In article <3ore5j$jhm at jhunix1.hcf.jhu.edu>, <Chris Thoburn> wrote:
>In article <3or8or$5bp at agate.berkeley.edu>, frauwirt at notmendel.Berkeley.EDU>(Ken Frauwirth (BioKen)) writes:
>>>>Perhaps it would be better to start with a more focused idea:
>>>>>> Why does the immune system even exist?
>>>
[snip]
>>having some sort of immune system gives a multicellular organism
>>a selective advantage. (Unfortunately, this is really the only answer one
>>can give to questions about why some adaptation survives the evolutionary
>>process). There are lots of parasitic organisms out there, and any animal
>>that wants to survive will need some way to deal with them.
[snip]
>>The "function" of both types of
>>immunity is to protect the organism from undesirables such as bacteria,
>>viruses, etc., they just use different strategies (detecting conserved,
>>decidedly non-host components, vs. producing lots of randomized recognition
>>molecules and keeping only the ones found to be useful). However, since
>>evolution is not directed, it is unreasonable to expect more than "because it
>>improves the organism's chances at reproducing" in response to this sort of
>>question. One might as well ask, "Why does the endocrine system exist?"
>>>>Perhaps some better questions might be:
>>>>"What types of 'undesirables' are most effectively dealt with by various
>> types of immune systems? Might this affect the strategies adopted by
>> different organisms?"
>>Several points:
> 1) Parasitism does not mean death. An organism may well carry a parasite load
> and be perfectly able to survive.
Perhaps not for all parasites, but for many it does mean death, especially in
immunocompromised hosts. And without an immune system, the parasite load
might very well be higher (and fatal).
> 2) I do not agree with you that the FUNCTION of immune systems is to protect
> an organism from 'undesirables'. I have always been bothered by this concept,
> finding no reason at all to beleive that the immune system 'protects' one from
> anything.
A problem with discussions such as this is that language often obscures the
intended meaning. What I meant is that the end result is that a (if not the)
major advantage of having an immune system over not having one is that an
organism is far less likely to succumb to infection by pathogens. "Function"
implies intent, and I do not believe that natural selection has conscious
intent. Whether or not the *original* advantage conferred upon the first
organisms to have an immune system was resistance to pathogens, well, that is
anyone's guess. But it seems that the major detrimental effect of destroying
the immune system (at least in mice and humans) is overwhelming
susceptibility to infectious diseases (and perhaps cancer).
> 3) I'm not sure that evolution can not be 'directed' under certain
> circumstances. I think that perhaps many possible machanisms fall under the
> broad category of 'evolution' and that some can indeed be focused.
Of course it "can" be directed (humans do it all the time - we call it
breeding), but I meant that prior to such interventions (e.g. when the immune
system was evolving), there was no conscious direction involved. If you had
any reproductive advantage over other organisms in your niche, you outcompeted
them. That might mean, "If you are better able to withstand invasion by
infectious organisms, you'll have more offspring."
> 4) The question of the reason behind the existance of an endocrine system is
> quite possibly the same reason behind the existance of the immune system. You
> dishearten me by insinuating that it is a foolish or worthless question.
> Blind faith has it's part in religion, but not science. A true Scientist
> (with a capital S) questions everything and does not dismiss a particular
> question as worthless simply because it is difficult to answer.
An interesting rejoinder, when you state "I don't believe that the immune
system 'uses' any principles... I think that perhaps it simply exists, time
passes, and things are different than they were before." That is (to me) a
very un-Scientific approach. Biology is a very deterministic science -
everything has a molecular mechanism. Things don't "just happen", but there
is some logic: stimulus/response. If the immune system simply "changes" with
no rhyme or reason, than to study it is an exercise in futility.
[snip]
> 'What' and 'How' are merely observation...'Why' is philospohy.
That is exactly my point - it is not Science. Science can only answer "what"
and "how" ("How did the immune system evolve" is not the same connotation as
"Why did the immune system evolve"). I love to discuss philosophy, but please
do not disguise it as science.
>>>>"What are the basic principles that immune systems use to differentiate
>> between the Good, the Bad, and the Irrelevant?" (This, of course, being the
>> question addressed by our "disappointing" exchanges of "unoriginal" ideas)
>>I don't beleive that the immune system 'uses' any principles or that it can
>differentiate between Good, Bad, and Irrelevant. I think that perhaps it
>simply exists, time passes, and things are different than they were before.
>>"What are the weaknesses of different types of immune systems, and are there
>> evolutionary considerations that might have maintained some of these
>> weaknesses (allergies, for example)?"
>>Since I think that the immune system simply exists and does not discriminte
>between self and non-self, allergies (and other so called weaknesses) simply
>happen. This makes sense to me without the need to consider anything as a
>weekness. Again, I don't think evolution 'considers' anything at all. It just
>happens.
>
As I stated above, I find it difficult to reconcile these views with a
Scientific approach. The study of biology (or any science) has the underlying
assumption that life (or physical) processes follow rules, and that we can
work out at least some approximation of those rules, and that we can then
apply those rules to predict phenomena. While I realize that chaos theoy and
particle physics have a degree of "unpredictability" to them, people who
study those fields realize that the question of "Where exactly is the
electron" is not worth pursuing. If there is no consistent mechanism by which
the immune system is induced to change (i.e things "just happen"), then its
study *is* "worthless", at least to Biology (with a capital B).
>>>>For someone complaining about a lack of original ideas, I noticed that you
>>did not contribute any of your own. What are *your* thoughts on the reasons
>>behind the evolution of an immune system?
>>As above, so below...
>>I tried to put some thoughts above. By your *your* I assume that you mean to
>insinuate that I as well have no original thoughts.
I did not mean to insinuate any such thing. I was simply pointing out that
you raised the question, walked away, and then complained that nobody
contributed any ideas, when you did not contribute any either. I did not mean
to suggest that you do not *have* original ideas, only that you did not
*share* them.
>>BTW I do sincerely appreciate the time you took to respond. From your tone I
>take it that you were displeased with my last post. I agree that I was
>somewhat of a jerk, I am 16 days now without a cigarette and this was just a
>difficult day. I appologize to everyone for my tone.
>> Chris Thoburn
My sincerest congratulations on surviving without your cigarettes. May you
enjoy many smoke-free days in the future.
BioKen
--
Ken Frauwirth (MiSTie #33025) _ _
frauwirt at mendel.berkeley.edu |_) * |/ (_ |\ |
Dept. of Molec. & Cell Bio. |_) | () |\ (_ | \|
Univ. of Cal., Berkeley "Yes, we have second bananas" - Torgo the White
