don_smith at att.net
Sat Jun 15 10:51:42 PDT 2002
Steve Bougerolle wrote:
> Evidence that one life form is related to another in no way provides us
> with a mechanism for one evolving into another. A clear record of
> accumulated varied mutations would of course suggest more clearly that
> it happened.
The vast majority of random mutations are lethal. Most are so lethal
that implantation does not occur or, if it does, a miscarriage occurs
later. Thus nearly all mutations are never noticed. A few that got by
are things like CF and MS and Sickle Cell Anemia. And Sickle Cell Anemia
as a single recessive gene turns out to be beneficial to those who live
with Malaria, which is probably why it is as prevalant as it is.
> It still does nothing to explain HOW.
Mutations occur all the time. Cosmic rays can cause mutations, many
chemicals can cause mutations, UV from the sun can cause mutations.
Misreading the DNA during replication also happens, which causes
Very, very rarely a mutation occurs that is actually beneficial, like a
myocin fiber that "twitches" a little more quickly making the recipient
a little faster. Now, if this occurs in a rabbit, and a fox is chasing
two rabbits, the slower rabbit gets eaten and the faster rabbit gets to
reproduce. And maybe the faster myocin causes the rabbit to starve more
quickly so in an area with severe winters, the slower rabbits reproduce
more because they can survive without food a little longer. So faster,
starvation-prone rabbits in the south and slower, starvation-resistant
rabbits in the north. Over a *very* long time other beneficial mutations
(longer legs, longer ears, thinner fur) occur and the southern rabbits
eventually become jack rabbits while the northern rabbits become artic
hares (short appendages, thick fur).
> These genetic
> methods are only a more advanced and reliable way of making a point
> that's fairly obvious already; some organisms look like they developed
> from other organisms. It still leaves unfilled THE big gap in
> evolutionary theory; a satisfactory mechanism that explains just how
> these changes can occur in such a way as to produce what you record.
I don't think you understand. Evolution *is* the mechanism the explains
how these changes occur.
> Don't misunderstand me - I find the subject fascinating, and I'm
> particularly interested in the "out of Africa" debate and theories of
> ethnic origins and so on. I'm also not interested in nutty religious
> explanations (to my mind, whether you explain an evolutionary step as
> "spontaneous simultaneous random mutations"
There is no requirement for "simultaneous". Several mutations occur in
different individuals, over a period of a thousand years. Looking at the
fossil record it only appears to be simultaneous.
> or "a miracle" is just a
> question of wording). But I do think there are problems with evolution
> as a scientific theory, and I like to keep scientists honest.
There is no problem with the overall theory of evolution, i.e., natural
selection of random mutations. I guess by problem, you mean it is still
a theory. It will *always* be a theory because there is no way to ever
prove it (without a time machine).
> In this case, what has perhaps triggered me is the last bit in that
> quote - "finding the evolutionary trees behind gene sequences". You are
> assuming that there are evolutionary trees, and looking for evidence to
> support your assumption. That's fair enough, but I find too many people
> tend to get carried away with that assumption and start to confuse it
> with absolute truth. I hope you're not one of them?
65 million years ago there were only a few species of small rodent-like
mammals. As you move forward through the fossil record more and more
different species of mammals appear and disappear until you have the
diversity of mammals the world over you see today. These are facts, not
theories. You could call it an inverted pyramid, but it looks like a
tree to me. Evolution is the theory that explains how the tree came
about and says that, indeed, the branches are all related.
Now, in my mind, none of this precludes the existance of God. Maybe he
set up the laws of physics at the big bang knowing the what the results
will be. What is a wonder is how exquisitely balanced those laws are,
because with very small variations, the universe would have collapsed
back again within a few thousand years or spread itself out too quickly
to form stars.
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