Friday, February 03, 2006

More On Evolution...

Natural Selection is the Heart of Darwin's Evolution Theory - But there are Some Real Problems...

At the risk of being pummeled I throw out these perfectly reasonable doubts about natural selection being at the root of macroevolution.

Source: Jerry Bergman, PhD

[Support for natural selection depends heavily upon the validity of its analogy with artificial selection (Tinkle, 1976). Darwin might have been justified in utilizing the animal breeding analogy to illustrate a limited process, but the use of natural selection as the major support pillar for macroevolution is problematic. In. the first chapter of The Origin, Darwin discusses extensively artificial selection and extrapolates far beyond what his data warrants (Gale, 1982). The two major problems with this analogy between artificial and natural selection include:

1) Almost all the traits that breeders breed for have nothing to do with survival, and thus nature would not select for them; we breed dogs for certain appearance traits, horses for speed traits, cows for milk traits, and chickens for egg traits.

2) Animal breeders have found that select traits are often lost if random breeding again occurs, or if breeding for other traits is done. Few if any permanent changes in the animal usually occur, only the probability of certain traits appearing is altered.

The problem, both then and now, was going from the known to the unknown. Humans have produced many new strains of animals through breeding which have made our life easier and more pleasant. Although these strains were different in certain major ways from their predecessors, they usually soon reverted back to the previous types if allowed to interbreed with them again. Totally new major traits were never developed, but existing ones were re-arranged and favorable ones retained so that certain traits were more pronounced. This type of evolution (if it could be called such) is often termed microevolution, as opposed to macroevolution. Breeding solid black horses is microevolution, breeding winged horses is macroevolution. This dichotomy is artificial, and a clear distinction cannot always be made-and what is now macro may be classified as micro, meaning possible. Microevolution is what we have achieved, thus have experimentally verified, and this is probably a more realistic definition. Macro is what we hypothesize could be achieved, or which, according to fossil evidence and conjecture, might have occurred in the past, given a set of assumptions about the fossil evidence.

Now that researchers have a tremendous amount of experience in breeding animals, it is clear that it can be carried only to a very limited level, and many traits tend to revert to where we started-fruit fly traits, after eight to ten generations, tend to revert back to normal (Tinkle, 1976). The fact is, extensive breeding by millions of researchers and breeders has not produced a single undisputed new species in 400 years of experimenting (Johnson, 1991). As Eiseley (1958, p. 223) noted:

... careful domestic breeding, whatever it may do to improve the quality of race horses or cabbages, is not actually in itself the road to the endless biological deviation which is evolution. There is a great irony in this situation, for more than any other single factor, domestic breeding has been used as an argument for the reality of evolution.

Deevey (1967, p. 636) concludes, "Remarkable things have been done by cross-breeding ... but wheat is still wheat, and not, for instance, grapefruit. We can no more grow wings on pigs than hens can make cylindrical eggs." A more contemporary example is the average increase in male height that has occurred the past century. Through better health care (and perhaps also some sexual selection, as some women prefer taller men as mates) males have reached a record adult height during the last century, but the increase is rapidly disappearing, indicating that we have reached our limit.

Darwin's error was in stretching this comparison too far, sooner or later we reach limits, and no one has yet observed helpful macroevolutionary changes taking place. Since we do not have several billions of years of direct observation, we have not been able to directly test this assumption. Nevertheless, some animals such as fruit flies live a very short period of time, enabling us to observe multi-thousands of their life generations. Even with a drastically higher artificial increase in the number of mutations, which are supposedly the source of variation which gives rise to the "stuff" from which natural selection can select, no evidence exists that large changes have, or can, occur (Lester and Bohlin 1984).

Even Gould (-1977, p. 39) admits ...... although I wear the Darwinian label with some pride, [I] am not among the most ardent defenders of natural selection" More blunt is Bethell (1976) who concludes, "Darwin's theory [of natural selection] I believe is on the verge of collapse. . . . Natural selection was quietly abandoned, even by his most ardent supporters, some years ago." Gould, in an article defending natural selection (1977, p. 40-41) admits that, "Bethell argues quite correctly that [Darwin] relied upon analogy to establish it [his definition of survival of the fittest] a dangerous and slippery strategy." Yet, many scientists are still struggling not only to define it, but also to demonstrate that it has a role in megaevolution (Maddox, 1991, p. 653).]

Now, mind you, these doubts and questions are not coming from Christians bent on discrediting Darwin to promote a Creationist agenda SO PLEASE don't come down on me because I happen to be Christian. These are reasonable questions by reasonable scientists. The last thing this debate needs is more nasty Richard Dawkins-like name-calling and condescension. Dawkins is a quick-witted, quick-tounged genius level scientist in his own right, but his style of argument is counterproductive and I'm afraid his fans have fully adopted it.

The whole point I have tried to make in previous posts is that there is plenty of dissension among scientists and biologists regarding some of Darwin's theories far outside of the religious arguments for a divine creation.

Let the pummeling begin.



CW

2 comments:

TJ Willms said...

You do sure seem to enjoy using your ribs to hurt other peoples hands. I hope this isn't some recessive genetic trait that will manifest itself later in the other members of your family ...

Timothy Birdnow said...

You are a brave man, Mr. Willms!