The theory of recapitulation, also called the biogenetic law or embryological parallelism—and often expressed as "ontogeny recapitulates phylogeny"—is a disproven biological hypothesis that in developing from embryo to adult, animals go through stages resembling or representing successive stages in the evolution of their remote ancestors. With different formulations, such ideas have been applied and extended to several fields and areas, including the origin of language, biology, cognition and mental activities,[1] anthropology[2], education theory[3] and developmental psychology.[4] While some examples of embryonic stages showing superficial features of ancestral organisms exist, the ontological hypothesis itself has been completely disproven for the field biology.[5][6][7] By contrast, there is no consensus against its validity outside of biology; recapitulation theory is still considered plausible and applied by some reasearchers in fields like Behavioral Development,[8] the study of the origin of language,[9] and others.
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The earliest recorded trace of a recapitulation theory, is by Egyptian Pharaon Psamtik I (664 – 610 BCE), which used it as an hypothesis on the origin of language.[10][11] The concept of recapitulation was first formulated outside of the field of biology. It was a widely held idea among traditional theories of the origin of language (glottology), assumed as a premise that children's use of language gives insights on its origin and evolution.[12]
The idea was reprised in 1720 by Giambattista Vico, in his highly influential Scienza Nuova.[12][13][14] The idea was first formulated into the field of biology in the 1790s among the German Natural philosophers,[15] after which it soon gained the status of a biogenetic law.[12]
The first formal formulation was proposed by Étienne Serres in 1824–26 as what became known as the "Meckel-Serres Law", it attempted to provide a link between comparative embryology and a "pattern of unification" in the organic world. It was supported by Étienne Geoffroy Saint-Hilaire and became a prominent part of his ideas which suggested that past transformations of life could have had environmental causes working on the embryo, rather than on the adult as in Lamarckism. These naturalistic ideas led to disagreements with Georges Cuvier. It was widely supported in the Edinburgh and London schools of higher anatomy around 1830, notably by Robert Edmond Grant, but was opposed by Karl Ernst von Baer's ideas of divergence, and attacked by Richard Owen in the 1830s.[16]
Ernst Haeckel attempted to synthesize the ideas of Lamarckism and Goethe's Naturphilosophie with Charles Darwin's concepts. While often seen as rejecting Darwin's theory of branching evolution for a more linear Lamarckian "biogenic law" of progressive evolution, this is not accurate: Haeckel used the Lamarckian picture to describe the ontogenic and phylogenic history of the individual species, but agreed with Darwin about the branching nature of all species from one, or a few, original ancestors.[18] Since around the start of the twentieth century, Haeckel's "biogenetic law" has been refuted on many fronts.[7]
Haeckel formulated his theory as "Ontogeny recapitulates phylogeny". The notion later became simply known as the recapitulation (OED: 'a summing up or brief repetition') theory. Ontogeny is the growth (size change) and development (shape change) of an individual organism; phylogeny is the evolutionary history of a species. Haeckel's recapitulation theory claims that the development of advanced species passes through stages represented by adult organisms of more primitive species.[7] Otherwise put, each successive stage in the development of an individual represents one of the adult forms that appeared in its evolutionary history.
For example, Haeckel proposed that the pharyngeal slits of the pharyngeal arches in the neck of the human embryo resembled gill slits of fish, thus representing an adult "fishlike" developmental stage as well as signifying a fishlike ancestor. Embryonic pharyngeal slits, formed when the thin branchial plates separating pharyngeal pouches and ectodermal grooves perforate, open the pharynx to the outside. Pharyngeal pouches appear in all tetrapod animal embryos: in mammals, the first pharyngeal pouch develops into the lower jaw (Meckel's cartilage), the malleus and the stapes. At a later stage, all pharyngeal slits close, only the ear remaining open.[19] But these embryonic pharyngeal arches, pouches, and slits could not at any stage carry out the same function as the gills of an adult fish.
Haeckel produced several embryo drawings that often overemphasized similarities between embryos of related species. The misinformation was propagated through many biology textbooks, and popular knowledge, even today. Modern biology rejects the literal and universal form of Haeckel's theory.[8]
Haeckel's drawings were disputed by Wilhelm His, who had developed a rival theory of embryology.[20] His developed a "casual-mechanical theory" of human embryonic development.[21]
Darwin's view, that early embryonic stages are similar to the same embryonic stage of related species but not to the adult stages of these species, has been confirmed by modern evolutionary developmental biology.
Although Haeckel's specific form of recapitulation theory is now discredited among biologists, it had a strong influence on social and educational theories of the late 19th century.
English philosopher Herbert Spencer was one of the most energetic promoters of evolutionary ideas to explain many phenomena. He compactly expressed the basis for a cultural recapitulation theory of education in the following claim, published in 1861, five years before Haeckel first published on the subject:[3]
If there be an order in which the human race has mastered its various kinds of knowledge, there will arise in every child an aptitude to acquire these kinds of knowledge in the same order.... Education is a repetition of civilization in little.[22]
— Herbert Spencer
The maturationist theory of G. Stanley Hall was based on the premise that growing children would recapitulate evolutionary stages of development as they grew up and that there was a one-to-one correspondence between childhood stages and evolutionary history, and that it was counterproductive to push a child ahead of its development stage. The whole notion fit nicely with other social Darwinist concepts, such as the idea that "primitive" societies needed guidance by more advanced societies, i.e. Europe and North America, which were considered by social Darwinists as the pinnacle of evolution.
The Austrian pioneer in psychoanalysis, Sigmund Freud, also held a favorable position towards Haeckel's doctrine. He was trained as a biologist under the influence of recapitulation theory at the time of its domination, and retained a Lamarckian outlook with justification from the recapitulation theory.[23] He also distinguished between physical and mental recapitulation, in which the differences would become an essential argument for his theory of neuroses.[23]
More recently, several art historians, most prominently musicologist Richard Taruskin,[24] have applied the term "ontogeny becomes phylogeny" to the process of creating and recasting art history, often to assert a perspective or argument. For example, the peculiar development of the works by modernist composer Arnold Schoenberg (here an "ontogeny") is generalized in many histories into a "phylogeny" – a historical development ("evolution") of Western Music toward atonal styles of which Schoenberg is a representative. Such historiographies of the "collapse of traditional tonality" are faulted by art historians as asserting a rhetorical rather than historical point about tonality's "collapse".
Taruskin also developed a variation of the motto into the pun "ontogeny recapitulates ontology" to refute the concept of "absolute music" advancing the socio-artistic theories of Carl Dalhaus. Ontology is the investigation of what exactly something is, and Taruskin asserts that an art object becomes that which society and succeeding generations made of it. For example, composer Johann Sebastian Bach's St. John Passion, composed in the 1720's, was appropriated by the Nazi regime in the 1930's for propaganda. Taruskin claims the historical development of the Passion (its ontogeny) as a work with an anti-Semitic message does, in fact, inform the work's identity (its ontology), even though that was an unlikely concern of the composer. Music or even an abstract visual artwork can not be truly autonomous ("absolute") because it is defined by its historical and social reception.
Faulty logic and problematic proposals relating the development of an individual to the development of the species turn up even today. The hypothesis that ontogeny recapitulates phylogeny has been applied and extended in a number of areas, including cognition and mental activities.
"...the premise that was inherent in it — that language ontogenesis reenacts language phylogenesis in a chronologically condensed way — is, arguably, a plausible one. As a matter of fact, traditional glottogenetic theories have always been implicitly shaped by it; and several current scientific approaches have adopted it as a working principle. Vico made it a basic tool of his reconstructive method."
Haeckel's law is currently applied to the development of language and Psammetichus' experiment is mentioned in the handbook of history of linguistics as "something like as a first application [of Haeckel's" law] in the science of language."