History
An early version of recapitulation theory, also called the biogenetic law or embryological parallelism, was put forward by Étienne Serres in 1824–26 as what became known as the "Meckel-Serres Law" which 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 as part of his ideas of idealism, and became a prominent part of his version of Lamarckism leading 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 embryology of divergence in which embryonic parallels only applied to early stages where the embryo took a general form, after which more specialised forms diverged from this shared unity in a branching pattern. The anatomist Richard Owen used this to support his idealist concept of species as showing the unrolling of a divine plan from an archetype, and in the 1830s attacked the transmutation of species proposed by Lamarck, Geoffroy and Grant. In the 1850s Owen began to support an evolutionary view that the history of life was the gradual unfolding of a teleological divine plan, in a continuous "ordained becoming", with new species appearing by natural birth.
In On the Origin of Species (1859), Charles Darwin proposed evolution through natural selection, a theory central to modern biology. Darwin recognised the importance of embryonic development in the understanding of evolution, and the way in which von Baer's branching pattern matched his own idea of descent with modification:
| “ | We can see why characters derived from the embryo should be of equal importance with those derived from the adult, for a natural classification of course includes all ages. | ” |
Ernst Haeckel (1866), in his endeavour to produce a synthesis of Darwin's theory with Lamarckism and Naturphilosophie, proposed that "ontogeny recapitulates phylogeny," that is, the development of the embryo of every species (ontogeny) fully repeats the evolutionary development of that species (phylogeny), in Geoffroy's linear model rather than Darwin's idea of branching evolution. Haeckel's concept explained, for example, why humans, and indeed all vertebrates, have gill slits and tails early in embryonic development. His theory has since been discredited. However, it served as a backdrop for a renewed interest in the evolution of development after the modern evolutionary synthesis was established (roughly 1936 to 1947).
Stephen Jay Gould called this approach to explaining evolution as terminal addition; as if every evolutionary advance was added as new stage by reducing the duration of the older stages. The idea was based on observations of neoteny. This was extended by the more general idea of heterochrony (changes in timing of development) as a mechanism for evolutionary change.
D'Arcy Thompson postulated that differential growth rates could produce variations in form in his 1917 book On Growth and Form. He showed the underlying similarities in body plans and how geometric transformations could be used to explain the variations.
Edward B. Lewis discovered homeotic genes, rooting the emerging discipline of evo-devo in molecular genetics. In 2000, a special section of the Proceedings of the National Academy of Sciences (PNAS) was devoted to "evo-devo", and an entire 2005 issue of the Journal of Experimental Zoology Part B: Molecular and Developmental Evolution was devoted to the key evo-devo topics of evolutionary innovation and morphological novelty.
John R. Horner began his project "How to Build a Dinosaur" in 2009 in conjunction with his published book of the same name. Using the principles and theories of evolutionary developmental biology, he took a chick embryo and attempted to change the development so it grew components similar to a dinosaur. He successfully grew buds of teeth, and is currently working on growing a tail, and changing the wings to claws. Horner used evolutionary developmental biology on a chick embryo because he knew he couldn't make an exact replica of a dinosaur since there is no more DNA so instead he just took the framework still in the chick's DNA that allowed it to evolve from a dinosaur.
Read more about this topic: Evolutionary Developmental Biology
Famous quotes containing the word history:
“There is no example in history of a revolutionary movement involving such gigantic masses being so bloodless.”
—Leon Trotsky (1879–1940)
“There is nothing truer than myth: history, in its attempt to “realize” myth, distorts it, stops halfway; when history claims to have “succeeded” this is nothing but humbug and mystification. Everything we dream is “realizable.” Reality does not have to be: it is simply what it is.”
—Eugène Ionesco (b. 1912)
“It’s a very delicate surgical operation—to cut out the heart without killing the patient. The history of our country, however, is a very tough old patient, and we’ll do the best we can.”
—Dudley Nichols, U.S. screenwriter. Jean Renoir. Sorel (Philip Merivale)