In his summation, Bateson reiterates his conviction that meristic discontinuity may represent a necessary phenotypic expression of an underlying mechanical regularity, and not a set of adaptations gradually crafted by natural selection: “To sum up: There is a possibility that meristic division may be a strictly mechanical phenomenon, and that the perfection and symmetry of the process, whether in type or in variety, may be an expression of the fact that the forms of the type or of the variety represent positions in which the forces of division are in a condition of mechanical stability” (1894, p. 71). In addition, Bateson could not resist a final and explicit anti-Darwinian dig in stating that such symmetrical forms would “owe their perfection to mechanical conditions and not to selection or to any other gradual process” (1894, p. 70).
Suspicion of history (as well as adaptation) as a cause of morphology. The pure formalist or structuralist not only rejects functional accounts based on slow building for utility, but also tries to avoid any appeal to deep history in explaining the origin of morphology. The pure structuralist prefers ahistorical accounts (see Chapter 11, Section 1, for modern versions), [Page 405] and seeks to explain form in terms of chemical and mechanical forces now operating through development. (Structuralists do not deny, of course, that history sets the presence of one mechanics, rather than another, in any particular lineage. But the analysis of immediate causes for current anatomies must still invoke present and intrinsic workings.)
Bateson best illustrates his full allegiance to the structuralist program by interpreting a range of putatively historical phenomena in terms of contemporary mechanics. He admits, for example, that highly variable parts, like mammalian third molars, often have little functional utility — and may therefore be “permitted” to range widely by a history of failing function. But Bateson still seeks a primary explanation in terms of current construction: “The oft-repeated statement that 'useless' parts are specially variable, finds little support in the facts of variation, except in as far as it is a misrepresentation of another principle. The examples taken to support this statement are commonly organs standing at the end of a meristic series of parts, in which there is a progression or increase of size and degree of development, starting from a small terminal member” (1894, pp. 78-79).
Similarly, the features that we call atavisms and attribute to past echoes should be viewed as alternate mechanical pathways. In this case, a Darwinian might invoke both styles of explanation, for even a historical vestige must be built along a current developmental route. But Bateson did not seem to grasp this necessary duality, and he often used the second aspect (mechanical pathway of building) to castigate the first (adaptational basis) — thus illustrating, by his error, the near exclusivity of his structuralist interpretations. Bateson uses simple mechanical analogs to make his point:
But all that we know is that now and then it shoots wide and hits another mark, and we assume from this that it would not have hit if it had not aimed at it in a bygone age. To apply this to any other matter would be absurd. We might as well say that a bubble would not be round if the air in it had not learned the trick of roundness by having been in a bubble before: that if in a bag after pulling out a lot of white balls I find a totally red one, this proves that the bag must have once been full of red balls, or that the white ones must all have been red in the past (1894, p. 78).
Evolutionary conclusions and implications for darwinism. The central thesis of Materials can be stated positively and succinctly: much variation (or at least the evolutionarily significant fraction) is discontinuous, mechanically and chemically built through heredity, and often well formed (and therefore potentially useful) by intrinsic construction. The primary cause of evolution, a process that also tends to be discontinuous, must therefore be located directly in the rules, patterns and directions of variation: “Is it not then possible that the discontinuity of species may be a consequence and expression of the discontinuity of variation?” (1894, p. 69).
But Bateson makes few positive claims in this mode. Rather he presents [Page 406] most arguments in a context of refutation — with Darwinian natural selection as the prime target, particularly the themes of insensibly gradual change and selective pressure guided by utility. In so proceeding, Bateson expresses no hostility for Darwin himself. Moreover, his strategy in separating Darwin's factual and theoretical achievements in order to render high personal praise also makes sense in this context. Bateson's style of refutation extends far beyond biology into broader and contemporary themes of science. Bateson regarded himself as an experimental modernist, upholding ideals of tractable science against a sterile speculative tradition that had taken hold in two areas of natural history — the guesswork of phyletic reconstruction and the hypothetical assignment of adaptive utility.
Bateson's attitude towards natural selection and adaptation provides a good indication of his procedures and prejudices. As stated above, Bateson uses several facts of discontinuous variation to downplay selection as a creative force. Consider just two arguments:
1. If rare and discontinuous variants may originate as well formed and potentially useful at their sudden appearance, why assume that normal forms must be gradually crafted to perfection by natural selection: “The existence of sudden and discontinuous variation, the existence, that is to say, of new forms having from their first beginning more or less of the kind of perfection that we associate with normality, is a fact that disposes, once and for all, of the attempt to interpret all perfection and definiteness of form as the work of selection. The study of variation leads us into the presence of whole classes of phenomena that are plainly incapable of such interpretation” (1894, p. 568).
2. If variation is inherently discontinuous and often large in effect, then selection can only choose among alternatives presented by internal causes, and therefore cannot operate as a creative force in evolutionary change. (Here, of course, Bateson merely recounts the standard argument on “creativity” advanced by nearly all non-Darwinian theorists.) Bateson, for example, writes about butterfly wingtips that exhibit either red or purple, but nothing in between: “It is easier to suppose that the change from red to purple was from the first complete, and that the choice offered to selection was between red and purple” (1894, p. 73).
But Bateson devotes his main thrust of argument to a methodological theme — to designating the tradition of adaptationist “story telling” as a poor substitute for experiment and proof. Some of the most powerful statements against this conventional, and still all too common, form of evolutionary conjecturing may be found in Bateson's 1894 book and later writings.
Bateson acknowledges the allure and fascination of adaptationist conjecture: “This study of adaptation and of the utility of structures exercises an extraordinary fascination over the minds of some . . . The amount of evidence collected with this object is now enormous, and most astonishing ingenuity has been evoked in the interpretation of it” (1894, p. 10).
Yet this so-called evidence, Bateson then asserts, represents little more than a set of conjectures about possible benefits, not a proof of actual (and gradual) construction for utility: [Page 407]
In these discussions we are continually stopped by such phrases as, “if such and such a variation then took place and was favorable,” or, “we may easily suppose circumstances in which such and such a variation if it occurred might be beneficial,” and the like. The whole argument is based on such assumptions as these — assumptions, which, were, they found in the arguments of Paley or of Butler, we could not too scornfully ridicule. “If,” say we with much circumlocution “the course of nature followed the lines we have suggested, then, in short, it did.” That is the sum of our argument (1894, p. v).
We might recognize the bankruptcy of such an approach, Bateson claims, if we looked inside ourselves and acknowledged that we undoubtedly could, and almost surely would, concoct an adaptationist scenario for any case better explained in another way (
as in the establishment, through random processes, of a rare discontinuous variant as the norm of a small island population):
In any case of variation there are a hundred ways in which it may be beneficial or detrimental. For instance, if the “hairy” variety of the moorhen became established on an island, as many strange varieties have been, I do not doubt that ingenious persons would invite us to see how the hairiness fitted the bird in some special way for life in that island in particular. Their contention would be hard to deny, for on this class of speculation the only limitations are those of the ingenuity of the author (1894, p. 79).
This lamentable practice, Bateson argues, giving natural history such a low reputation among the sciences, will only end when naturalists accept an alternate structuralist biology — for the key concepts of discontinuity and correlation must dismantle the strict adaptationist's necessary (but often unstated) view of organisms as malleable aggregations of independently improvable parts: “For the crude belief that living beings are plastic conglomerates of miscellaneous attributes, and that order of form and symmetry have been impressed upon this medley by selection only; and that by variation any of these attributes may be subtracted or any other attribute added in indefinite proportion, is a fancy which the study of variation does not support” (1894, p. 80).
Though Bateson, throughout the book, uses the rhetorical device of opposing discontinuity in variation to Darwinian gradualism, he also stresses the positive theme that internally generated saltations may represent, in themselves, the long-sought creative component of evolutionary change (with selection then operating as a subsidiary device to spread these novel features through populations): “If the evidence went no further than this the result would be of use, though its use would be rather to destroy than to build up. But besides this negative result there is a positive result too, and the same discontinuity which in the old structure had no place, may be made the framework round which a new structure may be built” (1894, p. 568). As a final [Page 408] contrast, and with a positive finish, Bateson writes: “A presumption is created that the discontinuity of which species is an expression has its origin not in the environment, nor in any phenomenon of adaptation, but in the intrinsic nature of organisms themselves, manifested in the original discontinuity of variation” (1894, p. 567).
Bateson ends his Materials with a striking plea (akin to an equally passionate statement in the preface to Simpson, 1944) for an end to the dichotomy of valuation that breeds discord and miscommunication between experimentalists and field naturalists. Bateson himself favored the experimental approach, and wrote his book to compel an appreciation of this “unfamiliar” methodology by his fellow naturalists. But he also understood that laboratory work cannot solve the problems of evolution without detailed knowledge of natural history derived from the field — and his book presents a magnificent compendium of empirical examples, spanning nearly 1000 pages, and mostly drawn from traditional descriptive literature. The integration so devoutly to be wished, Bateson argues, will arise from the study of variation — for naturalists can record the variety and understand its sway and distribution, while experimentalists can manipulate the results and hope to learn causes. Above all, variation must become the focus of union because the causes of evolution, including the origin of species, must lie within these Materials, properly ordered, manipulated, and explained. Bateson's plea deserves citation in extenso:
These things attract men of two classes, in tastes and temperament distinct, each having little sympathy or even acquaintance with the work of the other. Those of the one class have felt the attraction of the problem. It is the challenge of nature that calls them to work. But disgusted with the superficiality of “naturalists” they sit down in the laboratory to the solution of the problem, hoping that the closer they look, the more truly will they see. For the living things out-of-doors, they care little... With the other class it is the living thing that attracts, not the problem. To them the methods of the first school are frigid and narrow... With senses quickened by the range and fresh air of their own work, they feel keenly how crude and inadequate are these poor generalities, and for what a small and conventional world they are devised. Disappointed with the results, they condemn the methods of the others, knowing nothing of their real strength.... Beginning as naturalists they end as collectors, despairing of the problem, turning for relief to the tangible business of classification, accounting themselves happy if they can keep their species apart, . . . Thus each class misses that which in the other is good. But when once it is seen that, whatever be the truth as to the modes of evolution, it is by the study of variation alone that the problem can be attacked, and that to this study both classes of observation must equally contribute, there is once more a place for both crafts side by side: for though many things spoken of in the course of this work are matters of [Page 409] doubt or of controversy, of this one thing there is no doubt, that if the problem of species is to be solved at all it must be by the study of variation (1894, pp. 574-575).
For biologists, 1900 marks far more than the arbitrary turning of a century (in one mode of reckoning) because, in that year, the barrier that all evolutionists recognized as the chief impediment to further insight — ignorance about the causal basis of heredity — began to crumble with the rediscovery of Mendel's principles. Bateson himself well understood the strict limits that necessarily impeded further progress until the basis of heredity and variation could be established. He wrote Materials as an empirical list, largely because he could propose no causal guide to variation, and therefore hoped that a compendium might suggest some hints, or at least prove useful faute de mieux. He expressed frustration about this missing key at the end of Materials, and proposed that the basis of heredity be sought in breeding experiments: “But beyond a general impression, in this, the most fascinating part of the whole problem, there is still no guide. The only way in which we may hope to get at the truth is by the organization of systematic experiments in breeding, a class of research that calls perhaps for more patience and more resources than any other form of biological inquiry. Sooner or later, such investigations will be undertaken and then we shall begin to know” (1894, p. 574).
Bateson invented the word “genetics” (in 1905). He then fought for discrete inheritance against the biometrical school of Pearson and Weldon, made many important Mendelian discoveries during the first decade of the new science (application to animals as well as plants, elucidation of the phenomena of epistasis and linkage), founded the Journal of Genetics, and served as an effective spokesman for the new world order. In a late address of 1924 (published in 1928), he contrasted the Mendelian before and after, with special reference to Materials: “Only those who remember the utter darkness before the Mendelian dawn can appreciate what has happened. Stories, which then seemed mere fantasies, are now common sense. When I was collecting examples of variation in 1890, I remember well reading the fanciers' tales about dun tumbler pigeons being almost always hens, and about the 'curious effects of crossing' with cinnamon canaries, but I would never have dared to repeat them” (in Bateson, 1928, pp. 405-406).
In this light, the continuing saga of Bateson and evolutionary theory should tell a tale of pleasure and progress. He should, like de Vries (see pp. 425–439), posit an identity of his favored discontinuous variants with major Mendelian mutations, argue that the riddle of evolution has been solved in his terms, and proceed forward to greater discovery and satisfaction (at least until Fisher and others inaugurate the Modern Synthesis by upholding the efficacy, and Mendelian character, of small-scale continuous variation as well — a recognition that did not dawn widely until after Bateson's death). [Page 410]
In fact, Bateson's later career did not follow this happy scenario at all. Instead, he walked the all too common ontogenetic trajectory from young Turk to old fogey. He did rejoice in the potentially Mendelian character of discontinuity, but he altered none of
his earlier views and became, in the eyes of most younger contemporaries, an increasingly dyspeptic and conservative force (Arthur Koestler's characterization of Bateson, as a vitriolic opponent in the sad case of the Neo-Lamarckian Paul Kammerer, paints a colorful, though not entirely fair, portrait of Bateson's later career — see Koestler, 1971). Bateson continued his hostility to Darwinian and all other forms of functionalist explanation (hence his brutal opposition to Kammerer and other Lamarckians). Above all, the new genetics eventually ran away from him, primarily because he would not budge from his old, controlling belief in physical causation of phenotypic discontinuity by underlying wave-like or vibratory motions. Bateson took this idea so literally that he could never accept the “materialistic” chromosomal account of inheritance. Thus, he continued to insist, following his beloved “vibratory” theory, that transmission of hereditary information, while obeying the Mendelian rules of course, must be promulgated by force and motion, rather than by discrete particles.
Bateson delivered the Silliman lectures at Yale University in 1907 and, after considerable delay, published the text as Problems of Genetics in 1913, his major post-Mendelian statement on heredity and evolution. His views had changed very little from the themes and claims discussed in Materials in 1894. He rejoices in the Mendelian discovery, and gives a good account of early work, while focusing on the limits for evolutionary theory — particularly on his old problem of explaining meristic discontinuity, and his hope for a mechanical explanation based on waves and energy. “In Mendelian analysis we have now, it is true, something comparable with the clue of chemistry, but there is still little prospect of penetrating the obscurity which envelops the mechanical aspect of our phenomena” (1913, p. 32).
The Structure of Evolutionary Theory Page 65