Re: transitional fossils

>> PE's call for non uniform morphological change was in response to the non
>> uniform character of the fossil record. It is not based on population
>> genetics. If you do not presuppose evolution to begin with, then
>> population genetics does not particularly help. That is, population
>> genetics does not, itself, indicate PE.
>
> Gould and Eldredge's proposal was based on applying the consequences of
> the allopatric speciation model to the fossil record. They argued that
> the common pattern of species evolution in the fossil record was
> consistent with the expectation of the allopatric model and lineage
> splitting (cladogensis). Again the object of the PE model was speciation.

The allopatric speciation model was developed by Ernst Mayr, an
evolutionist. It is a qualitative model that he used to explain the data
assuming evolution is true. It does not come out of population genetics, per
se. Even Mayr admitted that no model explains the details of speciation
(involving anything more than minor morphological change which for some
would not even qualify as speciation):

"In particular, there is one problem that is not yet entirely solved. When
we look at what happens to the genotype during evolutionary change,
particularly relating to such extreme phenomena as highly rapid evolution
and complete stasis, we must admit that we do not fully understand them. The
reason for this is that evolution is not a matter of changes of single
genes; evolution consists of the change of entire genotypes." [What
Evolution Is, p. 272]

Indeed. Population genetics does not indicate that adaptative changes should
give the massive change required for evolution.

>> The term "Transitional forms" is not a theory-neutral description of the
>> data. Those forms are "transitional" if evolution is true. The bottom
>> line is that the fossil record is characterized by the rapid appearance
>> and then stasis of new species. Species persist for eons with little or
>> no change. You can try to align those species in "transitional" sequences
>> if you like. What you will find is a wide variety of patterns, all of
>> which evolution can explain by one means or another (gradualism, PE,
>> missing data, selection, no selection, environmental shifts, saltation,
>> co-evolution, and so forth). All of these explanations are used today,
>> but we still are left with rapid appearance and then stasis of new
>> species. Hence PE. It provides an explanation for those dashed lines
>> between the "transitional" species.
>
>
> The formation of new species is well-documented in the fossil record and
> observed today both in the field and under experimental conditions.
> Species formation is not something hypothetical. The fossil record of
> speciation includes examples of gradual change as well as more punctuated
> patterns. The debate is over which of these patterns are more typical and
> what genetic and environmental factors are at play.

What is important to understand about these examples from the field and
fossil record is that they involve minor morphological variations. The
genotype (and phenotype) has not undergone anything qualitatively like what
evolution needs. Even evolutionists doubt that these changes and their
mechanisms are sufficient to account for the larger changes evolution
requires.

> At higher taxonomic levels, transitional forms are known for many groups
> such that the definitions of these taxonomic groups break down and the
> fossil specimens cannot be easily classified.
>
> Note: If someone chooses to reject evolution a priori, then absolutely no
> fossil evidence regardless of how complete will be statisfactory for them.

Everybody slips up now and then, but ad hominems like this don't help.

> Another critical point is that many of the fossil transitions now known
> were predicted on the basis of evolutionary models. That is, the fossils
> were discovered after their existence was predicted. It is this
> predictive ability which makes evolutionary theory a powerful model for
> the history of life.

Yes, that is true. However, there are so many other predictions of evolution
that have been falsified that it is not clear how much value there is in
pointing to those predictions that were successful. Geocentrism has many
successful predictions to its credit as well.
Received on Sat Dec 3 21:52:13 2005