In a biological sense, a species is a class of living bodies, the members of which are similar in structure, and can breed indefinitely in their natural state. In the rather rare case of offspring from parent-animals of different species, we have a hybrid. The hybrid is usually sterile, but if it should have offspring, this will be an animal of the type of one of the parents of the hybrid. This fact is called reversion to type.
Minor groups of animals within the species are called varieties. When varieties are artificially cultivated, they are called breeds or races. The offspring of parent-animals of different breed is called a mongrel. A mongrel often shows marked characteristics of one out of several ancestral breeds; this reversion is called atavism.
Different species which have some common characteristic make a genus. A genus grouped with other similar genera constitutes a family. Families of similar type make an order. Orders are grouped as classes. Classes are grouped into phyla. The phylum is the most general biological class of organisms, that is, of living bodies.
That there are different species of living things, and of animals, needs no proof. The question is not of the existence of species, but of the origin of species.
We have already noticed the fact of the origin of life. Life does not come from nonlife. A living body is not the product of nonliving bodies. Life in its first origin can have no explanation except in creation; life came by creation from the First Cause, from the First Giver of Life, or, as many prefer, from God
But did God endow the lower living things with powers to develop into higher types of things? Have the species of living things, and notably of animals, a common origin in one living body, or in one type of living body?
Of course, the creator of the world can make his world as he chooses. If he chose to have all plant and animal bodies develop from a single parent-body of a lower type than any existing plant or animal, who shall say that he may not do so? Yet he must, in that case, have equipped the original body with the powers to develop superior life-forms. For no living body has any tendency in the way of reproduction except in its own kind. Even for this, of course, the living body has to be equipped.
Geology seems to indicate that the forms of bodily life that appeared on our earth were increasingly more complex; that there was an ascending scale of development among living bodies. We leave man out of this account, for, as we have noticed, science simply does not know any ancestors of man. Man’s most notable and characteristic powers and activities are of a nature superior, and essentially superior, to all organic function, and hence cannot have their explanation in an animal development or evolution.
There are two theories about the origin of species. One maintains the changelessness of species, and declares that one species does not develop into another. Each species, while diversified by varieties, clings to its essential type and shows a fixed tendency to retain it always. No body, and hence no living body, has the suicidal tendency of destroying itself so that an essentially different (even if superior) body may exist in its place. The defenders of the changelessness of species say that the Creator of Life made species as they are, either by a succession of creations at different times, or by a single creation of all species at once, although these species (like seeds all planted at the same time but destined to appear as plants at widely different seasons) have come into being at different stages of the earth’s development.
The other theory about the origin of species is that of transformed or derived species; it declares that one species is derived or descended from other species. This theory is accurately called transformism; it is more generally, and less accurately known as evolution. Evolution is of three types: monistic, Darwinian, and theistic.
- Monistic Evolution holds the theory that there is only one kind of substance, and that a material substance or bodiliness, which is diversified only by transient activity of a mechanical, physical, and chemical nature. The self-contradictory character of monism has already been shown in The Philosophy of Nature: A brief introduction to cosmology. And we have notice, in the present essay, the essential difference between living bodies and nonliving bodies, as well as the fact, admitted by science, that life does not originate in nonlife, and that living bodies come always from living bodies. The monistic evolution, which had its day of sweeping popularity in the 19th century under the influence of Ernst Haeckel, is now very generally abandoned as an explanation of the origin of life and of species.
- Darwinian Evolution is the theory that species come from one or two types of organisms of the lowest order, and that this is effected by a constant tendency of living bodies to acquire and transmit variations; that there is a struggle for existence among living bodies in which the fittest survive; that existing species are survivors of the struggle by reason of their superior natures, and thus are here by natural selection. This theory accounts for essential differences in living bodies by assigning accidental differences (or variations) in their ancestors. Here we have not an adequate explanation. The effect is greater than the sum of all its causes. Darwinian evolution also conflicts with experience, for species are clearly and sharply differentiated, as the botanist and the biologist will maintain, and are not reaching out towards other species; indeed, they cling strongly to type. Hybridization is possible, and varieties can be produced, but there is effort needed to effect these results, and the phenomena of reversion and atavism are ever present. Darwinian evolution, in its pure form, has now very few defenders. It does not account scientifically for the origin of species.
- Theistic evolution excludes man altogether (that is, man as man) from any evolutionary process, but admits that lower forms of life than the human form have come into their present state by a process of evolutionary development. This type of evolution sets out these incontrovertible and scientific facts: (1) Matter is not self-existent, but comes from a Creator; (2) Matter is not the source of life: life comes from a Creator; (3) Living bodies develop into bodies of superior species by a power — over and above the powers necessary for their proper existence and function — specially conferred by a Creator.
A philosophical theist may accept theistic evolution if he is satisfied with the evidence offered. But no type of evolution is scientifically established as fact, in spite of what some prominent voices in science may say. Evolution is a hypothesis, that is, a scientific guess. There is evidence that makes an evolutionary development of living bodies appear likely; there is no evidence that makes such a development a certainly known fact (in spite of those prominent voices, again). It is to be noticed that any type of evolution demands a Creator who set the process in motion, a Conserver who sustains it, and a Concurrer who goes along with it to support its activity and achievements. No evolutionary theory can, in the final analysis, dispense with a First Cause, A Creator, or, as some would say, God.
Can a theist hold the theory that man’s body has an animal origin? That is, can it be held as a hypothesis — since scientific knowledge on the point is presently out of question — that the body of a single individual man was an animal body (ultimately formed from the slime of the earth) into which a Creator (or God) breathed a human soul? For such a belief there is absolutely no evidence, yet the hypothesis in itself is not in open conflict with philosophical theism or even with Christian revelation.
The late Dr. Jonathan Dolhenty was the Founder and President of The Center for Applied Philosophy and the Radical Academy, and is Honorary Philosophy Editor at Self-Educated American. Self-Educated American has adopted these projects beginning with a republishing and preserving of all of Dr. Dolhenty’s work.
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