Tuatara: Volume 27, Issue 1, August 1984
Mayr vs. Croizat: Croizat vs. Mayr—An Enquiry
Mayr vs. Croizat: Croizat vs. Mayr—An Enquiry*
In this posthumous paper, Croizat responds to criticisms of panbiogeography made by Ernst Mayr in two 1982 publications. The response emphaizes some of the key features in his approach to evolutionary biology and biogeography, including his views on disjunctive distributions, the Darwinian concept of dispersal from centres of origin, differential rates of evolution and the role of taxonomy in biogeographical analysis. The distinction between panbiogeography and vicariance biogeography is stressed.
Keywords: biogeography, Croizat, Darwin, evolution, Mayr, panbiogeography, vicariance.
Anyone assuming that the literature of biogeography is necessarily scientific is in for a surprise, when learning that this literature is all too often subservient to strictly human foibles of conceit, obstinacy, illogical reasoning, etc. It is imperative that young students be informed of this because, if not, they will find it impossible to judge correctly what the press and their surroundings offer for their attention.
When I began in the 1940s to take a positive interest in the field of the geographic distribution of animals and plants, I did not know that I was stepping into a field of research already dominated by a formidable duo: Drs. G. G. Simpson and Ernst Mayr, firmly entrenched at the time in the American Museum of Natural History. This duo later enrolled Dr. P. J. Darlington, Jr. of Harvard University and others. Being unable to see eye to eye with these luminaries, as I will presently explain, and quite ready to tell it to the world, I took almost unwillingly upon myself the task to fight, as a nearly unarmed David, the fury of a touchy heavily armed Goliath.
The zoogeography heralded by Simpson, Mayr, Darlington, Dobzhansky, etc. needs not to be minutely picked apart for the benefit of the reader, when its very nature is made clear by the following opinion of Mayr:
“The distances between the various Antilles are so much shorter than the well substantiated jumps made by Pacific birds, I would not hesitate to accept transoceanic dispersal for the whole Antillean bird fauna without any major change of the present geological contours.” (Mayr; in Bond, 1948:208. c.f. Croizat, 1976:315; 1981:509)
The audacity of this fiat struck me on the spot as most remarkable, in no way compatible with the little I had already observed of the distribution of a number of plants in and outside the Antilles. If what Mayr was so unceremoniously handing be correct, zoogeography and phytogeography, respectively, must be antithetic sciences; a postulate that I rejected as if by instinct. If the whole of the biogeography of the Caribbean region could be reduced to a series of jumps (by no means “well substantiated” whether in the New or Old World, contrary to Mayr's extrarodinary claim) dispersal as a science of causes and effects had no longer reason to exist. Its most intricate problems could be disposed of with the affirmation that, e.g. Magnolia and Catharus have “jumped” from the Greater to the Lesser Antilles (or vice versa, who could say), using “means of dispersal” that, if absurd on the face of it could always be excused as “mysterious”.page 50
To cut it short: to ask Mayr, Simpson, Darlington, etc. for light in point of dispersal meant to ask them for bread and fish—recalling the Biblical dictum of Matthew 7.9—but receiving in return stones and serpents. Left thus in the lurch by the luminaries of the day, who struck me repeatedly as but misguided theorists, I “invented” the “panbiogeography”. I can take little credit for such a discovery, because I was merely refurbishing the Method that four centuries before my time, had put Kepler in the condition of bringing down to earth the law of the skies. This method—it is by no means a Theory (notice the difference please!)—consists purely and simply in accumlating facts, finding a way to render them graphic by orbits of tracks, finally comparing them on a statistical basis in order to abstract the causes and rules of their being what they Factually happen to be. Naturally, even this method will not work if left in the hands of parties lacking disciplined imagination, and a certain amount of general culture qualifying its beneficiary to distinguish as between mere details and basic essentials and the will to take pains in the execution of a promising pain. Anyhow, whatever the case be in details, the Method stands, and triumph it shall against all manner of theories.
The panbiogeographic method—Panbiogeography for short—had me convinced in less than a month from the start that, as an instrument of investigation and positive knowledge it was infinitely superior to the zoogeographic theories trumpeted in the name of Darwinian “respectability” by Mayr, Simpson, Darlington, etc. The case of these gentlemen rested on the notion of a centre of origin of the “species” out of which the “species” would emerge migrating by particular means of dispersal. This notion did not survive for me even casual consideration, and I promptly rejected it feeling what Ball was privileged to experience some thirty years later than my beginnings, and to express in neat words as follows:
“For me, Croizat's contribution is one of liberation. Once we have escaped from the necessity of seeking restricted centres of origin, and from the necessity of plotting routes of dispersal from these centres, and once we have seen the possibilities unfolded by concepts of vicariance and differential form-making then a new world of ideas opens up for us.” (Ball, 1976:422)
Never has my lifework received a higher praise than in these few lines by Ball. Of course, they mean nothing particular for those who are not at all interested in new worlds of ideas, and cling like oysters to “Darwinian tradition” and its supposed respectability.
Sure of my grounds, and ready to continue my work, I did not scruple taking issue—in a spirit faithful to the form of convention—with certain weighty statements by Mayr such as:
“Dealing with the origin of the bird-fauna of Hawaii, an ornithologist (Mayr 1943:47) writes as follows, “There is not a single serious modern student (I use the term serious advisedly) who believes in the former existence of land bridges between America and Hawii, or between Polynesia and Hawaii.” (Croizat, 1952:12)
Three years later, this author (Mayr 1946:12, 36) submits a diagram intended to elucidate the components of the bird-world of the Americas…, and explains that favourable conditions were lacking for tropical life to pass freely between Asia and America in the latitude of the Aleutians. This explanation is followed by a statement to the effect that,
“The close relationship between the Old and New World members of the Pantropical element, whose ranges are now widely discontinuous, proves that page 51 such a faunal exchange must have taken place, and this places the zoogeographer in a real quandary. The customary solution for the problem is to ignore it… In view of the improbability of a North Atlantic land connection, various attempts have been made to find new routes for the transpacific migration. I Mayr shall refrain from a discussion of the various proposed transpacific land bridges. They are faunistically possible, but find no geological support. There is, however, some evidence for considerable recent tectonic activity in and south of the Aleutian island region, as well as for a pronounced lowering of the floor of the Pacific as a whole.” (Mayr, 1946)
So far for my comment on Mayr's zoogeography, to which I was careful to add:
“It is not our intention ((Croizat's)), in quoting these statements and bringing forth this map, to imply that the author in question Mayr is glaringly inconsistent. Consistency—as it has been shrewdly remarked—may indeed be a mere synonym of obstinacy”. (Croizat, 1952)
All in all, I felt that not even so exalted a figure as Dr Ernst Mayr could be offended by what I have just quoted. True, its substance was devastating and the method it heralded hard indeed to refute, but so is science, ever changing, as it might seem, for the better. If Mayr, Simpson etc., obviously stood mired in quandaries that their theories could not avoid, why should not Croizat be welcome in producing a notable breakthrough fit to help everybody around?
Thus anticipating a lively, readily constructive discussion for and against the nascent panibiogeography—surely at that time particularly, a less than perfect doctrine in every detail—I was greatly mistaken. All I heard after a time from friendly sources was that Croizat was being made the object of an active whispering campaign unfavourable to his character, manner of working, etc. None of the zoogeographic luminaries of the day came out to refute my viewpoints, to dismiss the panbiogeography as a brainstorm, but—now it can be told (see Abele, 1982)—Simpson let it be known that Croizat wrote from an insane asylum, and Mayr had him dismissed as a contributor formally and substantially of prose so remote from science that no serious student could entertain Croizat at all. The strategy against my work and person was indeed murderous: the very name Croizat was taboo, must not be mentioned, and some 10,000 pages of my work should be treated as non-existent. Had I been made of less resilient and durable material, I should take my scientific life as ended in 1952 and—why not?—induced to commit suicide.
Such having been the situation, for at least a quarter century may the reader imagine how great was my surprise when learning that Dr Ernst Mayr had printed in this very year 1982, two works, one a full fledged book, the other a review; rigorously keeping up the old anti-Croizat taboo in the book, but throwing it out of the window in the review. I could hardly believe my eyes, all the more so in that Simpson and Darlington to the best of my knowledge still unflinchingly refuse to recognise that a certain Croizat ever was born to the light of this rather poor world. It all was as if the Pope—in person of Dr Ernst Mayr—had sold out the Vatican and turned Lutheran.
The first of these two titles is, The Growth of Biological Thought, with subtitle, Diversity, Evolution and Inheritance, (1982b). Pages 448-455 essentially cover the part of the opus dealing with biogeography. The second title is the review by Mayr of, Vicariance Biogeography, by Nelson & Rosen 1981, (1982 a) page 52 In The Growth of Biological Thought Mayr clings to his old taboo forbidding even to mention the name Croizat. Not so at all in the Review in which Mayr relents to the extent of repeatedly naming Croizat and “Croizatians”!
From the standpoint of psychology these two titles, dated of the same year stand as a priceless document of the manner in which Mayr thinks. It is easy to see by comparing the two that, with or without the burden of the anti-Croizat taboo, Mayr labours under the heavy liability of showing the world that he was right even when wrong. His writings are accordingly eminently forensic (forensic is mild) and as such they must be understood.
In view of the unusual nature of the Mayriana I intend to bring before my reader, I will present the evidence in two major sections referring in one to Mayr under the anti-Croizat taboo, the other when free from it. In both sections, I will quote first Mayr's own texts and then immediately append my own comments. I thus propose to liquidate a situation which has stood in the way of a normally progressive advance of biogeographic knowledge during the last forty years. Doctor Ernst Mayr may be anything and everything to everybody, but in my deliberate opinion at least he has no title to pose as a genuine biogeographer quite as much in 1948, when teaching Bond how to “understand” the ways and manner of dispersal in Antillean range (see the introductory page of the present article), as today.
1. Mayr Avoids Mention of Croizat
In the Growth of Biological Thought tidbits abound but only some I will bring before my reader. The main point of interest for us is to be found at p. 453, where we read:
“A somewhat eccentric biogeographic theory was proposed in the late 1950s, “vicariance biogeography”, which so far as I ((Mayr)) can understand it, stresses former continuities and downgrades the importance of longdistance dispersal… Quite logically, it found its chief support among ichthyologists, because primary freshwater fishes have a particularly low dispersal ability. Acutally, it does not seem that vicariance biogeography has introduced any new princples, since the occurrence of secondary discontinuities was already well known to Forbes, Darwin, Wallace, and other pioneers of biogeography (von Hosten, 1916). Darwin in particular was fully aware of the two causes for disjunction.”
Comment—This text, obviously referring to Croizat's Panbiogeography that came out of press “in the late 1950s” that is, 1958, holds a record for a maximum of inaccuracies, untruths and half-truths, tomfoolery, all in but eleven lines of print. The taboo forbidding Mayr to openly mention Panbiogeography is both noxious and ridiculous. And for the rest :(a) It is false that panbiogeography is a “somewhat eccentric theory” when it plainly is a positively constructive method of investigation of the records of geographic distribution of plants and animals, living and fossil, the world over. See Croizat 1952, 1958, 1960-1, 1962-4, 1968a, 1968b, 1976, etc; a bulk of organic literature in English, Spanish, French of close to 10,000 pages which Mayr nonchalantly wipes out for fuller misinformation of his credulous readers; (b) It is false to dump under the unfortunate designation “vicariance biogeography”, Croizat's panbiog (let us abridge this way the overlong word panbiogeography) 1952-1976, etc., and Nelson's highly theoretical mixture of Croizat's ideas and Hennig's sterile daydreaming (see: Nelson & Rosen, 1981, 1, 524; Nelson & Platnick 1981, ix, 543; Croizat, 1982); (c) What “vicariance biogeography” stresses is Hennig's “cladistics”. Panbiog rejects them and also page 53 rejects the importance of long-distance dispersal “because appeals to “long-distance” jumps, and the like are an integral part of the catastrophic theory wishing it, for example, that Antillean dispersal is a series of “jumps”. Mentioning the “importance of long-distance dispersal”, Mayr intends in reality to have an innocent reader believe that dispersal of that sort has place in biogeography today, still as it did in the “Zoogeography” of the 1940s, which is strictly tendentious; (d) That ichthyologists (do understand, D. E. Rosen and G. Nelson of the American Museum of Natural History of New York) endorsed “vicariance biogeography” (under this designation Mayr confusedly intends also panbiog) because fresh-water fishes have a “particularly low dispersal ability” is false as a matter of fact (see e.g., Cyprinids in Croizat 1958; 1: 712 fn.; 2a:41, Fig. 124, p. 142 ff) and childish as an argument; (e) The statement to the effect that “vicariance biogeography” has introduced no new principles is ambiguous. Panbiog is something that “vicariance biogeography” is certainly not. Mayr has no clear understanding, if any at all, of the subject he believes to master; (f) it is possible that Forbes, Darwin, Wallace, etc. had visualised what Mayr calls “secondary discontinuities” (see next on this) without however using their “knowledge” to any efficient purpose. Darwin was “fully aware” of nothing much because being “aware”—as Mayr claims—of the “two causes for disjunction”, he wrongly argued nevertheless the whole of dispersal with or without discontinuities/disjunction/disconnections (see, Croizat 1962-4:631 ff).
If what Forbes, Wallace, Darwin, etc., managed to work out had been successful, the situation today would be different from the one Mayr paints (p. 452) stating: “The explanation of the origin of discontinuities has continued to be one of the most controversial subjects in biogeography”. Why so, Doctor Mayr?
Clear as I hope up to this point, let us pay close attention to what Mayr theorises about discontinuities (disconnections, disjunctions, etc.). This theorising is inspired to repeat Mayr's preoccupation with long overseas jumps, colonising flights and the like, which all, he imagines, gives the lie to “vicariance”, and therefore proves that Mayr has been right in the 1940s, while Croizat has been wrong at all times.
As a typical case of primary discontinuity Mayr imagines (p. 452) the following:
“A primary discontinuity originates when colonists reach an isolated area and succeed in establishing a permanent population there. For instance, when Scandinavian insects and plants dispersed to Iceland in the post Pleistocene period, such colonisation, it is now quite certain, took place across a large watergap” (emphasis mine).
A secondary discontinuity (loc. cit.) originates owing to the
“fractionation of an originally continous range through a geoglogic, climatic or biotic event”. Adds Mayr without delay: “Unfortunately, the situation is not always…clear, leading to arguments as to whether or not long-distance dispersal could account for the discontinuity or, on the contrary, whether there is evidence for a former physical continuity” (emphasis mine).
If, as Mayr himself admits, to attempt a distinction between primary and secondary discontinuities leads to arguments, therefore to normally sterilising confusion, I would say that it is considerate toward science and its devotees to abstain from insisting on premature definitions. A definition is in order when its subject is definitely known; but when the page 54 subject is still obscure, evidently controversial, an explanation, not a definition is in order.
Mayr needs, however, definitions, whatever their merits as instruments of knowledge, which substantiate mentions of colonists reaching isolated areas across a large watergap by long distance dispersal. This breed of definition brings to the fore the paraphernalia of Mayr's zoogeography of 1940 vintage, which the development of the sciences of Earth and Life has killed for good during the last thirty years of slow grinding, (be it passingly remarked that panbiog had part in managing the funeral). It will still make an impression on the innocent reader however and induce him to accept as living the shadows of an empty past. I see no need of further expatiating on the primary and secondary discontinuities of Mayr when it is already clear that what is really in play is strictly propaganda and make-believe. Quite numerous and varied are the references to disconnection (discontinuities, etc.) in the indexes of my major work, and it is simply a false notion that discontinuities are, or still may be, one of the most controversial subjects of biogeography.
I see no further need to dig into Mayr's, The Growth of Biological Thoughts to have it proved with a great expenditure of printing space that Mayr is not reliable, labouring as he does under the weight of a silly anti-Croziat taboo and a constant obligation speaking from both corners of the mouth in order to refurbish a past surely dead. There is no rescuing today what for instance Mayr wrote in 1948 to Bond in adherence to a long, catastrophic line of opinionate, wrong zoogeography.
2. Mayr Mentions Croizat
I cannot guest the reasons which induced Mayr to mention my name and work after some thirty years of a self-imposed taboo prohibiting it at all, in a matter of a few months of the year in course, 1982. All I know is that to my great amazement, Dr Ernst Mayr abruptly began to take notice of my person and work in the review, Vicariance Biogeography (of Nelson & Rosen, 1981), he contributed to the ornithological magazine The Auk 99: (618-620).
In this noteworthy piece of “Mayriana”, Croizat is abundantly castigated, reproved, etc., so much indeed that to furnish a fairly complete rebuttal I ought to write out a small volume. Since I have myself written about 10,000 pages in which Mayr stands firmly dismissed by knockout from the ring of scientific biogeography, I wil not now write this small volume. Those of our readers, Mayr's and mine, wishing to be quite clear on the issue will please consult, for instance, Croizat 1962-4. Their time shall not be lost in vain.
And now, in detail:
(a) op. cit., p.618—Mayr declares himself dissatisfied with Nelson & Rosen's 1981 book, and writes:
“In view of the considerable amount of uncertainty about the meaning of the two terms dispersalism and vicariance, the reader would expect an introductory chapter with precise definitions and a clear formulation of the opposing viewpoints. Alas, there is no trace of such an exposition. Neither is Croizat's “panbiogeography” clearly defined, nor the term vicariance biogeography, apparently preferred by his latter-day disciples. The claim that “it derives its strength from the concept of relatedness, as expressed by…a cladogram” is evidently misleading because dispersalist explanations are just as much based on an analysis of relationship…Consistent with a current fashion, no opportunity is missed to denigrate Darwin and Darwinism… As the editors have failed to pinpoint the nature of the argument between the page 55 two schools and have badly misrepresented the views of their opponents, let me Mayr try to correct this deficiency”.
Comment—It is plainly useless that Mayr tries to “correct deficiencies” in a field that he does not know, nor will I bring here to record a long list of his errors, past and present, when I have pointedly spiked them over fifteen years ago in great detail. As to my “denigration” of Darwin, for example: Mayr has never read the motives of this “denigration” (Croizat 1962:4; 689 ff.), even less the “denigrations” of Gertrude Himmelfarb, whose strictures against Darwin, as a man and as a scientist, Gavin de Beer himself, Darwin's great admirer, could not dismiss as ill founded. After all: if Darwin had been indeed the genius who Mayr, Stephen Jay Gould, etc., delight in painting, it seems to me that his “great theory” would stand out of acute, constantly renewed controversies thus to match Kepler's and Newton's. Why should I waste my time and the reader's for the fun of pounding forever water in a mortar?
So, instead of wasting good print, just for pleasure to show the world bit by bit, piece by piece, I have driven eleswhere straight to the heart of the “Vicariance Biogeography” of Nelson & Rosen, 1981. May the reader please take good notice—which is usually not done—that the title in question has for its subtitle: Symposium of the Systematic Discussion Group of the American Museum of Natural History May 2-4 1979. Contrary then to what the near totality of biologists took for granted—I in the number—that Symposium did not have the purpose of ventilating the current status of biogeography in general: it was rigged up to promote the “biogeographic” opinions of a restricted circle of New York biologists having their headquarters in the American Museum of Natural History, of that grandiose city (Croizat, 1982).
Doctor Ernst Mayr knows of course nothing of this in his “review” of the failings of the New York Symposium which he pretends to censor, amend, etc. All he does is to insist on primary and secondary discontinuities, dispersal across the Bering Bridge, island hopping, colonisations across barriers, etc., in sum the flotsam and jetsam of the “zoogeography” that, as the humourless, stiff monoploy of Simpson, Mayr, Darlington, etc., managed to plague the world of science all the way from 1935 to the publication of Croizat's main works. The Mayrian claim (p.618) that:
“Prior to the discovery of plate tectonics and ocean floor spreading, biogeographers were forced to explain the old discontinuities as due to dispersal across the Bering Straits Bridge or to island hopping across the Indo—Australian archipelagos”
is of course spurious. As a biogeographer, I am “forced” to study only the biogeographic records of life, and to take logical account of what they reveal when objectively studied by averages the world over. What geological theories would say is of no account the moment these theories contradict the data from biogeography as such.
(b) (p. 619):
“If one finds trogons in the Old World and New World tropics, no “dispersalist” proposes that they dispersed across the wide Atlantic. Surely there was once a continuity, in this case perhaps the Eocene North Atlantic connections between Europe and Greenland. Actually, even the vicarianists cannot help but admit that distributions over an entire or several continents must have been the result of dispersal”.
Comment—Hidebound today, 1982, to his “zoogeography” of 1948, a taxonomist but not a biogeographer, Mayr stands under the hypnosis of page 56 “Holarctic dispersal”, and does not scruple to funnel through Bering Strait or by a “bridge” (whether solid land or built of islands as “stepping stones”) between Europe and Greenland, nothing less than the most “tropical” of birds, animals, plants, etc. Firm on the principles that Life and Land evolve together, assisted by a rigorous method of investigation—panbiog—, assured that evolution calls for constantly alternating spells of mobilism and immobilism; genuinely scientific biogeographers have precious little in common with the “vicarianists” fancied by Mayr for strictly polemical purposes.
(c) (p. 619): “The denial of dispersal forces the Croizatians into all sorts of eccentric geological theories. For instance, Croizat (p. 511) of ((Nelson & Rosen, 1981)) explains the Galapagos Islands as “a fragment of geological America, that was recast apparently in early Tertiary times, into a number of islands beset by volcanism”. The now-existing biota of the Galapagos is the product of evolution of the “ancient plant and animal life inherited as a whole from the American continent”. This remarkable assertion, albeit the necessary consequence of “panbiogeographical” dogma, is so totally refuted by the geological and biological evidence that no further comment is necessary” (italics mine).
Comment—A further final comment is in order: what I have underscored of the text above quoted is a plain falsehood. What blinded Mayr to take the responsibility of having published under his name so blatant a falsehood is a mystery to me (e.g. see Brundin, 1981:123).
(d) (p. 619): “Croizat also misses the point that in the process of a multiplication of species, a new species always originates at a circumscribed location…One would think that Croizat, after he had got several pages of maligning Darwin out of his system, would proceed to provide evidence for the falsity of Darwin's belief that “each species has proceeded from a single birth-place”, but one searches in vain either for such a falsification or for a “superior” replacement theory”.
Comment—Doctor George Gaylord Simpson is an excellent, quite trustworthy author whenever free of an overwhelming enthusiasm for Darwin and Darwiniana. He ranks very high in my estimation when, for example, resuming the march of evolution and taxonomy jointly (Simpson 1961; 23) he writes as follows:
“The bewildering array of tens of millions of minor species of animals, ancient and recent, tends to obscure the broader pattern of life history. Endlessly diverse as these groups seem to be, they represent variations on a small number of basic themes, general types of organisation;… (p. 31) The various classes of chordates, for instance, will be shown to have appeared in the record precisely in the sequence that would have been predicted on the basis of their relationships and increasing divergence from or advance beyond a prototype”.
This is simple, clear and vouched for by a master of palaeontology and systematics when not, alas, biogeography. Once established—and there is no overwhelming difficulty in learning whence, for instance, the Type of Organisation of Aves materialised—the primary type of organisation ramifies out into secondary types giving origin under and within Aves in general to separate types of Ratitae, Sphenisciformes, Trochiliformes, Passeriformes, etc. The mechanism of differentiation consists basically of differential combinations of the characters particularly belonging to the type itself, by virtue of which we do not expect an Ostrich to come out of the egg of a Colibri. The atavistic “type characters” not only are combined and recombined, but also implemented by the play of macromutations page 57 influenced by changes in “embryology” (let us understand that this is a field of which we do not know everything by far just now). Whatever the details, the type of organization is the basic source of characters, and their eventual combinations to generate taxonomy.
Nobody will be surprised hearing or observing that group-characters can combine to reproduce at short distance virtually indentical phenotypes. Everybody—or nearly so—gets starry-eyed on the contrary when finding phenotypes that are virtually indistinguishable at great distance and in clear disconnection as, for example, Euphorbia on the highlands of the Caucasus and Armenia, and on the high-grounds of the loftiest peak of Taiwan. Everybody is non-plussed when learning that a lone species of the woodpecker Picumnus occurs in Southeastern Asia and part of the Greater Sunda, strikingly isolated from the bulk of the genus in Tropical America. Anyone familiar with Vavilov's parallel variations in plant life will accept without much ado the statement by Malcolm A. Smith (1935:7) that:
“((In lizards)) the same type of evolution is not confined to a particular genus or family, but may be happening independently, in different parts of the world, in species that are not directly related to one another…; (p. 357, quoting Essex) “I have some doubt as to whether Ceylon Aconthias, ((a skink)), should be placed in the same genus as the South African ones, but, nevertheless, it is a closely related skink and belongs to the same stock, and is progressing along the same evolutionary path. I think it is more probable that the Ceylon species and the South African ones present the end of two divergent streams from an unknown centre.”
My feeling here is that no “unknown centre” is in play, only the well known standard track between Madagascar and India, which binds together many plants and animals.
Hearing this, many zoogeographers, cladists, disciples of Mayr, Nelson and Platnick, etc., will be raising an outcry that Malcom A. Smith and Croizat are a couple of innocents ignoring that skinks and like lizards are “tramps” always ready to use whatever occasional “means of dispersal” offer them a chance of performing spectacular feats of “extraordinary transoceanic colonisation”; therefore, the presumed consanguinity exhibited by skinks of South Africa and Ceylon-India is nothing but a “parallelism”, whatever parallelism might mean with these faithful custodians of the glory of Darwin.
This hardly credible, coarse, unscientific way of handling dispersal, whether with skink or “ballooning spiders”, etc., on the part of Mayr and his crew can, fortunately, be exposed referring to texts so precise, so easy of interpretation as not to leave doubt. To begin with, Mayr wrote as we already heard (see (d), above) a stern indictment of Croziat, saying:
“One would think that Croizat, after he had got several pages of maligning Darwin, would proceed to provide evidence for the falsity of Darwin's belief that “each species has proceeded from a single birth-place” but one searches in vain either for such a falsification or for a “superior” replacement theory”.
In presence of affirmation of the kind, I openly wonder whether Dr. Ernst Mayr is indeed compos sui; whether in sum Dr. G. G. Simpson did not mean Mayr instead of Croizat when visualizing somebody at the gate of an insane asylum. Darwin's belief that each species has proceeded from a single birth-place is stated in “On the Origin of Species”, Chapter xii, “Single Centres of supposed Creation” and reads:
“We are thus brought to the question which has been largely discussed by naturalists, namely, whether species have been created at one or more points page 58 of the earth's surface. Undoutedly there are many cases of extreme difficulty in understanding how the same species could possibly have migrated from some one point to the several distant and isolated points where now found. Nevertheless the simplicity of the view that each species was first produced within a single region captivates the mind. He who rejects it, rejects the vera causa of ordinary generation with subsequent migration, and calls in the agency of a miracle…if the same species can be produced at two separate points, why do we not find a single mammal common to Europe and Australia or South America?…The answer, as I believe, is, that mammals have not been able to migrate, whereas some plants, from their varied means of dispersal, have migrated across the wide and broken interspaces. The great and striking influence of barriers of all kinds, is intelligible only on the view that the great majority of species have been produced on one side, and have not been able to migrate to the opposite side” (emphasis Croizat's).
This is plain nonsense, which disqualified Darwin with finality not only as a “genius” but as a decent thinker. Darwin was incapable of rationalizing the nexus between form-making (the “origin of species”) and dispersal (“migration”), and appeals to other people's ignorance to join his own, assuring everyone in the game that by compounding the truth it is being born! This is fantastic, and Mayr can be legitimately charged with lack of scientific integrity for having withheld from his readers the quotation I show to my readers as a strict matter of duty. Is there indeed any need to “falsify” Darwin's falsehoods? Who “maligns” Darwin more than Darwin himself? Why goes Dr. Ernest Mayr to war against Croizat firing only blanks? I do not do that: I shoot to kill, and sometimes I do.
A very live cartridge in my defence—if need for it be—is ready-made in the following text by Malcolm A. Smith:
“When I was revising the genus Lygosoma, sensu Boulanger, I was surprised to find that a West African skink, Riopa guineense, was indistinguishable from one I had descrbed from Siam, R. herberti. There could be no question here of any geographical connection between the species: it was simply that the same set of characters had turned up twice. I think that this is what may have happened to Lygosoma maculatum and L. dussumieri, and also to Dasia olivacea and D. subcaerulea“.
Zoogeographers, Mayrists, cladists, vicariant-biogeographers (a la Nelson) etc., will appeal to the most fantastic tales, to so argue against M. A. Smith that it is absolutely impossible that he is in the right. Stuffed up to the gills with stale Darwinian formulae, entirely wanting an idea of recombination of characters, of type of organisation, of panbiog in short, these heroes of a defunct cause still make a lot of noise, alas.
If we coldly reason on a strict basis of fact—the panbiogeographic way—we learn (M. A. Smith 1935:312) that the genus Riopa has over 30 species distributed from Africa over Southern Asia to Polynesia and Australia, a perfectly normal range for plants and animals (see Croizat 1958, 1960-1, 1962-4, 1968 a.b. etc). All over this immense sweep of land and sea, characters befitting the types of organisation pre-Riopa, proto-Riopa, sub-Riopa, s. 1., Riopa s.s. in turn held sway more or less broadly over the ages, depending upon the vicissitudes of geology, climate, ecology etc.; always, however, broadly enough to assure us that Riopa occurs today both in West Africa and Australia, for example, not by “ballooning” via the stratosphere or on account of a truly “extraordinary capacity for tanscontinental dispersal” in Mayrian style; just by the interplay of natural causes over space by time having eventually returned here and there like and unlike taxonomic form-making.
Now then: is it contrary to reason to accept as normal that a particular page 59 combination of characters has “begotten” in West Africa and Thailand (Siam) a couple of Riopa species that are phenotypically (and taxonomically), obviously inseparable, therefore stand as a “single species” guineense-herbertin spite of distance? The “species” that is phenotypically one, will it also be genetically one? If sexual compatibility is the earmark of the “true species”, can we be sure beforehand that R. guineense male will accept as his sexual partner in procreation R. herberti female? In other words, what are the genunine relationships as between the phenotypic and the genotypic species, if any indeed. How is the conscientious naturalist to work out problems of this seemingly involved kind?
Before proceeding, let us record here a captial observation: a process is always more important than any of its byproducts. Riopa guineense and R. herbertiare separated by a distance of many thousands of miles as the crow flies. Lygosoma maculatum (Eastern Himalayas, Northcentral India, Assam, Burma, Southwestern China (Yunnan), Indochinese Peninsula southward to Tenasserim (Kra), Cambodia, Annam, Malaya, Andaman Islands), and its close ally, L. dussumieri (Southwestern India: Travancore mostly) stand at a glance at a much shorter distance from one another than do Riopa guineense and R. herberti. So too, Dasia olivacea (Tenasserim, Indochina south of 15° lat., Malaya, Andaman and Nicobar islands, Pulo Condor, Sumatra, Mentaweis, Natoenas, Java, Borneo) and D. sub-caerulea (Southern India: Travancore).
Assured for once that all these skinks answer the same biogeography, as to manner of taxonomic form-making and translation in space (“migration”)—indeed, it could not be otherwise as they all “move” within a close range of affinity—a competent biogeographer will not so much pay attention to the byproducts in detail as reckon on the process common to all the byproducts (genera and species: Riopa and Dasia, guineense/herberti, maculatum, dussumieri etc). This competent biogeographer will grasp the whole as nature herself does, not bit by bit as a shortsighted pedant will; as somebody in sum, who pays good coin to listen to a first rate concert as a whole, trombone with violincello, but can only argue that it is very droll that the trombone does not yield the same sound as the violincello. Shakespeare had it right: What fools these mortals be!
It is glaringly evident that she or he who does not understand the process will be in difficulty when trying to sort out its byproducts. It is a fact of the record that the zoologist and botanist lacking proper understanding of biogeography (correctly speaking, panbiog) will be unable to comprehend the reason why, for instance, phenotypes that cannot be set apart (see Croizat 1976; 1:338 ff.), prove to be sexually incompatible, which means that the very same “one species” phenotype proves to be genetically “two species”, If, of course, the test of sexual incompatibility is assumed as the final criterion of “speciation”. What is true of Troglodytes in the New World is no less true of Parus in Central and Eastern Asia (Croizat 1962-4:50g ff.), and, if with different details, of Gossypium (Croizat 1962-4:99).
In their unfortunate opus magnum, Systematics and Biogeography, (1981) Nelson and Platnick say (p. 6):
“The order in which the elements of space, time and form (and the respective disciplines primarily associated with them) are treated in this book is the reverse of the order…used in the title of Croizat's 1962-4 work. There are two reasons for this reversal. The first is that systematics, in providing classifications that summarise existing knowledge about the attributes of organisms, is a necessary practical prerequisite to the other fields. If our page 60 systematics is inadequate, it will scarcely be possible to do adequate work in biogeography, paleontology or embryology. The second reason for this reversal, and one of the themes of this book, is that hypotheses about the history of organisms in time are tested by statements about their attributes, and that hypotheses about the history of organisms in space are tested by statements about their history in time…; (p. 7). Considerations of scientific methodology…typically involve questions that are philosophical rather than scientific. From this we can conclude that one's general philosophy of science may greatly influence methodological discussions and decisions, and that it is therefore incumbent on scientists engaging in such discussions or making such decisions to present, as explicitly as possible, the philosophical point of view from which they argue…; (p. 13). The ranks, or categories, of genus and species have a particular significance, for they are the basis of binomial nomenclature…; (p. 34). Science is a way of viewing things as problematical…and the evidence for classification is problematical and deserves to be viewed as such…; (p. 42). Of the three elements of comparative biology, space has undoubtedly proven to be the most elusive… Exactly why this should be the case is not easy to say. One factor might be that at least a tentative classification must be available before biogeographic investigation can begin: one must first know that there is a certain taxon before one can investigate either its distribution or the causes of that distribution. To some extent, then, biogeography must lag behind systematics.”
This striking exhibit of pedantry and misplaced “philosophical” pomp and circumstance impels its oversanguine authors to give pp. 64-328 to “Form”: pp. 331-353 to “Time”; pp. 357-543 to “Space”, ending with the abject confession that the opus on the whole has yielded nothing concrete, added nothing to present knowledge, which means in my understanding that Nelson and Platnick have merely worked to increase all around confusion, taking their cue from misleading starting points. This striking confession after having spent over 500 pages to no concrete purpose absolves me from the task of checking in detail these same pages thus to expose in great detail lapses of the kind proving indeed ignorance of fundamentals. Nelson and his coauthor Platnick are not authentic biogeographers, which I will show true and correct through proper references if challenged. Time is overdue to call the score in plain words. If there is anything with which to start in the objective investigation of evolution this will be found not in the ever-shifting labels of taxonomic study, but in precise biogeographic work (Croizat 1960-lb:1451 ff.; 1962-4: 4 ff. without specifying beforehand what I was dealing with, plant or animal). I have also insisted (Croizat 1962-4; 519-520) that, in cloudy cases of taxonomy, the subspecies supplies data more important and reliable than the species, on account of the subspecies being more precisely localised than the species. The brainstorm afflicting Nelson and Platnick, and their colleagues at the American Museum of Natural History of New York (see the opening pages of Virginia Ferris's review 1980 of the 1979 symposium) to the effect that systematics and taxonomy must come first before biogeography, and that one ought to be a vociferous “philosopher” before becoming a commonsense naturalist; could be dismissed as an infantile affliction, if it did not prove to be catastrophic as an agent of pointless chatter and confusionism. Yes, indeed, Nelson & Platnick, etc., are one with Mayr, whatever be the appearances. They see themselves as brilliant horsemen fighting the good war of “science”, but what kind of horses are they riding? To look them in the mouth is appalling.
Returning now to Mayr's review of Vicariance Biogeography (The Auk 99, 1981):page 61
(e) (p. 619): “I believe all vicarianists are cladists…curiously, the Croizatians never attempt to falsify their own hypotheses.”
Comment—“Who are the “vicarianists”, and how should they be distinguished from the Croizatians? I, Leon Croizat, am certainly not a cladist, that is a follower of Hennig and Nelson. Then, why “falsify” the results of a method that returns no falsehood? These boys are lost in a sea of make-believe, “cladism”, “Popperism”, etc., of their own making to the extreme that common sense, precision of language, clarity of thought mean nothing any longer to them.
(f) (p. 619): “classical biogeographers have again and again strictly applied the canons of the hypothetico-deductive method…In the 1940s there were two hypotheses concerning the colonisation by birds of the islands between the Sunda and Sahul shelves… The two hypotheses permitted numerous predictions based on the distances of the islands and depth of the water between them. In a thorough analysis, I was able to show (Mayr 1944) that the predictions of the land-bridge hypothesis could be falsified in every case while those of the across-water-dispersal hypothesis were thoroughly confirmed.”
Comment—Mayr's (1944) “thorough anaylsis” of dispersal in Australasia led him to settle the problems of Antillean dispersal in 1948 in the expeditious manner we have seen (p. 00 above). He who may believe the Mayrian “thorough anaylsis” of exchanges having taken place in bird life in the Sunda-Sahul region, has no understanding of the geology, indeed extremely changing, island by island, of the region in question. In autodescribing himself (with Simpson, Darlington, etc.) as a “classical biogeographer” Mayr exaggerates even in his capacity as a propagandist.
(g) (p. 619): “Perhaps the greatest weakness of vicariant biogeography is its endeavour to explain the distribution of very different groups, by a single ancestral process (“track”) and, furthermore, to place the time of origin of the distribution patterns as early as possible, mainly Triassic-Jurassic, occasionally up to the mid-Cretaceous period. In that manner discontinuities can be atributed to geological events, permitting a neglect of dispersal. As more and more evidence shows, however, most of the higher taxa of terrestrial organisms, up to the rank of orders, originated only in the later Cretaceous and in the Tertiary, and hence cannot have been inhabitants of plates that had drifted apart in an earlier geological period”.
Comment— The author of this text has no title I can see to speak as a scientific biogeographer. May the reader decide whether he does violence to the record because of gross neglect, occult malice or the like all over. See on track, Croizat, 1962-4: 7, 1960-1; 1b: 1615 fn.; etc.
(h) (p. 620): “There are two major factors that determine the distribution pattern of a group—its dispersal abilities and the geological period when most of the dispersal took place. This is why earthworms and primary freshwater fishes have totally different distribution patterns from birds or butterflies”.
Comment—This is false by the record (see all my works). Its author has no interest in the truth, only in defending at all costs his past dereliction as a “zoogeographer” of sorts.
(i) (p. 620): “Croizat's thinking is well illustrated by his interpretation of the origin of the bird faunas of Pantepui (Venezuelan highlands). They represent for him a pre-Cretaceous continuity, with the gaps between the various mesas and the Andes secondarily produced by erosion. Therefore the age of the allopatric subspecies and even the nonvariable species is postulated page 62 to be greater than the length of the Tertiary. How can one take a biogeographer seriously who ignores the established ideas on the rates of evolution to such an extent?”
Comment—How can one take a “zoogeographer” seriously who distorts the clearest kind of factual evidence in order to build a factually calumnious case against a well informed, honest (pan) biogeographer? I never thought or said what Mayr charges me with. To explain: let us visualize, for instance, a fauna markedly “autochthonous” in which occurs at this hour side by side, a “modern” species of scorpion and a “modern” species of Thraupidae (passeriform birds). The record justifies the following questions: (i) Inasmuch as the two species A (scorpion) and B (thraupid bird) are today contemporaneous within the same fauna, does it follow that species A and B, respectively, are of the same age?; (b) Have the species A and B, respectively, entered simultaneously or not the fauna in which they occur today?
To answer these, and like questions is very easy if we reason the evidence logically, methodologically; impossible if we start with theories. Scorpions are a very ancient group, anterior to the Permian, while thraupid birds are a relatively recent group fully materialized only in the latest Cretaceous (it could not be later because it “colonises” with a multitude of vicariant forms the peaks and sides of cordilleras that rose mostly in Tertiary times). An already well defined, near-modern species of scorpion might accordingly have entered the fauna of which it is part today in the Jurassic, taking advantage of spells of mobilism and immobilism, in the geography, topography, ecology ruling at the time. In, let us say, Late Cretaceous, the primitive species, let us suppose, became extinct, leaving in its place a descendant species, the one surviving today.
The case is entirely different with Thraupidae. In the Jurassic, Thraupidae were non-existent which is far from meaning that they were absolutely non-existent for their remotest ancestors, some form perhaps of diminutive plumed dinosaur—for, had these potential ancestors never existed, their actual descendants never could materialise sooner or later that it be. Naturally, these remote “thraupid ancestors” went through Jurassic, Cretaceous, Tertiary repeated extinctions, new formations, etc., at a rhythm of evoltive change many times quicker than scorpions. In sum, once the types of organisation were established, scorpions—so far as we can know—moved on slowly, Thraupidae fast.
Being well informed of the march of events the world over, I could not think, of course, that the bird faunas of Pantepui (the southeastern Venezuelan highlands) represented “a pre-Cretaceous continuity” of Species with the bird faunas of the Andes, cordilleras, mesas of Venezula, Brazil, etc. The continuity postulated obviously was of Ancestors, out of which were locally to arise, in due course of time and events, the taxon geographically “pantepuian”, andean, etc. There can be no doubt whatever of where I always stood and still stand (Croizat 1976 Vol 2:563 ff.; Croizat 1952; 32 ff), and where Mayr got his lore from. He had it from F. M. Chapman (1931) (see Croizat 1952; 33), and during fifty solid years of “zoogeography”, “new systematics”, etc., it never occurred to him to verify his grounds and to progress accordingly so little as an inch. With eyes glued on the “species” as the supreme object of nature, Mayr refused to take me “seriously” because I ignored the “established ideas of the rates of evolution”, imagined by him! How unfortunate has been youth which for close to two generations has had to listen to such a page 63 “zoogeographer” as this pontificating ex cathedra in Harvard University. What he has managed to achieve is written very large in the total disarray of general studies of evolution and biogeography in North America.
(1) (p. 620, end); “Reading the volume, ((Nelson & Rosen, 1981, Vicariance Biogeography)) however, made me hope that someday someone will undertake a truly rigorous analysis of the vicariant claims in order to demonstrate conclusively how flimsy they are.”
Comment—Please, Dr Mayr, do not undertake the job, for in my considered opinion, Dr Ernst Mayr lacks status to speak as a biogeographer. The record proclaims it with finality, and much else could yet be added to round the scores of this article. The truth must be told. By the way, whose are the “vicariant claims” your condemn? Nelson's or Croizat's?
Conclusion Where is the Difference to be Found?
Even the most obdurate optimist will not deny that biogeography is a field of fundamental biology plagued by an excess of conflicting crosscurrents. Most strong among these currents is the one Darwin did sire as the “Theory of Geographic Distribution”, in “On the Origin of Species” (Chapter xii: Geographical Distribution, Single Centres of Supposed Creation), and which is quoted on p. 57.
In relatively few lines, that text brings to the fore all the classical concepts of Darwin's Geographic Distribution. That is to say, the Zoogeography/Phytogeography of Simpson, Mayr, Darlington, Gould, hosts of zoologists and botanists, all of whom have tenaciously stood by Darwin, swearing by Unitarian origin of species, centres of origin, means of distribution, migrations, barriers, etc., to this very day. Vaguely aware that the discoveries made in the sciences of the earth in the last twenty years have ruined Darwin's theory of “geographic distribution” (today identified by a growing number of biologists as dispersalism), some brilliant young blades are hard at work scheming out new, ever more involved theories to show that Darwin, say what one may, could not be wrong. Some older blades (e.g. Ernst Mayr) indeed go so far as to deny that Darwin could have been substantially wrong in anything important.
Years ago (Croizat 1962-4; 631 ff.;etc.), I raised the question whether Darwin's text cited above could be accepted as a final expression of the Darwinian theory of dispersal. My conclusion was that it was certainly so, and I have not altered my opinion (Croizat, 1981:503 ff.) in a recent review. Here, however there is still space left for me to underscore and to discuss a point of evidence richly deserving a minimum at least of print. I am certain that the text I am to quote from the continuation of the one already introduced has not been pondered as it evidently deserves to by any of my readers.
The text in question reads as follows: “Hence it seems to me Darwin, as it has to any other naturalists that the view of each species having been produced in one area alone, and having subsequently migrated from that area as far as it powers of migration and subsistence under past and present conditions permitted, is the most probable. Undoubtedly cases occur in which we cannot explain how the same species could have passed from one point to the other. But the geographical and climatic changes, which have certainly occurred within recent geological times, must have rendered discontinuous the formerly contiguous ranges of many species” (emphasis mine).
All in all, then, the theory of Darwin amounts to the following: The “species” draws its “origin”—whatever be the reasons of its birth, in space through time, which Darwin is incapable of formulating in a cogent, logical manner—and next indulges in “migration” using “means of dispersal” peculiar to it. Thus construed and presented, Darwin's world of ideas places the Species in the centre of the Biogeographic stage, and imposes upon the naturalist the obligation of enquiring about the species and its doings in spatial and temporal evolution in terms of origins, migrations and relative means of dispersal.
So much for the Darwinian text first quoted, which stands as such as the plain, undisputable birth certificate of Darwin's own theory of Geographic Distribution, meaning likewise of the “zoophytogeography’ of Simpson, Mayr, Darlington, Gould, etc., and the “dispersalism” that permeates more or less openly an enormous amount of the “biogeography”, however styled, now current.
Passing now to the second text quoted, the student is treated to a substantially different panorama. Here, the “species” moves and acts in space and time essentially in agreement with the Earth, its changes of geography, climate, etc., which determines the modalities of its displacement, transformation, vicariance, etc.
What this apparently unobtrusive change in panorama—be it noticed, forming part of the same Darwinian context—actually means is readily seen referring to a simple example, the very same that was starkly presented to my attention some 40 years ago and ruined on the spot for me the credibility of Darwin as a biogeographer.
When studying the botanical genus Euphorbia in warmer Central Asia, I learned that virtually the same species was found in stark disconnection native at one hand in the mountains of Armenia and the Caucasus, at the other hand on the highest peak, Mt. Morrison, of the island of Taiwan (Formosa). This species, already known to Linne as E. orientalis, I had meantime renamed E. calonesiaca, ex descr., rashly assuming that, given the distance between the two disconnected set of populations, they could not be “specifically” identical.
Trying to solve the conundrum, I did first appeal, naturally, to the “biogeographic” wisdom of Simpson, Mayr and their acolytes. The result judged by plain common sense (common sense, by the way, is always a first rate solver of “scientific” difficulties) was a total fiasco: in the first place, the lore of the gentlemen was short of arguments to settle the direction of migration, if any, west to east (Armenia—Taiwan)”, or vice versa. “Means of dispersal” to effect the “migration” were non-existent: the seed of Euphorbia is not palatable to animals and is wholly short of so called epizoic means of conveyance, etc. In sum, it was immediately evident to me that the “biogeography” of Darwin, Simpson, Mayr, etc., boiled down to a supposedly learned dream. Thus warned, I proceeded on my own to elaborate a Method—by no means a Theory once again—that would return to my satisfaction the answer that the pomp and circumstance of the putative authorities of the day was unable to deliver.
The Method I elaborated is the Panbiogeography. I will lose no time here with it, because some 10,000 published pages, very copious indices, etc., stand at the disposal of naturalists candid enough to enquire. I will here pointedly affirm that had Darwin been the genuis he was not, he would have readily understood that centre of origin, migration, means of distribution, etc., were—as he conceived them—flatus oris, not genuine scientific concepts. The issue truly at stake was thus not to be found in the page 65 first of the two statements quoted above, wherein are extolled centre of origin, migration, etc. The issue is only clearly perceived in constructive principle when, as in the second text quoted, Species and Earth are brought into conjunction with cause and effect.
The argument I have just spun to the effect that Darwin would have been very well advised in discarding concepts such as origin, migration, means, etc., will strike a great many readers as outlandish, inconsequential, opinionated against a great genius of biology, etc., etc.
Doctor Ian R. Ball has praised my life-work in a quite substantial manner (see p.50). He praises me personally as a liberator, as the pioneer who has opened new outlets to the future. Is it not curious that my work is extolled by a naturalist in excellent standing as having had the merit of throwing out as but confusing rubbish the very mainstays of the “geographic distribution” of Darwin, Simpson, Mayr, Gould, etc., etc? If Ball be right, what was born by Darwin was not a rational “Theory of Geographic Distribution”, but an unfortunate parody of it, which during a century has contributed to prevent the birth of a genuine science of dispersal.
The enormous damage that the Darwinian centre of origin, migration, means of dispersal, etc. have inflicted upon biology in the vital respect of Space and Time, compare with the quite as enormous damage done to the sciences of the Sky by the notion that to be perfect the celestial orbits must be circular, and the final evidence that the sun revolves around the Earth is afforded by the Sun rising and setting at opposite points of the terrestrial horizon. All of this, whether centre of origin or circular movement is plausible on visual grounds, but properly examined it does not at all prove what the vulgus, learned or not alike, take for granted at first glance.
Evidence to the effect that Mayr, for example, supposedly a great authority on matters of evolution, finally and easily mistook “zoogeo-graphic” appearance with biogeographic substance is scattered all over the pages of the article (1982: 618-620) in which he intends to refute panbiog (rather, what he takes for it most confusedly) in favour of his dispersalism rooted in the classical Darwinian props of centre of origin, migration, means of dispersal, etc.
Mayr writes, for instance, (p. 619): “Actually, even the vicarianists cannot help but admit that distributions over an entire or several continents must have been the result of dispersal”.
Vicarianists, Croizatians, etc., are, in the virtually unintelligible ideas of Mayr the unholy crowd that rebels against Darwin, Simpson, Mayr, Darlington, etc. And for the rest, the gentleman does not explain what he intends as dispersal being distinct from dispersal, but it seems clear that by distribution here he means active migration performed with the ordinary means of locomotion of an animal or plant. This being the case, I venture to ask what could be the biogeographic, scientific meaning and value of the statement that, e.g. Marsupialia, “migrated” in some unknown epoch starting with some hypothetical centre (Patagonia?, Canada?, New Guinea?, Tasmania?, etc.) using their legs as a means of dispersal/distribution? If Mayr does really believe that questions of this academic sort, and the rash of theories, guesses, chatter, etc., they beget indeed stand as a Science of Dispersal, he is mistaken, and squarely places himself outside the field of concrete science.
I will here repeat one more characteristic viewpoint of Mayr. He writes (p. 619): “One would think that Croizat,… would proceed to page 66 provide evidence for the falsity of Darwin's belief that “each species has proceeded from a single birth place”, but one searches in vain either for such a falsification or for a “superior” replacement theory”.
When not illiterate or—I hate the adjective—tetragonous against truth, the author of such a statement as this lacks the professional capacity of correctly judging biogeographical questions. The antidarwinian evidence he claims I have failed to return is contained in a detailed, plain, richly documented form in, for example, (Croizat 1962-4), to the indices and pages of which I refer the reader. The Theory of “Geographic Distribution” of Darwin (which also stands as the cornerstone of the “Zoogeography” of Simpson, Mayr, Darlington, Gould, etc., and all its subproducts) fundamentally rests on notions of centres of origin, migration, means of dispersal, etc., of popular inspiration, wholly incapable therefore of promoting scientific enquiry in reference to all kinds of authentic biogeographic problems.
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——, 1982: Vicariance/Vicariism, Panbiogeography, “Vicariance Biogeography”, etc.: A clarification. Syst. Zool. 31(3): 291-304.
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