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Orthogenesis is an obsolete biological hypothesis that have an innate tendency to evolution in a definite direction teleology, due to some internal mechanism or "driving force". According to the theory, the largest-scale trends in evolution have an absolute goal such as increasing biological complexity. Prominent historical figures who have championed some form of evolutionary progress include Jean-Baptiste Lamarck, Pierre Teilhard de Chardin, and Henri Bergson.
The term orthogenesis was introduced by Wilhelm Haacke in 1893 and popularized by Theodor Eimer five years later. Proponents of orthogenesis had rejected the theory of natural selection as the organizing mechanism in evolution for a rectilinear (straight-line) model of directed evolution. With the emergence of the modern synthesis, in which genetics was integrated with evolution, orthogenesis and other alternatives to Darwinism were largely abandoned by biologists, but the notion that evolution represents progress is still widely shared; modern supporters include E. O. Wilson and Simon Conway Morris. The evolutionary biologist Ernst Mayr made the term effectively taboo in the journal Nature in 1948, by stating that it implied "some supernatural force".Letter from Ernst Mayr to R. H. Flower, Evolution papers, 23 January 1948 The American paleontologist George Gaylord Simpson (1953) attacked orthogenesis, linking it with vitalism by describing it as "the mysterious inner force". Despite this, many museum displays and textbook illustrations continue to give the impression that evolution is directed.
The philosopher of biology Michael Ruse notes that in popular culture, evolution and progress are synonyms, while the unintentionally misleading image of the March of Progress, from apes to modern humans, has been widely imitated.
In 1922, the zoologist Michael F. Guyer wrote:
According to Susan R. Schrepfer in 1983:
In 1988, Francisco J. Ayala defined progress as "systematic change in a feature belonging to all the members of a sequence in such a way that posterior members of the sequence exhibit an improvement of that feature". He argued that there are two elements in this definition, directional change and improvement according to some standard. Whether a directional change constitutes an improvement is not a scientific question; therefore Ayala suggested that science should focus on the question of whether there is directional change, without regard to whether the change is "improvement". This may be compared to Stephen Jay Gould's suggestion of "replacing the idea of progress with an operational notion of directionality".
In 1989, Peter J. Bowler defined orthogenesis as:
In 1996, Michael Ruse defined orthogenesis as "the view that evolution has a kind of momentum of its own that carries organisms along certain tracks".
In 1898, after studying butterfly coloration, Theodor Eimer (1843–1898) introduced the term orthogenesis with a widely read book, On Orthogenesis: And the Impotence of Natural Selection in Species Formation. Eimer claimed there were trends in evolution with no adaptation significance that would be difficult to explain by natural selection. To supporters of orthogenesis, in some cases species could be led by such trends to extinction. Eimer linked orthogenesis to Lamarckism in his 1890 book Organic Evolution as the Result of the Inheritance of Acquired Characteristics According to the Laws of Organic Growth. He 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. Gould described Eimer as a materialist who rejected any vitalist or teleological approach to orthogenesis, arguing that Eimer's criticism of natural selection was common amongst many evolutionists of his generation; they were searching for alternative mechanisms, as they had come to believe that natural selection could not create new species.
Though evolution is not progressive, it does sometimes proceed in a linear way, reinforcing characteristics in certain lineages, but such examples are entirely consistent with the modern neo-Darwinian theory of evolution. 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. The term orthoselection was first used by Ludwig Hermann Plate, and was incorporated into the modern synthesis by Julian Huxley and Bernard Rensch.
Recent work has supported the mechanism and existence of adaptation, meaning that limited local orthogenesis is now seen as possible.
| + Theories of orthogenesis in evolutionary biology ! Author !! Title !! Field !! Date !! Lamarckism !! Mutationism !! Nat. Sel. !! Vitalism !! Features | |
| In his Philosophie Zoologique, inherent progressive tendency drives organisms continuously towards greater complexity, in separate lineages (phylum), no extinction. ("Lamarckism", use and disuse, and inheritance of acquired characteristics, was a secondary aspect of this, an adaptive force creating species within a phylum.) | |
| "Forces which are not directed—so-called blind forces—can never produce order." | |
| Wholly separate lines of descent with no common ancestor | |
| Combined orthogenetic constraints with Lamarckian use and disuse. "On the Origin of Genera"; See also Cope's rule (linear increase in size of species) | |
| An "idioplasm" transmitted inherited characteristics; many evolutionary developments nonadaptive; variation internally programmed. | |
| 1852 | Yes|| || || | Cultural value of progress; "Spencer has no rivals when it comes to open, flagrant connections of social Progress with evolutionary progress."—Michael Ruse
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| Origin of Species is somewhat progressionist, e.g. man higher than animals, alongside natural selection Pangenesis theory of inheritance by gemmules from all over body was Lamarckism: parents could pass on traits acquired in lifetime. | |
| Accompanied by epimorphism, a tendency to increasing perfection | |
| On Orthogenesis: And the Impotence of Natural Selection in Species Formation: trends in evolution with no adaptive significance, claimed hard to explain by natural selection. | |
| Creative Evolution | |
| Combined theory | |
| Hologenesis: a New Theory of Evolution and the Geographical Distribution of Living Beings | |
| Orthogenetic Evolution in Pigeons posthumous | |
| Chemical forces direct evolution, leading to humans | |
| based on Dollo's law of irreversibility of evolution (which can be explained without orthogenesis as a statistical improbability that a path should be exactly reversed) | |
| Directed loss of functions in microorganisms | |
| Start is random metakinesis, generating variety; then palingenesis (in Beurlen's sense, repeating developmental pathway of ancestors) as mechanism for orthogenesis | |
| Combined orthogenesis with Lamarckism (inheriting acquired characteristics after heat shock as dauermodifications, passed on by plasmatic inheritance in the cytoplasm) | |
| a force "working upon some definite law that we do not yet comprehend", compromise between special creation and natural selection, driven by large mutations involving chromosome alterations | |
| In book Human Destiny, essentially religious | |
| L'Homme et L'Evolution | |
| In book Cell and Psyche, essentially religious | |
| Basic Questions in Paleontology: Geologic Time, Organic Evolution and Biological Systematics; evolution due to periodic cycle of processes dictated by factors internal to organism. | |
| The Phenomenon of Man posthumous; combined orthogenesis with non-material vitalist directive force aiming for a supposed "Omega Point" with creation of consciousness. Noosphere concept from Vladimir Vernadsky. Censured by Gaylord Simpson for nonscientific spiritualistic "doubletalk". | |
| mechanistic, caused by developmental constraints or phylogenetic constraints | |
| Natural selection is immaterial so cannot work. |
The various alternatives to Darwinian evolution by natural selection were not necessarily mutually exclusive. The evolutionary philosophy of the American palaeontologist Edward Drinker Cope is a case in point. Cope, a religious man, began his career denying the possibility of evolution. In the 1860s, he accepted that evolution could occur, but, influenced by Agassiz, rejected natural selection. Cope accepted instead the theory of recapitulation of evolutionary history during the growth of the embryo - that ontogeny recapitulates phylogeny, which Agassiz believed showed a divine plan leading straight up to man, in a pattern revealed both in embryology and palaeontology. Cope did not go so far, seeing that evolution created a branching tree of forms, as Darwin had suggested. Each evolutionary step was however non-random: the direction was determined in advance and had a regular pattern (orthogenesis), and steps were not adaptive but part of a divine plan (theistic evolution). This left unanswered the question of why each step should occur, and Cope switched his theory to accommodate functional adaptation for each change. Still rejecting natural selection as the cause of adaptation, Cope turned to Lamarckism to provide the force guiding evolution. Finally, Cope supposed that Lamarckian use and disuse operated by causing a vitalist growth-force substance, "bathmism", to be concentrated in the areas of the body being most intensively used; in turn, it made these areas develop at the expense of the rest. Cope's complex set of beliefs thus assembled five evolutionary philosophies: recapitulationism, orthogenesis, theistic evolution, Lamarckism, and vitalism. Other palaeontologists and field naturalists continued to hold beliefs combining orthogenesis and Lamarckism until the modern synthesis in the 1930s.
The modern synthesis of the 1930s and 1940s, in which the genetics mechanisms of evolution were incorporated, appeared to refute the hypothesis for good. As more was understood about these mechanisms it came to be held that there was no naturalistic way in which the newly discovered mechanism of heredity could be far-sighted or have a memory of past trends. Orthogenesis was seen to lie outside the methodological naturalism of the sciences. (2026). 9781405156257, Wiley. ISBN 9781405156257
By 1948, the evolutionary biologist Ernst Mayr, as editor of the journal Evolution, made the use of the term orthogenesis taboo: "It might be well to abstain from use of the word 'orthogenesis' .. since so many of the geneticists seem to be of the opinion that the use of the term implies some supernatural force." For these and other reasons, belief in evolutionary progress has remained "a persistent heresy", among evolutionary biologists including E. O. Wilson and Simon Conway Morris, although often denied or veiled. The philosopher of biology Michael Ruse wrote that "some of the most significant of today's evolutionists are progressionists, and that because of this we find (absolute) progressionism alive and well in their work." He argued that progressionism has harmed the status of evolutionary biology as a mature, professional science. Presentations of evolution remain characteristically progressionist, with humans at the top of the "Tower of Time" in the Smithsonian Institution in Washington D.C., while Scientific American magazine could illustrate the history of life leading progressively from mammals to dinosaurs to primates and finally man. Ruse noted that at the popular level, progress and evolution are simply synonyms, as they were in the nineteenth century, though confidence in the value of cultural and technological progress has declined.
The discipline of evolutionary developmental biology, however, is open to an expanded concept of heredity that incorporates the physics of self-organization. With its rise in the late 20th-early 21st centuries, ideas of constraint and preferred directions of morphological change have made a reappearance in evolutionary theory.see, for example,
Popular perception, however, had seized upon the idea of linear progress. Edward Linley Sambourne's Man is But a Worm, drawn for Punch's Almanack, mocked the idea of any evolutionary link between humans and animals, with a sequence from chaos to earthworm to apes, primitive men, a Victorian beau, and Darwin in a pose that according to Tucker recalls Michelangelo's figure of Adam in his fresco adorning the ceiling of the Sistine Chapel. This was followed by a flood of variations on the evolution-as-progress theme, including The New Yorkers 1925 "The Rise and Fall of Man", the sequence running from a chimpanzee to Neanderthal man, Socrates, and finally the lawyer William Jennings Bryan who argued for the anti-evolutionist prosecution in the Scopes Trial on the State of Tennessee law limiting the teaching of evolution. Tucker noted that Rudolph Franz Zallinger's 1965 "The Road to Homo Sapiens" fold-out illustration in F. Clark Howell's Early Man, showing a sequence of 14 walking figures ending with modern man, fitted the palaeoanthropological discoveries "not into a branching Darwinian scheme, but into the framework of the original Huxley diagram." Howell ruefully commented that the "powerful and emotional" graphic had overwhelmed his Darwinian text.
Ruse concludes his detailed analysis of the idea of Progress, meaning a progressionist philosophy, in evolutionary biology by stating that evolutionary thought came out of that philosophy. Before Darwin, Ruse argues, evolution was just a pseudoscience; Darwin made it respectable, but "only as popular science". "There it remained frozen, for nearly another hundred years", until mathematicians such as Fisher provided "both models and status", enabling evolutionary biologists to construct the modern synthesis of the 1930s and 1940s. That made biology a professional science, at the price of ejecting the notion of progress. That, Ruse argues, was a significant cost to "people biologists still firmly committed to Progress" as a philosophy.
(2026). 9780262134194, Bradford. ISBN 9780262134194
In popular culture
In popular culture, progressionist images of evolution are widespread. The historian Jennifer Tucker, writing in The Boston Globe, notes that Thomas Henry Huxley's 1863 illustration comparing the skeletons of apes and humans "has become an iconic and instantly recognizable visual shorthand for evolution." She calls its history extraordinary, saying that it is "one of the most intriguing, and most misleading, drawings in the modern history of science." Nobody, Tucker observes, supposes that the "monkey-to-man" sequence accurately depicts Darwinian evolution. The Origin of Species had only one illustration, a diagram showing that random events create a process of branching evolution, a view that Tucker notes is broadly acceptable to modern biologists. But Huxley's image recalled the great chain of being, implying with the force of a visual image a "logical, evenly paced progression" leading up to Homo sapiens, a view denounced by Stephen Jay Gould in Wonderful Life.
Sliding between meanings
Scientists, Ruse argues, continue to slide easily from one notion of progress to another: even committed Darwinians like Richard Dawkins embed the idea of cultural progress in a theory of cultural units, , that act much like genes. Dawkins can speak of "progressive rather than random ... trends in evolution". Dawkins and John Krebs deny the "earlier Darwinian prejudice" that there is anything "inherently progressive about evolution", but, Ruse argues, the feeling of progress comes from evolutionary which remain in Dawkins's words "by far the most satisfactory explanation for the existence of the advanced and complex machinery that animals and plants possess".
Facilitated variation
Biology has largely rejected the idea that evolution is guided in any way, but the evolution of some features is indeed facilitated by the genes of the developmental-genetic toolkit studied in evolutionary developmental biology. An example is the development of wing pattern in some species of Heliconius butterfly, which have independently evolved similar patterns. These butterflies are Müllerian mimics of each other, so natural selection is the driving force, but their wing patterns, which arose in separate evolutionary events, are controlled by the same genes.
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