Nietzsche therefore criticizes those “genealogists” who mistake a current utility for a source of origin — for this erroneous argument “forces 'adaptation' into the foreground, which is a second-rate activity, just a reactivity ... This is to misunderstand the essence of life, its will to power. We overlook the prime importance which the spontaneous, aggressive, expansive, reinterpreting, redirecting and formative powers have, which 'adaptation' only follows when they have had their effect.”
Finally, Nietzsche reasserts the biological analog of the hand to reinforce his rankings and to reemphasize the importance of understanding historical origin, and of establishing criteria for separating origins from later utilities (in the face of difficulties outlined at the end of the quotation) in any truly historical study:
The procedure itself will be something older, predating its use as punishment, that the latter was only inserted and interpreted into the procedure (which had existed for a long time though it was thought of in a different way), in short, that the matter is not to be understood in the way our naive moral and legal genealogists assumed up till now, who all thought the procedure had been invented for the purpose of punishment, just as people used to think that the hand had been invented for the purpose of grasping. With regard to the other element in punishment, the fluid one, its “meaning,” the concept “punishment” presents, at a very late stage of culture (for example, in Europe today), not just one meaning but a whole synthesis of “meanings”: the history of punishment up to now in general, the history of its use for a variety of purposes, finally crystallizes in a kind of unity which is difficult to dissolve back into its elements.
EXAPTATION AND THE PRINCIPLE OF QUIRKY FUNCTIONAL
SHIFT: THE RESTRICTED DARWINIAN VERSION AS THE GROUND
OF CONTINGENCY
How Darwin resolved Mivart’s challenge of incipient stages
Darwin treated this issue of discordance between historical origin and current utility in his catchall Chapter 6 entitled Difficulties on Theory. Although this chapter amalgamates a potpourri of objections, and we may therefore conclude that Darwin regarded none of them as sufficiently central for separation [Page 1219] as a full topic in its own right, he does grant special prominence to functional shift as a solution to a range of issues, including the overtly opposite pairing of “organs of extreme perfection” and “organs of small importance.” He even dignifies the principle with a rarity in his own prose conventions, an adjective of intensification: “In considering transitions of organs, it is so important to bear in mind the probability of conversion from one function to another” (1859, p. 191, my italics).
But Darwin only came to appreciate the centrality of this principle when the book that he considered most cogent as a general critique of natural selection — St. George Mivart's On the Genesis of Species (1871) — led him to compose, for the 6th and final edition of the Origin of Species (1872), the only chapter ever added to his book, largely as a point by point refutation of Mivart's claims: the interpolated Chapter 7 entitled “Miscellaneous objections to the theory of natural selection.” As a further observation on stylistic questions, I'm sure that Mivart's decision to name his own book with a parody on Darwin's title must have caught Darwin's special attention, and perhaps his ire. In calling his work On the Genesis of Species (rather than the Origin), Mivart needled Darwin with the common taunt of the times (see pp. 139-140): that natural selection could play a minor and negative role in eliminating the unfit, but that some other “positive” force must generate the fit. (I suspect that most of us would prefer to have our ideas rejected as dangerously wrong, but at least interesting and worthy of anathematization, rather than dismissed as correct, but trivial.)
Mivart expresses the thoroughness of his condemnation (speaking of himself in the third person) with a common rhetorical strategy in Victorian science: claiming the ultimate fairness of an initially favorable impression, only dispelled and reversed by careful and objective consideration of a catalogue of empirical evidence. In this passage, Mivart asserts the “secondary and subordinate” role of natural selection, while claiming that another “positive” mechanism, able to generate the fit (of his book's title), must be sought (1871, p. 225):
He was not originally disposed to reject Mr. Darwin's fascinating theory. Reiterate endeavours to solve its difficulties have, however, had the effect of convincing him that that theory as the one or as the leading explanation of the successive evolution and manifestation of specific forms is untenable. At the same time he admits fully that “Natural Selection” acts and must act, and that it plays in the organic world a certain though a secondary and subordinate part.
The one modus operandi yet suggested having been found insufficient, the question arises, Can another be substituted in its place? If not, can anything that is positive, and if anything, what, be said as to the question of specific origination?
St. George Mivart (1817-1900) became something of a tragic figure in Victorian biology. He devoted much of his career to reconciling biology and religion in terms of his unconventional attitudes in each discipline — only to meet [Page 1220] ultimate rejection by both camps. At age seventeen, he abandoned his Anglican upbringing, became a Roman Catholic, and consequently (in a less tolerant age of state religion) lost his opportunity for training in natural history at Oxford or Cambridge. He became a lawyer but managed to carve out a distinguished career as an anatomist nonetheless. He embraced evolution and won firm support from the powerful T. H. Huxley, but his strongly expressed and idiosyncratic anti-Darwinian views incurred the wrath of Britain's biological establishment. He tried to unite his biology with his religion in a series of books and essays, and ended up excommunicated for his trouble six weeks before his death.
The ever-perceptive Darwin had chosen well for his primary source of worry. In this book, Mivart presents a thorough and logically inclusive account of structuralist evolutionary thought as a substitute for natural selection (complete with the usual linkage of channeling and saltation into a coherent primary critique). Mivart centered his attack upon an argument embodied in a phrase that still persists as virtually his only commonly recognized legacy to the history of evolutionary thought. He introduces this phrase as the title to his first substantive chapter (after some opening pages entitled “introduction”): “The incompetency of 'natural selection' to account for the incipient stages of useful structures.” (In my popular writing, I have referred to this critique as the “5 percent of a wing principle,” as expressed in the common layman's objection: “I can understand how wings work for flight once they originate, but how can evolution ever make a wing in Darwin's gradualist and adaptationist mode if five percent of a wing can't possibly provide any benefit for flight?”)
Mivart constructs this chapter as a compendium of examples where, in his judgment, no putative value could be assigned to early incipient stages (lepidopteran mimicry, flight, the placement of both eyes on the upper side of flatfishes, etc.). He then concludes (1871, p. 61): “That minute, fortuitous, and indefinite variations could have brought about such special forms and modifications as have been enumerated in this chapter, seems to contradict not imagination, but reason.”
Mivart then attempts to resolve this problem in the most obvious manner — by the saltationist claim that intermediary stages never existed, and that novel adaptations may arise in single steps. Interestingly, and as mentioned in Chapter 5 (p. 344), Mivart invokes the compelling structuralist model and image of Galton's Polyhedron (see pp. 342–351) to illustrate this centerpiece of his system (pp. 97-98):
Arguments may yet be advanced in favor of the view that new species have from time to time manifested themselves with suddenness, and by modifications appearing at once (as great in degree as are those which separate Hipparion from Equus), the species remaining stable in the intervals of such modifications: by stable being meant that their variations only extend for a certain degree i
n various directions, like oscillations in a stable equilibrium. This is the conception of Mr. Galton, who compares [Page 1221] the development of species with a many faceted spheroid tumbling over from one facet, or stable equilibrium, to another. The existence of internal conditions in animals corresponding with such facets is denied by pure Darwinians.
Mivart recognizes that any saltationist claim must resolve the two cardinal objections that lead many scientists to embrace the gradualism of Darwin and Lyell: (1) How, short of invoking something miraculous, can so many parts be altered together, and all at once, to produce a harmonious and adaptive result in a highly modified descendant; and (2) how can any theory of one-step transformation explain the parallel or convergent modification of sets of coordinated features, as found in many independent lineages?
Mivart faces these difficulties along the standard structuralist route, by calling upon the other concept so often twinned with claims for saltation: internally channeled change. If alterations, like isotropic Darwinian mutations, could modify an organism in any direction, then the difficulties stated above would become insuperable. But if jumps can only occur along certain limited routes, set by the internal structure of organisms and predisposed towards harmonious alteration of coordinated parts, then saltations become both limited in directional expression, and biased towards workability. Again, Galton's Polyhedron suggests such a linkage of saltation (facet flipping) with internally limited directionality (restriction of routes of change to positions underlain by adjacent facets). Mivart states (1871, p. 143): “All these difficulties are avoided if we admit that new forms of animal life of all degrees of complexity appear from time to time with comparative suddenness, being evolved according to laws in part depending on surrounding conditions, in part internal — similar to the way in which crystals (and, perhaps from recent researches, the lowest forms of life) build themselves up according to the internal laws of their component substance, and in harmony and correspondence with all environing influences and conditions.”
But what operational good can emanate from an invocation of such internal forces (even granting the logical soundness of the argument), if the nature of these forces remains unknown and mysterious, thus reducing their status to special pleading? Mivart even cites the classical literary spoof of such foolish arguments, as presented by the phony doctors of Moliere's hypochondriac: “But it may be again objected that to say that species arise by the help of an innate power possessed by organisms is no explanation, but is a reproduction of the absurdity, I'opium endormit parcequ'il a une vertu soporifique (p. 230)” (opium puts you to sleep because it possesses a soporific virtue).
In reply, Mivart points out that we also know nothing about the physical nature of Newtonian gravity, but still find the concept useful because such mathematical regularities as the inverse square law have explanatory, predictive and integrative power. Similarly, we may not know the actual workings of heredity, but we can, by empirical cataloguing and experimentation, determine sets of observed regularities in the variations of modern species. Following the traditions of 19th century structuralism, Mivart recommends the [Page 1222] study of natural “sports,” both the occasional large variants that can survive in nature, and the teratological malformations that may not be viable, but that illustrate the potential pathways of internally coordinated variation, following recognizable channels of ontogeny, sexual variation, etc. “It is probable therefore that new species may arise from some constitutional affection of parental forms — an affection mainly, if not exclusively, of their generative system” (p. 233).
In the added chapter to his 6th and final edition, Darwin refers to Mivart as “a distinguished zoologist,” and admits that he has presented all viable objections to natural selection “with admirable art and force” (1872b, p. 164). He then summarizes Mivart's structuralist alternative, describing first the claim for channeling, and then the argument for saltation. He rejects both, primarily because they lack either a known mechanism or verified cases; Darwin then reasserts his belief in the efficacy of gradualistic natural selection, working upon isotropic and undirected variation (pp. 187-188):
At the present day almost all naturalists admit evolution under some form. Mr. Mivart believes that species change through “an internal force or tendency,” about which it is not pretended that anything is known. That species have a capacity for change will be admitted by all evolutionists; but there is no need, as it seems to me, to invoke any internal force beyond the tendency to ordinary variability, which through the aid of selection by man has given rise to many well-adapted domestic races, and which through the aid of natural selection would equally well give rise by graduated steps to natural races or species...
Mr. Mivart is rather inclined to believe, and some naturalists agree with him, that new species manifest themselves “with suddenness and by modifications appearing at once.” For instance, he supposed that the differences between the extinct three-toed Hipparion and the horse arose suddenly. He thinks it difficult to believe that the wing of a bird “was developed in any other way than by a comparatively sudden modification of a marked and important kind”; and apparently he would extend the same view to the wings of bats and pterodactyls. This conclusion, which implies great breaks or discontinuity in the series, appears to me improbable in the highest degree.
Darwin acknowledges that Mivart's argument about incipient stages had been particularly troubling (p. 165): “The one new point which appears to have struck many readers is, 'natural selection is incompetent to account for the incipient stages of useful structures.' This subject is intimately connected with that of the gradation of characters, often accompanied by a change of function — for instance, the conversion of a swim-bladder into lungs.” Darwin notes that he had dealt with this issue in his original Chapter 6 on “difficulties,” admits that he had not paid the subject sufficient heed, and praises Mivart for an opportunity to correct his previous slighting (p. 185): “A good opportunity has thus been afforded for enlarging a little on gradations of structure, often associated with changed functions, — an important [Page 1223] subject, which was not treated at sufficient length in the former editions of this work.”
I will not describe Darwin's solutions to the problem of “incipient stages” at length, because I have already done so in Chapter 2, my exegesis of the Origin of Species. But I do need to emphasize the relevant point for this chapter — that both of his effective arguments against Mivart's supposed trump card invoke structural principles of constraint rooted in Nietzsche's “major point of historical method”: the discordance between historical origin and current function.
In his first argument, Darwin readily admits the “5 percent of a wing” problem, and then presents the incisive solution that becomes enshrined in evolutionary theory (by no fault of Darwin, who never used the term) under the most unfortunate name of “preadaptation.” Yes, five percent of a wing offers no conceivable aerodynamic benefit, and could not therefore either be formed, or converted into a full wing, under a smooth regime of natural selection for flight. But sequences forged by selection only presuppose continuity in differential reproductive success, not continuity in a single function. Thus, the incipient stages may have performed a different function, for which their 5 percent of a wing imparted benefits. Eventually, the enlarging proto-wing entered the domain of aerodynamic benefit, and the original function changed to the primary utility now exploited by most birds. Current function cannot be equated with reasons for historical origin. Mivart's cardinal objection disappears, thus explaining why “it is so important to bear in mind the probability of conversion from one function to another.”
Darwin roots his second argument in the related, but even more generalized, structural principle of redundancy — the inherent capacity (based on intrinsic structure rather than current function) of most organs to work in more than one way (either at the same time, providing dual benefits, or with one ut
ility overtly exploited by natural selection, and the other latent, providing unselected flexibility for future change). Darwin presents this argument in a fascinating manner by coupling two apparently opposite facts about redundancy: that a single function can be performed by more than one organ, and that a single organ can perform more than one function. Thus, an organ need not invent an entirely new function in some mysterious manner, but may evolve by intensifying a previously minor use, or even by recruiting an inherent but unexpressed potential. Meanwhile, the modified organ can abandon its previous major function because other organs can continue (or intensify) their former operation in the service of the same necessary task.
Thus, reptilian jawbones can become mammalian ear bones because they already played some role in sound transmission while they functioned primarily to articulate the jaw of therapsid forebears (the principle of two functions for one structure). They then become free to move into the middle ear because the transitional forms (as demonstrated empirically by such fossils as Diarthrognathus, and not only as a reasonable conjecture) possessed a double jaw joint (the reciprocal principle of two structures for one function) — and the bones of the old quadrate-articular joint could then become the [Page 1224] malleus and incus of the ear because the new dentarysquamosal joint was already “up and running,” thus avoiding the specter of an inconceivable intermediate with an unhinged jaw.
The Structure of Evolutionary Theory Page 194