The Human Choice - 9
Let us suppose that there was once a large island with vegetation, birds and various life forms. At some ancient time one of Earth's many natural disasters, in the form of a large earthquake, sinks the greater part of the island into the sea. All that remains visible is the top of a previously high plateau.
The birds were accustomed to living and nesting in the large trees and living on insects that they caught while flying among the branches. But those large trees are not adapted to grow at low levels in salt laden air and over the years they die back, become stunted and eventually disappear. They leave an island densely covered with small shrubs and bushes. The birds have been forced to live closer and closer to the ground until they have become ground dwellers, but are able to survive because there are no bird-eating predators.
Now what happens under the influence of genetic mutation and survival of the fittest? The birds have one major attribute that is no longer an advantage - the ability to fly. They also have another feature that is now of increased importance to their survival - their legs. It would be an advantage if their legs were stronger to enable them to run or hop more quickly through the undergrowth and so catch more insects.
All genes are afflicted by random damage! If, while the birds were living in the treetops there occurred damage to a flight gene, then the bird so damaged would be at a disadvantage - it would be less competitive.
The damaged bird and its gene would be self-eliminating and the flying ability of the colony maintained. But now that the birds are living in dense undergrowth it is flight ability that is a disadvantage; because of the dense undergrowth the wings cause obstruction whenever inadvertently spread as the birds attempt to catch their prey. In this situation every random destruction of a flight gene gives its bearer an advantage; therefore the ability to fly is eliminated.
That also gives rise to an additional bonus: the breeding out of unwanted features will allow more life-energy to flow to wanted features; the strength of the legs in relation to the body will improve because of reduced internal competition, genetic selection and increased exercise.
You will observe that destruction of flight ability in the above situation will occur "naturally and inevitably" but the strengthening of the legs is limited to the genetic alternatives already inherent in the bird. Mathematically speaking, if all the world's birds had been placed in this situation for all the time that birds have been living on earth, the potential for any one family to have acquired, by chance mutation, new genes to convert it, say, from a hopping bird to a running bird, would be so small as to be irrelevant to successful change. There is no evidence of any such creative change ever having occurred.
But ages pass, and at some time a ship is wrecked on the island; the survivors are a family of cats. The cats are easily able to catch and eat the flightless birds. The island being well populated by birds, the cats multiply rapidly.
Result: the bird population comes to an abrupt ending. But the cats, too, having long domestication, have lost much of their genetic ability to survive in the wild. Without shelter, and no easy supply of food, they also die out.
The above is the uncomplicated story of nature that agrees with the known facts and established evidence. Biology accepts the fact of specialisation (genetic degeneration); it is too obvious to deny. Yet specialisation is in complete opposition to creative evolution.
What is to be learned from that little story?
(a) That genetic specialisation will occur naturally, logically and inevitably, whenever a life-form finds itself in an environmental niche where some of its genetic load is of no advantage, more quickly if it is a disadvantage. The evidence is beyond dispute.
(b) Survival of the fittest is not a creative force, it is a maintenance force, it ensures the continuing health of the species in a particular situation. Even though, in principle, survival of the fittest may be even-handed, it is not creative or even-handed in long-term effect.
Because the destruction of genes occurs naturally and re-placement is to all practical purposes impossible, the long-term trend is to degeneration. The trees could not adapt.
This is the point that Muller and Waddington made: there is no law of nature that sets an over-riding standard of fitness. What is fittest in one environment will be unfitted to another, and the more ideally a life-form adapts to any specific environment the less will be its chances of survival if the environment critically changes. Had the birds of our little example not spent enough time in a ground-living environment to suffer critical loss of their flight genes, both the birds and cats may have survived in limited numbers.
The loss of a gene is, for practical purposes, a permanent loss. Here we see expressed in biology the form of a law of physics - the second law of thermodynamics. It is in the nature of systems, if left to chance, to degenerate.
NOTE: The preservation of the gene pool is now a major problem for science. There is a desperate rush to establish gene banks for plants, to do this for animals is more difficult.
In the process of breeding new plants and animals we are not actually creating new genetic ability; what we do is isolate the features we want and then "breed out" unwanted competitive genes.
This, more slowly, is what nature does.
The promotion of creative evolution (if not a deliberate deceit) is, at least, a manipulation and evasion of the evidence. choice9.htm