![Transformation of Argyropelecus olfersi into Sternoptyx diaphana](https://upload.wikimedia.org/wikipedia/commons/e/e9/Transformation_of_Argyropelecus_olfersi_into_Sternoptyx_diaphana.jpg)
Biological or process structuralism is a school of biological thought that objects to an exclusively
Darwinian
Darwinism is a theory of biological evolution developed by the English naturalist Charles Darwin (1809–1882) and others, stating that all species of organisms arise and develop through the natural selection of small, inherited variations that ...
or
adaptationist
Adaptationism (also known as functionalism) is the Darwinian view that many physical and psychological traits of organisms are evolved adaptations. Pan-adaptationism is the strong form of this, deriving from the early 20th century modern synthesis ...
explanation of
natural selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
such as is described in the
20th century's modern synthesis. It proposes instead that
evolution is guided differently, basically by more or less physical forces which shape the development of an animal's body, and sometimes implies that these forces supersede selection altogether.
Structuralists have proposed different mechanisms that might have guided the formation of
body plan
A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many.
This term, usually applied to animals, envisages a "blueprin ...
s. Before Darwin,
Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire (15 April 177219 June 1844) was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories. ...
argued that animals shared
homologous parts, and that if one was enlarged, the others would be reduced in compensation. After Darwin,
D'Arcy Thompson
Sir D'Arcy Wentworth Thompson CB FRS FRSE (2 May 1860 – 21 June 1948) was a Scottish biologist, mathematician and classics scholar. He was a pioneer of mathematical and theoretical biology, travelled on expeditions to the Bering Strait a ...
hinted at
vitalism
Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...
and offered geometric explanations in his classic 1917 book ''
On Growth and Form
''On Growth and Form'' is a book by the Scottish mathematical biologist D'Arcy Wentworth Thompson (1860–1948). The book is long – 793 pages in the first edition of 1917, 1116 pages in the second edition of 1942.
The book covers many top ...
''.
Adolf Seilacher
Adolf "Dolf" Seilacher (February 24, 1925 – April 26, 2014) was a German palaeontologist who worked in evolutionary and ecological palaeobiology for over 60 years. He is best known for his contributions to the study of trace fossils; constructi ...
suggested mechanical inflation for "pneu" structures in
Ediacaran biota
The Ediacaran (; formerly Vendian) biota is a Taxonomy (biology), taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period (). These were composed of enigmatic tubular and frond-sh ...
fossils such as ''
Dickinsonia
''Dickinsonia'' is an extinct genus of basal animal that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine. The individual ''Dickinsonia'' typically resembles a bilaterally symmetrical ribbed oval. Its a ...
''.
Günter P. Wagner
Günter P. Wagner (born May 28, 1954 in Vienna, Austria) is an Austrian-born evolutionary biologist who is Professor of Ecology and Evolutionary biology at Yale University, and head of the Wagner Lab.
Education and training
After undergraduate e ...
argued for developmental bias, structural constraints on
embryonic development
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm ...
.
Stuart Kauffman
Stuart Alan Kauffman (born September 28, 1939) is an American medical doctor, theoretical biologist, and complex systems researcher who studies the origin of life on Earth. He was a professor at the University of Chicago, University of Pennsylv ...
favoured
self-organisation
Self-organization, also called spontaneous order in the social sciences, is a process where some form of overall order arises from local interactions between parts of an initially disordered system. The process can be spontaneous when suff ...
, the idea that complex structure emerges
holistically and spontaneously from the dynamic interaction of all parts of an
organism
In biology, an organism () is any living system that functions as an individual entity. All organisms are composed of cells (cell theory). Organisms are classified by taxonomy into groups such as multicellular animals, plants, and ...
.
Michael Denton
Michael John Denton (born 25 August 1943) is a British-Australian proponent of intelligent design and a Senior Fellow at the Discovery Institute's Center for Science and Culture. He holds a PhD degree in biochemistry. Denton's book, '' Evolution ...
argued for laws of form by which
Platonic universals or "Types" are self-organised.
Stephen J. Gould and
Richard Lewontin
Richard Charles Lewontin (March 29, 1929 – July 4, 2021) was an American evolutionary biologist, mathematician, geneticist, and social commentator. A leader in developing the mathematical basis of population genetics and evolutionary theory, ...
proposed
biological "spandrels", features created as a byproduct of the adaptation of nearby structures.
Gerd B. Müller and Stuart A. Newman argued that the appearance in the
fossil record
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...
of most of the current
phyla in the
Cambrian explosion
The Cambrian explosion, Cambrian radiation, Cambrian diversification, or the Biological Big Bang refers to an interval of time approximately in the Cambrian Period when practically all major animal phyla started appearing in the fossil recor ...
was "pre-Mendelian" evolution caused by physical factors.
Brian Goodwin
Brian Carey Goodwin (25 March 1931 – 15 July 2009) (St Anne de Bellevue, Quebec, Canada - Torbay, Devon, UK) was a Canadian mathematician and biologist, a Professor Emeritus at the Open University and a founder of theoretical biology and bio ...
, described by Wagner as part of "a
fringe
Fringe may refer to:
Arts
* Edinburgh Festival Fringe, the world's largest arts festival, known as "the Fringe"
* Adelaide Fringe, the world's second-largest annual arts festival
* Fringe theatre, a name for alternative theatre
* The Fringe, the ...
movement in evolutionary biology",
[ denies that biological complexity can be reduced to natural selection, and argues that ]pattern formation
The science of pattern formation deals with the visible, ( statistically) orderly outcomes of self-organization and the common principles behind similar patterns in nature.
In developmental biology, pattern formation refers to the generation of ...
is driven by morphogenetic field
In the developmental biology of the early twentieth century, a morphogenetic field is a group of cells able to respond to discrete, localized biochemical signals leading to the development of specific morphological structures or organs. The sp ...
s.
Darwinian biologists have criticised structuralism, emphasising that there is plentiful evidence both that natural selection is effective and, from deep homology
In evolutionary developmental biology, the concept of deep homology is used to describe cases where growth and differentiation processes are governed by genetic mechanisms that are homologous and deeply conserved across a wide range of spec ...
, that gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
s have been involved in shaping organisms throughout evolutionary history
The history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day. Earth formed about 4.5 billion years ago (abbreviated as ''Ga'', for ''gigaannum'') and evide ...
. They accept that some structures such as the cell membrane
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...
self-assemble, but deny the ability of self-organisation to drive large-scale evolution.
History
Geoffroy's law of compensation
In 1830, Étienne Geoffroy Saint-Hilaire
Étienne Geoffroy Saint-Hilaire (15 April 177219 June 1844) was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories. ...
argued a structuralist case against the functionalist (teleological
Teleology (from and )Partridge, Eric. 1977''Origins: A Short Etymological Dictionary of Modern English'' London: Routledge, p. 4187. or finalityDubray, Charles. 2020 912Teleology" In ''The Catholic Encyclopedia'' 14. New York: Robert Appleton ...
) position of Georges Cuvier
Jean Léopold Nicolas Frédéric, Baron Cuvier (; 23 August 1769 – 13 May 1832), known as Georges Cuvier, was a French natural history, naturalist and zoology, zoologist, sometimes referred to as the "founding father of paleontology". Cuvier ...
. Geoffroy believed that homologies of structure between animals indicated that they shared an ideal pattern; these did not imply evolution but a unity of plan, a law of nature. He further believed that if one part was more developed within a structure, the other parts would necessarily be reduced in compensation, as nature always used the same materials: if more of them were used for one feature, less was available for the others.
D'Arcy Thompson's morphology
In his "eccentric, beautiful" 1917 book ''On Growth and Form
''On Growth and Form'' is a book by the Scottish mathematical biologist D'Arcy Wentworth Thompson (1860–1948). The book is long – 793 pages in the first edition of 1917, 1116 pages in the second edition of 1942.
The book covers many top ...
'', D'Arcy Wentworth Thompson
Sir D'Arcy Wentworth Thompson CB FRS FRSE (2 May 1860 – 21 June 1948) was a Scottish biologist, mathematician and classics scholar. He was a pioneer of mathematical and theoretical biology, travelled on expeditions to the Bering Strait an ...
revisited the old idea of " universal laws of form" to explain the observed forms of living organisms. The science writer Philip Ball
Philip Ball (born 1962) is a British science writer. For over twenty years he has been an editor of the journal ''Nature'' for which he continues to write regularly. He now writes a regular column in '' Chemistry World''. He has contributed to ...
states that Thompson "presents mathematical principles as a shaping agency that may supersede natural selection, showing how the structures of the living world often echo those in inorganic nature", and notes his "frustration at the ' Just So' explanations of morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
offered by Darwinians." Instead, Ball writes, Thompson elaborates on how not heredity but physical forces govern biological form. The philosopher of biology Michael Ruse
Michael Ruse (born 21 June 1940) is a British-born Canadian philosopher of science who specializes in the philosophy of biology and works on the relationship between science and religion, the creation–evolution controversy, and the demarcatio ...
similarly wrote that Thompson "had little time for natural selection", certainly preferring "mechanical explanations" and possibly straying into vitalism
Vitalism is a belief that starts from the premise that "living organisms are fundamentally different from non-living entities because they contain some non-physical element or are governed by different principles than are inanimate things." Wher ...
.
Seilacher's pneu structures
Like Thompson, the palaeontologist Adolf Seilacher
Adolf "Dolf" Seilacher (February 24, 1925 – April 26, 2014) was a German palaeontologist who worked in evolutionary and ecological palaeobiology for over 60 years. He is best known for his contributions to the study of trace fossils; constructi ...
emphasised fabricational constraints on form. He interpreted fossils such as ''Dickinsonia
''Dickinsonia'' is an extinct genus of basal animal that lived during the late Ediacaran period in what is now Australia, China, Russia and Ukraine. The individual ''Dickinsonia'' typically resembles a bilaterally symmetrical ribbed oval. Its a ...
'' in the Ediacaran biota
The Ediacaran (; formerly Vendian) biota is a Taxonomy (biology), taxonomic period classification that consists of all life forms that were present on Earth during the Ediacaran Period (). These were composed of enigmatic tubular and frond-sh ...
as "pneu" structures determined by mechanical inflation like a quilted air mattress
An air mattress is an inflatable mattress or sleeping pad.
Due to its buoyancy, it is also often used as a water toy or flotation device, and in some countries, including the UK, is called a lilo ("Li-lo" being a specific trademark -- derived ...
, rather than having been driven by natural selection.
Wagner's constraints on development
In his 2014 book ''Homology, Genes, and Evolutionary Innovation'', the evolutionary biologist Günter P. Wagner
Günter P. Wagner (born May 28, 1954 in Vienna, Austria) is an Austrian-born evolutionary biologist who is Professor of Ecology and Evolutionary biology at Yale University, and head of the Wagner Lab.
Education and training
After undergraduate e ...
argues for "the study of novelty as distinct from adaptation." He defines novelty as occurring when some part of the body develops an individual and quasi-independent existence, in other words as a distinct and recognisable structure, which he implies might occur before natural selection begins to adapt the structure for some function.[ Wagner, Günter P., ''Homology, Genes, and Evolutionary Innovation''. Princeton University Press. 2014. . Pages 7–38, 125] He forms a structuralist picture of evolutionary developmental biology
Evolutionary developmental biology (informally, evo-devo) is a field of biological research that compares the developmental processes of different organisms to infer how developmental processes evolved.
The field grew from 19th-century beginni ...
, using empirical evidence, arguing that homology
Homology may refer to:
Sciences
Biology
*Homology (biology), any characteristic of biological organisms that is derived from a common ancestor
* Sequence homology, biological homology between DNA, RNA, or protein sequences
*Homologous chrom ...
and biological novelty are key aspects requiring explanation, and that developmental bias (i.e. structural constraints on embryonic development) is a key explanation for these.
Kauffman's self-organisation
The mathematical biologist Stuart Kauffman
Stuart Alan Kauffman (born September 28, 1939) is an American medical doctor, theoretical biologist, and complex systems researcher who studies the origin of life on Earth. He was a professor at the University of Chicago, University of Pennsylv ...
suggested in 1993 that self-organization
Self-organization, also called spontaneous order in the social sciences, is a process where some form of overall order arises from local interactions between parts of an initially disordered system. The process can be spontaneous when suffi ...
may play a role alongside natural selection
Natural selection is the differential survival and reproduction of individuals due to differences in phenotype. It is a key mechanism of evolution, the change in the heritable traits characteristic of a population over generations. Charle ...
in three areas of evolutionary biology
Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. It is also defined as the study of the history of life fo ...
, namely population dynamics
Population dynamics is the type of mathematics used to model and study the size and age composition of populations as dynamical systems.
History
Population dynamics has traditionally been the dominant branch of mathematical biology, which has ...
, molecular evolution
Molecular evolution is the process of change in the sequence composition of cellular molecules such as DNA, RNA, and proteins across generations. The field of molecular evolution uses principles of evolutionary biology and population genetics ...
, and morphogenesis
Morphogenesis (from the Greek ''morphê'' shape and ''genesis'' creation, literally "the generation of form") is the biological process that causes a cell, tissue or organism to develop its shape. It is one of three fundamental aspects of devel ...
. With respect to molecular biology, Kauffman has been criticised for ignoring the role of energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat a ...
in driving biochemical reactions in cells, which can fairly be called self- catalysing but which do not simply self-organise.
Denton's 'Types'
The biochemist Michael Denton
Michael John Denton (born 25 August 1943) is a British-Australian proponent of intelligent design and a Senior Fellow at the Discovery Institute's Center for Science and Culture. He holds a PhD degree in biochemistry. Denton's book, '' Evolution ...
has argued a structuralist case for self-organization. In a 2013 paper, he claimed that "the basic forms of the natural world—the Types—are immanent in nature, and determined by a set of special natural biological laws, the so called 'laws of form'." He asserts that these "recurring patterns and forms" are "genuine universals
In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For exa ...
". Form is in this view not shaped by natural selection, but by "self-organizing properties of particular categories of matter" and by "cosmic fine-tuning of the laws of nature". Denton has been criticised by the biochemist Laurence A. Moran as anti-Darwinian and favouring creationism
Creationism is the religious belief that nature, and aspects such as the universe, Earth, life, and humans, originated with supernatural acts of divine creation. Gunn 2004, p. 9, "The ''Concise Oxford Dictionary'' says that creationism is 't ...
.
Gould and Lewontin's spandrels
In 1979, influenced by Seilacher among others, the paleontologist
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossi ...
Stephen J. Gould and the population geneticist
Population genetics is a subfield of genetics that deals with genetic differences within and between populations, and is a part of evolutionary biology. Studies in this branch of biology examine such phenomena as adaptation, speciation, and po ...
Richard Lewontin
Richard Charles Lewontin (March 29, 1929 – July 4, 2021) was an American evolutionary biologist, mathematician, geneticist, and social commentator. A leader in developing the mathematical basis of population genetics and evolutionary theory, ...
wrote what Wagner called "the most influential structuralist manifesto", "The Spandrels of San Marco and the Panglossian Paradigm
"The Spandrels of San Marco and the Panglossian Paradigm: A Critique of the Adaptationist Programme", also known as the "Spandrels paper", is a paper by evolutionary biologists Stephen Jay Gould and Richard Lewontin, originally published in the ''P ...
".[ They pointed out that biological features (like architectural spandrels) did not necessarily have ]adaptation
In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the po ...
as their direct cause. Instead, architects couldn't help creating small triangular areas between arch
An arch is a vertical curved structure that spans an elevated space and may or may not support the weight above it, or in case of a horizontal arch like an arch dam, the hydrostatic pressure against it.
Arches may be synonymous with vaul ...
es and pillar
A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...
s, as arches need (evolve) to be curved, and pillars need to be vertical. The resulting spandrels are exaptation
Exaptation and the related term co-option describe a shift in the function of a trait during evolution. For example, a trait can evolve because it served one particular function, but subsequently it may come to serve another. Exaptations are common ...
s, consequences of other evolutionary changes. Evolution, they argued, did not select for a protruding human chin: instead, reducing the length of the tooth row left the jaw protruding.[
]
Müller and Newman's pre-Mendelian evolution
Extreme structuralists like Gerd B. Müller and Stuart A. Newman, inheriting the viewpoint of D'Arcy Thompson, have proposed that physical laws of structure, not genetics
Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar wor ...
, govern major diversifications such as the Cambrian explosion
The Cambrian explosion, Cambrian radiation, Cambrian diversification, or the Biological Big Bang refers to an interval of time approximately in the Cambrian Period when practically all major animal phyla started appearing in the fossil recor ...
, followed later by co-opted genetic mechanisms. They argued further that there was a "pre-Mendelian" phase of the evolution of animals, involving physical forces, before genes took over. Darwinian biologists freely admit that physical factors such as surface tension can cause self-assembly
Self-assembly is a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction. When the ...
, but insist that gene
In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...
s play a crucial role. They note for example that deep homologies between widely separated groups of organisms, such as the signalling pathway
In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellula ...
s and transcription factor
In molecular biology, a transcription factor (TF) (or sequence-specific DNA-binding factor) is a protein that controls the rate of transcription of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence. The fu ...
s of choanoflagellate
The choanoflagellates are a group of free-living unicellular and colonial flagellate eukaryotes considered to be the closest living relatives of the animals. Choanoflagellates are collared flagellates, having a funnel shaped collar of interconne ...
s and metazoa
Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage in ...
ns, demonstrate that genes have been involved throughout evolutionary history
The history of life on Earth traces the processes by which living and fossil organisms evolved, from the earliest emergence of life to present day. Earth formed about 4.5 billion years ago (abbreviated as ''Ga'', for ''gigaannum'') and evide ...
.
Goodwin's morphogenetic fields
What Wagner calls "a fringe movement in evolutionary biology",[ the form of structuralism exemplified by ]Brian Goodwin
Brian Carey Goodwin (25 March 1931 – 15 July 2009) (St Anne de Bellevue, Quebec, Canada - Torbay, Devon, UK) was a Canadian mathematician and biologist, a Professor Emeritus at the Open University and a founder of theoretical biology and bio ...
, effectively denies that natural selection is important, or at least that biological complexity could be reduced to natural selection.[ This led to conflict with Darwinists such as ]Richard Dawkins
Richard Dawkins (born 26 March 1941) is a British evolutionary biologist and author. He is an emeritus fellow of New College, Oxford and was Professor for Public Understanding of Science in the University of Oxford from 1995 to 2008. An ath ...
. Goodwin related the old concept of a morphogenetic field
In the developmental biology of the early twentieth century, a morphogenetic field is a group of cells able to respond to discrete, localized biochemical signals leading to the development of specific morphological structures or organs. The sp ...
to the spatial distribution of chemical signals in a developing embryo. He demonstrated with a mathematical model that a variety of patterns could be formed by choosing parameter values to set up either static geometric patterns or dynamic oscillations, implying that the signalling system involved was somehow an alternative to natural selection.[ Dawkins commented "He thinks he's anti-Darwinian, although he can't be, because he has no alternative explanation."]
Criticism
While agreeing that pattern formation mechanisms such as those described by Goodwin exist, the biologists Richard Dawkins, Stephen J. Gould, Lynn Margulis
Lynn Margulis (born Lynn Petra Alexander; March 5, 1938 – November 22, 2011) was an American evolutionary biologist, and was the primary modern proponent for the significance of symbiosis in evolution. Historian Jan Sapp has said that "Lynn Ma ...
, and Steve Jones have criticised Goodwin for suggesting that chemical signalling forms an alternative to natural selection.[
Moran, a "skeptical biochemist", comments that 'structuralism' is a "new buzzword ... guaranteed to impress the creationist crowd because nobody understands what it means but it sounds very 'sciency' and philosophical."][ The philosopher of science Paul E. Griffiths writes that structuralists "view this structuring of the space of biological possibility as part of the fundamental physical structure of nature. But the phenomena of phylogenetic inertia and developmental constraint do not support this interpretation. These phenomena show that the evolutionary pathways available to an organism are a function of the developmental structure of the organism."]
Moran summarizes: "There's nothing in science that supports the views of the structuralists. We have perfectly good explanations for why bumblebees are different than mushrooms and why all vertebrates have vertebrae and not exoskeletons. There's no evidence to support the idea that if you replay the tape of life it will come out looking anything like what we see today. You can be confident that when you visit another planet you will not find vertebrates."[
The evolutionary developmental biologist Lewis Held wrote that "The notion that aspects of anatomy can be explained by physical forces (like expansion cracking) was advocated ~ 100 years earlier in D'Arcy Thompson's 1917 ''On Growth and Form'' and in Theodore Cook's 1914 book ''The Curves of Life''. Over the intervening century, various traits have been proposed to arise ''mechanically'' rather than ''genetically'': brain convolutions, cartilage condensations, flower corrugations, tooth cusps, and fish otoliths. To this kooky list we can now add the crooked smile of the crocodile, or at least the cracked skin that surrounds it."]
See also
* Alternatives to Darwinism
Alternatives to Darwinian evolution have been proposed by scholars investigating biology to explain signs of evolution and the relatedness of different groups of living things. The alternatives in question do not deny that evolutionary changes ove ...
* Eclipse of Darwinism
Julian Huxley used the phrase "the eclipse of Darwinism" to describe the state of affairs prior to what he called the "modern synthesis". During the "eclipse", evolution was widely accepted in scientific circles but relatively few biologists b ...
* Extended evolutionary synthesis
The extended evolutionary synthesis consists of a set of theoretical concepts argued to be more comprehensive than the earlier modern synthesis of evolutionary biology that took place between 1918 and 1942. The extended evolutionary synthesis was ...
* Orthogenesis
Orthogenesis, also known as orthogenetic evolution, progressive evolution, evolutionary progress, or progressionism, is an obsolete biological hypothesis that organisms have an innate tendency to evolve in a definite direction towards some go ...
Notes
References
{{Evolution
Non-Darwinian evolution
Philosophy of biology
Evolutionary biology