Classical Darwinism; Natural Selection

Classical Darwinism; Natural Selection

Evolution by Natural Selection

Many high school textbooks explain how variation, mutation and natural selection can help certain species of animals or plants survive or continue to exist. They don’t tell us however, how this mechanism (selection on variation) can cause one type of organism to arise from dead matter or turn into an entirely different kind of animal. This article was written for a particular textbook but most I have read have had the same flaw.

Perhaps this is because scientists know that while there is great variety within any animal kind, this variation is limited to the pre-existing information carried in the animal’s genes. This variation within beak sizes among finches or various skin or hair colors among humans for example, is what helps us to adapt to different climates and habitats. As animals migrate in small groups into different habitats, and become isolated from each other, the genetic information they carry is sorted out, with some information being concentrated in one group and some being lost altogether. When this kind of bottlenecking occurs, the small isolated population will reflect the concentrated information, but this comes at the cost of the overall loss of other information. Natural selection may favor a large beak size for example over smaller beaks in one location and after a while the information for smaller beaks may be lost.

These changes among animals are sometimes called micro-evolution or referred to as genetic drift. Darwin believed that micro-evolution (the sorting out of pre-existing information) could over time produce macro-evolution (the addition of large amounts of new information). A cat turning into a dog or an organ like the eye forming where there wasn’t one before.

In 1980 a group of scientists met to discuss the problem of macroevolution. The Journal Science reported, “The central question of the Chicago conference was whether the mechanisms underlying micro-evolution can be extrapolated to explain the phenomena of macro-evolution. At the risk of doing violence to the positions of some of the people at the meeting, the answer can be given as a clear, no.” Pierre Grasse, the famous French scientist said. “No matter how numerous they may be, mutations do not produce any kind of evolution.” He also said, “They modify what preexists, but they do so in disorder.”(3)

Why not? Because natural selection can only act on what is already there. Mutations are simply mistakes in the copying of pre-existing genetic information, and natural selection only favors “adaptations” that already exist. Natural selection cannot “choose” a fish with eyes over an eyeless fish unless the information for functioning eyes is already there. Natural selection cannot create eyes; it can only choose them as better for survival under certain circumstances. And no amount of accumulated random copying errors can produce the kind of complex, interacting information necessary to provide even the simplest eye, brain or heart, or the many tiny molecular machines that are necessary to their function.

Science has never observed a mutation which added complex information to any organism. (Some mutations can be beneficial even though they still represent an overall loss of information and always have a down side. The last I heard, they had listed about 186 beneficial mutations against 453,732 harmful mutations).They have observed thousands of mutations which cause a loss of information and injury to the health of animals. The reason we avoid x-rays or exposure to second hand cigarette smoke is that such exposure increases the chance of mutation and mutations are not advantageous for us. Stephen Gould in a college lecture stated,” A mutation doesn’t produce major new raw material…A mutation is not the cause of evolutionary change.” (2)

The textbook completely ignores these problems and appears to be trying to pass off micro-evolution (limited change based on existing information) as proof of macro-evolution (unlimited change requiring new information). This particular textbook gives no example of macro evolution where a mutation which added new information was observed In a review in Science of a paper by Brooks and Wiley, Roger Lewin quoted Brooks on the process of natural selection; “…It can weed out some of the complexity and so slow down the information decay that results in speciation. It may have a stabilizing effect, but it does not promote speciation. It is not a creative force as many people have suggested.” (4)

The same holds true for the human genome; “Because deleterious mutations are much more common than beneficial ones, evolution under this relaxed selection will inevitably lead to a decline in the mean fitness of the population.”Kondrashov, A. 2012. The rate of human mutation. Nature. 488 (7412): 467-468

Leading geneticists have said that this increasing load of mutations will eventually destroy the animal kingdom. How could the mechanism which is slowly destroying the complexity of living things be the same one that created them? It hardly seems likely

(2) February 14, 1980 lecture at Hobart and Smith College in honor of Mary Leaky. In Darwin’s Enigma, Ch. 5, p.106

(3) P. Grasse, Evolution of living Organisms, Academic Press, New York, 1977, p.88, pp.97,98

(4) Roger Lewin, Science 217,1239, 1982, see also Brooks and Wiley, Evolution as Entropy, University of Chicago Press,1986

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s