Re: Challenge for Darwinists - Protein Synthesis


Richard Forrest wrote:
Wall Of Sleep wrote:

Get it now?


No. I don't "get it". What evidence points to the variation in the
gene pool of 'humans' as being the result of random mutations as opposed
to the result of normal sexual reproduction?

Genes get spread through the gene pool by sexual reproduction. Mutation
creates new genes.

Actually, mutation *usually* produces new alleles (variants,
modifications) of old genes. Or (and this is evolutionarily important)
variants in the *regulation* of old genes.

The mutational events that *sometimes* produce new *genes* (defined by
gene locus rather than function) are duplications (including chimeric
duplications), insertions, and rearrangements. The number of new
*genes* that are required for evolutionary change is greatly
exaggerated by creationists. For example, the number of new *genes*
that were needed to make a human from the common ancestor with
chimpanzees can probably be counted on the fingers of one hand with
several fingers amputated. Changes in the *regulation* of old genes,
OTOH, will be somewhat more common and probably accounts for most of
the crucial differences. Interestingly enough, *regulatory* changes do
not involve long random walks before facing selective pressures.

Is all sexual reproduction
classified as "random mutation"?

Oh, for crying out loud! Do you seriously not understand the
difference between sexual reproduction, which is the melding of genes
from two individuals, and mutation, which is something which affects
those genes?

He got his sex education at a Christian School. A short lesson: Don't,
until you are married.

When the very first human 'couple'
mated, they produced an offspring that differed from both of them.

There was no "first human couple".

Ah, but in Creationist logic, there is. Otherwise we would not keep
hearing that they will believe in evolution when they see a cat give
birth to a dog. The idea that a species evolving might be like the
evolution of a language like French or English, with no single pair of
inventors but only change over time in a population seems to flit
through their brain like a neutrino through the earth.

Evolution affects populations, not
individuals. There is a turnover of all the genes within the
individuals in a population. New genes are created by mutation. Other
genes are lost because they are selected against.

This is very, very basic stuff.

This
was due to *normal* sexual reproductive process - not a "random mutation".

I guess if you see the world through evolutionary colored glasses, some
things seem self evident - but for those of us who are not so
indoctrinated, this needs explaining.

This has nothing to do with "indoctrination". These are facts which
have been observed, measured and recorded for decades.
1) Mutations happen. Every human carries over a hundred mutations.
2) These mutations are neutral in respect of selective pressure.
Although some parts of the geneome are more subject to mutation than
others, the incidence of such mutations is not affected by selective
pressures from the envirionment.
3) Mutations are carried to the next generation by sexual reproduction.

Or do I have to go through the basics of what happens when DNA material
from sperm meets the DNA material in an egg?

None of this is "indoctrination" in any sense of the term.

To my mind, a random mutation is
an error - a mistake.

To your mind, perhaps. So what? You know very little about the subject,
as you confusion between sexual reproduction and mutation demonstrates.

It's the cause of disease and genetic *defects*.

It's also the cause of new characters in populations.

I've always understood it to be an *unintended* consequence.

There is no "intention", and more than an object "intends" to fall to
the ground if you release it.

If
you're going to classify the normal variation produced during sexual
reproduction as "random mutation", then why is it commonly stated that
most mutations are harmful?

a) You are confusing normal variation - which is the combination of
existing genes - with mutation - which is the creation of new genes.
b) Most mutations are neutral - they have no affect one way or another
on the individual. Of the remainder, some are harmful and some are
beneficial, but these are terms which can only be applied in reference
to the selective pressures of the environment in which the popuation
lives.

Interestingly enough, in diploid organisms like us recessive mutations,
when they first appear, are effectively selectively neutral because
they have no phenotypic effect in the heterozygous state. It is only
when such a mutant allele is present in the context of another similar
recessive mutation that we see a selectively distinct phenotype. That
is, the allele itself is not "deleterious"; a genotype which is
homozygous for that allele produces a phenotype that can be. Just to
re-point out that the terms beneficial, detrimental, and neutral have
to be determined empirically rather than assigned. Context is crucial
to the determination of which adjective to use. Mutation means
"change", not "bad change".


By your ever-shifting definitions,

Nobody, as far as I am aware, has changed any definition of gene,
mutation or sexual reproduction one iota.

most mutations are beneficial

Where on earth did you get this idea?

or
neutral

Which they demonstrably are, as all humans (and all other animals for
that matter) carry over a hundred mutations.

- since the normal variation produced by sexual reproduction
*usually* produces an offspring of equal or greater 'survivability' than
it's parents.

No it doesn't! It generally produces individuals of much the same
"survivability" as it's parents.

The *mean* offspring will typically have roughly the same
"survivability" as the parents so long the environment is not greatly
altered or in cases of unusual genetics. In the extreme case of the
evening primrose, only 1/2 of their progeny survive (only the
heterozygotes; homozygotes die because of balanced lethals). As this
example shows, the variation around the mean can be quite great.

If you were only considering quantitative traits, the *mean* offspring
will have a phenotype intermediate between its two parents. The
survivability of the offspring will depend on the interaction of this
mean offspring and its environment. In the case of heterozygote
dysgenesis (the hybrid is less fit than either parent) you will have an
unstable equilibrium tending to result in loss of one of the parent
types or speciation events isolating them so that hybrids don't get
formed. Again, there can be considerable variance.

If we ignore the effects of mutation,
all sexual reproduction does is recombine existing genes. It is
mutation which provides the novelty which, although generally negative
in it's effects, can occasionally provide characteristics which are
beneficial.

It's very confusing trying to follow your logic!

It might be less confusing if you were to take the time to read a basic
biology textbook so that you clarify in your mind that sexual
reproduction and mutation are completely different things.


I stand by my statement that because of such shifting-sand definitions
as these, the "T"oE cannot *ever* be falsified.


Frankly, who cares if you stand by your statement or not?

The definitions used by evolutionary biologists have not changed. It is
your fundamental lack of knowledge of basic biology which causes you
such confusion.


RF
--
"Are we to believe that mere chance can accomplish that which has proven
quite impossible for the enlightened scientist to achieve? I regard
that notion as absurd!" John A. Davison, Ph.D. - AN EVOLUTIONARY
MANIFESTO: A NEW HYPOTHESIS FOR ORGANIC CHANGE
http://www.uvm.edu/~jdavison/davison-manifesto.html

.

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