Re: Blog: The Scars of Evolution.

On Mar 22, 7:21 pm, Treus <treusd...@xxxxxxxxx> wrote:
hersheyh wrote:
On Mar 22, 4:44 pm, Treus <treusd...@xxxxxxxxx> wrote:

Kindly try really hard to focus and state in as direct and succinct a
manner as you can exactly why any two species related by lineal
descent should connectable though your suggested mechanism _such that
each transitional zygote is viable_. This is not about adaptiveness
under environmental selection, with which no one is arguing.

That is NOT what I have to do.

Of course it is. Why would you suggest an evolutionary mechanism in
which one or more generations consist of a nonviable zygote?

No generation between humans and chimps *ever* consisted of a single
zygote, much less a nonviable single zygote. *All* the sequence
differences between the human and chimp genomes are viable because
they all exist in living populations.

*Your* claim is that there is NO
natural mechanism which can produce *sufficient* change in the time
available to account for the observed *difference* between humans and
chimps. *That* is the question I have been answering.

With incomplete answers if you can't account for viability at every
transitional state.

So which of the differences between the human and chimp sequences are
incompatible with life, either as a human or as a chimp or as
something in-between the ancestor and the current species? Are you
claiming that organisms can exist if they have *all* those differences
but cannot exist if they only have *some* of them?

Apparently
*you* think I should be answering some other question. I cannot help
it if you do not even understand the questions you asked.

Again, the question was whether *your* claim that there was NO natural
mechanism that could produce *sufficient* amounts of change in the
time available to account for the observed amount of difference that
exists between humans and chimps. Not the above self-contradictory
questions (if you are concerned about viability you are talking about
selection).

It is not contradictory because _inherent_ viability and
_environmental_ adaptiveness are clearly distinguished.


Let me be more explicit:

1) Basically, the entire *difference* between chimps and humans, which
are two different species, is due to the *difference* in their genome
sequence. That does NOT mean that all the *differences* in genome
sequence affect phenotype.

2) The only known natural processes that changes genome sequences are,
collectively, called *mutation*. There are several different types of
*mutation*: point mutation, indels (including duplications and
frameshifts), and rearrangements. But, as far as I know, there is NO
difference between the sequence of chimps and humans that cannot be
accounted for by *normal* mutational events. If you know of some
*specific* difference in genome sequence between these two species
(both genomes have been largely sequenced) that *cannot* be due to
normal mutational events, please tell me.

3) There are, as far as I can tell, only two natural mechanisms that
will fix in mutations and lead to *differences* in sequence between
two species over time: 1) random drift to fixation *if* the effect of
the mutation is essentially no effect or 'selectively neutral'. 2)
fixation of a difference due to that mutation being beneficial in a
particular environment. This would be selection *for* a difference.
Both of these mechanisms can be observed in the present. In addition,
there can be selection against fixation of a change, but *we* are only
interested in mechanisms that can generate *differences* in genome
sequence.

4) The slower of the two natural mechanisms that *can* produce change
in genome sequence over time (slower by orders of magnitude) is random
fixation of selectively neutral mutations over time. So, *if* even
this slowest mechanism *can* produce the observed amount of sequence
*difference* between the human and chimp genomes over the time
available, that means that *both* natural mechanisms, or, as is more
likely, a combination of the two, are certainly *sufficient* to
explain the observed amount of sequence difference between these two
species.

5) When I make the assumption that *all* the observed *difference* is
due to the slower mechanism of random fixation of selectively neutral
mutations, that makes it *less* likely that the observed amount of
change can be accounted for by the proposed mechanism. That is, it
means that I am not relying on the faster rates of change that could
be due to positive selection. I am willing to rest on the hypothesis
that *even* the slowest possible mechanism can account for *all* the
sequence differences between these two mechanisms. *That* is a test
of the *sufficiency* of the mechanism.

Unless you can point out some specific sequence which cannot even be
produced by even the *faster* mechanism of positive selection for
change or you can point out some sequence in one of these species that
cannot be produced by any known mutational processes, you have nothing
but assertion. Those are, AFAIK, null nonexistent categories. But
feel free to present examples.

You have presented an empty set of sufficient mechanisms because a
necessary condition of sufficiency is _viability of the zygote _ at
every generation. This you seem unable to deal with.

The requirement that *some* members of each generation be able to
reproduce is a given, or we wouldn't be here. But since both humans
and chimps exist with *all* the current sequence differences that are
present between them, you must somehow think that having only *some*
of those differences must be lethal. Why would that be if the only
mechanisms that *produce* *change* in sequence occur when the initial
mutational changes are either *selectively neutral* or *selectively
beneficial*? When the mutational changes are *selectively
detrimental*, there will be selection against those organisms with
that change, so that particular change will generally not be present
in the currently living populations except by new mutation (or because
the deleterious phenotype is recessive or not completely lethal).

The way that selection works (when it occurs, many mutations are
selectively neutral) is to *prevent* the accumulation of detrimental
traits in a population and *increase* the accumulation of beneficial
traits. Perhaps you think populations always include only a single
individual? It sounds like that is what you are thinking.

.

Relevant Pages

  • Re: Evolution: Survival of the Miss-est
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  • Re: Solid Argument Against Evolution
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  • Re: Blog: The Scars of Evolution.
    ... under environmental selection, with which no one is arguing. ... are two different species, is due to the *difference* in their genome ... sequence affect phenotype. ... collectively, called *mutation*. ...
    (talk.origins)
  • Re: Blog: The Scars of Evolution.
    ... under environmental selection, with which no one is arguing. ... are two different species, is due to the *difference* in their genome ... sequence affect phenotype. ... collectively, called *mutation*. ...
    (talk.origins)