Creation
vs. Evolution
Neo-Darwinism
As you would expect with a field of scientific inquiry, much
has been discovered since the time of Darwin. In particular,
current knowledge of genetics has been applied to evolution.
Consequently, the theory of evolution has been modified and
augmented. These new changes are referred to as Neo-Darwinism. An
even newer term that supercedes Neo-Darwinism has been coined by
Futuyma to cover the current ideas on evolution -- Modern
Synthesis. Following is a description of Modern Synthesis.
- The major tenets of the evolutionary synthesis, then,
were that populations contain genetic variation that
arises by random (i.e. not adaptively directed) mutation
and recombination; that populations evolve by changes in
gene frequency brought about by random genetic drift,
gene flow, and especially natural selection; that most
adaptive genetic variants have individually slight
phenotypic effects so that phenotypic changes are gradual
(although some alleles with discrete effects may be
advantageous, as in certain color polymorphisms); that
diversification comes about by speculation, which
normally entails the gradual evolution of reproductive
isolation among populations; and that these processes,
continued for sufficiently long, give rise to changes of
such great magnitude as to warrant the designation of
higher taxonomic levels (genera, families, and so
forth)."
- Futuyma, D.J. in Evolutionary Biology, Sinauer
Associates, 1986; p.12
For a fuller explanation of Modern Synthesis and
Neo-Darwinism, see the article, The
Modern Synthesis of Genetics and Evolution by Laurence
Moran. His main points are summarized here.
There are three important differences between Modern Synthesis
and Darwinism.
- Several mechanisms of evolution are recognized in
addition to natural selection, including random genetic
drift.
- Characteristics are inherited as discrete entities called
genes. Variation within a population is due to the
presence of multiple alleles of a gene.
- Speculation is (usually) due to the gradual accumulation
of small genetic changes. This is equivalent to saying
that macroevolution is simply a lot of microevolution.
Another good reference to check on this subject is Polymorphism
and the History of Evolutionary Theory.
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