Administrator2
New Member
RUFUSATTICUS
From: RufusAtticus
Creationists like to erroneously claim that it is impossible for the
accumulation of microevolutionary changes to produce macroevolutionary
changes. A "genetic barrier" is oftern cited to account for this, although
it is never identified. The hypothesis states, "there is a 'genetic
barrier' that prevents one 'kind' from evolving into another 'kind.'" I have
yet to see any attempt to justify this hypothesis using actual genetics or
science. Furthermore, there clearly is not a justification because modern
genetics has disproved this hypothesis (see below). However, it is another
creationist buzzword that has no actual scientific value.
The hypothesis of a "genetic barrier" was not originated by creationists. It
arose almost a hundred years ago by biologists/evolutionists to describe the
difference between macroevolution, evolution apparent between species, and
microevolution, evolution apparent within a species. Creationists like to
claim that the mechanisms from macroevolution are fundamentally different
from the mechanisms for microevolution; this is their genetic barrier. They
then assert that there is no evidence for macroevolution while
microevolution is well supported. They never show why any evidence
supporting macro is wrong; they just say it is. A long quote (please forgive
me) from Futuyma helps explains the issue:
<BLOCKQUOTE>quote:</font><HR>One of the most important tenets of the theory forged during the
Evolutionary Synthesis of the 1930s and 1940s was that 'macroevolutionary'
differences among organisms--those that distinguish higher taxa--arise from
the accumulation of the same kinds of genetic differences that are found
within species. Opponents of this point of view believed that
'macroevolution' is qualitatively different from 'microevolution' within a
species, and is based on a totally different kind of genetic and
developmental repatterning. The iconoclastic geneticist Richard Goldschmidt
(1940), who held this opinion, believed that the evolution of species marks
the break between 'microevolution' and 'macroevolution'--that there is a
'bridgeless gap' between species that cannot be understood in terms of the
genetic variation within species. Genetic studies of species differences
have decisively disproved Goldschmidt's claim. Differences between species
in morphology, behavior, and the process that underlie reproductive
isolation all have the same genetic properties as variation within species:
they occupy consistent chromosomal positions, they may be polygenic or based
on few genes, they may display additive, dominant, or epistatic effects, and
they can in some instances be traced to specifiable differences in proteins
or DNA nucleotide differences. The degree of reproductive isolation between
populations, whether prezygotic or postzygotic, varies from little or none
to complete. Thus, reproductive isolation, like the divergence of any other
character, evolves in most cases by the gradual substitution of alleles in
populations.
(Evolutionary Biology, third edition. 477-478)<HR></BLOCKQUOTE>
Barrierists believe, like Goldschmidt did, that macroevolution and
microevolution are fundamentally different; however, unlike Goldschmidt,
they use the absence of a macro-only mechanism as proof of a creator and
proof against evolution. The reason for the absence of a macro-only
mechanism is that the same mechanisms apply to both micro- and
macroevolution. This is not an "easy out" explanation, as they'd have
laymen believe. It is backed up by genetic and biological observations and
experiments. Goldschmidt was able to state his claim in 1940 because the
science of molecular genetics did not exist then. It wasn't until the 1950s
that Watson and Crick solved the structure of DNA and showed how genetic
information was passed in cell division via template strands. The genetic
code was later solved, explaining how DNA encoded proteins. Modern
sequencing strategies allow us to map molecular genetic mutations to actual
genes, demonstrating the variability of populations and the power of
evolution. These sequencing strategies also allow us to map the differences
between two organisms' genomes. The genetic distinctions for taxa can be
detected by comparing organisms from different taxa. The data generated from
such investigations show that distinctions between taxa follow the same
rules as distinctions within a taxon.
-RvFvS
From: RufusAtticus
Creationists like to erroneously claim that it is impossible for the
accumulation of microevolutionary changes to produce macroevolutionary
changes. A "genetic barrier" is oftern cited to account for this, although
it is never identified. The hypothesis states, "there is a 'genetic
barrier' that prevents one 'kind' from evolving into another 'kind.'" I have
yet to see any attempt to justify this hypothesis using actual genetics or
science. Furthermore, there clearly is not a justification because modern
genetics has disproved this hypothesis (see below). However, it is another
creationist buzzword that has no actual scientific value.
The hypothesis of a "genetic barrier" was not originated by creationists. It
arose almost a hundred years ago by biologists/evolutionists to describe the
difference between macroevolution, evolution apparent between species, and
microevolution, evolution apparent within a species. Creationists like to
claim that the mechanisms from macroevolution are fundamentally different
from the mechanisms for microevolution; this is their genetic barrier. They
then assert that there is no evidence for macroevolution while
microevolution is well supported. They never show why any evidence
supporting macro is wrong; they just say it is. A long quote (please forgive
me) from Futuyma helps explains the issue:
<BLOCKQUOTE>quote:</font><HR>One of the most important tenets of the theory forged during the
Evolutionary Synthesis of the 1930s and 1940s was that 'macroevolutionary'
differences among organisms--those that distinguish higher taxa--arise from
the accumulation of the same kinds of genetic differences that are found
within species. Opponents of this point of view believed that
'macroevolution' is qualitatively different from 'microevolution' within a
species, and is based on a totally different kind of genetic and
developmental repatterning. The iconoclastic geneticist Richard Goldschmidt
(1940), who held this opinion, believed that the evolution of species marks
the break between 'microevolution' and 'macroevolution'--that there is a
'bridgeless gap' between species that cannot be understood in terms of the
genetic variation within species. Genetic studies of species differences
have decisively disproved Goldschmidt's claim. Differences between species
in morphology, behavior, and the process that underlie reproductive
isolation all have the same genetic properties as variation within species:
they occupy consistent chromosomal positions, they may be polygenic or based
on few genes, they may display additive, dominant, or epistatic effects, and
they can in some instances be traced to specifiable differences in proteins
or DNA nucleotide differences. The degree of reproductive isolation between
populations, whether prezygotic or postzygotic, varies from little or none
to complete. Thus, reproductive isolation, like the divergence of any other
character, evolves in most cases by the gradual substitution of alleles in
populations.
(Evolutionary Biology, third edition. 477-478)<HR></BLOCKQUOTE>
Barrierists believe, like Goldschmidt did, that macroevolution and
microevolution are fundamentally different; however, unlike Goldschmidt,
they use the absence of a macro-only mechanism as proof of a creator and
proof against evolution. The reason for the absence of a macro-only
mechanism is that the same mechanisms apply to both micro- and
macroevolution. This is not an "easy out" explanation, as they'd have
laymen believe. It is backed up by genetic and biological observations and
experiments. Goldschmidt was able to state his claim in 1940 because the
science of molecular genetics did not exist then. It wasn't until the 1950s
that Watson and Crick solved the structure of DNA and showed how genetic
information was passed in cell division via template strands. The genetic
code was later solved, explaining how DNA encoded proteins. Modern
sequencing strategies allow us to map molecular genetic mutations to actual
genes, demonstrating the variability of populations and the power of
evolution. These sequencing strategies also allow us to map the differences
between two organisms' genomes. The genetic distinctions for taxa can be
detected by comparing organisms from different taxa. The data generated from
such investigations show that distinctions between taxa follow the same
rules as distinctions within a taxon.
-RvFvS