Re: The last ancestor of all life


Marc wrote:
Seanpit wrote:
Marc wrote:

< snip >

Exactly the same thing happens with antibody evolution. Each
generation of immune cells produces a range of variations of
antibodies. Those cells that produce just a little better match are
preferentially chosen out from among their peers to receive a
reproductive advantage. Very quickly, antigen specificity is improved
over time.

That *is* a feature of the immune system, but it does not change
the genes in the eventual offspring, there are no changes in the
gene pool with respect to the binding pockets of antibodies or
of the T-cell receptors (which control antibody production on a
basis of similar genetic effect). There is "evolution of an immune
response" in an individual. That is evolution (but only of immunity).
It is not evolution of a species.

I'm not talking about evolution of the species here.

You should be. That's what evolution is.

If you want to limit the definition like this, then fine. Have at it.
You only limit your own position here - not mine.

(It is NOT an immune response.)

You yourself have admitted that the changes of immune system
specificity are indeed a type of evolution - as do many others in this
forum. If you don't want to include immune system fine tuning as an
example of true evolution, that's fine! It only hurts your position,
not mine.

I'm only
interested in the evolution of functions here. I don't care if the
evolved function is passed on to the species offspring or not. I only
care if it passed on to the offspring of some kind. In this case, the
"offspring" are the immune system cells.

Changes in antibody binding sites are not changes in "function".

Oh really? There is no functional difference between various different
antibody binding sites as far as antigen specificity is concerned?

Clonal expansion of lymphocytes produces daughter cells, not offspring.

How is the clonal production of daughter cells not the same thing as
the clonal production of bacterial "offspring"? What is the
fundamental difference? How is one not capable of true "evolution" but
the other is?

It differs from one individual to another and the features are not
passed on in the sperm or egg to another generation in any form
that can be seen to be inherited. It is *not* evolution (of a species).

Another example of Sean twisting things around:

But, as you yourself said, it *is* evolution of the immune system
function within a particular individual.

That is NOT what I said. There is no "evolution of function".

Look just above here, my words were:
_There is "evolution of an immune response" in an individual._

Note that I put quotes around the part about immune response
to specifically note that changes do occur in an immune response
but that the use of "evolution" with regard to those changes is
not the same as using "evolution" with respect to gene pools and
changes in species over time.

I never said that the evolution was occurring in the host gene pool.
However, there are functional changes over time that are passed on to
the "gene pool" of the population immune system cells.

Importantly, I said "immune response" and not "function". There
is no change in the function of antibodies after B-cells undergo
somatic hypermutation. The affinity in the binding pocket changes
but that is not a change in "function".

A change in affinity would be meaningless unless this change had a real
useful functional effect.

You are getting to be as bad
as "UC" or "BROKENLADDER" in splitting hairs and in badly taking
ideas out of context. You are also misquoting me intentionally.

Talk about splitting hairs. It seems like you've been taking notes
from former Pres. Clinton! ; ) I've not misquoted you intentionally
at all. I'm simply amazed that you can argue that you see a difference
between a change in "immune response" and "function".

This is still Darwinian-style
evolution in that a population, a population of immune cells, evolves
improved antibody-antigen specificity over a few generations of immune
cells. You have everything you need. You have a population that
undergoes random mutations that affect functional aspects of that
population and passes these changes on, in a selectable manner, to
their offspring. It is the evolution of a population within an
individual. It still counts as evolution even though the individual
can't pass the information on to his/her own offspring.

How can it "count as evolution" when changes are not inherited?

The changes are inherited by the offspring of the immune system cells -
the clonally produced daughter cells. There is no fundamental
difference with this population compared to a bacterial population that
also reproduces in a clonal fashion. I'm simply amazed that you can't
seem to admit that there is a very real parallel here.

I'm also amazed that you don't seem to understand that you're arguing
against your own position here, not mine. It is a very common argument
in this forum and in literature that the immune system is an example of
real evolution in real time.

Gosh, you are thick.

Yeah - I get that a lot in this forum - shocking! ; )

You guys are really good with ad hominems. Part of your professional
training? - Dr. Buhler? I guess I just prefer substance over bluster
is all.

(signed) marc

Sean Pitman
www.DetectingDesign.com

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