Natural Selection and Macroevolution

Editor’s Note: First published in St. Louis MetroVoice 4, no. 2 (February 1994).

Darwin’s only observable evidence for “evolution in action” was the great variation that occurs within species of animals and plants under domestication. Darwin, who knew nothing of genetics, assumed that there was virtually no limit to this variation among the individuals of a species, though any breeder could have told him otherwise. In the first edition of his book On the Origin of Species, Darwin said that he had no difficulty imagining a race of bears entering the water to catch fish and then slowly developing wider mouths, shorter legs, and longer tails, until they evolved by chance into the great whales. Thus, Darwin extrapolated the observable but limited variation that occurs among the individuals of a species, into the unobservable evolution of fundamentally new animals.

Since evolution selects by the simple expedient of life and death, without death there could be no evolution.

Darwin reasoned that if pigeons and dogs can be selectively bred by man to produce certain desired traits, then nature itself can select for limitless traits by a process called natural selection. While breeders use intelligence to select for desired traits (such as physical appearance or strength), nature, in Darwin’s view, selects for those traits that promote survival itself. Since evolution selects by the simple expedient of life and death, without death there could be no evolution. On a recent Phil Donahue show, the well-known evolutionist Carl Sagan said that it took “lots of deaths in order to get us to where we are now. The secrets of evolution are time and death.” Christians might give some thought to the implications of this for the Gospel of Jesus Christ.

Darwin saw nature as a very hostile place where there was an overproduction of animals and a limited supply of food. He believed this led to a bloody struggle for existence among animals in which only the most fit survive. Thus, natural selection came to be defined as survival of the fittest. One of the problems with this “explanation” is that it is a tautology. A tautology is a circular statement such as “deafness causes loss of hearing”—while true, it adds nothing to our understanding. Which animals survive?—why, those that are fit. What do we mean by “fit”?—why, those that survive!

The classical Darwinian view of natural selection as survival of the fittest was later modified to mean differential reproduction. This interpretation of natural selection became popular in the 1950s under the name of neo-Darwinism. In the neo-Darwinian view, nature does not merely select for animals that survive, but for animals that leave the most offspring. Think this one through—according to Darwin the reason we are supposed to have evolution in the first place is that animals leave too many offspring, and there isn’t enough food to feed them. Now we are told by neo-Darwinists that the animals that leave the most offspring insure the continued survival of their species. Ironically, neo-Darwinists (like Paul Ehrlich) stridently insist that we humans must severely limit the number of our offspring if our species is to survive!

Almost all biology textbooks give the example of the peppered moth as observable evidence of natural selection. Peppered moths of the species Biston betularia range in color from mostly white with a peppering of black specks to nearly all black. At one time, it is claimed, the lighter colored moths of this species were the most numerous because they blended in with the light-colored bark of the trees they favored, and thus, were nearly invisible to their bird predators. Several years ago, air pollution caused the bark of these trees to darken, exposing the lighter moths to the birds. It is assumed that the birds ate the more visible white variety, leaving behind mostly the darker variety of the species, which lay hidden on the soot-darkened trees. To the evolutionist, this is observable evidence of evolution in action! But while the peppered moths may be an example of natural selection, they do not show the evolution of a fundamentally new kind of animal, or even a new species of moth.

There is, in fact, no known relationship between so-called microevolution and macroevolution.

Evolutionists like to refer to the sort of variation we see among individuals of a species as microevolution, implying that this is somehow related to the chance formation of fundamentally new animals by a process known as macroevolution. There is, in fact, no known relationship between so-called microevolution and macroevolution. Most evolutionists are quite aware of this (although you would never guess it from the explanations of evolution in the media, textbooks, and in the classroom). A report in the journal Science (210:883–87) on a recent macroevolution conference held at the Field Museum of Natural History in Chicago, summarized the views of participating evolutionists as follows:

The central question of the Chicago Conference was whether the mechanisms of microevolution could be extrapolated to explain the phenomenon of macroevolution. At the expense of doing violence to the positions of some people at the meeting, the answer can be given as a clear NO.

If this conclusion alone was shared with students in our schools, it would go a long way toward addressing the concern that evolution be critically evaluated in the classroom, rather than dogmatically indoctrinated.

We cannot select for genes that are not in the gene pool of the species.

One of the great achievements of modern science is the discovery of how it is possible for animals of the same species to show an immense range of variation without changing into completely different kinds of animals. Genetic analysis shows that the individuals of a species do not share an identical set of genes, but rather have a small number of alternative versions of many genes called alleles. Only clones have the same genes and are essentially identical—including the same sex. It would be a boring (and short-lived!) world if all the individuals of a species were identical clones of one another. The fact that each individual inherits allelic versions of genes from both parents insures that no two individuals will be exactly alike. Thus, we say that all the individuals of a species comprise a gene pool from which selection (either artificial or natural) can select. The important point is that we cannot select for genes that are not in the gene pool of the species.

Consider the remarkable species Canis familiaris, which includes over 150 varieties of dogs recognized by the American Kennel Club. Dogs as different as a 125-pound St. Bernard and a 3-pound Chihuahua are all the same species of animal! Still, there are limits to what can be achieved by dog breeders. They can breed for long legs and short legs (within limits), but they can’t breed for a flying dog with wings. The reason for this is simple: there are no genes in the entire gene pool of the species Canis familiaris that would produce wings, or any of the other countless specializations necessary for flight. For this, the evolutionist must look to mutations, their most ludicrous mechanism of all.