Stephen E. Jones wrote:
>In effect, Hoyle has discovered another level of Irreducible Complexity. If
>single-celled organisms don't use sexual reproduction with crossover (and
>are reproductively highly successful without it), and everything above
>single-celled organisms does use it, then how and why did single-celled
>organisms ever invent such an "exquisitely complex" system, and why don't
>we find them still using it today?
Some mechanism of recombination is needed; it doesn't have to involve
sexual reproduction. Single-celled organisms have all the mechanisms
they need. They can merge and they can move DNA via viruses, plasmids,
or whatever. They have greater flexibility than sexual reproduction would
give them. Sexual reproduction is more complex, but it isn't necessarily
more creative.
>Hoyle claims that the Neo-Darwinists have concealed how crucial
>sexual reproduction with crossover is to their entire system:
>
> "This latter advantage of sexual reproduction seems to be the
> strongest argument claimed in the books for it over the asexual
> model... Fisher's The Genetical Theory of Natural Selection carries
> the point in the exquisite ellipticities that were so
characteristic of
> Fisher. With quite some searching one can find it in Sewell Wright's
> treatise in four volumes Evolution and the Genetics of Populations
> (...1984) and more directly and clearly in J. Maynard Smith's The
> Evolution of Sex (...1978) What one does not find, however, is an
> appreciation of the really crucial aspect of the matter, that only
with
> sexual reproduction accompanied by crossover can positive mutations
> make headway against the deleterious mutations which occur with
> far greater frequency, and which otherwise would swamp the
> advantageous mutations, not permitting them to make any headway
> at all." (Hoyle F., 1999, p39).
'Swamping'? I thought it was the discovery of Mendelian particulate
inheritance that solved the problem of 'swamping'; particulate inheritance
of genes that occurs in all organisms, not just sexually reproducing ones.
>He notes that in response to this IC type arguments [re histone-4]" the
>Darwinists retreat into an untestable position":
>
> "Faced with this situation, neo-Darwinians retreat into an untestable
> position. Histone-4 evolved step by step they characteristically
> argue, with each step requiring no more than a single base-pair
> change. To the objection that step-by step evolution was not
> possible because histone4 is an all-or-nothing case, they reply by
> admitting that, while in the present situation this may be true, the
> situation as it once was differed in this respect. In a more primitive
> situation, histone-4 evolved step by step it is claimed, thereby
> retreating neatly into the unknowable and untestable, a device
> which, however, is not logically tenable because primitive systems
> without sexuality and crossover cannot evolve." (Hoyle F., 1999,
> p104).
What is a 'primitive system'? Why can't organisms without sexuality
evolve, as long as they have means of exchanging genetic information
such that you don't have only clonal lineages.
'Step-by-step' is such a straw man. Macroevolution can't be dismissed
without a mention, not when the evidence shows geologically instantaneous
origins at all levels.
>But now he opts for a type of front-loaded model with all the major genetic
>changes in place in the metazoa before the Cambrian Explosion.
There've been no major phenotypic innovations since the Cambrian,
why shouldn't the situation with the genes be analogous?
>This however contradicts what is in his unrevised book because he
>mentions major changes, (e.g. gaps in the fossil record and the
>reptilemammal transition) whch happen long after the Cambrian Explosion:
> Many changes should be traceable in the fossil record, which they
> have not been. The concept discussed in Chapter 6 of an externally
> incident genetic storm overcomes this difficulty, because both the
> chromosome sets P and M are exposed to the same external source
> of change." (Hoyle F., 1999, p138)
If you can accept a reptile-mammal transition I must wonder what gaps in
the fossil record do concern you. The homologies among reptile and
mammal skeletons can be a basis for all manner of theories of
transitions, but they are not proof of the time and the nature of the
divergence from a common ancestry.
>What I am excited about is that Hoyle's original "genetic storm" model,
>(which is what the evidence actually looks like), *is* in fact better
>explained
>by the progressive introduction of large blocks of new genetic code, by an
>Intelligent Designer. Indeed Phil Johnson on one of his tapes says that
>Panspermia is "the materialist version of supernatural creation"!
I have to wonder why a scientist would prefer the outlandish deus ex
machina of a 'genetic storm' to the possibility of macroevolution. Maybe
the notion of gradual evolution is so profoundly inculcated in us all that
macroevolution is unthinkable.
--Cliff Lundberg ~ San Francisco ~ cliff@noe.com
This archive was generated by hypermail 2b29 : Sun Jan 23 2000 - 21:39:52 EST