Microevolution versus Macroevolution: Two Mistakes
by Kirk Durston
I often observe that in discussions of evolution, both evolution skeptics and those who embrace neo-Darwinian evolution are prone to make one of two significant mistakes. Both stem from a failure to distinguish between microevolution and macroevolution.
The textbook for a genetics course I took at the University of Waterloo defined evolution as “changes in allele frequencies in a population over time.” An allele can be described as a variation of a particular gene. Defining evolution in this way can be misleading; it would be more accurate to call this variation. No new genes are required, just variation in existing genes or the loss of existing genetic information. This sort of variation is typically referred to as microevolution.
Microevolution (variation) takes place through genetic drift, natural selection, mutations, insertions/deletions, gene transfer, and chromosomal crossover, all of which produce countless observed variations in plant or animal populations throughout history. Examples include variations of the peppered moth, Galápagos finch beaks, new strains of flu viruses, antibiotic-resistant bacteria, and variations in stickleback armour. Each year, thousands of papers are published dealing with examples of microevolution/variation.
The mistake I often hear evolution skeptics make is to the effect that “evolution” is all rubbish, bunk, and false. They are often astonished to learn that variation (which they completely agree with) is defined as “evolution.” The solution is for evolution skeptics to be more precise on exactly what they have problems with. They can endorse microevolution (variation) but point out that a) it is misleading to call variation “evolution” and, b) their problems are with macroevolution.
The definition of macroevolution is surprisingly non-precise for a scientific discipline…
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