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Tuesday, April 29, 2014

Natural selection is a fact

Today's Greenville News, in an article on page 7a, has published a report from the Associated Press. That report says that South Carolina State Senator Mike Fair "says natural selection should not be taught as fact." Mr. Fair has made more news on this sort of topic recently, as he at first opposed the adoption of a South Carolina State Fossil, because of his belief in a six-day creation a few thousand years ago. He withdrew his opposition, because the proposer was an eight-year-old girl.

Mr. Fair is entitled to his beliefs, and they are, perhaps, more nuanced than suggested by the nine words quoted in the report, but this post takes them at face value, and refutes them.

Natural selection is a fact! Why is that so?

First, artificial selection works. Humans have selected breeds of dogs for various traits, and done similar selection with other animals. Plants, grown as crops or ornamentals, have also responded to the selective work of humans.

It is true that keeping track of butterfat production by cows, and deciding which bull to use in fathering the next generation, based on the production record of his daughters, is not exactly natural selection. But much selection of animals and plants, over the millennia of domestication, was simply looking at various characteristics, and deciding which seed to plant, or which animal to use in breeding. It was very low-tech, presumably operating without even written breeding or production records, and, we have reason to believe, worked very much like natural selection has.

Second, natural selection works in humans. No doubt Mr. Fair believes that all humans descended from an ancestral couple. If that was the case, how can we explain the differences between various groups of humans? Some of the differences may be due to chance,  but some of them, probably most of them, are due to natural selection. The Wikipedia article on "Human skin color" begins with these two sentences: "Human skin color ranges in variety from the darkest brown to the lightest pinkish-white hues. Human skin pigmentation is the result of natural selection." The article refers to solid scientific evidence for that second statement.

Third, and less obvious, but more compelling, natural selection works in the ordinary reproduction of organisms, including humans. Not in selecting for new forms, but in selecting so that current well-adapted forms persist. You may have seen an albino animal in the wild. I have. They are rare, but they do exist. Why are they so rare? Because Darwin's common-sense description of natural selection does, indeed, make sense. Organisms that have a tendency to have offspring that differ much from the norm are less likely to have their genes passed on to succeeding generations. A rabbit, in the wild, that can produce an albino offspring, is a rabbit that is less likely to produce surviving offspring than a similar rabbit that cannot produce such offspring.

God may, indeed, have created the first humans from scratch, or created the "kinds" of living things in separate special creative acts. But, even if both of those are true, He built natural selection into the system, just like He built gravity into the system, and natural selection, like gravity, influences the way things are, and serves to maintain God's good creation.

Mr. Fair should have read this post by a committed Young-earth creationist with solid scientific credentials, who says that evolution (by which he means natural selection) is not up for scientific dispute.

Thanks for reading.

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