome that has no function, then the mutation is meaningless. Not ‘very slightly deleterious’. Not ‘causes trait X in conjunction with gene Y’.

Disregarding nonfunctional DNA, if the effect is so slight that only in conjunction with other traits it can be selected against, these ‘groups’ of mutations will be weeded out.

C5: There’s a great deal of support for three. Loewe mentioned that in his paper. Pro says there is no experimental support for three, but is wrong here as well, albeit indirectly.

We know from a great deal of evidence that species are very, very old, at least compared to the time in which various sources Pro has cited say they should have gone extinct. We know that Muller’s ratchet and mutational meltdown can apply to populations (this is why genetic diversity is so important in endangered species[2]).

Now, here Pro says that you can’t slow down the ratchet enough to stave off extinction indefinitely. False. It’s quite easy, because Muller’s ratchet relies on irreversibility—it isn’t a true ratchet in organisms with sexual reproduction. The whole point of Muller’s ratchet is that when you have asexual organisms reproducing, and they do not undergo recombination, you can never have offspring with fewer mutations, but in sexual reproduction you can—you can put together non-mutated areas of the genome.

This isn’t always enough to avert Muller’s ratchet, because if the ratchet is turning at two ‘clicks’ each generation and turning back only one ‘click’, that’s still one net ‘click’. But if it turns back a number of ‘clicks’ equal or greater to the number of ‘clicks’ forward, Muller’s ratchet can be avoided. Thus preventing extinction.

Debate Round No. 4


Con has dismissed all of my arguments simply on the grounds that I am unable to access the full Kondrashov article. This is not so. Note that I have listed the two ways in which Kondrashov has answered his own question and have shown them to be wanting, he was even critiqued for his answers. If someone else indeed has answered the question, let Con cite him. I don’t see that anywhere.

As the focus has since shifted from my arguments to his points, I will let it be.

C1: Con once again is speaking phenotypically. I have shown that such is irrelevant to this debate. Even were one to have all fit phenotypes possible, genetic degradation will still occur.

Con actually strawmans my argument here. Not all mutations degrade the genome. Most do. The very few that “upgrade” the genome were estimated from Nachman (R4:4). Indeed, such mutations occur. However, they are not in a large enough quantity, even though they may be more than thought. Hence, overall genetic degradation occur.

Con is right that linkage blocks have a probability of forming with certain genes. This in fact does not oppose what I have said in any way. A linkage block with more degradational mutations than beneficial ones has the greatest probability of happening. This has been calculated multiple times through mutation rates, etc. (See previous round citations) As such, our arguments do not contradict here. In fact, even if in Con’s hypothetical case, a specific linkage block has no degradational mutations, that still leaves out all the other degradational mutations to the other linkage blocks, unless, of course, Con is willing to delete the rest of the genome. (See problems with deletion in above rounds) In fact, even if Con’s hypothetical case is right on every single possible point here, he will still be incapable of giving an explanation of how to remove degradational mutations from inside a specific gene. Gene splicing maybe?

C2: Con is correct on everything here. I see not how my arguments have been refuted in any way! See above round for explanation of why Nachman et. al. does not refute my arguments.

C3: I have already given an explanation for the delaying effect. Con does not like it, Con does not refute it.

C4: Once again, this does not contradict my own. Like I said above, even if 98% of the genome was non-functional, Loewe L has shown that humans will still become extinct. (See C5 for discussion on the falsity of the proposed explanation, which will lead the readers to the above rounds)

C5: I have conclusively shown in the last round that this “explanation” by Con has no experimental basis. Not only is recombination limited by both linkage blocks (see above) as well as the percentages of each category of mutation. It is highly disconcerting that if Con is right, then Loewe is wrong. There is no alternative between the two. I have already said at least twice in this debate that humans reproduce sexually. Loewe was calculating the time to extinction for humans, not some asexually reproducing organism. Con may indeed argue that Loewe did not indeed use a true ratchet, but I’m not so sure about that. Con has basically argued that his hypothetical recombination case, with no known experimental support, is indeed itself the experimental support for explanation (3). This is not so for the many reasons I gave throughout the debate.

I am certain that Loewe mentions several possible retarding factors on the ratchet, but as far as I’m aware, he has not provided any experimental evidence for his case. He even mentioned that there are several possible solutions. He has indicated that future research might solve the riddle, but after six years and more papers from him, none actually do solve the problem. Now, Con might say that there is a solution. These solutions, however, have no experimental support, like Loewe mentioned in the paper. Indeed, he does mention possible solution, but show them to have no experimental support.

Con’s argument still fails the recombination hurdle, which I explained in detail in the previous round.

I have thus shown that mutation will lead to the extinction of the human population within 20 million years, from 2006. Notice that the calculation does not begin with the start of humans, but from the present. Hence, Con’s objections regarding oldness of species means absolutely nothing to this debate.


I will strongly urge a Pro vote for these reasons:

Con has not provided any explanation for a retarding factor on degradational genomics outside of the hypothetical and no-experimental support areas.

In more than one instance, Con has not contradicted my arguments. In fact, he actually strengthened them

The whole debate centers around Loewe’s paper. Loewe has shown that humans will go extinct. Now, Con first tried to argue that junk-DNA would stop extinction by reducing the total degradational mutation rate, but I showed that the mtDNA is not junk. Instead, it is part of the coding regions. Con has not provided a good counter to this.

I have shown that Con strawmans my argument on one occasion. It is a minor strawman, but a straw man nonetheless.

I would request that voters vote solely based on information within this debate only.

I would like to thank Citrakayah for accepting and going through this fascinating debate with me.



The error here is the word ‘the’ in the phrase ‘the two ways’. Kondrashov uses the word ‘including’ thus we left with the question as to whether or not the full article contains further possibilities. I would also point out that at least one of Pro’s ‘critiques’ contained little to no mention of Kondrashov’s answers.

I’m also going to break from my formatting right now.

Overall, this debate rests on two foundations:

  1. Muller’s ratchet. Or, more accurately, the existence of something like it (in this case, a ratchet that can be turned backwards as well as forwards) that affects sexual populations.

  2. That this ratchet-like process will move faster forwards rather than backwards and thus cause all species to go extinct (not just humans).

Without these two foundations, or pillars, the argument collapses.

It’s fairly easy to knock down the second pillar in the case of humans. The chance that we would use some form of eugenics to keep ourselves from going extinct is hardly remote, whether it is unethical is another debate entirely (while I’m acutely aware of the slippery slope, I regard it as preferable to allowing a process of extinction that would result in great pain and suffering for many generations along the way). But humans are a special case, since we have genetic knowledge and gene sequencing. Rather, let’s look at a wild population of species <em>X</em>. It can be pretty much identical to us, but it doesn’t have our technology and medicine.

This ratchet-like mechanism demands that rate h, the rate of accumulation of harmful mutations, outpaces rate b, the rate of beneficial mutations (neutral mutations, which are, for reasons I’ve already stated, pretty common, are ignored here, as are environmental-dependent ones). Moreover, it demands that this be, at the very least, a highly common occurrence, if not a universal one. Now, to say that this ratchet-like mechanism exists and will cause the extinction of species as opposed to survival or evolution is a pretty extraordinary claim, and thus requires some pretty convincing evidence. Pro says that he has, and I’ll let his arguments stand for themselves rather than summarizing them.

Pro admits that the mechanisms I proposed can slow down the ratchet. He claims that they’re hypothetical and lack experimental support; I’ll let the reader determine the truth of that. In any event, though, since this isn’t a true ratchet, we only have to slow rate h down rather than stop it if we want rate b to be larger than rate <em>h</em>. The question, then, becomes, how far can we slow it down? I’ve given a variety of options for slowing the ratchet down, and will summarize them below.

  1. Genetic recombination. Contrary to Pro’s assertions, it is a valuable asset here, as I have repeatedly explained. Even a linkage block with more negative mutations than beneficial ones can be an asset of sorts—it allows negative mutations to be more efficiently filtered out by natural selection. The randomization inherent in recombination allows the chance for a generation to have fewer harmful traits, and fewer harmful genes, than the previous generation. The ratchet slows. And, in this case, the ratchet can reverse.

  2. As I’ve already explained, a good portion of the DNA is actually useless (I don’t know why Pro seems to think I’m referring to mtDNA here). This allows mutations to be truly, absolutely neutral. The ratchet slows.

  3. Purifying selection can and will weed out particularly harmful mutations before they become too prominent in the population, at least in populations of significant size. The ratchet slows.

The question, then, is whether or not the ratchet has slowed down enough for rate b to be equal to or greater than rate h. Maybe it has and maybe it hasn't, but Pro has given us no reason to think it hasn't, and thus has not fulfille his burden of proof.

My thanks to Muted for the debate. It was most stimulating.

Debate Round No. 5
10 comments have been posted on this debate. Showing 1 through 10 records.
Posted by wiploc 5 years ago

- Five rounds is a lot to ask people to read, unless you are sure that both participants are lucid and diligent, and that you won't just be rehashing already-covered points in the latter rounds.

- Pro had grammar problems, worse than Con's. But they rarely impeded comprehension, so I'll not give points for S&G.

- Pro claims that we each have 100 to 200 mutations, and that 40% of those are lethal. The obvious conclusion is that everyone reading this debate is dead. But, we aren't dead. Therefore, we know that Pro is wrong and Con is right. Victory must go to Con.

- Pro claims that live lasts only 20,000 years before extinction. In that case, life ended shortly after it began, millions of years ago. Or, as Con wittily put it: "The paleontological record is very, very, very wrong." The obvious conclusion, if Pro is right, is that none of the people reading this debate exists. But, we do exist. Therefore, Pro is wrong an Con is right. Victory must go to Con.

- Pro's sources and arguments are abstruse arcana. I can't follow them. He could be misrepresenting his sources, or quoting crazy people. I don't know what's going on. All I know is that we aren't all dead; therefore, Pro is wrong.

- Suppose Pro argued that all highways end after twenty miles. That's like arguing that all life ends after 20,000 years. All you'd have to do to refute him is drive 21 miles, or look at the paleontological record. If the conclusion of an argument is clearly false, one need not know whether the problem is invalidity or false premises. An argument with a false conclusion is necessarily unsound.

- Why would Pro try to convince us we're all dead? It's very strange. It's interesting that Con takes him seriously.

- The parties keep referring C1, C2 etc. If it's too much bother for them to put useful labels on their arguments, they should assume that it will be too much work for readers to scroll up over and over again to see the subjects.
Posted by morgan2252 5 years ago
Sometimes the character limit gets in the way...
I HATE when you have more to say than what the debate allows you to.
Posted by Citrakayah 5 years ago
This marks the first time I've run up against the character limit.
Posted by Citrakayah 5 years ago
But you managed to find the whole article?
Posted by Muted 5 years ago
I first got notice of it by reading Sanford's "Genetic Entropy," (Not cited in debate) where he did little other than cite it. He didn't actually quote or reference anything out of it. However, at the time I did not search for his article. When I began this debate, a few weeks after finishing the book, I recalled the article, and so I was specifically looking for something to make my case, which, by the way, is quite different from arguments presented by Sanford.
Posted by Muted 5 years ago
I'm sorry, not small, "slightly"
Posted by Muted 5 years ago
Search on Google Scholar, "Very small deleterious mutations." After several pages, you will find it.
Posted by Citrakayah 5 years ago
Out of curiosity, how did you get the Kardashov paper?
Posted by Muted 5 years ago
In regards to my selection argument, I did not plagiarize since I did not check out any source for the selection argument.
4 votes have been placed for this debate. Showing 1 through 4 records.
Vote Placed by drafterman 5 years ago
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Reasons for voting decision: I think the crux here was the fact that evaluation of mutations as beneficial or negative depends on environmental factors. Thus, even if Pro showed that mutations which are currently negative, even lethal, and would lead to human extinction, he'd have to show that they would remain lethal - that is, that the environmental factors which make them lethal would remain static. I do not see that Pro adequately refuted environmental factors.
Vote Placed by AshleysTrueLove 5 years ago
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Reasons for voting decision: Muted had a slight advantage in arguments because he rightly points out things that are not adequately answered by Citradkayah, also some of what muted said in last round was not answered at all by Citra. Muted points out that mutations are inconsitant with neo-darwinian evolution. Pro has many more, and better sources.
Vote Placed by morgan2252 5 years ago
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Reasons for voting decision: Both sides had good conduct and similar spelling and grammar. Both sides had sources. However, I felt that con's argument was more convincing for two reasons: (1) He points out that if humans would have died out 100 times over within just the time evolution allows for humans to have been around, why hasn't it happened to humans or other animals? (2) Because of natural selection, the human race wouldn't have died out because either the organism wouldn't be able to reproduce or wouldn't survive. It wouldn't get a chance to pass on it's deadly genetics. Even if lethal mutations are as common as pro claims, it would lead to the death of that organism, not to the entire species.
Vote Placed by wiploc 5 years ago
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Reasons for voting decision: RFD in comments.