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Orthogenesis also known as orthogenetic evolution is an obsolete biological hypothesis that organisms have an innate tendency to evolve in a unilinear fashion due to some internal mechanism or "driving force".[1][2]

American paleontologist George Gaylord Simpson (1953) in an attack on orthogenesis described it as "the mysterious inner force".[3] Classic proponents of orthogenesis rejected the theory of natural selection as the organizing mechanism in evolution for a rectilinear model of directed evolution. The term orthogenesis was popularized by Theodor Eimer.[4]

Which the emergence of the modern evolutionary synthesis, in which the genetic mechanisms of evolution were discovered, the hypothesis of orthogenesis was refuted.[5][6]


Orthogenesis was a term first used by the biologist Wilhelm Haacke in 1893. Theodor Eimer was the first to give the word a definition; he defined orthogenesis as "the general law according to which evolutionary development takes place in a noticeable direction, above all in specialized groups."[7]

In 1922, the zoologist Michael F. Guyer wrote:

[Orthogenesis] has meant many different things to many different people, ranging from a, mystical inner perfecting principle, to merely a general trend in development due to the natural constitutional restrictions of the germinal materials, or to the physical limitations imposed by a narrow environment. In most modern statements of the theory, the idea of continuous and progressive change in one or more characters, due according to some to internal factors, according to others to external causes-evolution in a "straight line" seems to be the central idea.[8]

Orthogenesis was often related to neo-Lamarckism; Eimer popularized the concept of orthogenesis in his book Organic Evolution as the Result of the Inheritance of Acquired Characteristics According to the Laws of Organic Growth (1890). In his work Eimer used examples such as the evolution of the horse to argue that evolution had proceeded in a regular single direction that was difficult to explain by random variation. To orthogenesis trends in evolution were often nonadaptive and in some cases species could be led to extinction.[9]

Peter J. Bowler has defined orthogenesis as:

Literally, the term means evolution in a straight line, generally assumed to be evolution that is held to a regular course by forces internal to the organism. Orthogenesis assumes that variation is not random but is directed towards fixed goals. Selection is thus powerless, and the species is carried automatically in the direction marked out by internal factors controlling variation.[1]

According to (Schrepfer, 1983):

Orthogenesis meant literally "straight origins", or "straight line evolution". The term varied in meaning from the overtly vitalistic and theological to the mechanical. It ranged from theories of mystical forces to mere descriptions of a general trend in development due to natural limitations of either the germinal material or the environment... By 1910, however most who subscribed to orthogenesis hypothesized some physical rather than metaphysical determinant of orderly change.[10]

Orthogenesis has been described as an "anti-Darwinian" evolutionary theory because of its stance on the Darwinian mechanism of natural selection.[11] After studying butterfly coloration Theodor Eimer published a widely read book on orthogenesis titled On Orthogenesis: And the Impotence of Natural Selection in Species Formation (1898). In the book Eimer claimed there were trends in evolution with no adaptive significance and thus would be difficult to explain by natural selection.[12] Stephen J. Gould wrote a detailed biography of Eimer. Gould wrote that Eimer was a materialist who rejected any vitalist or teleological approach to orthogenesis and explained that Eimer's criticism of natural selection was common amongst many evolutionists of his generation as they were searching for alternative evolutionary mechanisms as it was believed at the time that natural selection could not create new species.[13]


The orthogenesis hypothesis had a significant following in the 19th century when a number of evolutionary mechanisms, such as Lamarckism, were being proposed. Jean-Baptiste Lamarck himself accepted the idea, and it had a central role in his theory of inheritance of acquired characteristics, the hypothesized mechanism of which resembled the "mysterious inner force" of orthogenesis. Orthogenesis was particularly accepted by paleontologists who saw in their fossils a directional change, and in invertebrate paleontology thought there was a gradual and constant directional change. Those who accepted orthogenesis in this way, however, did not necessarily accept that the mechanism that drove orthogenesis was teleological. In fact, Darwin himself rarely used the term "evolution" now so commonly used to describe his theory, because in Darwin's time, evolution usually was associated with some sort of progressive process like orthogenesis, and this had been common usage since at least 1647.[14]

The Russian biologist Karl Ernst von Baer had believed in a teleological force in nature and was an influence on orthogenesis.[15] An early theory of orthogenesis was the "inner perfecting principle" of Carl Nägeli. According to Nageli many evolutionary developments were nonadaptive and variation was internally programmed. The Russian biologist Lev Berg developed his own theory of orthogenesis known as nomogenesis.[1] Albert von Kölliker's orthogenetic theory was known as heterogenesis.[16] The paleontologist Henry Fairfield Osborn also supported a theory of orthogenesis known as aristogenesis.[17] The philosopher Henri Bergson linked orthogenesis with vitalism by a creative force in evolution known as élan vital in his book Creative Evolution (1907).[18]

Scientists such as Metcalf (1914), Coulter (1915), Jordan (1920) and Lipman (1922) claimed evidence for orthogenesis in bacteria, fish populations and plants.[19][20][21][22] The zoologist Charles Otis Whitman was an advocate of orthogenesis and rejected Lamarckism, Darwinism and mutationism. Whitman only wrote one book on orthogenesis, which was published nine years after his death in 1919. Titled Orthogenetic Evolution in Pigeons, the book was published in a three volume set titled Posthumous Works of Charles Otis Whitman.[23] Stephen Jay Gould wrote that the book was written "too late, to win any potential influence".[24]

In 1930 the American zoologist Austin Hobart Clark attempted to modify orthogenesis with his theory of zoogenesis.[25] In the 1950s the German paleontologist Otto Schindewolf developed a theory of orthogenesis, which claimed that variation tends to move in a predetermined direction.[26] His theory became known as typostrophism and stated that evolution occurs due to a periodic cyclic model of evolutionary processes which are predestined to go through a life cycle dictated by factors internal to the organism.[27]

Collapse of the hypothesis[edit]

The orthogenesis hypothesis began to collapse when it became clear that it could not explain the patterns found by paleontologists in the fossil record, which was non-linear with many complications. The hypothesis was generally abandoned when no mechanism could be found that would account for the process, and the theory of evolution by natural selection became the prevailing theory of evolution.[28]

The modern evolutionary synthesis, in which the genetic mechanisms of evolution were discovered, refuted the hypothesis for good. As more was understood about these mechanisms it became apparent that there was no possible naturalistic way in which the newly discovered mechanism of heredity could be far-sighted or have a memory of past trends. Thus it fell outside the purview of the methodological naturalism of the sciences.

The orthogenetic hypothesis, however, died hard. Even Darwin was at first not opposed to orthogenic thinking, as this quote from the 1911 Encyclopædia Britannica demonstrates:

Darwin and his generation were deeply imbued with the Butlerian tradition, and regarded the organic world as almost a miracle of adaptation, of the minute dovetailing of structure, function and environment. Darwin certainly was impressed with the view that natural selection and variation together formed a mechanism, the central product of which was adaptation. From the Butlerian side, too, came the most urgent opposition to Darwinism. How is it possible, it was said, that fortuitous variations can furnish the material for the precise and balanced adaptations that all nature reveals? Selection cannot create the materials on which it is supposed to operate; the beginnings of new organs, the initial stages of new functions cannot be supposed to have been useful. Moreover, many naturalists, especially those concerned with palaeontology, pointed to the existence of orthogenetic series, of long lines of ancestry, which displayed not a sporadic differentiation in every direction, but apparently a steady and progressive march in one direction.[29]

Edward Drinker Cope put such a line of argument in the most cogent fashion; the course of evolution, both in the production of variations and their selection, seemed to him to imply the existence of an originative, conscious and directive force, for which he invented the term bathmism (Gr. βαθμ, a step or beginning). On the other hand, dislike of mystical interpretations of natural facts has driven many capable naturalists to another extreme and has led them to insist on the all-powerfulness of natural selection and on the complete indefiniteness of variation. The apparent opposition between the conflicting schools is more acute than the facts justify.... there is no connection between the appearance of the variation and the use to which it may be put... in one sense it is a mere coincidence if a particular variation turn out to be useful. But there are several directions in which the field of variation appears to be not only limited but defined in a certain direction. Obviously variations depend on the constitution of the varying organism; a modification, whether it be large or small, is a modification of an already definite and limited structure.... A continuous environment both from the point of view of production of variation and selection of variation would appear necessarily to result in a series with the appearance of orthogenesis. The history of the organic world displays many successful series and these, as they have survived, must inevitably display orthogenesis to some extent; but it also displays many failures which indeed may be regarded as showing that the limitation of variation has been such that the organisms have lost the possibility of successful response to a new environment.[29]

A few hung on to the orthogenesis hypothesis as late as the 1950s by claiming that the processes of macroevolution, the long term trends in evolution, were distinct from the processes of microevolution (genetic variation and natural selection) which were by then well understood and it was known they could not behave in an orthogenetic manner. Teilhard de Chardin, a Jesuit paleontologist, in The Phenomenon of Man (a book influential among non-scientists that was published four years after his death in 1959) argued for evolution aiming for the "Omega Point", while putting man at the center of the universe and accounting for original sin (Dennett 1995, von Kitzing 1998). The term Chardin used for this was "directed additivity". This form of orthogenesis has now also been abandoned as more about evolutionary processes has been discovered (Wilkins 1997).

The refutation of orthogenesis had some ramifications in the field of philosophy, as it questioned the idea of teleology or existence of immutable "forms" in nature, as first developed by Aristotle and accepted by Immanuel Kant, who had greatly influenced many scientists. Before the scientific and philosophical revolution that began with Charles Darwin's work, the prevailing philosophy was that the world was teleological and purposeful, and that science was the study of God's creation. The interpretation of evolutionary mechanisms (which of themselves assert neither necessary progression nor finality) as supporting a naturalistic worldview has led to a shift in what science and scientists are perceived to be.

Modern co-opted usage[edit]

Though linear, progressive evolution has been refuted, it is not true that evolution never proceeds in a linear way, reinforcing characteristics, in certain lineages at times, for example, during a period of slow, sustained environmental change, but such examples are entirely consistent with the modern neo-Darwinian theory of evolution.[30]

These examples have sometimes been referred to as orthoselection but are not strictly orthogenetic, and simply appear as linear and constant changes because of environmental and molecular constraints on the direction of change.[31][32] The term orthoselection was first used by Ludwig Hermann Plate, and was incorporated into the modern evolutionary synthesis by Julian Huxley and Bernard Rensch.[33]

See also[edit]


  1. ^ a b c Bowler, Peter J. (1989). Evolution: The History of an Idea. University of California Press. pp. 268-270. ISBN 0-520-06385-6
  2. ^ Mayr, Ernst. (1988). Toward a New Philosophy of Biology: Observations of an Evolutionist. Harvard University Press. p. 499. ISBN 0-674-89666-1
  3. ^ Simpson, George Gaylord. (1953). Life of the Past: An Introduction to Paleontology. Yale University Press. p. 125
  4. ^ Ulett, Mark A. (2014). Making the case for orthogenesis: The popularization of definitely directed evolution (1890–1926). Studies in History and Philosophy of Biological and Biomedical Sciences 45: 124-132
  5. ^ Levinton, Jeffrey S. (2001). Genetics, Paleontology, and Macroevolution. Cambridge University Press. pp. 14-16. ISBN 0-521-80317-9
  6. ^ Montgomery, Georgina M; Largent, Mark A. (2015). A Companion to the History of American Science. Wiley. p. 218. ISBN 978-1-4051-5625-7 "With the integration of Mendelian genetics and population genetics into evolutionary theory in the 1930s a new generation of biologists applied mathematical techniques to investigate how changes in the frequency of genes in populations combined with natural selection could produce species change. This demonstrated that Darwinian natural selection was the primary mechanism for evolution and that other models of evolution, such as neo-Lamarckism and orthogenesis, were invalid."
  7. ^ David H. Lane. (1996). The Phenomenon of Teilhard: Prophet for a New Age. Mercer University Press. p. 61. ISBN 978-0865544987
  8. ^ Michael. F. Guyer. (1922). Orthogenesis and Serological Phenomena. The American Naturalist. Vol. 56, No. 643. pp. 116-133.
  9. ^ Jan Sapp. (2003). Genesis: The Evolution of Biology. pp. 69-70. OUP USA. ISBN 978-0195156195
  10. ^ Susan R. Schrepfer. (1983). Fight to Save the Redwoods: A History of the Environmental Reform, 1917-1978. University of Wisconsin Press. pp. 81-82. ISBN 978-0299088545
  11. ^ Peter J. Bowler. (1992). The Eclipse of Darwinism: Anti-Darwinian Evolution Theories in the Decades around 1900. The Johns Hopkins University Press. pp. 141-181. ISBN 978-0801843914
  12. ^ Timothy Shanahan. (2004). The Evolution of Darwinism: Selection, Adaptation, and Progress in Evolutionary Biology. Cambridge University Press. p. 121. ISBN 978-0521541985
  13. ^ Stephen Jay Gould. (2002). The Structure of Evolutionary Theory. Harvard University Press. pp. 355-364. ISBN 978-0674006133
  14. ^ Darwin's Dilemma: The Odyssey of Evolution, Stephen Jay Gould, an essay in Ever Since Darwin: Reflections in Natural History, W. W. Norton, 1977, ISBN 0-393-06425-5
  15. ^ Marcello Barbieri. (2013). Biosemiotics: Information, Codes and Signs in Living Systems. Nova Science Publishers. p. 7. ISBN 978-1600216121. Eric Paul Jacobsen. (2005). From Cosmology to Ecology: The Monist World-view in Germany from 1770 to 1930. p. 100. Peter Lang Pub Inc. ISBN 978-0820472317
  16. ^ Alexander Vucinich. (1988). Darwin in Russian Thought. University of California Press. p. 137. ISBN 0520062833
  17. ^ David Rains Wallace. (2005). Beasts of Eden: Walking Whales, Dawn Horses, And Other Enigmas of Mammal Evolution. University of California Press. p. 96. ISBN 978-0520246843
  18. ^ Peter J. Bowler. (1992). The Eclipse of Darwinism: Anti-Darwinian Evolution Theories in the Decades around 1900. The Johns Hopkins University Press. pp. 116-117. ISBN 978-0801843914
  19. ^ Maynard M. Metcalf. (1913). Adaptation Through Natural Selection and Orthogenesis. The American Naturalist. Vol. 47, No. 554. pp. 65-71.
  20. ^ John M. Coulter. (1915). A Suggested Explanation of ``Orthogenesis in Plants. Science , New Series, Vol. 42, No. 1094. pp. 859-863.
  21. ^ David Starr Jordan. (1920). Orthogenesis among Fishes. Science, New Series, Vol. 52, No. 1331. pp. 13-14.
  22. ^ Chas. B. Lipman. (1922). Orthogenesis in Bacteria. The American Naturalist. Vol. 56, No. 643. pp. 105-115.
  23. ^ Castle, W.E. (1920). "Review of Orthogenetic Evolution in Pigeons". The American Naturalist 54 (631): 188–192. doi:10.1086/279751. 
  24. ^ Stephen Jay Gould. (2002). The Structure of Evolutionary Theory. Harvard University Press. p. 283. ISBN 978-0674006133
  25. ^ Austin Hobart Clark, The New Evolution: Zoogenesis, 1930
  26. ^ Chunglin Kwa. (2011). Styles of Knowing: A New History of Science from Ancient Times to the Present. University of Pittsburgh Press. p. 237. ISBN 978-0822961512
  27. ^ William A. Dimichele. (1995). Basic Questions in Paleontology: Geologic Time, Organic Evolution, and Biological Systematics, by Otto H. Schindewolf. Review of Palaeobotany and Palynology 84. 481-483.
  28. ^ Mayr, Ernst. (1982). The Growth of Biological Thought: Diversity, Evolution, and Inheritance. Harvard University Press. pp. 530-531. ISBN 0-674-36446-5
  29. ^ a b The Encyclopædia Britannica: A Dictionary of Arts, Sciences, Literature and General Information, Eleventh Edition, Copyright in all countries subscribing the Berne Convention by the Chancellor, Masters and Scholars of the University of Cambridge, Copyright in the United States of America by the Encyclopædia Britannica Company, London, May 31, 1911.
  30. ^ Jepsen, Glenn L. (1949). Selection. "Orthogenesis," and the Fossil Record. Proceedings of the American Philosophical Society. Vol. 93, No. 6, Natural Selection and Adaptation, pp. 479-500.
  31. ^ Jacobs, Susan C., Allan Larson & James M. Cheverud, (1995). Phylogenetic Relationships and Orthogenetic Evolution of Coat Color Among Tamarins (Genus Saguinus). Syst. Biol. 44(4): 515-532.
  32. ^ Ranganath, H. A., & Hägel, K, 1981. Karyotypic orthoselection in Drosophila. Natur Wissenschaften. 68(10): 527-528.
  33. ^ Levit, Georgy S; Olsson, Lennart. (2007). Evolution on Rails Mechanisms and Levels of Orthogenesis. In Volker Wissemann. Annals of the History and Philosophy of Biology 11/2006. Universitätsverlag Göttingen. pp. 113-115.

Further reading[edit]

Public Domain This article incorporates text from a publication now in the public domainChisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press.