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KRONOS Vol VIII, No. 4
THE SCIENCE OF EVOLUTION (CONCLUDED)
Perhaps nothing serves so well to distinguish Stansfield's The Science of Evolution (1977) from the books of Nilsson and Grassé as his unequivocal claim that "Scientists believe that the forces now operating in the world are those that have always operated (uniformitarianism), and that the universe is the result of their continuous operation" (p. 9). Not only does Grassé fail thereby to qualify as a scientist, no evidence against uniformitarianism could be used, because it fails to qualify as scientific. History is not allowed to refute scientific uniformitarianism .
Of course Stansfield cannot consistently maintain his uniformitarian position. Old-fashioned paleontology does have a role to play: it is still the original ladder up which evolutionists climbed. They cannot yet kick it away, because they are still confronted by some extreme creationists, who deny that any evolution has occurred. Stansfield asks rhetorically: "Have the species of organisms presently inhabiting the earth existed since the origin of life, or have entirely different species existed at different points in geological time?" (p. 67). The answer to this basic question cannot come from uniformitarianism: "The answer to this question is to be found in the science of paleontology (the study of fossils)." In a book of 600 pages, 18 are devoted to paleontology - the bare minimum necessary to acknowledge (but not discuss) the non-uniformitarian dimension of biological history. These even include one candid admission of the necessity of resorting to a cataclysm to protect evolution against the creationists:
The reason why Stansfield will have so little to do with paleontology as the science of evolution – with evidence from the past – is explained by his forthright definition of the evolutionist as one extrapolating backward through time:
This coherent theory of evolution is neo-Darwinism, a rigorous science. Natural selection is still at the heart of the science of evolution, but paleontology is not. The trouble with Darwin's theory was just a deficiency, and this was remedied by the discovery of the laws of heredity:
The neo-Darwinian theory is mathematical, genetic, mutational. The central neo-Darwinian – the man who finally demonstrated the truth of Darwinian evolution by forging "the modern synthesis" of genetics and the origin of species - is, according to Stansfield, Dobzhansky:
We might recall that Grassé's interpretation of this was "the insignificant modifications discovered by laborious analysis by Dobzhansky" (p. 171).
Significant or insignificant, the chemical details of genetic modification are treated by Stansfield lucidly and with carefully illustrated mathematical rigor for hundreds of pages. By page 510 he has reached Chapter 19, "Higher Taxa", the crucial test for neo-Darwinism as a general theory of evolution. Here he concludes that, given enough time and granting the arbitrary nature of higher taxa, there is no problem. The random processes of minute genetic variation and mutation when operating in geographical isolation, which results primarily from dispersal from centers of origin, requires nothing more to account for the evolution of higher categories:
But how, in what sequence of specific detail, are individual organisms at one level created from organisms at another level? Higher taxa may be unnaturally separated from one another by the accidents of extinction. However, this does not absolve those who claim that uniformitarian biological evolution is a scientifically established reality, that is explained and confirmed by generations of biologists practicing a rigorous science of evolution, from providing sequential details. This is not an illegitimate request, because Stansfield himself extols evolutionary creativity with italics and double exclamation marks. After providing a brief mathematical demonstration of how statistically improbable chance genetic change would be in itself, Stansfield plays his trump card and drops his poker face: "Under the guidance of natural selection, however, it might be possible for an extreme phenotype to be synthesized in about ten generations. This is the 'big gun' of evolutionary theory; this is creativity!!" (p. 196). Stansfield brings the big gun of evolutionary theory to bear not on the big problem of higher taxa but on the very small problem of variation in the garden bean (Phaseolus vulgaris). Needless to say, no one disputes the common origin of the varieties of Phaseolus vulgaris.
If the basic failure of Darwinian selection in explaining evolutionary creativity is the great gap between the genetics of micro change and the macro differences of higher taxa, how does non-Darwinian evolutionary theory solve the problem? Traditionally, Lamarckism was thought to be the one alternative as an evolutionary hypothesis. Before attempting to decide whether this requires us to classify Grassé as by and large a Lamarckian, let us note the extent to which Lamarckians can still be found in the ranks of twentieth century biologists. Stansfield tells us that "Bacteriology was, indeed, the last stronghold of Lamarckism" (p. 260) but that in 1943 Salvador Luria and Max Delbruck dealt it a fatal blow: "This classical experiment broke the back of Lamarokian dogma and gave birth to the science of bacterial genetics" (p. 328). In the next section, we will encounter both some oft-dismissed old-fashioned macro Lamarskians (of the alleged giraffe neck sort) and also some very current and difficult to dismiss Lamarokians of the micro sort. Lamarckism has had its back broken so many times that this is less newsworthy than evidence that the back is healed.
THE COLD WAR IN BIOLOGY
In our effort to determine what, if anything, the science of evolution can be, we are also trying to provide a bit of a European perspective, which most discussions for American audiences lack. Americans have not heard as much about Lamarckian interpretations as they might, and when they do hear of them, the source is likely to be, first or second-hand, a European one. One that we will be emphasizing here is American by virtue of final residence, but European by training and temperament. This is Carl Lindegren. His point of view is especially interesting, because it reveals kinds of experimental data not much emphasized by Americans and also because when he finally felt compelled to speak out, in his small and obscurely published book The Cold War in Biology ( 1966), it resulted in an extremely provocative analysis that traced scientific positions back to some rather unscientific attitudes about old Lamarokism and new Lysenkoism.
The possibility of direct environmental influence on evolution is being studied now not so much in terms of leaves beyond the reach of short-necked giraffes as of cytoplasm inside the cell, yet beyond the nucleus. Perhaps the best way to explain this version of Lamarckism to laymen is by way of the mule. All working mules are big and strong by virtue of having a horse and not an ass for a mother. Although the opposite hybrid combination has the same genetic (i.e. Mendelian) contributions from its parents, only the male that grows out of the egg of a horse has its crucial characteristics from the horse. Classical genetics has difficulty providing a convincing Mendelian explanation of this. For non-Mendelians, like Lindegren, the explanation is simple: "The working mule carries horse cytoplasm" (p. 44).
Mules are a vivid example, but they do not – as sterile hybrids – touch the heart of the matter. Individuals of fully compatible species need to be involved so that a long series of generations can be tested. Paramecium may be coming to be for non-Mendelian genetics what Drosophila is for Mendelian genetics. But ironically, this is not at all the way it was intended by the grand old man of Paramecium studies T. M. Sonneborn, a true-blue Mendelian. Here is Lindegren's characterization of him:
What this is building up to is an issue far transcending the technical biological question
of cytoplasmic inheritance. Once grant this possibility and then not just Lamarckism but
Lysenkoism as well must be reconfronted. Next to nothing is understood about the nature of
non-genetic inheritance except the fact of its occurrence. Lysenko did not perhaps know much
about the Mendelian genetics of animals, but he was a successful plant breeder (the Burbank
Botany is always a thorn in the side of zoology, and especially so on the question of genetics. That some plants some of the time can reproduce by cuttings, without any germ plasm, without any genes, is well known: "In plants the sex cells are not separated from the soma. A vegetative cutting, grown by simply putting a twig into the ground, can produce flowers and seeds, hence soma can produce sex cells. Lysenko was primarily a botanist and well acquainted with this phenomenon" (p. 58).
It seems possible even to graft parts of one species of plant onto parts of another species and produce thereby viable offspring that partake of the genetic structure of both. (However, the question of "graft hybrids" has been complicated by experimental difficulties and the ad hoc Mendelian hypothesis of "chimera".) Much data demonstrating non-Mendelian inheritance have long been available and well known, especially in Europe. Although these data have been contaminated by the political hostility of the Cold War, Europeans were not impressed when Americans finally began "discovering" these anomalies. In 1961 Sonneborn reluctantly announced that
Now for years, Lindegren had been attempting to convince his American colleagues of similar conclusions derived from his own extensive experimentations on yeasts. He was working in a European tradition, however, and was not having much success with Americans, even in keeping his experiments afloat financially. Lindegren was no Lysenkoist but still not orthodox enough for the times, which required outspoken anti-Lysenkoism in the name of scientific freedom:
Ironically, it was American capitalism that saved Lindegren's research project at a crucial period when the scientific establishment would not. The dedication of his book reads: "It is one of the very real advantages of capitalism that the individual entrepreneur is free to sponsor creative activity in any field. It is a pleasure to dedicate this book to the late Mr. James Diego Veron of Anheuser-Busch, Inc., who assumed the responsibility of sponsoring yeast genetics during a most crucial period" (p. v).
With this as a very brief background, here is what Lindegren says of Sonneborn's statement quoted above:
Debate can indeed be a derogatory concept in science. Lindegren laments that: "Just how to get a full scale debate going in a matter of this kind is one of the truly unsolved problems of biology and, probably, of other sciences as well" (p. 98). Scientists have perhaps been more concerned with suppressing heresy than in promoting debate. Lindegren is thus able to savor the irony of Sonneborn's new work on the paramecium, which involves more than just unexpected data in the laboratory: "It is ironic that Sonneborn, who was a member of the Committee for Scientific Freedom which opposed the teaching of Lysenkoism ..., should have demonstrated an authentic graft hybrid, thus confirming Lysenko . . . " (p. 50).
From the point of view of phylogenetic taxonomy, the implications of recent work on cytoplasm inheritance are disturbing. The explanations are lacking, but the phenomena seem indisputable: "stable autonomous structures are present in the cytoplasm and are capable of transmitting acquired characters" (p. 53). How are we to determine, then, what similarity of characters indicates common origin and what indicates acquisition? This does not exist as a practical problem of classification at the level of different species of paramecium, but there are no clear limits to what is possible. Lindegren, following Fritz Went (another European), draws attention to the strange occurrence of convergence not in different regions due to the same kind of ecological pressure (e.g., Mooney 1977) but in the same region among different kinds of organisms. One of several botanical examples is the eucalyptus-type leaf (long, elliptical, sickle-shaped, bilaterally symmetrical, xeromorph), which is essentially restricted to Australia. It occurs in various kinds of ecological contexts and in various kinds of seemingly phylogenetically unrelated plants – not just among eucalypts and close relatives. On the other hand, the unrelated plants with eucalyptus-type leaves (for example, acacia) have relatives in the same genera and families outside Australia, which though they occur in ecological contexts similar to those in Australia, have different sorts of leaves. Lindegren concludes: "Went's theory tends to support the Michurinist practice of mixed plantings and inseminations. It indicates that plants grown together, no matter how different they may be, become similar by asexual hybridization . . . " (P 53)
What is termed Lysenkoism in the West is more properly termed Michurinism, after the plant breeder who participated in the Bolshevik Revolution and became an official hero of the USSR for his efforts to improve horticulture at a time of very great need. There was nothing particularly Marxist in his approach (although it is more compatible with Marxism than with Mendelism). As Lindegren emphasizes, "His philosophy of plant breeding was the philosophy common to all plant breeders before the advent of Mendelism. He believed that a plant grown under favorable conditions grows well and transmits to its seedlings the ability to grow even better" (p. 55). There is not much to go on in terms of scientific hypothesis here, but there is as part of Michurinism a large body of empirical breeding experience for which Mendelism offers no explanation. Lindegren holds no brief for Michurinism as a scientific theory or hypothesis, but he does conclude that, its Cold War critics notwithstanding, "the real value of Michurinism lies in its exposure of the fallacy of Mendelism" (p. 65).
A few years after the publication of Lindegren's book, Went presented his material in a
long article – "Parallel Evolution" ( 1971). He treats eight different cases of phylogenetically
inexplicable convergence that is regionally so conspicuous as to demand a non-Darwinian
explanation. On the basis of these, he boldly suggests the possibility that "Burbank and
Michurin were successful in transferring desirable characters between non-breeding species by
growing their material in such large numbers that occasionally non-sexual transfer of
characters (such as seedlessness) occurred".
Because the phenomenon that Went focuses on is so rarely mentioned – and his study ignored rather than criticized – here is an abridgment of Went's summary of his argument against the development of eucalypt-type leaves being explicable in terms of adaptation through natural selection:
The eucalypt leaf is only one of eight examples in a sample that Went provides of a phenomenon that may well be the rule rather than the exception among plants – a phenomenon that by ordinary, Darwinian, expectations is nothing short of amazing. Here (in his own words) are Went's conclusions:
So much for the amazing amount of convergence where divergence is expected. Let us now sample the opposite extreme: the amazing amount of divergence where near identity is expected. Research in genetics is turning up fantastic (i.e., capable of eliciting exclamation marks from otherwise staid scientists) kinds of unsuspected variation. These are beyond the ability of any theory of genes and chromosomes to explain in lawful terms but are in accord with what breeders have long recognized. A particularly vivid example (though quite an ordinary appearing small plant) is Claytonia virginica. Its chromosomal aberrations are not typical, but how atypical they are is difficult to say (a common grass Poa pratensis is a similar example). In any case, this is a particularly well-studied instance of the impossibility of determining species and hybridizability from chromosome analysis. Lysenko would certainly have taken the new data about C. virginica as supporting his contentions about the possibility of graft hybrids. Walter Lewis summarizes these data and indicates what chromosome counts had been expected to establish:
If there is any Popperian element in the science of genetics (to say nothing of genetics as the science of evolution), Mendelism has been either refuted or seriously diluted by ad hoc hypotheses. Mendelian principles explain half the story of heredity; some sort of Lamarckian principles must be developed to explain the external influences that the concept of the gene, of DNA as the unmoved mover, cannot.
IV. LAMARCKISM AND ORTHOGENESIS
Those biologists willing to flirt with Lamarckism are likely to be those also willing to
flirt with orthogenesis. This has no particular connection with evolution as conceived in the
USSR, which in most respects remains avowedly Darwinian.
In view of this, it is not likely that Lindegren thinks he has a theory that will solve the problem of evolutionary orthogenesis. However, he does briefly indicate the direction of his own research with yeasts. What he suggests, and what has since become at least respectable to debate, is that under certain circumstances some kind of correlation exists between environmental pressure and non-random mutations in the direction of an inheritable ability to accommodate the pressure. Lindegren claims to have "demonstrated that the capacity of a yeast cell to achieve the ability to use a particular nutrient, which it could not previously use, may be due to the occurrence of a mutation that is specifically effected only by exposure to the presence of the nutrient, not by accidental mutation followed by selective growth of the mutant" (p. 103). Precisely how this occurs is not understood, except that it is something new that bypasses the unmoved mover.
How does this fit with the "classical" experiment of Luria and Delbrück, which demonstrated that this sort of thing did not happen? According to Lindegren, the limiting factor on their experiment was the same as on August Weismann's "classical" experiment with the tails of mice. Weismann amputated tails for twenty-two generations with no effect on the heredity of tails. Half a century before Luria and Delbrück's much more refined experiment with bacteria, it was claimed of Weismann that he "broke the back of Lamarckian dogma". But according to Lindegren, the "fallacy" (p. 103) of this conclusion is that there is no environmental pressure involved. Lamarck's theory calls for the organism to consciously direct itself toward the attainment of some felt need. Lamarckism is positive; the classical anti Lamarokian experiments tested only negative factors. Lindegren, on the other hand, created a condition in which the yeast needed what it previously could not use. Not only did the organism seem to mutate so as to achieve a new ability, it seemed to pass on this new ability to succeeding generations.
It is a long way from Lindegren's results with yeast (even if true) to Grassé's directed evolution of Phyla (even if not called orthogenesis). Yet they are equally non-Darwinian, and they are equally a matter of direction rather than chance. Grassé agrees with Lindegren's contention that "it has become increasingly apparent that the inheritance of acquired characters must be considered seriously" (p. 110). In one way or another, evolutionary theory must account for the systematic acquisition of the new. On the one hand, Lindegren emphasizes the cytoplasm as the most interesting unknown factor in such acquisition. On the other hand, Grassé emphasizes the acquisition of new genes. But neither is in accord with classical Darwinism, or with classical Mendelism, or with the latest "revolution" in biology - DNA as the genetic code, the unmoved mover.
The final chapter of Grassé's book is entitled "A New Interpretation of Evolutionary Phenomena". Considering the fact that, at this point, Grassé has led us through more than 200 pages of essentially negative analysis of the problem of evolution in a book subtitled Evidence for a New Theory of Transformation, we would be justified in thinking that the author has been artfully leading us up to a grand finale – like a detective story. Yet here we continue to be informed that
Is this just in reference to the Darwinian doctrine of biological evolution? Will Grassé stand up at the end as a Lamarckian? Not on page 203: "The Lamarckian and Darwinian theories, in whatever form, do not resolve the major evolutionary problem - that of the genesis of the main systematic unity, the fundamental organizational schemes." However, a few pages later, as he begins at last to reveal his theory of internal creation of new genes in response to external influence, he points out that his theory is quite compatible with Lamarckian theory:
Wintrebert is the well-known French neo-Lamarckian who, like Lindegren, is approaching the problem at the micro (chemical) level rather than the macro (neck and tail) level. Grassé treats Wintrebert sympathetically, and quite agrees with the thematic title of his book Le vivant créateur de son évolution – the living creator of its own evolution.
How does the living organism create its own evolution? At his most candid, Grassé admits that "the means employed by the cell to create novelty escape us, but are nonetheless there" (p. 21 1). These internal means are "there" in at least as believable a sense as the external selection of chance mutations is there: "the credibility of the intervention of internal factors in evolution is at least as strong as that of natural selection based on problematical variations" (p. 21 5). All that Grassé has to offer in the end is the creation of new genes rather than the mutation of old genes: "creative evolution is not solely explained by the modification of preexisting genes but demands the genesis of new ones" (p. 217). Like Lindegren, he rejects the concept of autonomous genes and acknowledges the certain but obscure role of cytoplasm: "DNA does not manifest its properties, let us say its powers, unless the cytoplasm (conceived in its totality) allows it to do so" (p. 218).
What Grassé has new to offer is not positive, but it is negatively very significant - even "revolutionary". The dogma of a decade or two that DNA is the unmoved mover – the code and not the coded has now been overturned:
Since Lindegren wrote his book, much experimentation has been conducted along the lines that he pursued, although its implications for evolutionary theory have not been emphasized. Yet even so, such experimentation demonstrates only the possibility of inheritance of acquired characters – not the process by which new species originate (to say nothing of new phyla). Grassé briefly reviews this line of research and concludes that "the work mentioned proves the existence of a molecular mechanism which in given circumstances brings the organism external information and fits it into the DNA of the genetic code. For an evolutionist, this is of tremendous importance" (p. 223).
Needless to say, this importance will gladden the hearts of the non-Darwinian evolutionists more than those of the Darwinian. The Anglo-American science of evolution is still officially committed to the neo-Darwinian synthesis of natural selection and Mendelian genetics, of which Julian Huxley has been a major long-time spokesman: "it is no longer possible to believe that evolution is brought about through the so-called inheritance of acquired characters." He sweepingly assures us that "all the theories lumped together under the heads of orthogenesis and Lamarckism are invalid". Indeed, they have ceased to exist in science: "They are out: they are no longer consistent with the facts.... they have now only historical interest" (1953:35)
Be that as it may, the back of Lamarckism looks anything but broken. Lindegren's book has been largely ignored, but in the past few years work equally heretical has appeared and been professionally noticed. The tendency among Anglo-American biologists to dismiss French representatives of Lamarckism as relics of the past has now come up against the forthright attempt of E. J. Steele "to reopen serious discussion of the possibility that Lamarckian modes of inheritance can contribute to our understanding of evolution". This comes from the first page of his little book Somatic Selection and Adaptive Evolution: On the Inheritance of Acquired Characters (1979), a book based on sustained and rigorously conducted experiments in immunology. Steele emphasizes that "unlike the metaphysical research programme of Darwinism . . . Lamarckism is a philosophy which can be experimentally tested" (p. 10).
Lest it be thought that only in the past decade have experimental data really justified taking seriously the inheritance of acquired characters, it should be noted that both Lindegren and Steele attempt to rehabilitate the experimental work of Guyer and Smith (e.g., 1918, 1920). This was an extensive and rigorously detailed test of the sort now being championed by Steele, but which was almost completely ignored by the profession for half a century. It is not just outsiders who can be ostracized for their heretical studies; Guyer was president of the American Society of Zoologists.
In conclusion, let us turn Huxley's manifestly erroneous and self serving judgment on its head. He dismisses opposing positions because "they have now only historical interest". It is much more reasonable to say that in the science of evolution there is only historical interest. The more knowledgeable evolutionary biologists become, the more historical they reveal their subject to be. From Grassé's "Conclusion" comes this chastening admission, so at variance with what the title of his book seemed to promise:
American evolutionists are certainly correct in seeing a serious need for defense of evolution. The science of evolution is in deep trouble - scientific trouble. But whether this can be met by Committees of Correspondence is another question.
3. The one notable error in Lindegren's account of Cold War biology is his claim that "No
mention of Burbank has ever been made by Lysenko although ... the philosophies of both
workers are identical" (p. 57). Indeed their philosophies of nature/nurture are identical, and in
fact Lysenko repeatedly praises "Burbank, a biologist of genius" (1954: 351-2).