Evolutionist please explain why a leading geneticist who is also a Professor of Biology states that most mutations are deleterious?

Question

Professor of Biology Micheal Lynch, Genome, Cell & Developmental Biology of Indiana University. He is not at creationist and Indiana.edu is not a creationist website (I know how you guys are).

On his profile page he gives an outline of his studies, papers, rewards and research. If you look under "The Role of Mutation in Evolution." He states , " Although mutations provide the ultimate material upon which natural selection depends, most mutations are deleterious, and in certain settings can lead to a substantial fitness load."

http://www.bio.indiana.edu/faculty/directory/profile.php?person=milynch

Every time I have made this claim that most mutations are deleterious I have been shot down by evolutionist and told I don't know what I'm talking about or that I got that from some creationist website. I've even even explained why most mutations are deleterious before only to be laughed out. I would like to know if any evolutionist can explain this away?

Answer 1

Why do people who oppose evolution think that these things have never before occurred to evolutionary biologists. Most mutations aredeleterious? Really? Well what a shock. A mutation is when a gene changes. Prior to the mutation the gene may have worked fine. So what would you expect a mutation to do other than cause harm. This is known and well understood. I note with interest the lengths you go to cite a professor who says that mutations are deleterious but provide not reference to the evolutionary biologists allegedly denying that most mutations are not harmful.



However, the adjective MUST be clearly noted. Most mutations are harmful. Most is NOT the same as all. Some mutations are neutral they have no effect. The genetic code is degenerate: more than one codon can code for the same amino acid. The mutation may produce the same protein or one that is so similar it makes no difference.



Some mutations confer benefits. That has why evolution takes so long. Beneficial mutations do not come along everyday. That is basically what evolution does. It sorts the good mutatations from the bad ones.



Again a very pedestrian question from an evolution denialist which I would expect an average 18 year old high school biology student to be able to dismiss. I constantly hope that one day the evolution denialists will pose a challenging question.

Answer 2

I see nothing to be surprised about in your question. I am just an ordinary person but that doesn't mean it is compulsory for me to be stupid. Ordinary people can read and understand stuff. I have no idea what you mean by 'an evolutionist'.



Since mutations are random it makes sense that at least half would not be beneficial. Even that fails to address the point because the impact of a mutation is related to the organism in which it occurs and the environment of that organism at that time. If a mutation has a negative effect for that organism in that environment, it is likely that the organism will be less able to compete or less able to reproduce so that 'unhelpful' mutation is less likely to be propagated.



If there is a change in the environment, a previously 'bad' mutation might actually offer some benefit. Nature constantly evolves so that organisms adapt to the prevailing environment. Those that do not adapt quickly enough die out.



Some 'bad' mutations persist where they are on a recessive gene and only become a problem if two carriers choose to reproduce. That is not uncommon.



In many cases, we can live with the consequences of a adverse mutation. For example, people with ginger/red hair are far more sensitive to ultra-violet light so they simply limit their exposure.



While most mutations are very likely to be deleterious, the mutations that survive are more likely to afford some advantage. I see no mystery in that and no need for banner waving or denial.

Answer 3

Actually, mutations could or could not be deleterious. If it occurs in an important site of our DNA such as in a gene or in a promotor (a region that controls expression of a gene), a mutation could have an effect on the phenotype, negative or positive. I hesitate to use positive/negative because lets say a mutation causes people to have purple eyes, this is not a negative thing, but neither is it positive. A change to purple eyes is just simply a change in the phenotype. However there are certainly some changes that can be negative in the genome, even deathly, but in actuality most mutations have NO effect. Less than 2% of our genome codes for DNA! That is a lot of non-coding regions that would not be affected by Also, every 3 bases codes for an amino acid in a protein, since the third base is variable a mutation in such a site would often still codes for the same amino acid and not change the resulting protein.



So to answer your question, most mutations actually have no effect on the phenotype. Some mutations do, but out of those only some can be truly be known as negative while the rest can be neutral or possibly even have a positive effect.

Answer 4

Biologists in general and geneticists in particular have been thinking and writing about this sort of thing for almost a hundred years. If there is anything that you can come up with that has not been thought about and probably experimented on already, up to 50 or more years ago then I'll burn my hat.



No "evolutionist" has ever seriously claimed that all or even most mutations are beneficial. Some have no effect and many are detrimental and some don't matter all that much.



There are 20 amino acids that are coded for by the RNA. There are four different nucleotides in RNA. It takes three of these codons to define an amino acid. A three-nucleotide sequence is called a codon. Since any codon may have each of the three nucleotide positions filled by any of the four codons, that means there are 4 x 4 x 4 combinations, that is, 64.



So 64 combinations code for 20 amino acids. Subtract 4 for codons that mean start and stop, and you have 60 doing the actual coding. Do you see that there are 40 codons that are not needed? Now, open a new tab on your computer and search for the "genetic code". You will find that in many cases changing the third nucleotide, or in four or so cases the first has no effect on the amino acid being coded. This is a "substitution mutation". Yes, this is still a mutation, and is called "a silent mutation" because it has no effect.



Now if you change the first or second nucleotide, you will mostly get a change in the amino acid. That might have some effect. However, all active proteins have structural regions and active regions, it does not matter whether they are enzymes, antibodies, cytokines, lymphokines, cell surface receptors, protein hormones etc.



What all these have in common is that it almost does not matter what the amino acid sequence of the structural region is, as long as it does not interfere with the active region. Even in the active regions, some "conservative substitutions" may be made, such as glycine for alanine or valine for leucine. These are only two of several such substitutions. which might be made without altering the activity of the enzyme, antibody etc very much. In these cases problems occur if the structural region interferes with the active region or if a non-conservative substitution happens in an active region.



This is particularly obvious in genes that code for basic structures such as body size, growth rates and bilateral symmetry. Many of these genes are highly conserved and while the structural regions may be highly varied in amino acid sequence, the active regions have remained functionally the same in organisms as varied as rice and humans.



Another example is the common use of insulin by diabetics. Until fairly recently, cow or pig insulin was used, and both of these differ from human insulin, yet they still worked. In about 1978 it was found how to make human insulin in microorganisms and most insulin is now genetically engineered human insulin from microorganisms. Yet "synthetic" insulin where one or two amino acids have been deliberately changed such as Lispro have some uses, such as quicker action or longer persistence in humans.



On top of all that, most proteins are coded for by RNA sequences that give a protein longer than needed. Bits at both ends may be clipped off before the protein is put to use. If the mutation is in the part clipped off, there is usually no effect.



Now another form of mutation is called a frameshift, which happens when a nucleotide is removed, this usually cannot be translated into a protein or if it can be, makes something unrelated to the original and by comparison is useless nonsense. Organisms that suffer badly from this often die before being born. In humans, this affects about 20 to 50% of conceptions, the embryo often dies before the woman is even aware she is pregnant. If you are born and survive infancy and childhood, congratulations, you are likely to be genetically good enough.



Evolution works on the few mutations that are either good enough, silent or a few beneficial ones.

Answer 5

Sure most mutations are deleterious. That's the whole point. The mutations that cause an animal to be abnormal in some way either don't survive in the womb or die shortly after birth. Just because a genetic mutation is deleterious doesn't mean that evolution can't take place using the mutations THAT GIVE AN ADVANTAGE TO AN ANIMAL OR PLANT IN SOME WAY.

Answer 6

What you're missing, is that in 3.5 billion years of mutations, that's a LOT of mutations. So what if most of them are deleterious? That's NOT the same as saying ALL of them are. You really only need a few that are beneficial--if they happen to occur in the "right" ones (e.g. homeotic genes), that's like getting over a hump of activation energy--a single master control gene may control expression of scores of downstream regulatory and structural genes, changing their developmental timing and/or location of expression. Since the 1980s there have been scores of homeotic mutations documented in flies, worms, mice, humans and other species. Throughout the long history of life on Earth, clearly enough beneficial ones occured to promote diversification. Remember that today, we only see the results of successful variation--the unsuccessful variation has been culled out. Mutations may also be neutral under prevailing environmental conditions, but at some later point may prove to be either deleterious or beneficial if there is a sufficient change in the environment.



You imply that "random" mutations are the sole source of genetic variation. That is 1930s-era thinking, and it is long obsolete 1) We've known for at least a decade, that mutations are not necessarily random--there are documented "hotspots" in the genome that are highly susceptible to mutation. 2) Mutations are not the sole source of genetic variation. Gene flow via horizontal gene transfer--even across phyla--is also important, as is the ordinary genetic shuffling resulting from recombination during generation of ova and sperm.



Finally, unguided genetic variation is only half the story. Selection is the other half, and that is NOT random. Particular environmental conditions determine whether a given type of variation is going to be either beneficial, deleterious, or neutral. I expect that Michael Lynch fully understands all the above, even if you DON'T. You can't just pick and choose which aspect of the full process you think you can attack, thinking that by doing so you invalidate the whole thing. That's disingenuous and only serves the kind of rhetorical gamesmanship and trickery for which creationists are notorious.

Answer 7

why?

1) he aint a "Leading geneticist"



2) you want me to explain why just 1 scientist says what he does? - that just stupid



3) Its irrelevant in evolution

why ?-

there is no such thing as "deleterious" in evolution, cos there is no way of knowing what is a "better" or "worse" mutation.that will lead to a new species.

(e.g if a mutation leads to a creature that can swim well but loses the use of its legs (i e what might appear deleterious) this would be a creature far more likely to survive if its environment were to become flooded over a creature with several legs that cant swim

i,e THAT creature survives and breeds, but those without the "deleterious" mutation die off cos they drown



That is- what you might think a deleterious mutation could become a distinct substantial evolutionary advantage, BUT there would be no way of knowing this just be examining the creature



time and the environment determine whats deleterious and what aint - nothing else)

Answer 8

OK. You've found a successful professor who has made - in a simplified explanation on his faculty information page - a vague statement about most mutations being deleterious. What's your point? I could argue against that using data from other studies, just like there are frequently ongoing debates about the nitty-gritty details... but it doesn't really have that much bearing on the theory of evolution as a whole, which I know that you're trying to argue against. It's one of the small details that is important to an in-depth understanding of the subject, but doesn't change the validity of the theory.

Answer 9

Do not understand your point. How many are MOST? 99%? 51%



If the Professor is correct about MOST, then a minority of mutations ARE NOT deleterious and those are the mutations responsible for The Role of Mutation in Evolution.



Modern day examples: 100 years ago, 7-foot tall men were considered freaks. The chances of them finding a suitable mate to create more seven footers was highly unlikely. You saw few 7 foot men. Then came professional basketball and the creation of many millionaires which made 7-foot men desirable mates.



7-footers are now relatively uncommon, but they are now prime candidates for natural selection and it is not uncommon to find multiple 7-foot men on college campuses.

Answer 10

What's to explain, if the mutation is deleterious the creature in question don't survive to breed.

The creatures that don't have that mutation continue on as normal, it's only the positive mutations that get passed on in most cases.

Answer 11

He should know better. Either that or he was trying to fit a statement into a tight space. Most mutations are neither deleterious or beneficial in themselves. They become one or the other (or neither) in relation to the environment. Example: the color of mice. In White Sands (NM), a mutation to change the coat white was beneficial. A mutation to change the coat to black was deleterious. On the nearby basalt flats, the values were reversed.

Answer 12

Throwing mutations into the genome of an organism is like firing a shotgun under the hood of a car. There is a very fine machinery at work, and any change will almost certainly be harmful. It is possible that it will be helpful, but chances are slim as it will most likely render the protein or whatever the DNA codes for unusable.

Answer 13

Mutations are random, so yes most are deleterious, it takes nature to select the ones which are a benefit to the species affected. This is basic to the theory of evolution and natural selection.

Answer 14

Any mutation that obstructs any vital pathway kills the foetus before implantation. They happen, they are fatal and almost no one knows they have happened.

This is not the shuffle of normal genes, this is a killer mutation - almost ALL mutations are lethal.

The small number of neutral mutations are mostly in the immune system - this is why almost all of the world is immune to the Black Death - natural selection removed the vulnerable.

Answer 15

Most mutations are negative. I'm not sure why you have a problem with this simple fact of genetics. Evolution filters them out using the usual statistical population methods.

Answer 16

Because it is true. Even the ones that are beneficial are information losing.

I don't know one example of a beneficial information adding mutation.

Answer 17

Because he's wrong. Most mutations are neutral.

Answer 18

Most are benign. They neither help nor harm. The next most common are harmul. And, the least common are helpful. Conditions change, though. So what was harmful can become beneficial under new conditions.