This is apparently some confusion over my post about why natural selection is not random. It’s a fairly elementary issue at hand, but it evidently needs to be addressed. One reader mentions,
Natural selection is a product of selective pressures. Those selective pressures are random in that they do not try to produce anything specific (ie: original appendages, limbs, organs, organ systems, body plans, etc… or the DNA that codes for them).
This user is right so far, even if the language is a bit dicey. A particular environment produces conditions to which a population then responds. A research job from a biology professor of mine will do fine here: there are two species of fish in a stream, one small, one large. This stream is divided into two sections: an upper area and a lower area. The division is due to a small waterfall. Now, the small fish in the top section of the stream tend to be vibrant in color while the lower small fish are a more gray color. The hypothesis is that the large species of fish is unable to traverse the waterfall so thus unable to eat the upper small fish, hence their vibrancy. So the research team takes some large fish and introduces them into the area with the vibrant fish. Sure enough, the fish lose their vibrancy pretty quickly. Conclusion: The hypothesis was not falsified because a correlation between color vibrancy and survival was shown upon introduction of the large fish species to the upper stream.
So now here’s where the user goes awry.
Hence, natural selection is random.
He concludes that because the selective pressures happen without regard to a particular species that the reaction of the species is thus random. Do you see the inane logic? This is like saying that because what particular rocks, gas, and space junk goes into the making of a planet can be called random that the force behind the accretion process – gravity – is random.
It’s all very simple. Natural selection is the process of differential survival of organisms based upon how they respond to a given environment. That means that natural selection happens with regard to adaptability. And maybe this is the kicker for this silly creationists. That’s really all “non random” means – with regard to adaptability. That’s why any aspect of genetic drift or mutation is considered random. It happens regardless of whether an organism will do better, worse, or the same in its survival. Were natural selection random then we should expect to see a number of vibrant fish swimming around the upper stream which is in comparable proportion to the number swimming around prior to the introduction of the large fish species. Of course we do not see anything like that. What we do see is differential survival based upon the response of the organism to a particular environment – the fish which survived were less vibrant, on average, than the fish which were quickly eaten.