Carolus Linnaeus

Swedish botanist

• Born: May 23, 1707
• Birthplace: Råshult, Småland, Sweden
• Died: January 10, 1778
• Place of death: Uppsala, Sweden

Linnaeus created a new classification system for all of nature, establishing in the process the modern binomial system of nomenclature for organisms.

Early Life

The father of Carolus Linnaeus (KAR-uh-luhs luh-NEE-uhs) adopted the name Linné and the Latin form, Linnaeus, while studying for the ministry. Ordained in 1704 at the age of thirty, the minister married Christina Brodersonia, the daughter of the vicar of Stenbrohult. In addition to his pastoral duties, Nils Linné was an enthusiastic gardener and was particularly knowledgeable about herbs. Carolus Linnaeus, his eldest son, was born on May 23, 1707, and soon exhibited an avid interest in botany. As a young child, Linnaeus enjoyed taking nature walks with his father and developed a firsthand knowledge and appreciation of plant and animal life.

School, however, was not enjoyable for the younger Linnaeus, and his only successes came in the physical and mathematical subjects. He had tremendous powers of observation, and in his four autobiographies he often commented on his own “brown, quick, sharp eyes.” His physics teacher, Johan Rothman, recognizing Linnaeus’s penchant for empiricism, encouraged him by giving him Hermann Boerhaave’s and Joseph Pitton de Tournefort’s works to read. At Rothman’s urging, Linnaeus’s parents agreed to send him to medical school. In 1727, at the age of twenty, he went to southern Sweden and entered the University of Lund, but he transferred the following year to the University of Uppsala, which not only was nearer his home but also had a reputation for higher standards. His knowledge of botany and understanding of nature soon brought him to the attention of Olof Celsius, a theology professor and dean, who took him into his home.

While still an undergraduate, Linnaeus conducted research on the reproductive structures of plants, gave lectures on botany (attracting large audiences), and received travel grants to collect materials for research on both natural materials and human customs and habits. During one of these trips, he met his future wife, Sara Elisabeth Moraea, the daughter of the wealthy town physician of Falun. Linnaeus was granted permission to marry her (and thus have access to her father’s wealth) on the condition that he go to the Netherlands to obtain the degree of doctor of medicine, a degree not then available in Sweden. Linnaeus went to the small and not-too-rigorous university in Harderwijk, where he took his doctor’s degree in a few weeks. He then went to Amsterdam and Leiden, where he met a number of noted scientists, and through these contacts was able to secure the patronage necessary to continue his research. During the three years he spent in the Netherlands, he published the work for which he is best known, Systema naturae (1735; A General System of Nature: Through the Three Grand Kingdoms of Animals, Vegetables, and Minerals, 1800-1801).

Linnaeus returned to Sweden, married Sara, tried to establish a medical practice in Stockholm, and became increasingly disillusioned with medicine as a career. Finally, in 1741, he was named professor of botany at Uppsala. His fame spread, and he attracted students from many countries to join him in identifying new species and classifying them. The period of the late 1740’s to the 1750’s was the apogee of his career.

Life’s Work

Linnaeus was interested in a wide range of topics in natural history, but his primary interest was classification. His goal was to produce a system by which one could correctly identify organisms, and his method was to use the common Aristotelian technique of downward classification. This method involved taking a class of objects, dividing it into two groups (for example, the class of living organisms can be divided into animals and nonanimals), and continuing the process of dichotomous divisions until only the lowest set, the species, which could not be further divided, remained. Such a system was highly artificial, since the basis for many of the divisions was arbitrary. Based on his philosophical and theological commitment to the argument from design, however, Linnaeus believed that if the correct character was chosen as the basis of division, natural relationships would be revealed. In his characteristically arrogant manner, he claimed to have discovered that correct trait and built his system around it. He called it his “sexual system.”

Linnaeus first presented his ideas in A General System of Nature. In its first edition, the book contained only about a dozen pages and presented what Linnaeus referred to as a natural system. His only taxonomic groupings at this stage were class, genus, and species. In this work, he accepted the ideas of earlier taxonomists that species, which he took as the starting point for his system, were immutable and that each one had been created at the beginning of time. Moreover, he believed that every species must be strictly intermediate between two other species in order to maintain the plenitude of the chain of being.

Plants were assigned to a particular species based on the number and position of their reproductive parts (hence the term “sexual system”). Four elementary criteria were used to classify a plant: number, shape, proportion, and situation. Thus, to assign a plant to a particular species, one counted the number of stamens (the pollen-bearing male organs) and pistils (the female organs), examined them to see if they were separated or fused, compared relative size, determined their position vis-à-vis each other and the other flower parts, and found out whether both male and female elements were on the same flower. Species that had obvious similarities were brought together into a higher-level grouping labeled “genus”; similar genera were grouped into classes. Linnaeus believed that only the first two categories—species and genus—were natural ones, with higher division existing only as an artificial aid for the ordering of nature.

Since the primary purpose of a classification system, as far as Linnaeus was concerned, was to allow one to know the plants, that is, to be able to name them quickly and accurately, it did not matter if the system mixed natural and artificial categories. The value of the Linnaean system was that any botanist who learned a few parts of a flower and fruit could come to the same decision as to its name that Linnaeus did. This value was quickly recognized and greatly appreciated given the state of plant taxonomy at that time. It is estimated that in 1600, a total of approximately six thousand plants had been recognized; by 1700, an additional twelve thousand plants had been discovered. It was therefore crucial to know what a plant was and to what group of plants it belonged. Linnaeus immediately became famous for the way in which he solved these problems. His victory was complete when Bernard de Jussieu, the leader of French botany, declared in 1739 that the Linnaean system was preferable to that of the Frenchman Tournefort.

Linnaeus was not content with his first attempt. He published Fundamenta botanica (1736; foundation of botany) the following year and Classes plantarum (1738; classes of plants) two years later. Including A General System of Nature, which went through ten revisions by 1758, these works contain the basis of all the essential changes that Linnaeus would bring to systematics. By the tenth edition of A General System of Nature, which had grown to two volumes and 1,384 pages, Linnaeus had added the category “order” above class, and he recognized twenty-four classes of plants. The number of pistils determined the order to which the plant was assigned, while the number of stamens determined the class. Moreover, he had begun to use the only two natural categories—genus and species—as the basis for naming plants.

The contribution for which he is best known, the binomial system of nomenclature, was first articulated in Species plantarum (1753; species of plants), in which Linnaeus himself classified more than eight thousand plants from all over the world. Yet Linnaeus viewed the binomial system as only a minor modification and outgrowth of his sexual system. Having assigned an organism to a particular genus and species as a result of the characteristics of the reproductive organs, he suggested using the Latinized names of the genus and species together to identify a specific plant. This reform is currently viewed as his most lasting contribution to biology, for it could be retained even when the specific Linnaean system of classification was rejected in favor of one acknowledging phylogenetic relationships.

During his later years, Linnaeus was increasingly plagued by poor health. He suffered from migraine headaches, rheumatism, fevers, and bouts of depression. In 1761, he was ennobled and appointed a member of the Swedish House of Lords. In 1774, he suffered the first of a series of stroke-like attacks, which he called his “message of death.” A second attack in 1778 left him totally incapacitated, and he died in the early winter of that year. A family quarrel between his widow and daughters, on one side, and his son, on the other, over possession of his library, herbarium, and papers was finally settled in favor of his son, who died shortly after the arrangements were completed. Linnaeus’s widow then sold the collection to a London physician, J. E. Smith, who, along with two friends, founded the Linnean Society, the organization that would become famous for first receiving the papers of Alfred Russell Wallace and Charles Darwin on their theory of evolution by natural selection.

Significance

Peter J. Bowler described Linnaeus’s goal for his work very well when he wrote:

If the species were created by God, one could assume that a rational Creator would have formed the world according to a meaningful order that man himself could hope to understand. Linnaeus believed that he had been privileged to see the outline of the Creator’s plan and his efforts to represent it would become the basis of a new biology.

In fact, his “new biology” was more adapted to botany than to zoology. With his system, he was personally able to classify more than eighteen thousand species of plants. His attempts to classify animals, however, created duplications and confusion, primarily because he could not find a characteristic that would work for animals the way reproductive structures did for plants. His inclination to classify everything can also be seen in his attempts to classify diseases, humans, and even botanists.

Linnaeus should not be regarded as merely a taxonomist. His essays and lectures provide evidence that he was exploring ideas that would now be considered basic to ecology and biogeography. He sought to develop, within both a theological and biological context, a concept of the harmony of nature. Finally, he tried not to allow his philosophical or theological positions to blind him to his data. As a result of his evidence, he revised his views on fixity of species to allow for a kind of evolution—formation of new species by hybridization—below the genus level.

Bibliography

Blunt, Wilfrid. The Compleat Naturalist: A Life of Linnaeus. New ed. Princeton, N.J.: Princeton University Press, 2001. Originally published in 1971, some critics consider this the definitive biography. Blunt recounts Linnaeus’s life and work, quoting from Linnaeus’s writings and placing his botanical discoveries within the context of eighteenth century Enlightenment thought. Contains an appendix describing Linnaean classification, and two hundred illustrations, including some eighteenth century botanical drawings.

Bowler, Peter J. Evolution: The History of an Idea. Berkeley: University of California Press, 1984. Bowler traces the interactions of philosophy, natural history, and taxonomic systems to show their effects on the concepts of species and species change. He furnishes an excellent context for Linnaeus and shows the effect of his work on future evolutionary ideas.

Fara, Patricia. Sex, Botany, and Empire: The Story of Carl Linnaeus and Joseph Banks. New York: Columbia University Press, 2004. Despite its title, the book focuses more on Banks and Linnaeus than on sex and botany, describing how Linnaeus developed a system to classify organisms and how Banks, who never met Linnaeus, popularized the classification system.

Frängsmyr, Tore, ed. Linnaeus: The Man and His Work. Berkeley: University of California Press, 1983. This edited collection of works by Swedish scholars describes the personality of Linnaeus and examines his contributions to botany, geology, and human anthropology. It also looks at him as a Swedish national hero, trying to understand the difference between the man and his works, and the myth which has developed.

Gardner, Eldon J. History of Biology. 3d ed. Minneapolis, Minn.: Burgess, 1972. The chapter “Systematizers of Plants and Animals” describes the various pre-Linnaean systems of classification, the contributions of Linnaeus (including a minimum amount of biographical material), and the post-Linnaean strategies with respect to taxonomy. There are helpful chronological and reference sections at the end of the chapter.

Gilbert, Bil. “The Obscure Fame of Carl Linnaeus.” Audubon 86 (September, 1984): 102-114. This relatively short article gives personal glimpses of Linnaeus while discussing his many scientific contributions. It does not analyze the strengths and weaknesses of his works, but it does create a good introduction to his ideas and the intellectual environment in which he worked.

Hankins, Thomas. Science and the Enlightenment. New York: Cambridge University Press, 1985. The last third of chapter 5 is an excellent introduction to the philosophical commitments underlying eighteenth century taxonomy, showing how Linnaeus was both a product of his time and an innovator. The bibliography for the chapter provides the serious reader with several references dealing with specific issues concerning Linnaeus’s system.

Mayr, Ernst. The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Cambridge, Mass.: Harvard University Press, 1982. Mayr’s treatment of Linnaeus places his work within the context of other naturalists, making clear the extent to which Linnaeus depended on other ideas and the degree to which his work was original.

Weinstock, John, ed. Contemporary Perspectives on Linnaeus. Lanham, Md.: University Press of America, 1985. This series of essays covers a number of aspects of Linnaeus’s work, including his relationship to Scholasticism, his impact on the development of evolutionary theory and the impact of evolutionary ideas on Linnaean taxonomy, the connection between Linnaeus’s theology and his understanding of ecological relationships and the problem of extinction, his anthropology, and his status as a Swedish folk hero.