Evolution and the Human Immune System

Introducing a new topic here...Do any of you creationists out there know how the human immune system works? Any takers? The number of variants of bacteria out there are staggering. Since to create a specific protein requires a specific DNA sequence, how on earth could any animal at all possibly be able to produce proteins designed to selectively bond to these incredibly varied bacterial surfaces? Only about 1,000 active genes had the possibility of being involved in the process, and yet there are countless antibodies that our body can produce.This was a long standing question in the scientific community, and was finally solved by Susumu Tonegawa, leading to a Nobel Prize in 1987. He discovered that not all of the genes in a person's body are identical, at least when it comes to lymphocytes. When a lymphocyte is produced, it randomly activates one element in each of six "families" of genes.Now, if you were to inject a mouse with a specific antigen, and were to sample the DNA of its different B lymphocytes, you would find that none of them produce an antibody that has much of an affinity to the antigen. However, if you kept taking regular samples, you would find that the cells' DNA in this region steadily converges on a specific pattern. The changes in the DNA (and consequently, the antibody) steadily decrease, until the body is left with as near-perfect of an antibody for bonding to the specific antigen as possible - and that antibody is being produced en masse. In fact, if you follow the progression of the DNA, it follows a "family tree" structure, with branches and inheritance, that steadily migrates towards fitness for bonding to the antigen.What could be causing this? It turns out that at specific stages in their lifecycle, B lymphocytes increase the mutation rate of specific genes by more than 1000-fold ("hypermutation"). In the body, when the lymphocites produce an antibody that can bond, even weakly, to an antigen, they begin to produce large numbers of antibodies and to multiply quickly; this suppresses the production and multiplication of other types of B lymphocytes. The better the bond, the faster they multiply and produce antibodies (and thus, suppress the less effective lymphocytes more). However, with their rapid mutation rate, many of their copies have the antibody that they're producing slightly vary. This reshapes and restructures the protein by small amounts in different places. Most of these changes make it bond worse than the original, but a few will bond better. These in turn produce more antibodies and reproduce more quickly, and suppress their poorer competitors.This discovery has enabled much of the progress that has been seen in medical research involving the immune system in the past few decades.Oh, but my mistake - natural selection can't work... Right?------------------
"Illuminant light,
illuminate me."

Oh, but my mistake - natural selection can't work... Right?Judge:
Not at all..natural selection occurs in creationist models.In fact natural selection would happen more (in some ways) in a creationist model.

Care to elaborate judge? I have yet to see a creationist model other than "goddidit" and none that invoke natural selection. But would be interested to hear your input.
cheers,
M

Natural selection has long been an important feature of the creation model (as has allopatric speciation), and in fact was proposed by a creationist several years before Darwin (we suspect he 'borrowed' the idea from Blyth).The creation model recognizes NS as primarily a conservation mechanism. Since NS can only work with pre-existing genes, NS generally promotes loss of genetic information; the evolutionary model on the other hand argues that NS is capable of promoting genetic information gain over time. Given the countless experiments we've done on rapidly reproducing species, we can't find one provocative example of genetic information increase where there should be many if molecules-to-man evolution really occurred.

Rei, through your lens you see evolution, through my lens I see incredible design. How did such a complex program evolve?

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Natural selection has long been an important feature of the creation model (as has allopatric speciation), and in fact was proposed by a creationist several years before Darwin (we suspect he 'borrowed' the idea from Blyth).

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Well, seing as most scientists were creationists then, that's no real shock Nonetheless, I have seen many creationists try and argue against natural selection. It's good for you that you accept it.

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Since NS can only work with pre-existing genes, NS generally promotes loss of genetic information; the evolutionary model on the other hand argues that NS is capable of promoting genetic information gain over time.

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Are you trying to change this into a discussion about "information" as opposed to natural selection?

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Rei, through your lens you see evolution, through my lens I see incredible design. How did such a complex program evolve?

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Incredibly simply. The more possible genes that can be selected from in each family of genes, the better the organism can fight off disease. Likewise, the more families there are, the better. There are many sequences in DNA which are quite clearly analogues of each other, cut and shifted up or down the chromosome - a good example is the piece of DNA that contains the genes for red and green color vision, for which not only the gene, but the whole section of DNA around it is nearly identical except for scattered mutations (which, on the gene, change the target wavelength for the cone). There are rare cases in which there is yet another copy - a third copy - which codes for yet another wavelength, and people with this tend to have a very slightly better ability to distinguish colors in the red/green range. Note that the gene for recognizing blue is unrelated.If possible proteins to select from in developing immunity were duplicated, and then slight mutations occurred, the proteins would fold and bond differently with different antigens, and provide a distinct advantage in the number of possibilities.In the original case, you have a simple multicellular organism, perhaps something no larger than daphnia, running into the problem that bacteria are able to out-adapt them due to their faster reproductive rate. We'll look at a starting timeframe here in which the organism has only the basic ability to code for a simple set of antibody proteins, and reproduces from the possibilities based on how well they're bonding (we can go back further if you want). The organism would have trouble still at keeping up with bacteria - there's only so many cell receptors that they can have to test how well each antibody that they have the ability to code for bonds to an antigen, only so much DNA that they can have for producing the proteins, etc. But, if one of these simple creatures, due to a mutation, began coding for a slight mutagen that targets that region of the DNA, it would immediately gain an advantage for at least increasing how different the immune systems of the child organisms were from their parents. Stronger, more targetted mutagens, and mutagens which are produced more often when antigens are more common, are in turn more likely to be selected. If another protein develops that even slightly changes the cell's reproductive timing based on how good of a bond its antibodies are getting with the antigen - even through throwing off one of the cell's many timing feedback mechanisms - the cell can reproduce more quickly. A similar development can occur for the level of antibody production. And yet another similar development can occur for apoptosis of ineffective lymphocytes.Note that none of these stages need to have multiples steps occur at the same time. In fact, it is fairly irrelevant as to what order these steps go in, or if they're simultaneous. And, you'll note, no step requires a *particular* mutation. There are many, many ways each feedback system could be altered. Lastly, the first "step" in each stage needs to only have a slight effect, which is, through natural selection (which you accept the occurrance of), made more common.------------------
"Illuminant light,
illuminate me."

M:Care to elaborate judge? I have yet to see a creationist model other than "goddidit" and none that invoke natural selection. But would be interested to hear your input.
cheers,
MJudge:
Sure. Here is an online book first linked here by the "evil" Dr Borger.
http://www.evolutionisdegeneration.com/start.htmlThe Author includes Charles drawin in the credits..."Charles Darwin, biologist. For his love of living nature, his insight, and for turning the world upside down. "He credits Darwin with bringing Natural selection to our attention and includes natural selection in his creationist theory.This link touches on it as well.
http://www.creationevolution.net/

Hi judge,
Thanks for the links but could you specifically cite the part of those websites that apply? Mostly Scheele argues that macroevolution cannot occur and that genetic change is exclusively degenerate (both of which are not supported by the way). Also your initial claim was that creationists are more interested in natural selection and variation than evolutionary biologists and nothing from that site gives me that impression. Sorry for being dense but it would help me out if you could quote the specific parts of your citations that you think apply.No I have not forgotten Borger cheers,
M

Hi mamuthus.
I'll have to re-read it to find it. I am going from memory that he credits darwin with (discovering?) natural selection.
I tried to find it today but it was whilst I was at work and could not find the part I seemed to remember.My claim would be that in some ways creationists would beleive in more natural selection. Overall of course they would not, but I imagine any claim of "hyper-evolution" would need faster evolution than currently proposed (at times) and thus would logically include "faster" natural selection, as part of this "faster" change.

Hi judge, no problem take your time. I will comment though that hypermutation would actually run counter to natural selection at some level. You would need more neutral mutations for hypermutation to be visible. Hypermutation in a gene would be invisible since the majority of mutations would be selected out if they destroyed the genes function.Faster evolution would not require hypermutation..only mutations and selection at specific types of loci for example Hox genes. A small change can have a huge effect...just some random thoughts.

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In the original case, you have a simple multicellular organism, perhaps something no larger than daphnia, running into the problem that bacteria are able to out-adapt them due to their faster reproductive rate. We'll look at a starting timeframe here in which the organism has only the basic ability to code for a simple set of antibody proteins, and reproduces from the possibilities based on how well they're bonding (we can go back further if you want). The organism would have trouble still at keeping up with bacteria - there's only so many cell receptors that they can have to test how well each antibody that they have the ability to code for bonds to an antigen, only so much DNA that they can have for producing the proteins, etc. But, if one of these simple creatures, due to a mutation, began coding for a slight mutagen that targets that region of the DNA, it would immediately gain an advantage for at least increasing how different the immune systems of the child organisms were from their parents. Stronger, more targetted mutagens, and mutagens which are produced more often when antigens are more common, are in turn more likely to be selected. If another protein develops that even slightly changes the cell's reproductive timing based on how good of a bond its antibodies are getting with the antigen - even through throwing off one of the cell's many timing feedback mechanisms - the cell can reproduce more quickly. A similar development can occur for the level of antibody production. And yet another similar development can occur for apoptosis of ineffective lymphocytes.

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I must say, that was one grandiose tale! This is called a just-so story. Do you know how many different antigens there are out there? That is the reason for the ingenious design of the immune system to handle a number far greater than the number of proteins that can be programmed for them in the DNA. In your example, the odds of extinction would be astronomical but you conveniently ignore this. Methinks this GA stuff has clouded your thinking!To be honest, I don’t feel like debating the irreducible complexity of the immune system. It’s been done a zillion times already on the net.

Hi again mammuthus.Here are a couple of quotes. In this first quote he says Darwin discovered something like natural selection.Charles Darwin hardly knew anything about genetics. It was quite easy for him to set up a theory in which he didn't have to think of the complex reality of DNA, genes and protens. However, he did discover that there's 'biological change' and something like 'natural selection'. The mistake Darwin made is that he interpreted this into a certain direction, assuming all 'higher' animals evolved from 'lower' animals. If biological change should be given a direction, it would be downhill: Degeneration instead of evolution.and further on......Darwin's ingeniousity is clearly seen from the fact that he found out species change and that he was able to identify the mechanism: natural selection. Natural selection is the opposite of human selection with breeding. Darwin hardly knew anything about heredity - he wrote a book about 'blending inheritence' which was found to be completely beside the truth - and he also did not have the knowledge of genetics.
From here.http://www.evolutionisdegeneration.com/summary.html[This message has been edited by judge, 09-09-2003][This message has been edited by judge, 09-09-2003]

Mr. Williams Could you please me with the creation model that includes natural selection and perhaps give us your definition of natural selection?

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I must say, that was one grandiose tale! This is called a just-so story.

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Hey now, that's completely unfair. You presented the situation as if it were impossible. I quite clearly demonstrated a lineage in which an organism with an immune system that cannot do this mutation/selection of genes gets to one which can. Then you criticize me for a "grandiose tale"!No more childishness. If you wish to defend your argument, you need to explain what is unreasonable about the line of progression presented occurring. And again, if your argument sums up to "there are other ways it coud have occurred than this", then you're actually helping my case. So, please explain what is flawed with this.

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Do you know how many different antigens there are out there? That is the reason for the ingenious design of the immune system to handle a number far greater than the number of proteins that can be programmed for them in the DNA. In your example, the odds of extinction would be astronomical but you conveniently ignore this.

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My god, did you completely ignore my post? Please, answer honestly. Because I just showed that *any* improvement in the number of antibodies that the organism can produce increases the odds of survival. Now, I ask a direct question:Do you acknowledge that any increase in the number of antibodies that the organism can produce increases its odds for survival?From there, I went on to discuss how a mutagen that effects this region of the organism's genetics increases the variance in the population when it comes to resistance to organisms, without raising the overall mutation rate and thus risking genes that have been working well and should be mutating at a much lower rate.Do you acknowledge that it would be an advantage to increase the diversity in the population when it comes to the ability to resist diseases, even if each organism can only produce the same total number of antibodies?From there, I went on to discuss how if that mutagen became more targetted and more powerful through successive changes to the protein, that's advantageous compared to a poorly targetted weak mutagen.Do you acknowledge this?(I can keep on going... in short - at what stage do you claim that there would be a problem with this line of progression?)I want serious debate, not your hand-waving dismissals. And you can say "it's been debated" all that you want, however, I have not seen any refutation for this line of progression conducted. Point me to one, do it yourself, or acknowledge that the evolution of this system is quite possible.------------------
"Illuminant light,
illuminate me."

Hi judge,I fail to see how either of those supports the idea that creationism finds hypermutation, natural selection, or allele frequencies or any other measure of genetic change over time more relevant than the theory of evolution.The first paragraph suggesting that Darwin proposed a lower to higher scheme of evolution is unclear to me from my reading of the Origin of Species...though some of the terminology used by Darwin and his contemporaries would today be taken as offensive..much like the reaction you would probably get in New York City if you called an Afro American a negro. In any case, besides there being no support for degeneration I still fail to see how this supports your initial premise.The second passage makes a false assertion, that artificial selection works in a way unrelated to natural selection...and then does not support the assertion...the rest goes on to point out that Darwin and most of his contemporaries did not know anything about the mechanisms of heredity i.e. genetics and then goes on to ignore the fact that there has been over 150 years of research since the publication of the Origin of Species where scientists did know about heredity.Again, I fail to see how any of this supports creationism or the premise that creationist interpretation somehow relies on mutation or natural selection at all.