Human evolution theory utilizing concepts of neoteny & female sexual selection
An etiology of neuropsychological disorders such as autism and dyslexia, and the origin of left handedness.

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Mivart

Mivart: bibliographical excerpts


"In the present context, Mivart is of particular interest because he appears to be the first systematic thinker to make individual ontogentic development central to his view of the basis for evolutionary change. Like most writers who followed him in this vein, Mivart stressed the definite or constrained nature of individual variation, so that such variations were neither random nor indefinite, as they were in Darwin's version. ... Mivart is not interested in the complete overthrow of natural selection but merely wishes to demote it to the subordinate context of operating along with many other known and unknown causes or influences, which he explicitly labels as "obscure and mysterious." He view for an internal natural law that causes organisms to change rapidly and harmoniously: "the efficient presence of an unknown internal natural law or laws conditioning the evolution of new species forms from preceding ones, modified by the action of surrounding conditions, by 'Natural Selection' and by other controlling influencs" (p. 45). So Mivart, like Thomas Huxley before him, believes in evolution as a fact without believing in natural selection as its main or most formidable agency. ... As stated previously, Mivart differs from Darwin in his (Mivart's) stress on the internally constrained variation of each species. He also differs with Darwin in the way he sees changes in the environment operating. With his eye always on the individual, especially the environing conditions of individual development, Mivart sees severe changes in the environment as bringing out new phenotypes or variations as a consequence of an alteration in the conditions of development: this is the developing organism's direct response to altered conditions of the developmental medium. Thus, Mivart takesDarwin's enormous catalogue of changes in plants and animals under domestication as an occasion to point out that the enormous change in environing conditions brings out new variations on which selection can now operate-- Mivert's point throughout his book being that natural selection works on "what was born fit." Mivarts also takes pains to point out that such changes are not infinite and are stricktly limited by unknown internal factors." Gottlieb, G (1992) Individual Development & Evolution. Oxford Univ. Press: New York p. 40-42)

"Consistent with his earlier observations, Mivart believed that the capacity of tendency to change was itself heritable and thus passed on in the process of evolution. In sum, Mivart believed that evolution was brought about by the united action of internal and external forces that serve to change individual ontogenetic development, sometimes resulting in abortions and monstrosities, and , at other times, in harmonious (self-consistent") new organisms. Mivart contrasts his view to that of Richard Owen, who believed that "every species changes in time, by virtue of inherent tendencies thereto." Owen called his delimited concept of evolution "derivation" and viewed each species as having an "innate tendency to change irrespective of altered circumstances" (Desmond, 1982). Mivart expressly ascribed greater weight to external influences, opperating in conjunction with internal ones, in bringing about evolution. While the power of Darwin's concept of natural slection is that it specifies the variety and nature of external influences that guide and determine evolution, is says nothing about how the changes originate. ("Natural selection can do nothing until favourable variations chance to occur." {Darwin, 1859}.) Mivart's contribution was to specify that constrained alterations in individual development, produced by reproductive peculiarities of the parents or changes in external conditions, are the necessary basis of evolution. As Pere Alberch was to say so well a century later, "In evolution, selection may decide the winner of a given game but development non-randomly defines the players" (Alberch, 1980, p. 665). In many important details, Mivart also anticipated the contemporary concepts of macromutation and punctuated equilobria, the related notions that infrequent, relatively rapid, large-scale changes accurately portray the tempo and mode of evolution (reviewed by Stanley, 1981). In sum, with special reference to our reviews of the ways in which the role of individual development in evolution has been conceptualized, Mivart's belief that changes relevant to evolution occur during ontegeny ("after or before birth, either in their embryonic, or towards... their adult, condition") is a most significant departure from previous thought on this topic. Lamarck, Darwin, and Haeckel all held that the only mode of evolutionary change was a change in adulthood, when a new stage got added on to the end of ontogeny (terminal addition). Mivart's insight on the importance of early ontogenetic change was not to be taken up again until much later (described in Chapters 8 and 9). Meanwhile, Haeckel's concepts of phylogeny and ontogeny got translated into the notion that there are tw o sources of input to individual development (nature and nurture), a dichotomy that became so firmly established (reified) that the study of genetics and embryology got separated, to the detriment of both fields." (Gottlieb, G (1992) Individual Development & Evolution. Oxford Univ. Press: New York pp. 46-7)

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