The evolution escape clause

The distinction that evolution deniers make between microevolution and macroevolution is different from other misunderstandings of evolution and I think that distinction affects how we deal with it when we are trying to teach evolution.

This distinction is different from the other misunderstandings because it isn't so much a misunderstanding as it is an escape clause for evolution denial. Other misunderstandings often occur in the general public, even those who are just ignorant of evolution but not opposed to it. The micro/macro distinction is brought up and sharpened only by those who need to actively deny evolution. They use it as a way to avoid the cognitive dissonance that comes with seeing evidence for evolution. If they can safely put the evidence into the category of microevolution, then they can compartmentalize it and feel comfortable with it. I think it is important to show the problems with this compartmentalization if people are to understand evolution.

If we show strong evidence for evolution of peppered moths or finch beaks, they can say that it is just microevolution and act as if it has no relevance at all to the main question. Once it is put in that category, they don't even have to consider whether it might be part of a larger case for evolution. If we show the evolution of new species of cichlid fish, they can say they are still just fish, or a new virus is still a virus. Their concept of kind and microevolution is very flexible, so they can fit a lot of evidence into that comfortable category of microevolution. They can say "have we ever seen a cat evolve into a dog" or similar gross distortions of evolution. I think the stronger the evidence, the bigger the macroevolutionary comparison they will use. If you show very strong evidence for evolution within a large category, they will say "it still doesn't show bacteria to humans" (as if that is what you were trying to do. Moving the goal posts is very popular).

The most basic misunderstanding about micro and macroevolution is that macroevolution as an idea arose as an extrapolation of microevolution. This is obviously not the case. The Origin of Species deals almost entirely with evidence for macroevolution. Darwin had not observed microevolution, nor did he have a good theory of population genetics. In place of microevolution, Darwin could only look at artificial selection and the variation within species. The categories of evidence for evolution--fossils, comparative development, comparative morphology, biogeography, etc., are all evidence for macroevolution.

I can understand how the lay public would think this. It is much more irresponsible when people who should be informed in the science and history make that mistake. Phillip Johnson, considered the father of intelligent design, has stated "[to Darwinists] only a modest amount of confirming evidence is needed to prove the whole system, and so they point to the peppered moth example as virutally convlusive". To suggest that evolution is accepted to any substantial extent due to a few microevolutionary examples is simply irresponsible.

Macroevolution was accepted by the scientific community by the late 19th century, but it wasn't until the modern synthesis in the 30s that there was agreement about the microevolutionary mechanism. To this day, most disputes in evolutionary biology deal with the microevolutionary mechanism. There is no dispute at all about common descent. So creationists get it completely backwards when they suggest that microevolution is better supported than macroevolution.

Although scientifically macroevolution is more strongly supported than the microevolutionary mechanisms, I think many people find the evidence for microevolution harder to deny, because it does not rely on scientific inference and it does not require the stretching of the imagination that great amounts of time involve. Most creationists do not use a careful definition of microevolution as being below the species level. Rather it is simply whatever the evidence and their imagination cannot deny. The importance thing is to put that evidence safely away behind a wall.

In my next post I will talk about ways to break down this escape clause in teaching evolution.