IMPACT January 1991---- (Part 1),No. 211 

ON THE CHANGING DEFINITION OF THE TERM "SPECIES"

By Kenneth B. Cumming, Ph.D.*

 

Nelson{1} has written, "The 'species problem' is perennial (Howard,

1988), and speciation remains as much a black box as ever (Jackson,

1988). If we examine these problems we find a spectrum of solutions:

some writers claim that everything, or everything important, is

known; others claim that nothing, or nothing important, is known

(Hull, 1988). I claim that the problems are insoluble, for they stem

from a false assumption: that there is an empirical difference

between species and the taxa such that species evolve through

speciation of other species.... Evolution of taxa is not a phenomenon

confined to the species level except in neo-darwinian theory, which

in this respect is simply false."

One would think that surely by now scientists would have

agreed on the definition of this fundamental term in systematics --

Species. In truth, while most biologists would quickly offer their

preferred definition when asked, each could also be unsettled by

challenging their response with an alternate interpretation. What is

the underlying problem in this uncertainty? I believe it lies in the

presuppositions of the various writers.

In this first of a series of Impact articles, the term

"species" will be examined to demonstrate the wide diversity of

definitions. No attempt will be made to give detailed explanations of

the concepts involved in the following definitions at this time. In

forthcoming articles the terms of "speciation" and "specialization"

will be reviewed. It is expected that a comparison of evolution and

creation thinking on these terms will lead to a sharp separation of

perspective on the "species problem."

Species Concepts

Let us start with Aristotle and work our way foward to a creationists,

to speculate on the rationale for the various definitions. Goerke{2}

states, "The earliest scientific classification of objects in nature

was made by Aristotle in the fourth century B.C., and the principles

he established retained their authority well into the sixteenth

century and even into the seventeenth." He divided plants into

trees, bushes, and herbs, and animals into those with and those

without circulatory systems (very generally vertebrates and

invertebrates). Mayr{3} adds, "Typological thinking ... according to

this concept the vast observed variability of the world has no more

reality than shadows of an object on a cave wall, as Plato puts it in

his allegory. Fixed, unchangeable 'ideas' underlying the observed

variability are the only things that are permanent and real.... The

concepts of unchanging essences and of complete discontinuities

between every eidos (type) and all others make genuine evolutionary

thinking well-nigh impossible."

"Linnaeus did a great service to taxonomy when he invented a

definite terminology for the systematic categories and showed that

they could be arranged in a graded hierarchy: species, genus, family,

order, and class... he adhered always to an essentially static and

morphological species concept."{4} Thus, Linnaeus, about 1735,

believed that species was a term for an objective and highly separate

group of organisms; as a creationist he wanted to delineate the

Genesis "Kinds" in his systematics. Members of the group did vary,

but by and large, the history of the group (lineage) showed a

consistency of traits since the type was formed.

Darwin's(5) interpretation of species in 1859 was simply

practical: "I look at the term species as one arbitrarily given for

the sake of convenience to a set of individuals closely resembling

each other...it does not essentially differ from the term variety

which is given to less distinct and more fluctuating forms." To him a

species was any group of organisms that competent naturalists said

said was a species. All organisms were seen as part of a continuum

from some single primeval entity.

The next major different concept in the term species was

introduced around 1940 by Dobzhansky and Mayr: It was the biological

species concept. For a long time this thinking has saturated much of

the evolutionary literature. Mayr(6) presents his definition: "A

biological species definition, based on the criteria of crossability

or reproductive isolation, has theoretically fewer flaws than any

other... Species are groups of actually or potentially interbreeding

natural populations, which are reproductively isolated from other

such groups." Obviously, this is a much more concrete interpretation

of species for evolutionary considerations than Darwin's, and more

dynamic than that of Linnaeus. However, this concept does not lend

itself to understanding the process of speciation.

Thus, Templeton(7) reviewed the problems associated with

various "biological species concepts" and introduced his cohesion

concept, "that defines a species as the most inclusive group of

organisms having the potential for genetic and/or demographic

exchangeability. This concept borrows from all three biological

species concepts. Unlike the isolation and recognition concepts, it

is applicable to the entire continuum of reproductive systems

observed in the organic world. Unlike the evolutionary concept, it

identifies specific mechanisms that drive the evolutionary process of

speciation." There are other concepts(8),(9) that have been put

foward that could be developed, but let's go on to a different line

of thought from three phylogenetic examples used above.

Henning,(10) as a cladist, views biological diversity with a

different goal in mind than the phylogeneticist. "...in a

hierarchical system, each group formation relates to a 'beginner'

which is linked in 'one-many relations' with all of the members of

that group and only those. In morphological systems, the "beginner'

which belongs to each group is a formal idealistic standard

(Archetype) whose connections with the other members of the group

are likewise purely formal and idealistic. But in the phylogenetic

system, the "beginner" to which each group formation relates is a

real reproductive community which has at some time in the past really

existed as the ancestral species of the group in question,

independently of the mind which conceives it, and which is linked by

genealogical connections with the other members of the group and only

with these." The cladist definition of species is similar to that of

Mayr, above--the reproductive communities that occur in nature.

However, due to the unique methodology of morphological resemblance

systematics, different principles of classification are employed

above and below the specific level. Cladism is essentially typological.

As a final example, I would like to review a creationist

concept of species. ReMine(11) has recently put foward an alternate

systematic methodology to the prevalent phylogenetic systems. He

calls it "discontinuity systematics." In the scheme, he explains that

"species" was merely the Latin word for "kind." For various reasons,

he coins terms releated to the synthetic Hebrew word "baramin" to

apply to working definitions of this innovative system. Frank

Marsh(12) originally combined the Hebrew root words bara ("create")

and min ("kind") into the term "baramin." Although there is no direct

statement to this effect, the term "holobaramin," or its subset

"monobaramin," might include or in some instances be synonymous with

species,. Yet the emphasis is upon experimentally circumscribing the

continuities and locating the real gaps or discontinuities in nature.

Empirical research on delineating holobaramins is just starting.

SUMMARY

With tongue in cheek, I originally entitled this article, "On the

Origin of 'Species,'" to play on the history of the term species as a

concept. Most of the systematic literature would certainly deal with

phylogenetic definitions of the taxonomic class--species.

Nevertheless, there are some uses, both old and new, that refer to

species typologically. Granted, most typological cladists would never

associate with a creationist perspective, for they are through-going

evolutionists, even if they do not agree with Darwinian or even

neodarwinian extrapolations. The following table might represent a

partial summary of representative methods involving the species concept.

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| Species |

| Systematic Taxon |

| Concepts's Author Methodology Synonym |

|--------------------------------------------------------------|

| Aristotle typology essence |

| Linnaeus typology kinds |

| Darwin phylogeny variants |

| Myar phylogeny isolates |

| Templeton phylogeny exchangeables |

| Henning typology clades |

| ReMine typology holobaramins |

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Biosystematic users of the term 'species' mentioned in this article,

except possibly in cladistics, appear to imply real reproductive

communities of organisms, when they deal with non-fossil species. It

can be seen that the definition of species, which started out

essentially as a morphological term, has taken on a functional or

operational meaning. Underlying this dynamic component are

presuppositions related to variance--limited or unlimited. In the

next article of this particular series, the evidence for speciation

will be discussed.

REFERENCES

1. G. Nelson, Species and Taxa: Systematics and Evolution, in D. Otte

and J.A. Endler, Speciation and its Consequences (Sunderland,

Massachusetts), Sinauer 1989) pp. 73,74.

2. H. Goerke, Linnaeus (New York, Charles Scribner's Sons, 1973), p.90.

3. E. Mayr, Animal Species and Evolution (Crambridge, Massachusetts,

The Belknap Press of Harvard University Press, 1979, p 9.

4. E. Mayr, Systematics and the Origin of Species (New York, Columbia

University Press, 1944), p. 102.

5. C. Darwin, The Origin of Species by Means of Natural Selection, or

the Preservation of Favored Races in the Struggle for Life (New York,

Avenel Books, 1970), p.108.

6. E. Mayr, 1944, op cit, p. 120

7. A.R. Templeton, The Meaning of Species and Speciation: A Genetic

Perspective, in D. Otte and J.A Endler, Speciation and its

Consequences (Sunderland, Massachusetts, Sinauer, 1989), pp. 25.

8. J. Cracraft, Speciation and its Ontology. The Empirical

Consequences of Alternative Species Concepts for understanding

Patterns and Processes of differentiation, in D. Otte and J.A.

Endler, Speciation and its Consequences (Sunderland, Massachusetts,

Sinauer, 1989), pp. 28-59.

9. A.G. Kluge, "Species as Historical Individuals," Biology and

Philosophy 5 (1990): 417-431.

10. W. Hennig, Phylogenetic Systematics, in T Duncan and T.F Stuessy,

Cladistic Theory and Methodology (New York, Van Nostrand Reinhold

Company, 1985), p. 14

11. W.J. ReMine, "Discontinuity Systematics: A New Methodology of

Biosystematics Revelant to the Creation Model," Ms. presented at The

Second International Conference on Creationism, 1990. held at

Pittsburgh, Pennsylvaina on July 29-August 4, 1990.

F.L. March, Fundamental Biology (Lincoln, Nebraska, Marsh

Publication, 1941), p. 100.

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* Dr. Cumming is Professor and Dean of the Institute for Creation

Research Graduate School.

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