SCIENCE - MEN OF FLOWERS

The great Tree of Life –The tangled bank – Publishing – Anthropocentrisms – Kew Gardens - Voyaging - In Australia – Darwin’s botanical ignorance - Darwin learns botany – the Hookers - ‘The Origin of Species’ – Artificial and Natural Selections –Paleo-botany – Super-continents or migration? - Orchidiae – – Brown and Sprengel - Cross-fertilisation – The necessity of sex – Sexual selection – The utility of beauty - Colour vision – Marketing Memes – ‘fatal to my theory’: Kelvin and Jenkin – Darwin runs out of time – Darwin runs faster - Pangenesis – ‘Let us imagine’ -  Mendel - Life, the unfinished experiment

Despite Charles Darwin’s confessing in 1843 to an ‘entire ignorance of Botany’, he had, before his death in 1882, inherited the laurel of Jupiter Botanicus. On the centenary of The Origin of Species in 1959, population geneticist J. B. S. Haldane valued Darwin ’s botanical researches more highly than his earlier work on evolution. In truth, those elements were inseparable, since he supported natural selection with studies of plants, notably their sexual reproduction. So significant was flora to Darwin ’s conceptualising of evolution that he elaborated on the metaphor of a branching bush to illustrate his version of descent with modification:

The green and budding twigs may represent existing species; and those produced during each former year may represent the long succession of extinct species. At each period of growth all the growing twigs have tried to branch out on all sides, and to overtop and kill the surrounding twigs and branches, in the same manner as species and groups of species have tried to overmaster other species in the great battle for life. The limbs divided into great branches, and these into lesser and lesser branches, were themselves once, when the tree was small, budding twigs; and this connexion of the former and present buds by ramifying branches may well represent the classification of all extinct and living species in groups subordinate to groups. Of the many twigs which flourished when the tree was a mere bush, only two or three, now grown into great branches, yet survive and bear all the other branches; so with the species which lived during long-past geological periods, very few now have living and modified descendants. From the first growth of the tree, many a limb and branch has decayed and dropped off; and these lost branches of various sizes may represent those whole orders, families, and genera which have now no living representatives, and which are known to us only from having been found in a fossil state. … As buds give rise by growth to fresh buds, and these, if vigorous, branch out and overtop on all sides many a feebler branch, so by generation I believe it has been with the great Tree of Life, which fills with its dead and broken branches the crust of the earth, and covers the surface with its every branching and beautiful ramifications.

Speciation was neither a ladder with steps, nor a chain with missing links. No direct line ran from homo sapiens to gorillas, instead, and always, divergent varieties suggested their lineage.

As if to compensate for the transparency of his illustration of natural selection by a single branching bush, Darwin concluded The Origin of Species with an invitation for his readers

to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us.

As a scientist, Darwin strove to disentangle that appearance of chaos from a regularity which in no way was divinely ordained. Advancing on those precepts, his successors are revealing how the tangled bank of soil, worms, birds, insects and plants is evolving through law-bound exchanges among unicellular archaea and bacteria.

Hence, the vegetable kingdom played a bigger role in Darwin ’s science than it now does in his popular reputation. Indeed, in the opening chapter of The Origin of Species, dealing with ‘Variation under domestication’, animals compete for space with apples, cabbages, gooseberries, pears, strawberries and wheat. Chapter eight on ‘Hybridisation’ relies on flowers for much of its materials, as do the chapters on geographic distribution. A few years later, Darwin was beginning ‘to think that they [plants] are more wonderful than animals’, and just before his death had been pleased ‘to exalt plants in the organic scale’.

In fulfillment of a promise in The Origin to ‘detail all the facts, with references, on which my conclusions have been grounded’, Darwin published seven volumes on botanical subjects: On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects, and on the Good Effects of Intercrossing (1862 and 1877), Insectivorous Plants (1875), The Movements and Habits of Climbing Plants (1875), The Effects of Cross and Self Fertilisation in the Vegetable Kingdom (1876), The Different Forms of Flowers on Plants of the Same Species (1877) and The Power of Movement in Plants (1880). In addition, he compiled the 1,000-page Variations of Animals and Plants under Domestication (1868). Out of his stock-market speculations, he underwrote the index of the specimens at Kew Gardens , known officially as Nomenclator Botanicus Darwinius.

Notwithstanding these outpourings about plants, media interest in Darwin ’s theory of evolution remains fixated on animals, principally and pointlessly the missing links from primates to humankind. Yet, the heart of Darwin ’s account is that all species originate from a single organism. Hence, we are related to bananas as well as to chimpanzees. Anthropocentrism accounts for some of the bias against the vegetable. Bishop Wilberforce is remembered for twitting Thomas Huxley about whether his ape ancestors were on his mother’s or his father’s side, not for demanding to observe a turnip striving to become a cleric. Although the shared origins of flora and fauna are as menacing to the creationists as is a common ancestor for gorillas and human beings, the latter challenges our pride of species whereas our cousinage with legumes seems so remote as to be irrelevant. Not even many philosophers think of parsnips as possessing rational souls. Moreover, the advantages that geneticists derive from experimenting on fruit flies (Drosophilia) have skewed the focus onto the fly away from the fruit. This imbalance of expert interest had not been the case among Darwin ’s cohort for whom tampering with Nicotiana provided results more swiftly than did the breeding of Pouter pigeons.

Bound for Botany Bay
Darwin ’s contributions to botany had an shifting relationship to the flora of Australia . Before he had been born, British naturalists knew of its abundance from the collections that Joseph Banks and Daniel Solander had made with James Cook, displayed at Botany Bay House in the Royal Botanical Gardens, Kew . Banks enriched that imperial treasure by dispatching Archibald Menzies, who collected at King George Sound in 1791, followed by Robert Brown with Matthew Flinders from 1800 to 1805,# George Caley from 1800 to 1808, and Alan Cunningham after 1816. However, even had Darwin been as interested in botany as he was in geology before joining H.M.S. Beagle he could not have become familiar with the resources at Kew because the Gardens were in decline, and not revived as a scientific centre until after his return.

The offer of a berth on the Beagle in 1831 had a tendril to the vegetable kingdom since it came via the Professor of Botany at Cambridge, Joseph Henslow, with whom, Darwin recalled, he had, as an undergraduate during 1831, ‘lived much … often dining with him and walking with’, mostly to discuss geology. Darwin audited Henslow’s lectures three times for their survey of the state of scientific knowledge more than for any botanical expertise. Henslow had been Professor of Mineralogy before being elected to the chair of botany, where his reforms included relating plants to soils, which opened a path to considering how environment contributed to variation, a linkage which prefigured Darwin ’s intellectual progress, culminating in his last book, The Formation of Vegetable Mould, by the Action of Worms (1881).

Darwin went on board the Beagle as companion to Captain FitzRoy who feared insanity if status obliged him to dine alone for years on end. After the designated naturalist, naval surgeon Robert McCormick, quit four months into the voyage, Darwin extended his collecting beyond rocks and beetles, yet he missed much that was under his nose, notoriously, the speciation of finches at the Galapagos atoll, admitting in the third volume of Zoology of the Voyage of Beagle: Birds: ‘Unfortunately I did not suspect this fact until it was too late to distinguish the specimens from the different islands of the group; but from the collection made for Captain FitzRoy, I have been able in some small measure to rectify this omission’. John Gould sorted out the muddle.

When Darwin visited Australia between January and April 1836, he was in the wrong places or at the wrong times of year to appreciate our flora. Entering Sydney Harbour with expectations of a ‘verdant country’, he regretted that the shores evoked the desolation of Patagonia . When he traveled inland, the ‘extreme uniformity of the vegetation’ depressed him, the more so because of its ‘peculiar pale green tint; without any gloss’, the ‘brown pasture’ around Bathurst seeming ‘wretched’. Along the Derwent, he took pleasure in cultivation reminiscent of England , the ‘bright yellow fields of corn, and dark green ones of potatoes, appear very luxuriant’, though he was also struck by some fern-trees. King George’s Sound proved to be the dullest time in his five years of voyaging, the grass-trees ‘coarse’.´ His chapter on Australia concluded: ‘he who thinks with me will never wish to walk again in so uninviting a country’. Had the Beagle arrived in July, Darwin would have seen wattles in bloom, and stood to be amazed at the flowering of a biota, which is distinctive of the continent’s south-west, now a magnet for tourists. By the time he wrote On the Origin of Species during 1859, he acknowledged Australian flora to be ‘rich in species’, and apologised for his dismissal of it: ‘… it seems to me to be as rash in us to dogmatise on the succession of organic beings throughout the world, as it would be for a naturalist to land for five minutes on some one barren point of Australia, and then to discuss the number and range of its productions’.

Darwin learned much of what he had needed to know on board only once back in England as he made a name for himself from 1839 to 1843 by co-editing the five volumes on the Beagle’s collections, none of which dealt with botany because of Henslow’s inability to classify the specimens, a task completed in the 1850s by Darwin’s closest friend, Joseph Hooker.

Darwin ’s poor preparation for Australian flora contrasts with the training of Hooker whose father had been professor of botany at Glasgow before taking charge of Kew Gardens in 1841. The younger Hooker eventually wrote up his 1840-41 researches in Van Diemen’s Land in Flora tasmaniae (1860) as Part III of The Antarctic Voyage of H.M. Discovery Ships ‘Erebus’ and ‘Terror’, in the Years 1839-1843. Countering Darwin ’s disappointment, Hooker reported that ‘[t]he flora of Australia has been justly regarded as the most remarkable that is known’, with more unique examples than most regions with an estimated 8,000 species. During the five years to 1859, Hooker catalogued 7,000 Australian specimens in the Kew Herbarium, a labour equal to Darwin ’s on barnacles. Darwin badgered him for specimens and guidance, for example, on the sex of Australian trees for The Origin.

In an essay accompanying Flora tasmaniae, Hooker proposed his own account of natural selection, about which he had been Darwin’s first confidant, a disclosure which Darwin regretted in case he had prevented his friend from arriving ‘at the figorific mixture independently’. The chances of Hooker’s becoming a third co-discoverer of natural selection were slender since he admitted that it was only after the ‘ingenious and original reasonings’ by Darwin and Wallace before the Linnaean Society in 1858, that he had accepted that ‘species are derivative and mutable’. Even so, he shifted about. While species evolved, the naturalist had to describe each specimen as if it were ‘fixed’. On the publication of The Origin late in 1859, Hooker became the most reliable and responsible defender of natural selection, the rock on which the coming generation built their science.

The Origin of Species
If the botanical materials for The Origin had been written in collaboration with Hooker, the book’s rhetorical arrangement was Darwin ’s alone, his opening chapter being an exercise in persuasion more than an exemplar of scientific reasoning. Darwin began with artificial breeding, not with natural selection, which he reserved till chapter four. This arrangement was a gambit towards insinuating his grand theory. He deployed the evidence from artificial selection to prepare his readers’ minds for the possibility of descent with modification through natural selection. Artificial selection also provided Darwin with an explanation for why ‘we cannot recognise, and therefore do not know, the wild parent-stocks of the plants which have been longest cultivated in our flower and kitchen gardens’.µ  

Although artificial breeding suggested that the mutation of species was possible and showed how common ancestry was concealed, a hurdle remained: domestication exposed the maker’s hand, as Wallace remonstrated. Darwin ’s answer was that farmers or fanciers did not plan for long-term transformations into a new species, but merely corrected one feature at a time, weeding out ‘rogues’. The intention to enhance a single characteristic could not leap over the step-by-step processes of natural selection.

While instances of the artificial selection of plants were plentiful, the paleo-botanical record was barren compared with the evidence from rocks, and slighter even than the scatter of skeletal fossils, matters to which Darwin addressed himself in a chapter ‘On the Imperfection of the Geological Record’. A plant which became extinct left little trace beyond its putative connections to others that had branched from some common ancestor. Darwin ’s generation had no tools, neither conceptual nor experimental, to demonstrate how surviving species confirmed that lineage.

When Darwin did opine on fossil plants he was wrong, being convinced that coal came from mangroves, a view from which Hooker could not dissuade him. Here, too, a persistence in error stemmed from commitment to a larger disagreement with Hooker over geology. Barnacle-like, Darwin stuck fast to his vision of land masses rising and falling into the seas to deny the catastrophism he feared to be lurking in Hooker’s reliance on a break-up of super-continents to explain the presence of similar plants in Tierra del Fuego, Tasmania and Kerguelen. Darwin accepted that land masses subsided to leave behind islands or coral atolls, and rose to form continents, allowing continents to evolve vertically, but not sideways. Noting the presence of related species across oceans, Darwin ‘admitted that these facts receive no explanation on the theory of evolution’. Nonetheless, he devoted chapter eleven to refuting Hooker’s position. To support his alternative of migration, he germinated seeds after their prolonged emersion in salt water, and propagated others extracted from bird droppings. The idea that drove Darwin towards distraction is now taken for granted as Gondwana.

Orchids
Despite obstacles to the establishing of descent with modification across the botanical record, Darwin’s first book after The Origin wove studies of the most ‘advanced’ genera of plants - orchideae - with high theory to produce On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects, and the Good Effect of Intercrossing. In 1841, the leading English botanist of his age, Robert Brown, had advised Darwin to read a 1793 study by Christian Konrad Sprengel of the fertilisation of plants by insects, birds and breezes. Darwin recalled that Brown ‘spoke highly of it to me, and remarked that only those who knew little of the subject would laugh at him … Few people now doubt the correctness of C. K. Sprengel’s view, that the bright and conspicuous colours of flowers serve to attract insects from a distance’. Francis Darwin wondered ‘whether Brown ever planted a more fruitful seed than in putting such a book into such hands’.

Although Darwin pictured orchids as the ‘fairyland of science’, he demonstrated how their fertilisation supported natural selection: ‘orchids ought to show us how ignorant we are of what is useful’ and thus ‘quite to repudiate the doctrine of beauty being created for beauty’s sake’. Introducing The Effects of Cross and Self Fertilisation in the Vegetable Kingdom in 1876 as ‘the complement of that on Orchids’, Darwin stressed ‘how admirably these plants are constructed so as to permit of, or to favour, or to necessitate cross-fertilisation’. A creationist might have interpreted the co-adaptation of flowers and insects as proof of the harmony installed by a beneficent designer. Darwin took the opposite tack. Descent with modification through natural selection is possible because inheritance can vary with sexual reproduction.*

Darwin envisaged his volume on orchids as a reply to the eight Bridgewater Treatises (1830s) which, guided by the Archbishop of Canterbury and funded by the penitent Earl of Bridgewater, had discerned divine beneficence in every twig and tweet. Zoologist Michael Ghiselin lauds Darwin ’s treatise on orchids as a botanical equivalent of Voltaire’s Candide in its demonstrating that all is not for the best. Reading Darwin’s refutation of the argument from design is a slog compared with the Enlightenment satire. Nonetheless, in constructing his analysis, Darwin ventured beyond adding to the ramparts of ‘brute facts’ that he was building up around The Origin. He interpreted the intricacies of fertilisation as rough fits to maximise propagation of each organism. Such contrivances were not proof of the design that Rev. Dr William Paley had popularised in Natural Theology (1802), concluding that there must be a master craftsman behind complexities such as the human eye. No longer impressed by this reasoning, Darwin now appreciated that no skilled worker would assemble such contraptions as those he discerned in the fertilisation of orchids.

More is involved here than the assault on teleology that had delighted Frederick Engels on reading The Origin. In Paley’s Natural Theology, god had been the prime mover, but the reproduction of life called for no divine interference, and mutation of species did not challenge this arrangement. However, once Darwin got rid of god as creator, he had to identify a device which kept reproduction going. Without such a mechanism, he was stuck with the miraculous that some evolutionists relied on to explain the origin of life itself, with god breathing into handfuls of dust, as Darwin amended the re-print of The Origins to imply. Other scientists had yet to escape from a belief in spontaneous generation as an every day event, for instance, in yeast.

Sexual selection
Darwin knew that no one could conduct experiments to refute or confirm the theological account of the origins of life, or even for speciations, since those moments were unrepeatable. Instead, he launched a flanking action by asking ‘why sex?’, in other words, why the near universality of one method of reproduction, namely, cross-fertilisation, and not self-fertilisation, which seemed to be more advantageous to the persistence of each species. Moreover, why were most hermaphroditic plants capable of cross-fertilisation? Indeed, why were even plants with the equipment for self-fertilisation incapable of doing so, that is, were self-sterile? His answer was that sex was almost universal so as to guarantee variation, not just to propagate. His inquiry now turned to ‘why variation?’ The answer was for the mutation of species. The Oxford Past Masters volume summed up Darwin ’s findings: ‘flowers are devices to ensure cross-fertilisation by insects’. This interaction was not just to pass on characteristics but to do so in a way which added to the persistence of those individuals through higher rates of fertility and with greater vigour.

Darwin ’s recognition that the opposite sex is the most potent resource in an organism’s environment is less applicable to plants than to animals. As much as plants need an intermediary, whether a bird or an insect, the competition for pollen among the fertilising agents is of a different order from the competition between those creatures to fertilise others of their kind, as Wallace explained in an 1877 essay on ‘Colour in Plants’. Male competitiveness cannot apply among plants, and rarely to their interaction with insects, although a few plants mimic the appearance of insects to attract them, an instance of co-adaptation as faking it. Plants can not select their fertilising agents according to their appearance for fitness. Indeed, animals and plants fertilise along distinct pathways.

Darwin ’s answer to ‘why sex?’ justifies the significance that scientists award to his botanical work. Indeed, even posing the question ‘why sex?’ merits praise. Linneaus’s classifying plants by their sexual features horrified almost as much as did Freud’s views about children’s sexuality. Despite the shift towards prurience that had been underway from the 1790s when grandfather Erasmus’s verse treatise, The Love of the Plants, became the most popular English poem, neither Parson Malthus nor valetudinarianism deterred Charles from fathering ten children, from flirting into old age and from favouring fiction with pretty girls. In his Orchid book, he valued ‘the figure of Pterostylis trullifolia from Mr Fitzgerald’s great work’ for showing ‘plainly the relation of all the parts’, its sex organs. Experiencing Darwin’s illustrations as ‘more lurid than Georgia O’Keefe’s flower paintings’, the literary critic Stanley Hyman appreciated how Darwin had dramatisied the life of plants by concentrating on their fertilisation.

Here, Darwin began this argument from a disjunction between his observations and the argument from design – one instance of his counter-hypothetical-deductive method. The ‘structure, colour, ornament’ of living forms were more prolific than was necessary for reproduction. An omniscient omnipotence could have achieved that purpose with greater economy. So, why was so much sex appeal on display? Darwinians used such extravagance against the creationists, asking whether it was evidence of divine ornamentation? If the latter, then god was a trickster. Darwin ’s evidence for sexual selection drove creationists into picturing their god as an aesthete. They were back to ‘the good, the true and the beautiful’, as were several prominent Darwinians. Darwin had turned the tables on the creationists. Just as Paley had proved design by the foolishness of supposing that a watch could have come into existence by chance, Darwin challenged the association of design with aesthetics. Beauty in nature was neither for its own sake, nor a prelude to the celestial vision, but of use in the struggle for survival.

An erstwhile disciple, St George Mivart, a Roman Catholic, then turned Darwin ’s argument about a superabundance of appeals against sexual selection. If features had been retained because of their contribution to reproductive success, why were so many gradations of colour found in a peacock’s tail? Surely, mating could have been achieved by fewer spangles. To rebut this critique, Darwin applied his historical approach – that law of higgledy-piggledy - to the mutation of species. Not every attribute was equally ‘useful’ on every day across thousands of years: ‘the plant then becoming slightly modified, but still retaining its hooked seeds, would form an endemic species, having as useless an appendage as any rudimentary organ’. This recognition of the transience of utility was another example of his denying purpose and perfection:

If we admire the several ingenious contrivances, by which the flowers of the orchis and of many other plants are fertilised through insect agency, can we consider as equally perfect the elaboration by our fir-trees clouds of pollen, in order that a few granules may be wafted by a chance breeze on to the ovules?

Features that did not attract had been selected against through previous cycles of mating, leaving a plenitude of neutral characteristics: ‘Variations neither useful nor injurious would not be affected by natural selection, and would be left a fluctuating element …’.

Darwin aimed his volume on orchids at that strand of the market that could afford glasshouses and gardeners, like the Darwins and the Wedgwoods. The book sold well to genteel society but provided the Duke of Argyll, in his Reign of Law (1868), with a weapon with which to harry Darwin about colours and features for sexual selection rather than as God’s plaything. Drawing a line is not easy between Argyll’s opinion that ‘Ornament as much an End in the Workshop of Nature as in the Jeweller’s Workshop’ and Darwin ’s comment that ‘the Orchideae exhibit an almost endless diversity of beautiful adaptations.’ Both sides assumed that what was beautiful to humans was also attractive to other species. Darwin , for instance, could not believe that the ‘horn-like protuberances in the cocks of certain fowls &c’, were ‘attractive to the females.’

Colour vision
The anthropocentrism and anthropomorphism shadowing Darwin ’s account of the beautiful becomes blatant when set against the physics and physiology of colour perception. Colours are not qualities in the objects being viewed. No rose is red in itself. Our apprehension of that colour is possible because its petals have absorbed all the other frequencies in the spectrum, reflecting back the red ones to eyes that have cone receptors capable of recognising those wavelengths. Not all sighted creatures are equipped with the same mechanisms for distinguishing colours. Some are blind to them. Primates are trichromatic, a characteristic which homo sapiens share with apes but not with monkeys from the New World . Birds, reptiles and some fish can distinguish four.

To prove that when a house-fly lands on the ‘irritable labellum’ of a Caladenia dimorpha it has been attracted by what Darwin calls the ‘beautiful’ requires showing that the insect has a nervous system capable of the discriminations of a naturalist. Proposing aesthetic appreciation in bugs must begin from the differences in the apprehension of light waves by each genus. As Wallace observed, the capacity for delineating colours needs to be known for each insect and bird before a biologist can demonstrate that the colour sense of a bee is the same as that of a honey-eater, let alone that of a human being. A bee can register ultra-violet but not red. With no way to be sure whether a moth registered emerald against crimson or only tonal patterns, a majority of Darwin ’s generation cross-fertilised their evidence and guesses with anthropomorphism.

In addition to differences in the physical capacities of species to discern colours is the fact that human beings alone evaluate them through cultural inheritances, as John Gage documents in his Colour and Culture (1993) and Colour and Meaning (1999). Those learned preferences are peculiar to our species and specific to time and place, varying between classes and ethnicities. The association of boys with blue and girls with pink is an instance of the invention of tradition by the marketing industry in the twentieth century to sell more baby clothes. Previously, pink was more likely to be the male colour because of its association with blood. ‘Born to the purple’ expressed the expense of producing cloth of that hue until the development of aniline dyes after 1856 cheapened both its cost of production and social esteem. Because of the by-products that William Perkin had extracted from coal tar, Darwin was able to get a dove dyed magenta to see if that tint affected its sexual attractiveness. Throughout the twentieth century, mass marketers standardised swings in fashionable colours to reduce production costs and to limit losses from unsaleable apparel while ensuring renewed sales out of planned obsolescence. Britain ’s Colour Council, with its Royal patrons, has had more influence over what Anglo-Celts consider beautiful than our genetic inheritance of photocells for distinguishing the tint Edinburgh Rose from Clarence Rose.

‘fatal to my theory’
While Argyll and Mivart appealed to the devout, two other sets of critics struck from within the demesnes of science. The first were geo-physicists taking temperatures down mine-shafts who revised the age of the earth down from several hundred million years to as few as one hundred on the count of their spokesperson, Sir William Thompson (later Lord Kelvin). That span was too brief for the mutation of a bacteria into a human brain, which needed many more millions of years. Not for the last time, physicists were as errant as they were arrogant. After 1900, the discovery of radium and related elements brought the calculation of the age of the earth up towards four billion years, longer than Darwin ever imagined possible. Those researches came decades too late to exorcise the ‘odious spectre’, as Darwin depicted Thompson’s claim.

A Professor of Engineering, and Thompson’s business partner, Fleeming Jenkin, delivered the second challenge in 1867 by pointing out that a variation in one individual would be diluted before it could initiate a mutation. He gave the example of a white person interbreeding with a population of blacks. The whiteness from a single breeder could have no effect on the sable race. Such a shift required mass miscegenation. Darwin accepted Jenkin’s demonstration that descent with modification through natural selection was a statistical improbability because, like almost everyone else at the time, he assumed that inheritance proceeded through a ‘blending’ of all the elements of an organism. ‘Swamping’ undermined Darwin ’s position.

Confronted with twin assaults from geophysicists and mathematicians, Darwin could have adopted one of three strategies. First, he might admit defeat; secondly, he could cleave to evolution but admit causes that accelerated modification; or, thirdly, he could take the challenge from Jenkin as a starting point to uncover the inner working of inheritance. Darwin opted for a variant of retreat while embarking on a line of inquiry to sustain natural selection as the prime, though not the sole mechanism. Once he accepted the judgement of the geo-physicists, he sought mechanisms which went faster than natural selection for bringing about mutation. To that end, he made room for inheritance of acquired characteristics.

No accelerator could rebut Jenkin. Darwin needed a different structured dynamic. In Darwin ’s words, ‘[t]he laws governing inheritance are quite unknown’. Following van Baer’s discovery of cells in 1828, little work was done on their functioning until the 1880s. Darwin conceived pangenesis, with ‘pan’ highlighting that every characteristic of the mates was carried by zillions of ‘gemmules’ through the sperm and germ cells to the new generation. This explanation proved a nullity but Darwin developed it to ward off the creationists. In all his wrong-turns and dead-ends, he never sought refuge in any purpose outside the mechanisms for survival. As a materialist, he pursued physical causes within the processes of inheritance, with nary a trace of a Life Force.

Darwin knew that blending was not universal. Throwbacks were an embarrassment to families when features from a non-white ancestor popped up in a later generation. The same happened with pigeons and primula, when they were referred to as ‘sports’. He knew of no offspring reverting to some one ancestor after the twentieth generation. But why did the reversions occur at all? As early as The Origin he reported instances that could have triggered a quest for an answer:

To keep up a mixed stock of even such extremely close varieties as the variously coloured sweet-peas, they must be each year harvested separately, and the seed then mixed in due proportion, otherwise the weaker kinds will steadily decrease in numbers and disappear.

To ascribe this pattern to the survival of the fittest told him nothing about how what took place inside each plant might effect natural selection.

‘Let us imagine’
By coincidence, the concepts and data needed to refute Jenkin emerged at the same time as physicists disproved the calculations of Kelvin. Researchers into the laws of inheritance replaced blending with separation and recombination, sparked by the reinterpretation of an 1866 article by the Austrian monk Gregor Mendel on the cross-breeding of garden peas. Its author was nowhere nearly as reclusive, or his journal as obscure, as legend has us believe. Given Darwin ’s omnivorousness for information, his failure to encounter the issue of the proceedings of the Brunn Society of Natural Science carrying Mendel’s 44-page report was a matter of chance. After all, the German Academy of Naturalists had made Darwin a member in 1857, and he received advance notice in 1863 of the exactly preserved fossil of a reptilian bird uncovered in Germany . As Darwin kept in touch with developments around the globe, Downe became a clearing house for specimens and manuscripts with experts and cranks clamouring for attention. Had Darwin not been so methodical, we might suppose that Mendel’s paper arrived in the post, only to be lost under the bird skins, Queensland wax flowers and piles of the Gardeners’ Chronicle.

Let us adopt one of Darwin ’s favourite moves by relying on our imagination to  picture his reading Mendel in the late 1860s. His German and mathematics were adequate for him to understand the ratios. If not, his sons were on hand to clarify, or his statistician cousin, Francis Galton, to carry him beyond the binomial. Technical capabilities, however, do not guarantee comprehension. Would Darwin ’s response have been that attributed to Huxley upon reading Darwin and Wallace on natural selection – ‘How extremely stupid not to have thought of that’? Almost certainly not. At a psychological level, making one breakthrough can mean that its discoverer never sees past that insight, or even around it. (Upholders of quantum theories put Einstein into that category.)

Now let us take a further leap into Darwin ’s imaginary to watch him conducting Mendel’s experiments for himself. He cross-bred plants, including garden peas. He had the patience and meticulousness to carry through seven years of collecting data, as he demonstrated in 1862 by putting off publication of the results of experiments on Lythrum salicaria until he could make ‘126 additional crosses’. Part of the explanation for Darwin ’s failure to propose Mendel’s ratios was that his elaborating the intricacies of fertilisation deflected his interest. It seems likely that Mendel himself did not understand just how his discoveries had overturned blending. Thirty more years of research into the cells were needed before biologists could grasp the significance of his ratios.

Conclusion
Darwin’s ‘great Tree of Life’ challenged the place that trees, whether actual or allegorical, held in the minds of Anglicans, whether the fruit of the Tree of Good and Evil in the Garden of Eden, which to led to the Fall, or the agony of the Christ on a tree redeeming humankind. The Origin needed no declaration of disbelief for Christians to recognise that its author rejected their vision of life eternal. More generally, Darwin ’s exaltation of the botanical represented the triumph of materialism over the Philosophical Idealism that had allowed Immanuel Kant in The Critique of Judgement (1790) to proclaim that the discovery of cells in 1828 through to DNA in 1953, via chromosomes and proteins, and onto polymerase chain reactions and genetically modified canolla, could never take place:

to hope that a Newton may one day arise even to make the production of a blade of grass comprehensible, according to natural laws ordained by no intentions, such an insight we must absolutely deny to man.

Indeed, Kant thought it ‘absurd for man even to conceive of such an idea’. No botanical Newton arose to do all that; instead, a parade of researchers, standing, by turns, on each other’s shoulders, rendered risible Kant’s conviction that the inner lives of plants must remain unknowable.  

Life, and our knowledge of it, are best understood in light of ‘ Darwin ’s orchid’ (Angraecum sequepedale) which long defied efforts to observe its fertilisation. Anti-Darwinians contended that no creature could reach the nectar which was 30cm down a spur. In 1903, a researcher on Madagascar identified a moth (Xanthopan morgani) with the necessary length of proboscis. Less than optimal design, like gaps in knowledge, are proof against perfection and purpose. The sub-title that Nobel laureate in physiology Salvator Luria gave to his 1974 essays is as true for organisms as it is for our understanding of their modifications: ‘the unfinished experiment’.

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