The dinosaur connection: A reinterpretation of T.H. … Connection to... · The Dinosaur...

The Dinosaur Connection: A Reinterpretation of T.H. Huxley's Evolutionary View

MARIO A. DI G R E G O R I O

Darwin College Cambridge, England

The tradit ional understanding of T. H. Huxley's role in the history o f evolutionary ideas has been based on certain prominent biographical, even autobiographical, material: that Huxley was a colleague of Darwin, that he was apparently forthright in his defense and exposit ion of Darwin's ideas almost immediately after publication of the Origin o f Species, that he was - in short - "Darwin's bulldog," ~ reacting to the Or/g/n as an overdue "flash of light. ' '2

Michael Bartholomew's 1975 analysis of Huxley 3 argues that there was no real turning point in Huxley's scientific approach after the publication of the Origin o f Species, and that even after 1859 Huxley held a basically pre-Darwinian at t i tude to science. Whether or not one agrees with Bartholomew's view, his article contr ibuted to a change of perspective among scholars working on Huxley's scientific thought.

A cursory examination of Huxley's scientific work reveals that he began to deploy the idea of evolution only in 1868, nine years after publication of the Origin, scarcely the response one would expect upon receipt o f a blinding inspiration; Huxley's own research, in other words, seems to contradict any claim that the Origin o f Species persuaded him of the value of the concept of evolution. Closer scrutiny of Huxley's work, even subsequent to 1868, reveals further that one of the obviously distinctive features o f Darwin's theory - the notion of natural selection

- fails to appear at all. A question therefore arises: was Huxley, despite his reputat ion and his self-assessment, actually a "Darwinian" at all?

My own view is that after 1859, under the influence of Darwin, Huxley was persuaded of the value of evolution only as a working hypothesis in respect to the phenomena of organic nature; he supported

1. Leonard Huxley, ed., The Life and Letters of Thomas Henry Huxley, 2 vols. (New York: Appleton, 1900), I, 391.

2. Francis Darwin, ed., The Life and Letters of Charles Darwin, 3 vols. (Lon- don: Murray, 1887), II, 197_

3. Michael Bartholomew, "Huxley's Defence of Darwin," Ann. ScL, 32 (1975), 525-535.

Journal of the History of Biology, vol. 15, no. 3 (Fall 1982), pp. 397-418. 0022-5010/82/0153/0397 $02.20. Copyright © 1982 by D. Reidel Publishing Co., Dordrecht, Holland, and Boston, U.S.A.

MARIO A. DI GREGORIO

Darwin's theory publicly as a kind of "program" worthy of serious consideration but not yet ready for broad application because of natural selection, its basic tenet. He integrated evolution with his scientific work only after 1868, when he found the way to avoid reference to natural selection. Indeed, when he finally applied evolution to the study of animal life, it was gaining wide acceptance in scientific circles and was strongly supported by the zoological school of Jena, headed by Ernst Haeckel and Carl Gegenbaur. a

The main outlines of the progression of Huxley's own zoological research indicate a striking harmony with the progression of zoology in the work of his German contemporaries and colleagues;his espousal of the idea of evolution in systematics is both chronologically and methodologically interwoven with theirs. This suggests strongly that Huxley in his own research should be seen essentially as integrated into the mainstream of the German community of zoological thought. The young Huxley had been heavily influenced by German science - especially by Karl Ernst von Baer's embryological typology - and only works conceived in that tradition were in a position to have a decisive influence on his view of descent. Gegenbaur and Haeckel were the heirs of von Baer's tradition, and they strongly supported the application of evolution to the study of animal life. Haeckel's two- volume Generelle Morphologie s was published in 1866; only two years later Huxley did start to apply the notion of evolution in his scientific research, and thereafter he consistently did so.

If Huxley underwent a "conversion" to evolutionism, it took place in the late 1860s under the influence of Haeckel and German science. If one considers the views held by Huxley in the early stages of his career, this outcome was inevitable.

THE ROOTS

In order to understand why Haeckel had such a strong impact upon Huxley's science, one needs to consider Huxley's scientific roots. It is there that one finds the solution to the puzzling problem of Huxley's attitude to evolutionism.

In the first half of the nineteenth century the theoretical problem that had preoccupied continental naturalists and Richard Owen, the

4. Georg Uschmann, Geschichte der Zoologie und der zoologischen Anstalten in Jena, 1779-1919 (Jena: Fischer, 1959).

5. Berlin: Reimer, 1866).

i

398

The Dinosaur Connection: Huxley's Evolutionary View

leading British morphologist , was the type concept. 6 As Emanuel Rhdl wrote, "Das Wort 'Plan' schwebte auf allen Lippen. ' '7 While Georges Cuvier believed in four plans to account for the different structures detectable in the animal world, I~tienne Geoffroy St. Hilaire supported the view of a single unifying plan. Goethe 's interpretat ion was an ideal Urplan, to which all modifications discovered in nature were to be referred. Richard Owen in Britain was a strong supporter of the existence o f an ideal plan that he called the "archetype."

Dov Ospovat proposes a very interesting hypothesis to which I wish to refer, since Huxley is a perfect example of the correctness of the argument. 8 Broadly speaking, Ospovat detects two different ways of interpreting natural phenomena, and these were in sharp conflict during the first half of the nineteenth century. On the one side was the tradit ion of Cuvier's teaching, according to which there is no uni ty of type, and in which the stress is on teleological adaptations. It is arguable whether the "essence" o f Cuvier's view was teleology, but what is important is that this is how supporters of the rival view interpreted him. On the other side, by the 1830s a number of British biologists had repudiated what they thought was Cuvier's teleology and referred to the works of the renowned embryologist von Baer; they applied his embryological methods to the type concept and to classification as the major support for an understanding of the relationships in the living realm.

Von Baer, Christian Pander, and Heinrich Rathke had given great impetus to embryology as the key to the understanding of nature. 9 Rathke in 1825 discovered the gill slits of mammalian and chick embryos; ~° the first volume of yon Baer's masterly f)ber Entwickelungs-

geschichte der Thiere was published in 1828, and the second in 1837. ix

6. Richard Owen, The Archetype and Homologies of the Vertebrate Skeleton (London: Van Voorst, 1848).

7. Emanuel Rhdl, Geschichte der biologischen Theorien seit dern Ende des siebzehnten Jahrhunderts, 2 vols. (Leipzig: Engelmann, 1905), II, 22.

8. Dov Ospovat, The Development of Darwin's Theory: Natural History, Natural Theology, and Natural Selection, 1838-1859 (Cambridge: Cambridge University Press, 1981).

9. See E. S. Russell, form and Function (London: Murray, 1916), pp. 113- 145.

10_ Heinrich Rathke, "Kiemen bei S~iugetier," 1sis (1825), 747-749; and "Kiemen bei V6geln," Isis (1825), 1100-1101.

11. Karl Ernst yon Baer, Ober Entwickelungsgeschichte der Thiere, 2 vols. (K6nigsberg: Borntrhger, 1828/1837); the Schlussheft of the second part was edited by L. Stieda in 1888.

399


Von Baer lived at a time when the Naturphilosophie was taking Germany and the German-speaking countries by s torm? 2 Yet the results of his inquiries are largely independent of any sympathies he may have had for the views of that highly speculative at t i tude to nature;~3 for von Baer's researches were based on rigorous experiments. Basically, he accepted the type concept, but used embryology to provide the major criteria for his typology. According to him, the embryological types start from a common point - hence the unity of nature is preserved; they diverge to follow distinct paths of development

- accounting for the diversity detectable in nature. As Ospovat has shown, 14 von Baer's work was initially introduced to British audiences by Martin Barry, a Scottish physician who in 1836-1837 published "On the Unity of Structure in the Animal Kingdom." is This was followed by William B. Carpenter 's Principles o f General and Comparative Physiology. t6

In France Henri Milne-Edwards was a dedicated supporter of the use of embryology in classification; in a famous 1844 paper, partially translated into English four years later, 17 he claimed that since embryos are more similar to one another than their adult forms are, it is embryology which indicates the clearest affinities we can discover. In his Monographie des poissions du Vieux Rouge ou syst~me d~vonien (OM Red Sandstone) des lies Britanniques et de Russie, ta Louis Agassiz of Switzerland applied the results of embryology to the study of paleontology. He wanted to find the proper systematic place of the Devonian fish to demonstrate that types through the history of the earth, animal classes through the history of their families, and embryos through the stages of their development, experience the same phases,

12. E. R. Lankester, "Karl Ernst von Baer," The Academy, 10 (1876), 608. 13. Arthur W. Meyer, Human Generation (Stanford: Stanford University

Press, 1956), pp. 6465. See also B. E. Raikov, Karl Ernst yon Baer, 1792-1876." sein Leben und sein Werk (Leipzig: Barth, 1968).

14_ Dov Ospovat, "The Influence of Karl Ernst von Baer's Embryology, 1828-1859: A Reappraisal in Light of Richard Owen's and William B. Carpenter's 'Palaeontological Application of yon Baer's Law,'" J. Hist. Biol., 9 (1976), 1-28.

15. Edinburgh New Phil. J., 22 (1836-1837), 116-141,345-364. 16. London: Churchill, 1839_ 17. Henri Milne-Edwaxds, "Consid6rations sur quelques principes relatifs

la classification naturelle des animaux, et plus particuli~rement sur la distribution mbthodique des mammff~res," Ann Sci. Nat., 1 (Zool.)(1844), 68-99;translated inAnn. Nat. Hist., 2 (1848), 70-78.

18. NeuchMel: Soleure chez Jent et Gassmann, 1844_

400


led by the same pensbe cr~atrice - a mot i f that makes sense of the phenomena of nature. Agassiz believed that the fish of the old red sandstone represented the embryological stage of the history of the

fish type. After an early memoir of 1845, "On a Hitherto Undescribed Struc-

ture in the Human Hair Sheath," 19 Huxley's scientific career benefited enormously from his voyage on board H.M.S. Ratt lesnake. 2° As a result of this trip he became a master in invertebrate morphology; he discovered that the organs of the Coelenterata were made of two membranes, 21 although the term "Coelenterata" had been used for the first time by Heinrich Frey and Rudolf Leuckart in 1847. 22 He opposed the related theories of alternation of generation and of parthenogenesis, 2a thus clashing with the authori ty of Richard Owen; 24 he studied the echinoderms and tried to show that they were related not to the Radiata but to the Annelida. :s

In dealing with such problems o f invertebrate morphology, Huxley had to face some fundamental theoretical problems that had a strong influence upon his search for order in nature. This search consti tuted a thread that was to connect all the facts he had revealed and described and make sense of the affinities and relationships he had discovered.

But Huxley was unable to accept the Cuvierian view of teleological adaptat ion. In "On Natural History as Knowledge, Discipline and Power, ''26 Huxley emphasized that morphology demonstrates the modeling of living forms upon a very smal /number of plans or types.

19_ London Med. Gaz., 1 (1845), 1340; The Scientific Memoirs o f T_ H. Huxley, 4 vols. (London: Macmillan, 1898-1903) I, 1-3. Hereafter referred to as Scientific Memoirs.

20. Julian Huxley, ed., 1". 1-1. Huxley's Diary o f the Voyage o f H.M.S. Rattle- snake (London: Chatto & Windus, 1935).

21. Thomas H. Huxley, "On the Anatomy and Affinities of the Medusae," Phil. Trans. Roy. Soc. (1849), p. 2, 413-434; Scientific Memoirs, I, 9-32.

22. See Mary P. Winsor, Starfish, Jellyfish and the Order o f Life (New Haven: Yale University Press, 1976), p. 78.

23. Thomas H. Huxley, "Observations upon the Anatomy and Physiology of Salpa and Pyrosoma,'" Phil. Trans. Roy_ Soc. (1851), pt_ 2,567-594; Scientific Memoirs, I, 38-68. George James Allman wrote to Huxley on May 30, 1852: "You have I think triumphantly demolished the whole system of Alternation of generations and its cousin Parthenogenesis." (HP.10.63)

24. Richard Owen, On Parthenogenesis (London: Van Voorst, 1849). 25. Thomas H. Huxley, "Lectures on General Natural History," Med_ Times

Gaz., 12 (1856), 489_ 26. Proc. Roy. lnst., 2 (1854-1858), 187-195;Scientific Memoirs, I, 305-314.

401


He attacked those who supported what he called "utilitarian adaptations" (where 'hatilitarian" means "purposive"), including in his attack not only Cuvier, the father o f this doctrine, but Paley and the natural theologians. For them, Huxley argued, "the structure of living beings is, in the main, such as would result from the benevolent operation, under the conditions o f the physical world, of an intelligence similar in kind, however superior in degree, to our own." But this was for Huxley patently false: he stated his belief that "utilitarian adaptation to purpose is not the greatest principle worked out in nature, and that its value, even as aft instrument of research, has been enormously overrated." 27

This passage is of extreme interest. It shows Huxley's rejection of teleology and clearly declares his belief in the possibility of finding some "great principle" to connect and interpret the various features and relationships of nature : that great principle was yon Baer's embryological type.

In 1853 Huxley translated the fundamental fifth Scolium of the Entwickelungsgeschichte into English. The translation appeared in Scientific Memoirs, a short-lived magazine (initially edited by Richard Taylor and later by Huxley, John Tyndall, and William Francis), that specialized in the memoirs of foreign scientists.2S

Huxley not only championed von Baer's embryological typology in his public statements, he also applied it to his scientific work. As he explained in 1856, it is the application of embryological results to the method of the type that the biologist must follow in his inquiry:

For animals . . . like all living beings, not only are, but become; and it is within the limits of logical possibility, that the adult forms anatomically similar, should be genetically different; that they should have arrived at a similar point by different roads. Before,

27. Ibid., pp. 306,307. Huxley's view was criticized by Hugh Falconer in "On Professor Huxley's Attempted Refutation of Cuvier's Laws of Correlation in the Reconstruction of Extinct Vertebrate Form," Ann. Mag. Nat. Hist., 1 7 (1856), 476-493.

28. Thomas H. Huxley, "Fragments Relating to Philosophical Zoology, Selected from the Works of K. E. yon Baer," (Taylor's) Scientific Memoirs (Nat. Hist.), 3 (1853), 176-238. On Huxley and von Baer see Hans Querner, "Karl Ernst von Baer und Thomas Henry Huxley," SudhoffsArchiv, 62 (1978), 131-147. For the German influences on Huxley (especially that of Goethe) see Erling Eng, "Thomas Henry Huxley's Understanding of Evolution," Hist. Sci., 16 (1978), 291-303.

402


then, we can affirm that two animals are constructed upon a common plan, or that two parts are homologous (which simply means that they are modifications o f corresponding members of a common plan) we must be able to show that these parts of these animals, have passed through a corresponding series of developmental stages. It is the absence o f this reference to development which is the vice of the ordinary works. 29

Thus, if we want to discover the homologies between, say, the various families o f the Medusae, we must refer to two embryological criteria:

Now, the organs of two animals or families of animals are homologous when their structure is identical, or when the differences between them may be accounted for by the simple law of growth. When the organs differ considerably, their homology may be deter- mined in two ways, either: - 1, by tracing back the course of development o f the two until we arrive by similar stages at the same point; or, 2, by interpolating between the two a series of forms derived from other animals allied to both, the difference between each term of the series being only such as can be accounted for by the laws of growth . . . Both methods may be made use of in investigating the homologies o f the Medusae. a°

It is this kind o f evidence he adduced with respect to the echinoderms:

[All forms of echinoderm larvae] can be reduced to one very simple hypothet ical type; having an elongated form, traversed by a straight intestine, with the mouth at one extremity and the anus at the other, and girded by a circular ciliated fringe; just like the larvae of some Annelids. 3a

Thus " the Echinoderms and Entozoa then do not form properly any port ion o f a spherical Radiate Type but are rather modifications of the Annulose Type." a2

29. T. Huxley, "Lectures on General Natural History," p. 432. 30. T. Huxley, "On the Anatomy and Affinities of the Medusae," p. 24. 31. Thomas H. Huxley, "Report upon the Researches of Prof. Miiller into the

Anatomy and Development of the Echinoderms," Ann. Mag. Nat. Hist. (2nd ser), 8 (1851), 1-19; Scien tific Memoirs, I, 103-121 ; quotation on 109.

32. HP.37.12.

403


Huxley's researches on the mollusks provide further evidence. His most important memoir on this topic is "On the Morphology of the Cephalous Mollusca . . . ,,3a Here he endeavored to give an account of some general problems concerning these animals, starting with their anatomic characteristics and employing embryological reasonings. Huxley argued that in order to achieve the definition o f the type of the mollusks, the naturalist must become aware of the "laws of development" o f the Heteropoda and Pteropoda and from them assess of "what archetypal form they may be modifications. ' 'a4

Finally, his 1858 memoir, "On the Vertebrate Skull, ' 'as concluded that "there is a general plan or primordial type which is manifested in the highest forms most clearly in their earliest development - an embryological archetype therefore." a~

However, one should not fail to realize that Huxley's interpretat ion of yon Baer's view of different embryological types was a "radical" one that approached Cuvier's more discontinuous view of nature. In fact, Huxley argued as follows:

If, however, all Cephalous Mollusks i.e., all Cephalopoda, Gastero- poda, and Lamellibranchiata be only modifications by excess or defect of the parts o f a definite archetype, then, I think, it follows as a necessary consequence that no anamorphism takes place in this group. There is no progression from a lower to a higher type, but merely a more or less complete evolution of one type.

It may indeed be a matter of very grave consideration whether true anamorphosis ever occurs in the whole animal kingdom. If it do, then the doctrine that every natural group is organized after a definite archetype, a doctrine which seems to me as important for zoology as the theory o f definite proport ions for chemistry, must be given up. 37

33. Phil. Trans. Roy. Soc., 142 (1853), pt. 1, 29-66; Scientific Memoirs, I, 152-193_

34. Ibid., p. 153. 35. Proc. Roy. Soc., 9 (1857-1859), 381-457; Scientific Memoirs, I, 538-606. 36. Russell, Form and Function, p. 161. 37. Scientific Memoirs, I, 192_ When Huxley used the word "anamorphism,"

the term was quite recent in the scientific literature and meant progression from a lower to a higher type (in other words, a synonym of "anamorphosis"). The word "evolution" is used in its embryological sense of the enlaxgement and development of some parts during the life of the embryo.

404


Huxley here strayed from von Baer. In fact, he denied that there can be any transit ion from one type to another, modifications occurring only within the type; this implies that there is no continui ty between the different types of animal organization, a view Huxley maintained after 1859 with respect to the relationships between invertebrate and vertebrate types, as Von Baer, on the other hand, had simply postulated the existence o f four major types recognizable through embryological divergence.

HUXLEY AND EVOLUTION

Huxley's early memoirs show that he was in search of a pat tern that could guarantee the harmony and order of nature. The type concept, as interpreted by Huxley after yon Baer, did indeed provide him with such a pattern. None o f Huxley's zoological memoirs prior to 1868 applied the notion o f evolution. A good example from the 1860s of his continuing use of "pure" morphology is his survey in 1861 of the taxonomic posi t ion o f the ganoids ) 9

Huxley's approach to the classification of these fish was along the traditional lines set up by Agassiz in 1844. 4° Indeed, Huxley's paper was simply a correction of the classifications of Agassiz and Pander, 4~ which also took into account the contributions made by a group of paleontologists, geologists, and zoologists that included Hugh Miller, 42 Frederick M'Coy, 4a Philip Egerton 44 and, marginally,

38. Thomas H. Huxley, Manual of the Anatomy of lnvertebrated Animals (London: Churchill, 1877), pt. 4.

39. Thomas H. Huxley, "Preliminary Essay upon the Systematic Arrangement of the Fishes of the Devonian Epoch," Mere. Geol. Sur. U.K. (1861); Scientific Memoirs, II, 421-460. After 1854 Huxley shifted from invertebrate morphology to vertebrate paleontology: see Life and Letters, I, 127-129.

40. Agassiz, Monographie des poissons du Vieux Rouge. 41. Christian Heinrich Pander, Uber die Saurodipterinen, Denderodonten,

Glyptolepiden und Cheirolepiden des devonischen Systems (St. Petersburg: Kaiserlichen Akademie der Wisserischaften, 1860).

42. Hugh Miller, The OM Red Sandstone (Edinburgh: Johnstone, 1841 ). 43. Frederick M'Coy, "On Some Fossil Fish of the Carboniferous Period,"

Ann. Mag_ Nat. Hist., 2, n.s. (1848), 1-10,115-133. 44. Philip Gray Egerton, "Catalogue of Fossil Fish in the Collections of

Lord Cole and Sir Philip Gray Egerton, Arranged Alphabetically, with References to the Localities, Geological Positions, and Published Descriptions of the Species," Phil Mag., 8 (1848), 366-373.

405


Johannes Mtiller. as Starting from the single problem of the systematic position of Glyp t o l em us , *s Huxley showed that this form presents some common characteristics with five other genera. On these grounds he proposed to group the six genera into the Glyptodipterini (a family of the subordo Crossopterigidae, ordo Ganoidei), to be divided into two subfamilies - the rhombiferous Glyptodipterini, with diphycercal tails, and mostly rhomboidal scales; and the cycliferous Glyptodipterini, with heterocercal tails and cycloid scales. Huxley's final classification of the Ganoidei - a very important contribution to the knowledge of fossil fish - was entirely traditional insofar as it applied only anatomical reasoning and did not refer to either the fact or the possibility of evolution. 47 Although the state of knowledge when Huxley wrote this memoir was hardly sufficient for a survey to include phylogenetic arguments, the complete absence of any reference to evolution indicates that in the early 1860s Huxley was not prepared to see the problems of practical zoology - in this case of comparative anatomy and paleontology - in an evolutionary light.

By 1868 Huxley had started to apply evolution to his scientific work: the idea of transitional forms occupied most of his specifically scientific works dealing with evolution, of which a typical example is his study of the dinosaurs. 4a The primary idea is that dinosaurs are the crucial link between reptiles and birds. Huxley's view was shared by a number of nineteenth-century paleontologists, including Edward Cope 49 and Othniel Marsh s° in America and John Phillips in

45. Johannes MOiler, "Ober den Ban und die Grenzen der Ganoiden und iiber das natiirliche System der Fische," Berlin Abh. (1844), 117-126 ; "Nachtrag zur Abhandlungen 'Ober den Ban der Ganoiden,' " Berlin Abh. (1845), 33-35, translated into English by J. W. Griffith, (Taylor's) Scientific Memoirs, 4 (1846), 499-558.

46. John Anderson, "On Dura Den Sandstone", Rep. Brit. Ass. (1859), pt. 2, 97 ; "Report on the Excavations in Dura Den," Rep_ Brit. Ass, (1860), pt. 1,32-34.

47. T. Huxley, "Preliminary Essay," pp. 443-444. 48. Thomas H_ Huxley, "On the Animals Which Axe Most Nearly Intermediate

between Birds and Reptiles," Geol_ Mag., 5 (1868), 357-365 ; Scientific Memoirs, I11,303-313, See also his "On the Classification of the Dinosauria, with Observa- tions on the Dinosaurla of the Trias," Quart. J. Geol. Soc., 26 (1870), 32-50; Scientific Memoirs, III, 487-509_ A third paper by Huxley on this subject is "Further Evidence of the Affinity between the Dinosaurian Reptiles and Birds," Quart. J. Geol. Soc., 26 (1870), 12-31;Scientific Memoirs, III, 465-486_

49. Edward Drinker Cope, "Synopsis of the Extinct Batrachia and Reptilia of North America," Trans. Am. Phil. Soc., 14 (1871), 1-252.

50. Othniel C_ Marsh, "Classification of Dinosauria," Am. J. Sci_ Arts, 23 (1882), 79-84;Nature, 25 (1882), 244-246.

406


England. s~ That reptiles and birds are closely allied was one of Huxley's main zoological assumptions, and he often proposed to group them under the common heading of "Sauropsida"; this concept forms the core o f his memoir, "On the Classification of Birds . . . " of 1867, s2 which prepared the anatomical ground for his evolutionary survey of the relationship between birds and reptiles.

The beginning of his memoir "On the Animals Which Are Most Nearly Intermediate between Birds and Reptiles," published in 1868 for the Geological Magazine, is striking, being a sort of confession to the scientific truth of evolution:

Those who hold the doctrine of evolution (and I am one of them) conceive that there are grounds for believing that the world, with all that is in it and on it, did not come into existence in the condition in which we now see it, nor in anything approaching that condition, sa

Huxley claimed that the most serious objection to evolution would be the occurrence o f gaps between the various animal forms; despite the imperfection of the geological record, the evolutionist would feel uncomfortable were he not able to provide the paleontological "missing links":

It is admitted on all sides that existing animals and plants are marked out by natural intervals into sundry very distinct groups: - Insects are widely different form Fish - Fish from Reptiles - Reptiles from Mammals - and so on. And out of this fact arises the very pertinent objection, - How is it, if all animals have proceeded by gradual modification from a common stock, that these gaps exist?

We, who believe in Evolution, reply, that these gaps were once non-existent; that the connecting forms existed in previous epochs o f the world's history, but that they have died out.

Naturally enough, then, we are asked to produce these extinct forms

51. John Phillips, "'Notice of Some Specimens of Megalosaurian Bones in the University Museum of Oxford," Quart_ J_ Geol. Soc., 26 (1870), 13-16: written in 1868, and reprinted in Scientific Memoirs, III, 466-470_

52. Proc. Zool. Soc. (1867), 415-472;Scientific Memoirs, II1,239-297. 53. T. Huxley, "On the Animals," p. 303.

407


of life. Among the innumerable fossils of all ages which exist, we are asked to point out those which constitute such connecting forms, s4

It is clear that the problem of the missing links, which tormented nineteenth-century evolutionists, is one that concerns the evolution of large groups, in which the aspect o f natural selection is secondary, ss In this memoir Huxley gave an example o f the evolutionist 's capacity to provide a startling case of forms connecting groups above the species level. In order to do so, he compared birds and reptiles, first pointing out the main differences between them. He showed that existing birds differ widely from existing reptiles. The Ratitae (birds like the ostrich, rhea, emu, Apter),x, and Dinornis), which are inept at flying, seem to be closer to reptiles than the other birds, the Carinatae; however, their resemblance to reptiles is still slight, and they cannot fill the gap between the two classes. One must therefore refer to fossil forms, and solve the problem by answering two questions:

1. Are any fossil Birds more reptilian than any of those living? 2. Are any fossil Reptiles more bird-like than living reptiles? And I shall endeavour to show that both these questions must be anwered in the affirmative, s6

Huxley then recalled the circumstances of Archaeopterix litho- graphica, whose discovery has captured the imagination of the scientists of two centuries. In 1861 the impression of a feature of this creature was discovered by Hermann yon Meyer, s7 and in the same year Haeberlein found its skeleton. Owen was able to study the remains that had been bought by the British Museum: sa for once, Huxley and Owen agreed, for both detected the ornithic characteristics of Archaeopterix. s9

54. Ibid., p. 304. 55. Bernhard Rensch, Evolution above the Species Level (New York: Colum-

bia University Press, 1960), p. 57. 56. T. Huxley, "On the Animals," pp. 306,307. 57. Hermann yon Meyer, "Reptilen aus dem Stubendandstein des obern

Kempers," Palaeontographica, 7 (1858-1860), 253-346; 14 (1865 -1866), 99-124, 58. Richard Owen, "On the Archaeopterix of von Meyer, with a Description

of the Fossil Remains of a Long-Tailed Species from the Lithographic Stone of Solenhofen," Phil Trans. Roy. Soc., 153 (1863), 33-47.

59. In the opposite camp Andreas Wagner, the Munich anti-Darwinian, tried to demonstrate that Archaeopterix was no evidence for evolution: see J. A. Wagner, "Ober ein neues, augenblicklieh mit Vogelfedern versehnes Reptil aus den Solenhofener lithographischen Schiefer," Sitz. bayer. Akad. Wiss., 2 (1861), 30-38.

408

The Dinosaur Connec t ion : Huxley ' s Evolu t ionary View

It is still the oldest k n o w n bird, and Huxley considered it to be closer

to reptiles than any m o d e r n bird. 6° In 1868 Huxley presented an ent ire

memoi r on this fossil to the Royal Society . 6~ Archaeopterix therefore provides the aff i rmat ive answer to ques t ion 1. As for ques t ion 2, Hux ley did no t believe that the characterist ics o f p terodactyls sufficiently

approach the orni thic type , and therefore " the passage f rom Repti les

to Birds is no t f rom flying Rept i le to f lying Bird. ' '62

In Huxley ' s view the ex t inc t reptiles that we must regard as the

connec t ing forms are the dinosaurs. Dinosaur s tudy had been greatly

advanced by the discoveries made in the early 1830s by Hermann

yon Meyer, the wel l -known German paleontologist . In England, no t

surprisingly, it was Richard Owen w h o became an au thor i ty ; he was

the one who later coined the name "d inosaurs" (which means " terr ible l izards") .63

The fossil that is the closest available form to the missing link

60. T. Huxley, "On the Animals," p. 308. 61. Thomas H. Huxley, "Remarks upon Archaeopterix Hthographica," Proc.

Roy. Soc., 16 (1868), 243-248; Scientific Memoirs, 340-345. As Frederick Burkhardt has pointed out, Huxley does not refer directly to

evolution in his scientific papers addressed to the Royal Society, since there they would have been considered mere "speculations" not worthy of remark. There is one exception, "On the Characters of the Pelvis in the Mammalia, and the Conclusions Respecting the Origin of Mammals Which May Be Based on Them," published in the Proceedings of the Royal Society of 1879; but by then evolution was more widely accepted in scientific circles and the reference to it appears briefly near the end of the memoir. On the other hand, Huxley introduced evolution into papers written for less orthodox groups, such as the more progres- sive Linnean Society or journals like the Geological Magazine. For the Royal Society, only structural and paleontological evidence was presented - indirect evidence for evolution. See Burkhardt, "England and Scotland: The Learned Societies," in Thomas F. Glick, ed., The Comparative Reception of Darwinism (Austin: University of Texas Press, 1972), pp. 32-80; and Proc. Roy. Soc., 28 (1879), 395405 ; Scientific Memoirs, IV, 345-356.

62. T. Huxley, "On the Animals," pp. 308-309. 63. Richard Owen, "Report on British Fossil Remains," Rep. Brit. Ass.

(1841), 60-204. Dinosaurs became quite fashionable in the 1850s, when B. W. Hawkins reconstructed, under Owen's supervision, several life-size models. These vast creatures were assembled in a special "Dinosaur Island" at the Great Exhibi- tion. In 1854 a dinner was held inside the model of lguanodon for 34 guests, Owen himseff sitting in its head. See Owen, Geology and Inhabitants of the Ancient World: The Animals Constructed by B. W. Hawkins (London: Bradbury & Evans, 1854); and Adrian J. Desmond, The Hot-Blooded Dinosaurs (London: Blond & Briggs, 1975), pp. 119-121.

409


between reptiles and birds is Compsognathus longipes, s4 according to Huxley the most bird-like of all the dinosaurs. It is a creature about two feet long, something like a chicken, and was described for the first time by Andreas Wagner. 6s Writing about this creature, Huxley maintained that

notwithstanding its small size (it was not much more than two feet in length), t.his reptile must, I think, be placed among, or close to, the Dinosauria: but it is still more bird-like than any of the animals which are ordinarily included in that group . . . It is impossible to look at the conformation of this strange reptile and to doubt that it hopped or walked, in an erect or semi-erect position, after the manner of a bird, to which its long neck, slight head and small anterior limbs must have given it an extraordinary resemblance. ~

Moreover, as Huxley pointed out in 1876,

It is certain that Compsognathus must have walked on its hind legs.

The question then, naturally arises, did the gigantic Dinosauria, such as Iguanodon and Megalosaurus, have the same mode of progression? This seems, at first sight, hard to believe, but there is considerable reason for thinking that it may have been the case. 67

From paleontological evidence we can conclude that toward the

64. Its modern taxonomic position is as follows:

Order: Saurischia Suborder: Theropoda

Infraorder: Coelurosauria Family : Procompsognathidae

Genus and S p e c i e s : Compsognathus Iongipes, late Jurassic, Europe

From John H. Ostrom, "'Archaeopterix and the Origin of Birds," Biol. J. Linn. Soc., 18 (1976),91-182.

65. J. A. Wagner, "Neue Beitr~ige zur Kenntnis der umweltischen Fauna des lithographlschen Schiefers: Compsognathus longipes," Abh. bayer, Akad. tqiss., 2 (1861), 30-38.

66. T. Huxley, "On the Animals," pp. 311-312. 67. Thomas Huxley, "On the Evidence as to the Origin of the Existing Verte-

brate Animals," Nature, 13 (1876), 388-389,410-412,429-430,467-469,514- 516 ; 14, 33-34; Scien tific Memoirs, IV, 163-187; quotation on 182_

410


beginning of the Mesozoic there were semierect animals, possibly endothermic, with two ornithic feet. Such bipeds were either reptiles or birds, or, more probably, both. All this is obviously strong evidence for the evolutionary view, and thus

there is nothing very wild or illegitimate in the hypothesis that the phylum of the class Ayes has its root in the Dinosaurian reptiles.

The facts of paleontology, so far as Birds and Reptiles are concerned, are not opposed to the doctrine of Evolution, but , on the contrary, are quite such as that doctrine would lead us to expect; for they enable us to form a conception of the manner in which Birds may have evolved from Reptiles, and thereby justify us in maintaining the superiority of the hypothesis, that Birds have so originated to all hypotheses which are devoid of an equivalent basis of fact. 6a

In subsequent years Huxley became increasingly confident in the application of evolution to zoology, as his surveys of the crocodiles 69 and of the vertebrates 7° published in the 1870s show. At the same time, he maintained the type concept as a major reference, both in those memoirs and in his famous monograph The Crayfish. 71 The following 1877 quotation provides evidence of the use Huxley makes of the type concept in a new evolutionary context:

68. T. Huxley, "On the Animals," p. 312. Huxley's view of the dinosaurs was abandoned in the twentieth century, especially after the publication of Gerhard Heilmann's influential book, The Origin o[ Birds (London: Witherby, 1926). Today it has been revived by a group of paleontologists led by John H. Ostrom of Yale University; see his "'Archaeopterix and the Origin of Bixds";"The Ancestry of Birds," Nature, 242 (1973), 136; "The Origin of Birds," Ann. Rev. Earth Planet. Sci., 3 (1975), 55-77; "The Osteology of Compsognathus Iongipes," Zitelliana, 4 (1978), 73-118. I am grateful to Ostrom for sending me some of his publications, and to the B.B.C. for sending me the script of their broadcast, The Hot-Blooded Dinosaurs. Ostrom's view is criticized by A. D. Walker, "Evolution of the Pelvis in Birds and Dinosaurs," in S_ M. Andrews, R. S. Miles, and A. D. Walker, eds., Problems o f Vertebrate Evolution (London: Academic Press, 1977), pp. 319-386.

69. Thomas H. Huxley, "On Stagonolepis robertsoni, and on the Evolution of the Crocodilia," Quart. J. Geol. Soc., 31 (1875), 423-438; Scientific Memoirs, IV, 188-241. See also his "The Crocodilian Remains Found in the Elgin Sand- stones, with Remarks on the Ichnites of Cummingstone," Mere. Geol. Sur. U.K_, 3; Sciennfic Memoirs, 188-241.

70. T. Huxley, "On the existing vertebrate animals." 71. London: Kegan Paul, Trench & Co., 1879.

411


1. The Parasuchia, 2. The Mesosuchia,

3. The Eusuchia,

in the in the Middle Mesozoic rocks from the

in the later Mesozoic rocks and in the Tertiaries from the

Trias and perhaps earlier

Upper Lias to the Wealden

Later Cretaceous to Recent Epoch

In other words, the order o f occurrence of these three divisions of the Crocodila in t ime, coincides with the order in which they depart from the Lacertilian type, and put on special crocodilian characters; and thus, paleontological fact is in precise accordance with the needs o f the theory of Evolution. The evidence in favour of the general development of existing from ancient Crocodilia, is in fact as cogent, though not so complete, as that by which the origin of the horse from a three-toed ancestor has been demonstrated. ~2

By 1880 Huxley was wholeheartedly convinced of the possibility of drawing phylogenies of the vertebrates, which he thought would be based upon what he called the "law of evolution":

Given the common plan o f the Insectivora and of the Rodentia, and granting that the modifications of the structures of the limbs, o f the brain, and of the alimentary and reproductive viscera which occur among them may exist and accumulate elsewhere, and the derivation o f all the Eutheria from animals which, except for their simpler placentation, would be Insectivorous, is a simple deduction from the law of evolution. 73

He did not hesitate to postulate the occurrence of a group of animals that would fill the paleontological gaps in the "submammalian" stage of evolution. He proposed the name Hypotheria (hypothetical animals):

72. T. Huxley, "The Crocodilian Remains," p. 231. The Trias is considered to be 215-190 million years ago; the Upper Lias to the Wealden is about 150 million years ago; and the Later Cretaceous to Recent Epoch is from 120 million years ago.

73. Thomas H. Huxley, "On the Application of the Laws of Evolution to the Arrangement of the Vertebrata and More Particularly of the Mammalia," Proc. Zool. Soc. (1880), 649-661 ; Scientific Memoirs, 457-472; quotation on 467.

412


"I do not doubt that when we have a fuller knowledge of the terrestrial Vertebrata of the later Palaeozoic epochs, forms belonging to this stage will be found among them. ''74

HUXLEY AND HAECKEL

In all these memoirs we find assembled the elements that influenced Huxley's thought. Darwin is conspicuous in this discussion by his absence. Undoubtedly Huxley never freed himself from some aspects of the conception of science he held before 1859, the Origin o f Species notwithstanding. Rather, he tried to subsume them under a comprehen- sive evolutionary frame - putting new wine into old bottles, or, better, using old ingredients in a new recipe. This probably explains why Henry Osborn claimed that Huxley made no original contribution to the theory of evolution, 7s and why Bartholomew denied that Huxley really changed his outlook after 1859. 76 The concept of the type, its embryological interpretation after yon Baer, the search for the missing links, and the drawing of phylogenies h la Haeckel, all found a place in Huxley's view.

Most people acquire their basic beliefs in the early stages of their lives, and in the remainder of their existence those beliefs come into confrontation with particular problems. If these individuals are creative enough, they make new discoveries and propose new interpretations of facts hitherto uncomprehended. I think it is clear that Huxley formed his scientific beliefs in the late 1840s and early 1950s and that they were molded by his study of "German" science. Slowly Huxley moved toward an evolutionary approach to the phenomena of living nature, but his evolutionism was not strictly and straight- forwardly a Darwinian one. As a matter of fact, if we searched for such an "orthodox" approach elsewhere in the group who supported Darwin from the very beginning, we should be disappointed. The fact is, as Peter Vorzimmer has shown, 77 there were so many unanswered questions that "orthodoxy," if such a word makes any sense, was virtually impossible.

74. Ibid., p. 468. 75. Henry Fairfield Osborn, Impressions of Great Naturalists (New York:

Charles Scribner's Sons, 1928), p. 140. 76. Bartholomew, "Huxley's defence of Darwin." 77. Peter Vorzimrner, Charles Darwin: The Years of Controversy (London:

London University Press, 1972).

413

MARIO A. D1 GREGORIO

Our narrative thus far has shown Huxley as effectively a participant in the German zoological community and its development, and has hinted that Darwin is a less central figure in that development than we are accustomed to thinking. Unquestionably, Darwin rescued evolution from the disrepute into which it had fallen in the hands of earlier authors; he made it scientifically respectable again. But insofar as natural selection is concerned, its clear focus on the interaction between animals and their natural environment meant that it did not directly address the concerns of contemporary systematology and therefore was not readily applicable. The German community, and Huxley with it, reacted to the general rehabilitation of the idea of evolution only when the implications of paleontological discoveries sank in and made genealogical and phylogenetic exercises practicable as well as newly fashionable. The key, for the German community, was the realization that the idea of descent could be placed at the forefront of an essentially yon Baerian typology. If we want to understand why Huxley started applying evolutionary reasoning to his scientific research only in the late 1860s, we must examine the German scientific environment.

Ernst Haeckel's Generelle Morphologie der Organismen appeared in 1866, and he and Huxley met in London the same year. Haeckel claimed that then Huxley was "deeply" interested in his "daring endeavour"; with less than humourous enthusiasm, Haeckel stated that the Generelle Morphologie was

the first endeavour to base the general outlines of organic morphology on the theory of descent as it had been revived by Charles Darwin . . . For in that work I had tried to carry into direct effect that theory, and had given the first sketch of organic pedigrees, the exhibition of which had, by the newly-founded theory of descent, been made the special task of Phylogenetic Systematologyfl s

Since Huxley's first memoir in which evolution appears is dated 1868, two years after the publication of Haeckel's book, it seems to have taken Huxley some time to assimilate the view propounded there. With reference to his memoir of 1868 on the dinosaurs, Huxley wrote to Haeckel on January 21,1868:

78. Ernst Haeckel, "Thomas Henry Huxley and Carl Vogt," Forth. Rev., 58, n.s_ (1895), 464-469 ; quotation on 466.

414


In scientific work the main thing just now about which I am engaged is a revision of the Dinosauria - with an eye to the Descendenz Theorie! The road from Reptiles to Birds is by way of Dinosauria to the Ratitae - the Bird 'Phylum' was Struthious, and wings grew out of rudimentary fore limbs.

You see that among other things I have been reading Ernst Haeckel's Morphologie.79

We need to fred out why Haeckel was so successful in gaining Huxley's approval. First of all, it is essential to point out that Haeckel's theory of descent (Descendenztheorie) was largely based upon the reinterpretation of yon Baer's embryological results in light of the concept of evolution. For Haeckel, ontogeny was the short and rapid recapitulation of phylogeny; the individual during its development repeats the major changes in form achieved by its ancestors during their paleontological history, s° Haeckel expressed the essence of his thought in the following passage from the Generelle Morphologie:

Phylogeny, or the paleontological development of blood-related forms which leads to the establishment of genuses, orders, families and all the other categories of the organic world, is a physiological process which, like all other physiological functions of organisms, proceeds of absolute necessity by mechanistic means.

These means are the atomic and molecular motions which piece organic matter together, and the limitless variegation evidently achieved in the process of phylogenetic development expresses a similar limitless variegation first in the concatenation of organic matter and then in the subtle compounds of which the active plasma of the constituent plastides of all organisms is composed. The phylogenetic or paleontological development of the main trunk and its diverse subordinate categories is therefore neither the pre- meditated purposeful result of a creative intelligence nor yet the outcome of some mysterious vital force of nature, but rather the

79_ Georg Uschmann and I. Jahn, eds., "Der Briefwechsel zwischen Thomas Henry Huxley und Ernst Haeckel," ICiss. Zeitschr. Univ. Jena, 9 (1959-1960), Math. Naturwiss., 1 (2), 7-33;quotation on 15.

80. See Stephen Jay Gould, Ontogeny and Phylogeny (Cambridge, Mass_: Harvard University Press, 1977).

415

MAR10 A. DI GREGORIO

simple and necessary operation of that familiar physical and chemical process identified by physiology as the operative mechanism in the development of organic matter.a1

This view of evolution from the perspective of the physiologist and morphologist (based upon embryology), and this strictly mechanistic view of biology (based _upon physics and chemistry), was entirely shared by Huxley.a2

For Huxley the success of the typological approach to the theoretical problems of zoology consisted in its ability to discover the orderly "pattern" of nature, through the detection of relationships existing between the types: if you want to understand nature, you must compare the different types of organization with reference to the different levels of development within each type. Now, if you replace the modifications of the type that you have detected through your application of comparative embryology by actual historical genealogical connections, you have both preserved your existing knowledge of the pattern of nature and created the Descendenztheorie. William Coleman has shown that this was done by Carl Gegenbaur, Haeckel's friend and colleague at Jena. aa Coleman emphasizes that in the 1870 reprint of his Grundziige der vergleichenden Anatomie, originally written in 1859 a few months before the Origin o f Species, a4 Gegenbaur replaced the relationships between the types that he had detected by genealogical connections, writing in 1870:

The theory allowed what previously had been designated as Bauplan or Typus to appear as the sum of the structural elements of animal organisation which are propagated by means of inheritance, while modifications of the structures are explained as being adaptations . . . From the standpoint of descent theory the "relatedness" of organisms loses its figurative meaning. Whenever we encounter, through the use of precise comparison, demonstrable agreement in structural organisation, this indicates common ancestry founded on inheritance.BS

81. Haeckel, Generelle Morphologie, II, 365. 82_ Thomas H. Huxley, "On the Physical Basis of Life," Forth_ Rev., 5, n.s.

(1868), 129-145; Collected Essays (London: Macmillan, 1893-1894) I, 130-165_ 83. William Coleman, "Morphology between Type Concept and Descent

Theory," J. Hist. Med., 31 (1976), 149-165 ; Uschmann, Geschichte der Zoologie. 84. Carl Gegenbaur, Grundziige der vergleichenden Anatomie (Leipzig;

Engelmann 1859); reprint ed., 1870). 85. Quoted in Coleman, "Morphology," p. 163.

416


As Oscar Schmitt put it in 1872, the new trend in zoology was to base classification on the genealogical expression of the types .86 This is exactly what Huxley did in his memoirs published from 1868 on. We can now understand why Huxley maintained the concept of the type throughout his career in science: for him, discovery of the order of nature was the ultimate goal of the philosophical zoologist, and that was guaranteed by the type concept. Only a theory based upon that concept could possibly convince him. When Haeckel's Descendenztheorie did so, there was no impediment to Huxley's application of evolution in his scientific research. Huxley became increasingly confident about evolution, and by 1883 could claim that zoologists Fred illustrations of the fact of evolution even among the invertebrates, as in the case of the pearly nautilus. 87

CONCLUSION

If I am correct in my delineation of the relationship between Huxley and the "German communi ty ," I think it follows that Huxley's own research is not the place to look for evidence of any direct impact, positive or negative, of the publicat ion of the Origin o f Species, especially prior to the late 1860s when systematologists in general began to adjust. The same line of thought also dispels the expectation-in- principle that the doctrine of natural selection ought to be featured somewhere in those works of Huxley that deploy the idea of evolution; for that expectat ion is countered by the observation of the substantial irrelevance of natural selection to the current concerns of systematics. Endorsing evolution and endorsing natural selection are not the same thing. Both his heavily qualified acceptance of natural selection and the survey of his research show that Huxley became an evolutionist, but not of the Darwinian kind.SS

86. Ibid.,p. 169_ 87. Thomas H. Huxley, "Evolution, As Illustrated by the Pearly Nautilus,"

Nature, 28 (1883), 187-189;Scientific Memoirs, IV, 69-79. 88_ Thomas Huxley, "The Darwinian Hypothesis," The Times, December 26,

1859 (A); Collected Essays, II, 1-79; "The Origin of Species," West_ Rev.. 1 7, n.s_ (1860), 541-570_ Of course, the German view and Darwin's are perfectly compatible, and Darwin referred to yon Baer's embryological method in the Origin of Species (London: Murray, 1859), pp. 439-450. See Gavin de Beer, "Darwin's Views on the Relations between Embryology and Evolution," J. Linn. Soc. (Zool_), 44 (1958), 15-23.

417


A cknowledgments

For their suggestions and encouragement I wish to thank William F. Bynum, Sydney Smith, Michael Bartholomew, David Kohn, Dov Ospovat, Frederick Burkhardt, and my friend Nick Gill. I am grateful to J. Pingree of the Imperial College Archives for her help with the Huxley Papers and for granting me permission to quote from them.

418

The dinosaur connection: A reinterpretation of T.H. … Connection to... · The Dinosaur...

Documents

Transcript of The dinosaur connection: A reinterpretation of T.H. … Connection to... · The Dinosaur...