Science in Christian Perspective

 

 

The "Kind of Genesis and the Species" of Biology*
WILBUR L. BULLOCK Ph.D.
Assistant Professor of Zoology
University of New Hampshire

From: JASA 4 (June 1952): 5-7
*Paper presented at the Sixth Annual Convention of the American Scientific Affiliation, New York, August, 1951,

During the evolution-creation debates that were so popular in the first quarter of the 20th century one of the most important conflicts centered around the problem of "fixity of species." At that time it was generally assumed that "kind" of Genesis 1 and "species" of biology were synonymous. Therefore, since Genesis implied that these kinds or species were stable units, the Christian became an ardent defender of the fixity of species. Indeed, precedence for a stand on the immutability of species had already been set by such biological greats as Agassiz and Cuvier while the main exposition of the concept could be traced back to Linnaeus himself. In the past 50 years, considerable thought and study has gone into the species concept and some important changes have been made that bear heavily on this old problem of species fixity. A challenging problem thus presents itself to the Christian biologist. What is the relationship between "kind" and the newer concepts of species, and is there a Christian concept of species? Mixter (1950) made a contribution to this problem by pointing out that the word "kind" is a rather general term that may have several meanings. He further pointed out the difficulties involved in assuming synonym for "kind" and "species." Without any further consideration of the former term at this time, let us consider the problem of species as it manifests itself in that area of modern biology known as taxonomy or systematics.

One of the oldest approaches to the study of the living world around us has been in the cataloguing or classifying of plants and animals. The resultant type of biology-systematics or taxonomy-has, in recent years, been drastically revised to play a major role in outlining the course of evolution. From this has arisen the current twofold aim of modern taxonomy: (1) to name and describe animal forms and (2) to arrange these forms in an order that will indicate their evolutionary relationships. For the Christian, it now becomes necessary to analyze these objectives of modern taxonomy and to attempt to discern any correlation between the facts of this taxonomy and the Scriptures.

At first sight the naming and describing of animal forms seems to be a relatively simple task. Certainly Adam had no great difficulty in Genesis 2:19,20 where we are told: "And out of the ground the Lord God formed every beast of the field, and every fowl of the air; and brought them unto Adam to see what~ he would call them: and whatsoever Adam called every living creature, that was the name thereof. And Adam gave names to all cattle, and to fowls of the air, and to every beast of the field." However, our difficulties soon become apparent when we actually try to catalogue the forms we see in the world around us. This dilemma is perhaps best illustrated by the remark of the entomologist: "Where was I to put a beast or a bug when the next one that's exactly like it is entirely different the next time you look at it?" Not only does this exclamation of exasperation indicate difficulty in assigning an animal form to its taxonomic niche (or species) but it intimates that the niche itself is none too reliable.

The task of defining the "species" is one of formidable proportions. Such is the nature of the task that many have been led to deny the reality of the species. Historically, we can follow through from the fixed species of Linnaeus (1758) to the relative, "passing parade" concept of Haeckel and Darwin, to the modern polytypic species of Mayr, et al. As these attitudes varied in time, so do they vary with the particular animal or plant group involved and with the approach of the taxonomist. In this manner there is little correlation between the species of bacteria, protozoa, helminths, insects, or vertebrates. For example, witness the absurdity of applying a bacterial species concept to helminths as done by Wilhelmi (1940).

"Species" of helminths may be defined tentatively as a group of organisms the lipid free antigen of which, when diluted to 1:4000 or more, yields a positive precipitin test within one hour with a rabbit antiserum produced by injecting 40 mg. of dry-weight, lipid-free antigenic material and withdrawn ten to twelve days after the last of four intravenous injections administered every third day.

Among the earliest concepts of species is that which considers the species to be a group of animals of similar morphology and not overlapping in this respect with any other group. This is basically the concept of Linneaus (1758). It is a much maligned concept but is still used today by many modern taxonomists. Gates (1946) relies considerably on this concept in his evaluation of primate evolution. Students in many of the invertebrate phyla use it in cataloguing new forms. Indeed, it would be impossible to begin a taxonomic study of an unworked group without a morphological introduction. However, this concept has its shortcomings. The selection of characters that are "significant" tends to become quite subjective. Besides, the significance of these characters varies from one group to another. Rensch (1934) illustrates this by noting that folds in the shell mouth of certain snails are reliable for species identification whereas in other snails individual variation makes them useless. Witness also the widely divergent views on the classification of the Trematoda. depending upon whether suckers, excretory pattern, reproductive system, or life cycle is used as its basis.

Another approach to a species concept, and one that has achieved considerable popular acclaim, is on the basis of interbreeding. One of the better known manifestations of this concept is illustrated by the state. ment that "all forms belong to one species which can produce fertile hybrids." This is a very appealing definition but it has many limitations. (1) It cannot apply to the Protozoa or to hermaphroditic groups. (2) There are too many obvious exceptions. For example, several well known species of Drosophila are capable of producing at least some fertile hybrids. Moore (1946 a,b) showed th-at crosses between Seographically widely separated races of the frog, Rana pipiens produced defective "hybrids" whereas crosses between two species R. pipiens and R. palustris, from the same area produced normal hybrids capable of reproduction. Still another example of the unreliability of this definition is illustrated by the shad genus, Pomolobus. These marine fishes go up the bays and rivers to spawn in brackish water during the spring of the year. At least, in the region of Durham, New Hampshire, P. aestivalis and P. pseudobarengus overlap in their spawning seasons. Much interbreeding is now taking place so that it is quite difficult to distinguish the two species. Thus the presence or absence of fertile hybrids is not a reliable species character.

A somewhat improved version of the interbreeding species concept is that of Mayr (1942). "Species are groups of actually or potentially, interbreeding natural populations, which are reproductively isolated from other such groups." This definition avoids a consideration of hybrid sterility but still retains the limitations shown by the sterility concept. It can not apply to many invertebrate groups nor does it explain the hybrids between sympatric species.

Still other species concepts have utilized genetics, physiology, or immunology as their basis. However, general application of these criteria have yielded little but confusion in the taxonomy of the greater part of the animal kingdom. It is not surprising then to find many adherents to what Mayr (1942) characterizes as the "practical species concept"; namely, that a species is a systematic unit which is considered a species by an authority on the group. This concept reduces the species to the depths of subjectivity. It creates an ephemeral, highly limited species that serves only a given group of authorities in a given group of animals or plants.

Thus it can be seen that at the present time there is no real concept of species. Indeed it is easy to become pessimistic about the very existence of the species as a valid biological unit. However, most authorities in the field of taxonomy and evolution still maintain that the species is a real and useful entity (Mayr, 1942; Goldschmidt, 1940; Huxley, 1940). This is particularly true for animal groups which are well "worked" taxonomically. In these groups the various factors in variation (geography, temperature, altitude, etc.) are most clearly understood, and it is in these groups (e.g. birds) that the "polytypic" species dominates the scene.

The polytypic species is a concept that had its beginnings with Kleinschmidt (1900) in his Formenkreis theory. This Formenkreis was a sort of super species which took into account the factors involved in the variations of populations under differing environmental conditions. Kleinschmidt further recognized the strong possibility of supernatural intervention in bridging the gaps between related Formenkreis. Such a concept-minus the supernatural intervention-is the basis of Goldschmidt's modern mutationist theory. Unfortunately, what Kleinschmidt lacked in genetics, GOldschrnidt lacks in making any contribution to the species problem. In general, the polytypic species has led to the lumping of many varieties, previously described as distinct species, into only a few species. Such a concept applied to man would lead to the inclusion of all living and fossil man into one or at most two species. This seems to be in greater harmony with the Scriptural observation that "God hath made of one blood all nations of men." The reverse procedure as applied to man (Gates, 1946) leads to a great diversity of terms and serves only to support favored phylogenetic fancies. Some species, as pointed out by Huxley (1940), appear to vary little and hence are considered monotypic.

One more problem should be considered. That is the "subspecies." To Goldschmidt (as well as Kleinschmidt) the subspecies merely indicates the multiplicity of variations within the species. To the majority of present day evolutionists (e.g. Mayr, Dobzhansky), however, the subspecies represents an incipient new species. Should this latter concept prove correct then Christians must certainly look for the units of creation (kinds?) elsewhere than at the species level. Should mutationism triumph then the polytypic species concept might solve the problem. Much long and laborious taxonomy must be performed before anything definite can be said about the limitations of the species unit.

In summary, the species concept in modern biology is far from settled. The prevailing opinion is that there is a real entity in the species but whether this can be defined to satisfy all plant and animal groups is problematical. Consequently, the species, at present, is basically human concept. It is an interesting biological problem but probably does not bear any real relationship to the "kinds" of Genesis. It is possible that further developments in this field will shed light on this complex problem. Meanwhile, it is ill advised to champion the cause of fixity of species under the banner of Christianity.

Dobzhansky, Th. 1941. Genetics and the origin of species. Second edition. New York.

Gates, R. R. 1948. Humian ancestry: from a genetical point of view. Cambridge, Massachusetts.

Goldschmidt, R. 1940. The material basis of evolution. New Haven.

Huxley, J. S. 1940. The new systematics. Oxford.

Kleinschmidt, 0. 1930. The formenkreis theory and the progress of the organic w~orld. London.

Mayr, E. 1942. Systematics and the arigin of species. New York.

Since the manuscript was prepared there has come to the attention of the author several papers bearing upon the relationship of taxonomy to evolution which indicate a growing feeling of caution and dissatisfaction on the part of taxonomists and students of evolution. Gilmour (1951: Nature 168:400) stresses the point that natural classification is not essentially and primarily phylogenetic. This points up the general feeling expressed earlier in the year in the same publication in the report of the 1950 meeting of the Systematics Association of Great Britain. Here the difficulties of "phylogenetic classification" were discussed and the speculative nature of the process emphasized.

Dr. I. Cowperthwaite, the session chairman, then asked for discussion from the floor.

Mr. Meyers: I would like to make a comment on the paper, to this extent, that I believe we, as Christians, should be rather careful of just what he warned us against, this business of getting out on a limb. A lot of times we say things which we, at the moment, say are theology and doctrine and then later on, in the light of new discoveries, we have-to back down and that always makes Christianity look bad, especially in the face of the world. Not too many years ago in my own lifetime the pastor said that it was a sin to bob the hair. Well, pretty soon everybody was doing it and then it wasn't a sin anymore. That's certainly an illustration of the thing that goes on. It's the same way with this fixity of species. We get ourselves out on a limb and we say there are only so many kinds. Well, I wonder how long Adam would have to live to count all of the various kinds if one used all the various different animals that there actually are. If he were to count every one that we now know, I'm sure he'd have to live much more than his 900 and some years.

Dr. H. Hartzler: This is not my field. I'm not here to talk to the point. This just gives me an opportunity to say something concerning the purpose of the ASA. I think this paper is a good illustration of the fact that in science we are continually striving for the truth. We do not add up the truth. Many so called scientists claim they have all these words. But when it comes to the ASA, we are very much concerned that the Lord Jesus Christ may be known through our work and how are we to contact our homes and science if we cannot talk to them in their language. That's the purpose of this organization . . . that we may go to a man in any field and show him that the Bible that we believe is not wrong. Now that's a big task.

Bullock: I'd like to add just one word along the same line. When it comes to the question which we are going to discuss, on presenting Christ to the students in our Christian and secular colleges-and I happen to represent a secular institution-we find that you've got to meet these people on common ground. Now, I could get up here and, I suppose, talk way over your heads on this subject of the fixity of species. But I've dis cussed that problem of fixity of species with some of the members of my own department, some of my graduate students and I guarantee, when you discuss it with these people, that it's not too long before you realize and recognize that this is just one part of a much greater issue. You can't get into a discussion of that nature for very long before you're getting right down to the bed rock of the infallibility of Scriptures, the sinfulness of man, and redemption through Jesus Christ. You can't avoid it. I think we do tend perhaps to sort of skim over these very basic things because we've agreed on them to begin with, but you take the same approach and the same argument with an unbeliever and you'll eventually wind up discussing the infallibility of Scriptures and the deity of the Lord Jesus Christ.