The origin of species: the Australian connection

A doctor in the Australian garden – Linnaeus, his tercentenary and Australian flora

22 May 2007

Professor John Pearn AM
Professor of Paediatrics and Child Health
University of Queensland

Professor John Pearn is a senior paediatrician and historian, and a former Surgeon General of the Australian Defence Force. John established the first genetics clinic in Queensland and worked with the World Health Organisation and UNESCO on health issues. He has received many honours, including Queensland Senior Australian of the Year in 2005 and Queensland Father of the Year in 1994.

For his services to medical toxicology, botany, ethnobotany and the history of biology, he was awarded the Tercentenary Wedgwood Medallion of the Linnean Society of London on 30 September 2004.

He is a prolific author, writing more than 100 research articles, 15 books and 30 book chapters in the fields of health and heritage as these relate to medicine, biography and military history. In 2001, his book A doctor in the garden: Australian flora and the world of medicine was published, with the proceeds from book sales going to the Royal Children's Hospital in Brisbane.

An ABC radio interview with John
www.abc.net.au/queensland/stories/s1396174.htm

Australian and New Zealand Society for History of Medicine
www.anzshm.org.au/index.html

Flora of Australia online
www.environment.gov.au/biodiversity/abrs/online-resources/flora/main/index.html

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In May 2007, the Smithsonian Institution in Washington announced the launch of a US$50 million project, The Encyclopedia of Life. This project of breathtaking ambition will eventually make all knowledge of the world's 1.8 million known species freely available online. To be known and catalogued and to be indexed and thus 'retrievable', each of these species has a scientific name. The project has been described as 'the greatest thing since Linnaeus'.¹

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In 2007 the scientific world celebrates the tercentenary of the birth of Linnaeus, whose system of naming things was described several decades ago in the scientific journal Science as "one of the twenty greatest inventions in the entire history of scientific investigation". Prior to his era, plants for example were described by a noun and perhaps ten or more adjectives; and the basic designator bore no relationship to that of other plants which seemed intuitively to be related to it. Linnaeus' brilliance was to bring order to this domain. His invention of the binomial system of nomenclature has stood, essentially unmodified in principle, for 250 years.

Today we take names for granted. However, I am always 'brought up short' when I read the First Principle of the International Rights of the Child, published by the United Nations in 1959, which enunciated the fundamental dictum that 'Every child shall have a name and a nationality'.² Didn't at least every child in the world have a name? My experience as a resuscitationist-intensivist and paediatrician following the Rwandan genocide soon disabused me of that naïve assumption. There, in 1994, the more than 300 toddler orphans for whom I was providing basic medical care did not have any known original name - they were survivors who had been salvaged from among the many heaps of bodies in that terrible carnage of April-May 1994.³

Scientists since recorded history had given names to living things which they encountered. In hunter-gatherer, pre-literate societies all members of each tribe knew the detailed names of hundreds of local plants and hundreds of animals which they encountered in the hunting range of their tribal lands.⁴ However, such names were essentially random, each with its origin usually lost in the shadows of the past. In contemporary times, different names are often ascribed to the same plant or animal. Every bird watcher knows that the Australian magpie is totally unrelated to the European magpie. Every fisherman knows that the word 'perch' in many parts of Australia, refers to any one of more than a dozen different fishes⁵; and furthermore that Australian perch are totally different from the 'perch' of other countries. In this example, the Nile Perch (Lates niloticus), was first described by Linnaeus himself from an African specimen in 1753.⁶

Prior to Linnaeus and his science-changing publications of 1735⁷, 1740⁸ and 1758⁹, many scientific thinkers had sought the holy grail of a logical, acceptable and most importantly useful system of naming objects, both living and inanimate, in our world.¹⁰ As Isaac Newton famously acknowledged, great discoveries are not made in isolation, but are always built upon the work and disseminated experience of others.

Early taxonomists

The history of science acknowledges Aristotle (384-322 BC) as the pioneer of the concept of developing systems to classify forms of life and in this context was the scientific founder of the discipline of taxonomy.

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He promoted the passionate philosophy that it was personal careful observation that should be the foundation of theory, and not the reverse. Following the publication of his De Anima, he was acknowledged as the pioneer who committed to the written word his profound belief that the essential truths of humankind could be the better interpreted by observation and experiment, rather than by meditation and worship.

Aristotle initially classified animals and plants according to their names in common use; and further classified animals depending on whether their principle domain of movement was air (birds), water (fishes) or land. Aristotle was described by one of his contemporaries as 'short and slender of make, with small eyes and a sarcastic expression of countenance'; and in the anonymous Vita, as one who was 'small, bald, stuttering, lustful and with a hanging paunch'. His influence in the world of science, in philosophy and in medicine came not from his physical presence, but from the logic and sheer power of his spoken word and the system and discipline of his writing.

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Almost two millennia later, the Pope's (Clement VIII) personal physician in Rome, Professor Andrea Cesalpini (1519-1603) was the modern pioneer of biological classification. Although he believed that plants had souls, in his attempts to develop an observation-based system of classification he sought what he believed was the most fundamental property which he called the substantia of plants:

We look for those similarities and differences which make up the essential nature of plants, not for those which are only accidental to them [quae accidunt ipsis]; for things perceived by the senses become comprehended primarily from their essential nature and only secondarily from their accidents.¹¹

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Unlike earlier workers, Cesalpini felt that such accidentia as size, season of flowering, fragrance and habitat, were not of sufficient Substantia to be the basis of his system of classification. He regarded the fruits (and secondarily the seeds borne within them) as the most fundamental feature of plants. For this reason 'he brought together the trees that bare fruit similar to acorns - oaks, chestnuts, beech, and hazel.. He gathered up the trees that produce one-seeded fruit with wings; elm, lime, plane, sycamore and ash'.¹² In all, Cesalpini arranged some 768 plants in systematic order according to the form of their fruits and seeds.

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A further development was 'the rules for a modern system of nomenclature'¹³ which were laid down in 1690 by the English plantsman and physician, John Ray (1627-1705), a Cambridge biologist who was ultimately expelled from the University of Cambridge for refusing to take the loyalty oath¹⁴. In his Methodus Plantarum Nova, initially published in 1682 and amended in 1703, he enunciated 'six rules for classification'. Described as 'solitary, modest, principled, and persistent'¹⁵, and by himself as 'often ill, physically and mentally', one of Ray's important contributions was to provide an essential tool for taxonomists, specifically the delineation of 'petals' (from the Greek 'petalon') as a distinct and specific anatomical structure within the flower, rather than as a 'flower leaf'. Using this new descriptive anatomical tool, he described plants in detail, and from these anatomical descriptions arranged them according to 'the likeness and agreement of the principle parts'. ¹⁶

John Ray felt that not only fruits and seeds should be used as a form of classification (as Cesalpini had taught), but that what today would be regarded as the number and form of petals and the calyx (the collection of sepals).

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His detailed observations led him to discover that one group of flowering plants produced seedlings with one leaf, such as lilies, whereas others produced two. In 1682 he felt that this distinction was a fundamental property to be used in classification, and the names 'monocotyledon' and 'dicotyledon' were given to either one or the other of the two great primary groups of flowering plants. Ray noted that the great majority of common garden plants (such as roses, geraniums and hollyhocks) were dicotyledons and had leaves which were usually net-veined. Besides the specifics of his description and classification of individual plants, Ray enunciated general rules for such classification. His 'third rule' was that the anatomical features used to group plants should be 'obvious and easy to grasp'.¹⁷

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It was Dr Nehemiah Grew MD FRS (1641-1712), a medical practitioner of Coventry and London, who was to provide the key step which enabled his successor, Linnaeus, to develop his definitive system of classification.¹⁸

Nehemiah Grew was the son and grandson of courageous non-conformist ministers who had lost their estates, living and professional roles as preachers, rather than compromise their religious beliefs. Grew studied medicine in Leiden and practised as a successful general medical practitioner initially in Coventry and later in London. He did not commence his botanical studies until 1664, when he was 23 years of age. He had long been interested in comparative mammalian anatomy. After he had established his own garden, it occurred to him that plants might also be worth studying and classifying 'since both of them (animals and plants) came at first out of the One Hand'.¹⁹

Much of Grew's pioneering work has passed into the general corpus of botanical science, and into our lay knowledge of plants - so much so that his findings are now taken for granted and their origins in Grew's work have so often been lost. It was Grew who first gave an account of the structure of seeds. He described the plume, the radicle and the lobes of cotyledons. He first described the leaves of germinating seeds and their venation patterns; and the rolled arrangement of emergent fern leaves. His approach was both indicative and an exemplar of the great paradigm shift in science which occurred in his era - the embodying of Baconian principles of objective assessment and experiment - principles that were to characterise the science which we know today.

Grew's greatest discovery was the sexual anatomy of plants.

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The idea that plants might have sexuality had been suggested to Grew by Sir Thomas Millington, of the Royal Society. Grew investigated this phenomenon and showed that each stamen (with its attached pollen) is a male sex organ and that the pistil corresponded to the sex organ of female animals. Grew published these findings in The Anatomy of Plants in 1682²⁰, which like Linnaeus' tenth edition of Systema Naturae, is today also regarded as one of the great books in the history of science. In 1671 Grew described the 'attire' or stamens of flowers, their function then unknown. He noted that they were unlikely simply to be ornaments, since they could be overlooked easily by a casual glance. 'Nor was it satisfactory to suppose that they are provided by the Divine Author at the dining table and lodging for his smaller creatures'.²¹ Grew's intuition was that they had some fundamental primary importance, and in The Anatomy of Plants he first suggested that they might be involved in reproduction.

The possibility that plants possessed sexual organs was offensive to most, and shocking to some. The Bishop of Carlisle, the Reverend Samuel Goodenough (1643-1827), was one of a number of prudish botanists who rejected the entire concept and pilloried Grew.18,²² Eventually, Grew's discoveries in plant anatomy were to be widely accepted, but his observations were not exploited for more than a century after his death, when Linnaeus recognised that the number of stamens in the flower might (in John Ray's terms) be an easily recognisable and fundamental tool to classify plants into a primary grouping of classes.

Grew's contributions were acknowledged and commemorated by Linnaeus a century later (1753) when the latter raised the new genus Grewia to commemorate the formers life and works. Species of Grewia flourish and grow in many countries both as native trees and as ornamental cultivars. Their form, diversity and beauty is a witness to the diligence, courage and contributions of one who had the self-discipline to record and the courage to publish what his curiosity revealed.

Carl Linnaeus

Linnaeus' life is well known and more than thirty biographies have been written about this singular man.

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He himself was to write that 'I was born on the night between the 22nd and 23rd May 1707, just in the finest part of the spring, when the cuckoo had proclaimed the arrival of summer'. He was born the son of a village pastor in the impoverished village of Rashault in the district of Smaland in Sweden. It was a time of uproar and turmoil in Sweden. In 1710, when Linnaeus was three years of age, plague was rife and the harvests poor; and the burden of crippling taxation 'had reduced the material conditions of life to less even than the reasonable minimum to which the poor of that region were already accustomed'.

The boy's early passion for plants and animals in the countryside led to many travels and adventures in the local woods. The influence of the dramatically-changing Swedish seasons remained with him forever. Even after he had become a famous medical teacher and was financially secure, many of his early experiences of poverty influenced his persona. His upbringing engendered in him both a religious orthodoxy and a humble personality. Linnaeus himself recorded that 'I never really left the Smaland milieu of my childhood'.

His schooling was not a success and at the age of seventeen years his father removed him from his school, the Vaxjo Grammar School, and apprenticed him to a shoe-maker. Fortunately, the local general medical practitioner, Dr Johan Rothman, 'having on one chance occasion spoken with the young man, realised that he had about him the mark of another destiny'. He was encouraged to study medicine and botany. As Linnaeus was still too poor to enter university, Dr Rothman acted as an advocate on the lad's behalf and the youth was employed as a copyist in the library of the University of Lund. He studied clandestinely in the library at night.

In 1728 Linnaeus commenced medical studies. It was whilst he was a medical student that he conceived of the idea, building on the works of earlier taxonomists, of using the sexual reproductive organs of flowers as a system of classification.

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Whilst still a medical student in 1735, he published Systema Naturae, which ran to eighteen editions throughout the next 100 years. His Fundamenta Botanica was published in 1736, and his Genera Plantarum in 1737. For three years (1735-1738) he worked in Holland, as assistant to Dr George Clifford, a physician and banker at the village of Hartecamp, near Haarlem. At the age of 31 Linnaeus returned to Sweden, practised as a physician in Stockholm for three years and thereafter went to Uppsala where his research concerning the classification of plants and animals continued. He was appointed as a teacher in the University of Uppsala where he became a much-loved and esteemed mentor of medical students.

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In the University Botanical Garden at Uppsala he cultivated coffee and rice plants, cocao trees, the ginger plant and the papyrus reed, various species of tea and different species of cacti and lilies from many parts of the world. He landscaped his garden such that it was divided into 24 classes, arranged according to the 'sexual system' of classification which he had developed.

His joint appointment, like most of the other senior medical teaching positions in Europe of his era, was that of the combined Chair of Medicine and Botany. As Professor Linnaeus he became famous for his conducted field collecting trips with his medical students on Sunday rambles, collecting and classifying flowers and discussing relevant aspects of materia medica - the procedures by which active principles can be extracted from leaves and flowers, roots and bark. It is recalled that the townspeople of Uppsala always knew when Linnaeus and his students were returning from their Sunday excursions, as there was much singing due to the wine drunk and the picnic eaten at lunchtime in the woods. The boisterous and laughing group of the teacher surrounded by his students would return to the town with their collections of medicinal plants and with flowers in their hats.²³

At a time when university teaching throughout Europe was universally formal, and in Sweden where it was particularly so, Linnaeus' lectures struck a new and fascinating chord. They were recorded as being

.inexcusably merry, particularly those on dietetics, the subject field in his official duties to which he perhaps especially liked to imply himself. As a lecturer, Linnaeus was often dramatic and slightly shocking, full of examples from contemporary life and from his own experience, concrete but not in the least wooden, and a mixture of medicine and moralism suited him specially.

His courses became hugely popular and he developed not only a major undergraduate following but also an esteemed postgraduate reputation as well.

Aftermath

Linnaeus' system of classification brought with it another legacy. That legacy was the infrastructure by which the names of worthy individuals could be memorialised. Linnaeus himself established this system, incorporating into his formal Latin generic and specific taxonomy the names of Greek gods and other figures from classical mythology.

This is perhaps most romantically illustrated by his creation and formalisation of many of the vernacular names of butterflies in common local use.²⁴

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To the butterflies he assigned the genus name Papilio, and within it he assigned a Latin name to each of the 142 species known to science in his time. He named almost all of the species after legendary figures from ancient Greece. They were names that every educated person knew from the Homeric and other legends of antiquity. Among what today are called the swallowtail butterflies, he chose individual names which comprised the entire central cast of the Trojan War.²⁵ Hector, Paris, Helen, Ulysses, Achilles, Nestor and all the other heroes flit about our forests and gardens today. Papilio ulysses, the beautiful metallic-blue swallowtail butterfly of north Queensland, features on postage stamps and is the tourist emblem of much of north Queensland including the islands of the Great Barrier Reef. Linnaeus named this beautiful creature, Papilio Ulysses [sic], gave it the number 20 in the genus Papilio and defined the species as that swallowtail with [translated from the Latin]:

Rounded wings of radiant blue, the hind wings dark with underneath eye spots in the septums, living in Asia.²⁶

To other creatures he assigned formal Latin names which he invented, or translated from those in local use in regions where the creatures were to be found. One stomb shell he called 'The Devil' (Strombus lucifer).²⁷

It is fitting that the early pioneers of biological classification - Aristotle, Theophrastus, Cesalpini, the Bauhin brothers, Ray, Grew and Rivinus - should all have their 'monuments more enduring than bronze'²⁷ in the scientific names of plants and animals bestowed by scientists in the Linnaean system.

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Aristotle is commemorated in the genus Aristotelia²³, a genus of six species of which four are endemic to Australia.²⁸ Linnaeus himself raised the new genus Caesalpinia (in the family Caesalpiniaceae) to honour Andrea Cesalpini (1519-1603) who besides serving as personal physician to the Pope (Clement VIII) was the first to classify plants by the anatomical features of their flowers and seeds. His De Plantis Libri was published in 16 volumes. Today, 'his' genus Caesalpinia contains 100 species of which four occur in Australia.²⁹, ³⁰

When Linnaeus died on 10 January 1788, it was recorded that:

Linnaeus died only physically; his spirit was kept alive by a multitude of followers at the world's universities.

His name is recorded in thousands of plants and animals that bear his name throughout the living world.

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Linnaeus chose one plant, a beautiful white snowdrop-like bell of the northern European woods, to be his own eponymic memorial. The original type specimen of this plant, the monotypic Linnea borealis, was described by him as:

A plant of Lappland, lowly, insignificant, disregarded, flowering but for a brief space, from Linnaeus who resembles it.³¹

His humility, in which he saw himself as a tiny part of the 'great and extensive works of God' is a paradox in the context of his influence throughout the scientific world; but a seemly and fitting paradox in which his towering contributions were acknowledged in the tercentenary year of his birth.³²

The concept of genus and species has in itself undergone change since Linnaeus' era. With the development of DNA markers, the relationships of old branches and limbs of the family trees of botany, zoology and of human evolution are constantly being challenged. For two centuries after Linnaeus, a species was regarded as a group of plants or animals all of which were identical in type, and which conformed to a holotype specimen preserved in a reference museum. Today, a species is regarded as 'a live population occupying space during a finite time in nature, varying under the conditions to which its members are exposed by both the inorganic and the living environment. a morphological type is no longer sufficient to define a species'.³³

Brilliant as Linnaeus' system of classification was, like any system it used a set of arbitrary primary tools. Anatomic structures, albeit refined to the point of electron photomicrography, remained the basic tool for biological taxonomists until the 1970s. In 1969, W. Arber discovered a new class of enzymes, restriction endonucleases, which were further defined by D. Nathans and H.O. Smith in 1971. Such were discovered to cleave DNA into fragments of reproducible and defined size. This comprised the crucial step which led to the sequencing of nucleotide bases of DNA, and therefore the definition of individual genes of living organisms. Such principles apply equally to viruses and to whales. In the last decades of the twentieth century, molecular DNA diagnosis thus became a more fundamental tool for taxonomists. Today, biologists follow a best-practice paradigm that it is the genome which determines structure and therefore is a more logical primary basis for classification. This has meant that many of the classic Linnaean designations into species and even genera have been reassigned.

Some living organisms, particularly plants, have always proved difficult to classify using their anatomical features alone. Recently-developed DNA analysis has enabled these to be classified with confidence but still using the underlying principles of Linnaean taxonomy.

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One of the best examples is that of the world's largest flower, a spectacular parasite assigned in the nineteenth century to the genus Rafflesia. It is a satisfying example of the great unity of science, that the DNA probes of 2007 (the tercentenary of Linnaeus' birth), have enabled this wondrous but enigmatic flower to be classified in the family Euphorbeaceae, the botanic family originally raised by Linnaeus himself to honour Euphorbus (fl.30 BC-20 AD), one of Julius Caesar's military surgeons, who served in Mauritania at the limit of the Roman Empire during Caesar's rule.

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The tercentenary of Linnaeus' birth has been a time of critical appraisal and audit of the significance of his work. His place in the history of the cultural evolution of humankind and in the chronology of science remains secure.

Professor Carl Linnaeus brought order and understanding to the wondrous diversity which is to be found in the living world. Our contemporary challenge is to preserve it.

Acknowledgements

I thank Professor Sue Serjeantson of the Australian Academy of Science; Emeritus Professor Trevor Clifford FLS, sometime Professor of Botany at the University of Queensland; Mr Ross McKinnon AM FLS, Curator of the Brisbane Botanic Gardens; Ms Belinda Wallis, Professor Richard Wootton, Mrs Lynne Packer and Associate Professor James Nixon AM, all of the University of Queensland; and the Royal Children's Hospital and Royal Children's Hospital Foundation, all for much encouragement.

Footnotes

1. McKenna P. Life on Earth - the ultimate catalogue. New Scientist 2007; 194: 14.
2. Pearn, John. Reflections of Rwanda. A selected Photo-archive of Service with the Forward Surgical Team, The Australian Medical Support Force, UNAMIR II, Rwanda. Brisbane, Amphion Press, 1995: 20,21,28-30,50,51,54,64-66,87-95.
3. Covacevich J, Irvine T, Davis D. A Rainforest Pharmacopoeia. In: Pioneer Medicine in Australia. Brisbane, Amphion Press, 1988. Chapter 12: 159-174.
4. Grant EM. Grant's Guide to Fishes. Seventh Edition. Scarborough (Qld), E.M. Grant Pty Ltd, 1997. [Barber Perch: 207; Black Perth: 393; Chandra Perch: 812; Common Gurnard Perch: 767; Golden Perch: 816; Moses Perch: 360; Puttynose Perch: 556; Yellowtailed Perch: 276].
5. Ibid: 202.
6. Linnaeus, Carl [as Caroli Linnaei], Systema Naturae Iteratis Vicibus Prodiit. Leiden, J.F. Gronovium, 1735.
7. Linnaeus, Carl [as Caroli Linnaei], Auctum Animalium Nomen Claturis, Characteribus. Holmiae, 1740.
8. Linnaeus, Carl [as Caroli Linnaei], Systema Naturae Per Regna Tria Naturae. Tomus I. Editio Decima, Reformata. Holmiae, Laurentii Salvii, 1758. [A photographic facsimile of the First Volume of the Tenth Edition (1758). London, Trustees of the British Museum (Natural History), 1956].
9. Atran S. Cognitive Foundation of Natural History: towards an anthropology of science. Cambridge, Cambridge University Press, 1990: i - xii; 1-50.
10. Cesalpini, Andrea. De plantis Libri XVI. [Translated from the 'Dedication']. Florence, 1583. LIB I, Cap. XIII.
11. Pavord, Anna. The Naming of Names. The Search for Order in the World of Plants. London, Bloomsbury, 2005: 235.
12. Ibid: 372-386.
13. Ray, John. Methodus plantarum nova. London, 1682. Later, Methodus plantarum emendata. Amsterdam, 1703.
14. Pavord, Anna. Op. Cit. See Ref 11: 372.
15. Ray, John. Catalogus plantarum circa Cantabrigiam nascentium. Cambridge, 1660. Preface.
16. Pavord, Anna. Op. Cit. See Ref 11. Notes: 436.
17. Pearn, John. Nom et Lumiere: Enlightenment through nomenclature. Aust NZ J Surg 1997; 67: 508-511.
18. Arber A. Quoted in Nehemiah Grew 1641-1712. In: Oliver F.W. (Ed.). Makers of British Botany. Cambridge, Cambridge University Press, 1913: 44-64.
19. Grew, N. The Anatomy of Plants. Books I,II,III and IV. London, Rawlins, 1682.
20. Ibid: 39.
21. Baines, JA. Grewia. In: Australian Plant Genera. Sydney, Society for Growing Australian Plants, 1978; 169.
22. Pearn, JH. A Doctor in the Garden. Brisbane, Amphion Press, 2001.
23. Aristotle (384-322BC): 44-45.
24. Linnaeus Carl. Systema Naturae. 10th Edition. Holmiae, Laurentii Salvii, 1758. [A Photographic Facsimile of the First Volume of the Tenth Edition (1758). London, Trustees of the British Museum (Natural History), 1956]: 458-488.
25. Ibid: 459-462.
26. Ibid: 462.
27. Ibid: 744.
28. Baines JA. Aristotelia. In: Australian Plant Genera. Sydney, Society for Growing Australian Plants, 1981: 47.
29. Ibid. Caesalpinia : 70.
30. Pearn JH. Op. Cit. See Ref 23. Professor Andrea Cesalpini 1519 - 1603: 113.
31. Cunningham, Michael. 'Deserving of Italics'. Hortus 2004; 18: 84-94.
32. Shaughnessy, Elaine. Development Report: April 2007. Exciting [Linnaean] Society Developments for the Linnaean Tercentenary Year. The Linnaean 2007; 23: 7-8.
33. De Beer G. In: The Photographic Facsimile Edition of the First Volume of the Tenth Edition (1758) of 'Caroli Linnaei Systema Naturae'. London, British Museum (Natural History), 1956: iii-v.