Q. E. D., or New Light on the Doctrine of Creation Part 4

When we look at the matter in this light, it is very evident that there are mult.i.tudes of long recognized specific distinctions that ought to be discarded. For instance, there are some twenty odd "species" of wild pigs scattered over the Old World, which Flower and Lydekker a.s.sure us would probably "breed freely together."[16] The yak and the zebu of India, and the bison of America, would on this basis have to be surrendered, for it is well known that they will all breed freely with the common domestic cattle, as well as with one another. Perhaps all or nearly all of the dozen or more "species" of the genus _Bos_ would thus be included together. All of the dogs, wolves, and others of the _Canidae_ might thus be considered as fundamentally a unit. The cats (_Felidae_) are well known to breed freely together, Karl Hagenbeck of Hamburg having crossed lions and tigers as well as others of the family.

Practically all of the bears have been crossed repeatedly, and the progeny of these and other crosses are quite familiar sights at the London Zoological Gardens. Among the lower forms of life even more surprising results have been attained by Thomas Hunt Morgan and others.

[Footnote 16: "Mammals Living and Extinct," pp. 284-285.]

It would, however, be a very hasty conclusion to say on the basis of these facts that there are no natural limitations to groups of animals and plants. But we are entirely warranted in concluding from these facts that in very many cases, perhaps in most, our system of taxonomic cla.s.sification of animals and plants has gone altogether too far, and that scientists have erected specific distinctions which are wholly uncalled for and which confuse and obscure the main issues of the species problem. Among the workers in botany and in every department of zoology there have always been the "splitters" and the "lumpers," as they are familiarly called; the former insisting on the most minute distinctions between their "species," thus multiplying them; the latter being more liberal and tending to diminish the number of species in any given group. For a generation or more in the recent past the "splitters"

had things pretty much their own way; but of late there is a growing tendency to frown down the mania for creating new names. Even yet it is with the utmost reluctance that long established specific distinctions are surrendered, as is ill.u.s.trated in the case of the mammoth, which is acknowledged by some of the very best authorities to be really indistinguishable from the modern Asiatic elephant. Several fossil bears were long listed in scientific books; but they are all acknowledged now to be identical with the modern grizzly, and as we have already intimated all the modern ones ought to be put together. These modern rationalizing methods have made but a slight impression on the vast complex of the fossil plants and animals, affecting the names of only a few of the larger and better known forms. In the realm of invertebrate palaeontology, however, the "splitters" are still holding high carnival, in spite of the efforts of some very prominent scientists in the opposite direction. For palaeontologists still follow the irrational course of inventing a new name, specific or even generic, for a form that happens to be found in a kind of rock widely separated as to "age"

from the other beds where similar forms are accustomed to be found. As Angelo Heilprin expresses it, "It is practically certain that numerous forms of life, exhibiting no distinctive characters of their own, are const.i.tuted into distinct species _for no other reason than that they occur in formations widely separated from those holding their nearest kin_."[17]

As a result of these methods this same author declares: "It is by no means improbable that many of the older _genera_, now recognized as distinct by reason of our imperfect knowledge concerning their true relations.h.i.+ps, have in reality representatives living in the modern seas."[18]

[Footnote 17: "Geographical and Geological Distribution of Animals," pp.

183, 184.]

[Footnote 18: _Id_., pp. 207, 208.]

But the situation is very little better when we come to deal with plants and animals of our modern world. Because, with the many thousands of students of natural science all over the world, each anxious to get into print as the discoverer of some new form, the systematists have a dead weight of names on their hands that by a rational and enlightened revision could doubtless be reduced to but a fraction of their present disheartening array. For as the result of the extensive breeding experiments now being carried on under the study of what is called Mendelism (a term that will be explained in the next chapter), it has been found that great numbers of the "species" of the systematists or cla.s.sificationists will not stand the physiological test of breeding, that is, they are found to breed freely together according to the Mendelian Law. As William Bateson remarks:

"We may even be certain that numbers of excellent species recognized by entomologists or ornithologists, for example, would, if subjected to breeding tests, be immediately proved to be _a.n.a.lytical varieties_, differing from each other merely in the presence or absence of definite factors."[19]

The following from David Starr Jordan, the leading American authority on fishes, will serve to show how numerous have been the new names invented in recent years, all tending further to confuse and complicate the problem of what is a species:

"In our fresh-water fishes, each species on an average has been described as _new_ from three to four times, on account of minor variations, real or supposed. In Europe, where the fishes have been studied longer and by more different men, upwards of six or eight nominal species have been described for each one that is now considered distinct."[20]

[Footnote 19: "Mendel's Principles of Heredity," p. 284, 1909.]

[Footnote 20: "Science Sketches," p. 99.]

And again:

"Thus the common Channel Catfish of our rivers has been described as a new species not less than _twenty-five times_, on account of differences real or imaginary, but comparatively trifling in value."[21]

[Footnote 21: "Science Sketches," p. 96.]

Perhaps the reader will tolerate another somewhat long quotation because of the light which it sheds on this whole problem.

"Some years ago we had a parasite of a very destructive aphid down in our books as _Lysiphlebus tritici_. In carrying out our investigations it became necessary to find out whether this parasite had more than a single host insect, and whether it could develop in more than one species of aphid. To this end, recently emerged males and females were allowed to pair, after which the female oviposited in several species of aphids. Both parents were then killed and preserved and all of their progeny not used in further experiments were also preserved, and thus entire broods or families were kept together. In this way females were reared out of one host species and allowed to oviposit in others, until, often after several hosts had been employed, it would be bred back into the species whence it first originated. In all cases the host was reared from the moment of birth, while with the parasite both parents and offspring were kept together.

"The result of this little fragment of work _was to send two genera and fourteen species to the cemetery_--you may call it Mt. Synonym Cemetery, if you choose--while the insect involved is now _Aphidius testaceipes_.

The systematist who studies only dried corpses will soon be out of date."[22]

[Footnote 22: F.M. Webster, of the U.S. Dept. of Agriculture, in _Science_, April 12, 1912, p. 565.]

IV

Now all this is not given to intimate that there is no scientific justification for the term "species," but to make plain to my non-professional readers what every well-informed biologist already knows, namely, that at the present time the "species question" is still in a very unsatisfactory state. The facts given above would strongly suggest that there probably is indeed such a thing as a species, in the sense a.s.signed by Linnaeus, who as we have seen wished to make it a designation covering all the descendants of each distinct kind originally created. But this original aim of Linnaeus is to-day not merely ignored but treated with lofty contempt; for according to the prevailing theories of evolution, all the manifold diversities of life in our modern world have come about gradually as the result of a slow development by natural process, and hence it would be vain beyond measure to attempt to determine the limits of a "species" in the sense understood by Linnaeus.

But we may conclude, from the facts presented above, that if there is such a naturally delimited group as a "species" in the Linnaean sense of the word, it by no means coincides with what now pa.s.ses under this name, but might include many so-called species, often a whole genus, or even several.

With this in mind, we must pa.s.s on to consider the next step in our study, as to whether new "species" are now coming into being in our modern world under scientific observation, either natural or artificial.

VI

MENDELISM AND THE ORIGIN OF SPECIES

"Had Mendel's work come into the hands of Darwin, it is not too much to say that the history of the development of evolutionary philosophy would have been very different from that which we have witnessed."[23]

[Footnote 23: William Bateson, "Mendel's Principles of Heredity," p.

316.]

I

From the latter part of the eighteenth century, attempts were continually being made to explain the origin of all organic forms by some system of development or evolution. Buffon had dwelt on the modifications directly induced by the environment. Lamarck had made much use of this idea, claiming that such modifications were transmitted to posterity, and claiming the same for the structural changes produced by use and disuse. Lamarck's work did not become at all popular while he lived, chiefly through the overpowering influence of Baron Cuvier, who had an equally fantastic scheme of his own, which may well be termed a burlesque on Creation and in which an extreme fixity of "species" was a cardinal doctrine. Erasmus Darwin and Robert Chambers in England also tried to make a theory of evolution believable; though their efforts were but little more successful in gaining the ear of the world.

But to all that had gone before Charles Darwin and A.R. Wallace (1858) added the idea of "natural selection," or "the struggle for existence,"

to use the respective terms coined by each of these authors, as the chief means by which the effects of variation are acc.u.mulated and perpetuated so as to build up the modern complexities of the plant and animal kingdoms. Partly because it was a psychological moment, from the fact that the uniformitarian geology of Lyell with its graded advance of existences from age to age seemed absolutely to demand some evolutionary explanation; partly because artificial selection was a familiar idea of proved value in selective breeding, and "natural selection" seemed an exact parallel carried on by nature in the direction of continual improvement; but perhaps more largely because the abstract idea of "natural selection" involved so many intricate separate concepts that for nearly a generation scarcely two naturalists in the world could state the whole problem of the theory exactly alike;--on all these accounts the theory of natural selection, or of the "survival of the fittest," to use the phrase of Herbert Spencer, became in the latter decades of the nineteenth century well-nigh universal.

But about 1887 a faction or school arose who criticized the main idea of Darwin and Wallace and fell back on the Lamarckian factor of the transmission of acquired characters as really the essential cause of the process of evolution. Herbert Spencer, E.D. Cope and others did much to criticize natural selection as inadequate to do what was attributed to it, dwelling on the importance of the transmission of acquired characters. Spencer even went so far as to declare, "either there has been inheritance of acquired characters, or there has been no evolution." These Neo-Lamarckians argued that natural selection alone can neither explain the origin of varieties, nor the first steps in the slow advance toward "usefulness." An organ must be already useful before natural selection can take hold of it to improve it. Selection cannot make a thing useful to start with, but only (possibly) make more useful what already exists. Until the newly formed buds of developing limbs or organs became decidedly "useful" to the individual or the species, would they not be in the way, merely so many hindrances, to be removed by natural selection instead of being preserved and improved? But, in this view of the matter, they argued, what single organ of any species would there be that must not thus have appeared long before it was wanted?

Or to use the pungent words quoted with approval by Hugo de Vries at the end of his "Species and Varieties" (pp. 825, 826), "Natural selection may explain the survival of the fittest, but it cannot explain the arrival of the fittest."

This side of the argument is dwelt upon at some length by Alex. Graham Bell, as reported in a recent interview. He says:

"Natural selection does not and cannot produce new species or varieties or cause modifications of living organisms to come into existence. On the contrary, its sole function is to prevent evolution. In its action it is destructive merely,--not constructive,--causing death and extinction, not life and progression. Death cannot produce life; and though natural selection may produce the death of the unfit, it cannot produce the fit, far less evolve the fittest. It may permit the fit to survive by not killing them off, if they are already in existence; but it does not bring them into being, or produce improvement in them after they have once appeared."[24]

[Footnote 24: _World's Work_, December, 1913, p. 177.]

Opposing these Neo-Lamarckians were such prominent scientists as August Weismann, A.R. Wallace, E. Ray Lankester, who strenuously opposed the idea that "acquired characters," or more precisely _parental experience_, are ever transmissible. In the subsequent years the greatest variety of experimental tests have been applied to secure the hereditary transmission of any sort of such acquired characters, with uniformly negative results. One of the most elaborate of these experiments was conducted by a German botanist, who transplanted 2,500 different kinds of mountain plants to the lowlands, where he studied them for several years alongside their relatives, natives of these lowlands. He found that their mountain environment had made absolutely no permanent change in their structures or habits, which soon conformed exactly with those of their relatives which had lived in the lowland environment for centuries. Many similar efforts have been made to confirm this doctrine of the transmission of acquired characters; but their universal failure is like that of mechanics in trying to invent perpetual motion.

Thomas Hunt Morgan sums up the present situation in the following words: "To-day the theory has few followers among trained investigators, but it still has a popular vogue that is wide-spread and vociferous." And we may add that the extent of its spread is directly proportioned to the need felt for this doctrine as a support of the theory of evolution, while the vociferance of its advocates is inversely proportioned to the evidence in its support.

As a result of extensive modern experiments and discussion, biologists have grown very cautious, and are by no means so positive as they were twenty years ago in affirming just _how_ species have come into existence. Echoes of this old controversy between the two leading schools of biologists are occasionally heard; but the enthusiasm with which they set out a half century ago to solve the riddle of plant and animal life has largely given way to a purpose to discard speculation and patiently to observe and record actual facts. For with natural selection discredited in the house of its friends, and Lamarckianism under grave suspicion from want of a single well authenticated example, it is hard to see what there is left of the biological doctrine that has so dominated scientific thought for a half century. If each of these opposed schools of scientists are right in _what they deny_, the whole theoretical foundation for the origin of new kinds of animals and plants is swept away,--absolutely gone. For if an individual really cannot transmit what he has acquired in his lifetime, how can he transmit what he has not got himself, and what none of his ancestors ever had? And if natural selection cannot start a single organ of a single type, what is the use of discussing its supposed ability to improve them after the machinery is all built?

II

Such was the general condition of theoretical biology about the beginning of the present century. In the meantime those who were dealing with the empyrical or experimental side of these problems were seeking for the causes of and the rules for variation. All living things vary from one generation to another; the question was, Why do they vary? and do these variations really represent new characters comparable to new species in the making? or are they, so to speak, but an elastic reaction of the internal vital elasticity of the organism, all the while latent and only seeking a favorable expression, to return again under other conditions to the former type?

The effort to reduce these variations to law and system was pursued by thousands of investigators, with varying but at all times perplexing and disappointing results. But in the year 1900 the scientific world awoke to the surprising fact that a patient obscure investigator had already solved most of the puzzles of variation and heredity some thirty-five years before. Gregor Mendel, born a peasant boy, trained as a monk, and afterwards appointed Abbot of Brunn, had in the year 1865 published the results of his experiments in breeding, which had been ignored or forgotten until rediscovered in 1900 by de Vries and two others simultaneously. From this point Mendelism, as it is now called, has steadily gained ground, until at the present time it can be said to be the dominating conception among biologists the world over regarding the problems of heredity.

Mendel worked chiefly with peas, crossing different varieties. In his methods of investigation he differed from all previous investigators in concentrating his attention upon a single pair of alternative or contrasted characters at a time, and observing how these alternative characters are transmitted.

Thus when he crossed a tall with a dwarf, giving attention to this pair of contrasted characters alone, he found that all the first hybrid generation were talls, with no dwarfs and no intermediates. Accordingly he called the tall character _dominant_, and the dwarf character _recessive_, and a pair of contrasted characters which act in this way are now called _factors_ or sometimes called _unit characters_. But on allowing these hybrids to cross-fertilize one another in the usual way, Mendel found that in the second generation of hybrids there were _always_ _three talls to one dwarf_ out of every four. Further experiments proved that these dwarfs of the second hybrid generation _always bred true_, that is, one out of four; and that one out of the remaining talls always bred true, making another quarter of the total; while the remaining fifty per cent. proved to be mixed tails, always acting as did the original hybrids, splitting up in the next generation in the same arithmetical proportion as before.