chemical basis morphogenesis offprint philosophical von turing alan mathison (1 Ergebnisse)

First edition. TURING AND THE SECRET OF LIFE. First edition of the extremely rare true offprint (without price to front wrapper), of Turing's last major published work, which was "in every respect ahead of its time" (Copeland, p. 510). Taking his cue from the zoologist D'Arcy Thompson, who held that the forms of living things are to be explained in terms of the operation of physical forces and mathematical laws, Turing presents here the first mathematical theory of embryology. "At a time when Crick and Watson were using X-ray diffraction to establish the structure of DNA, Turing was grappling with a theoretical understanding of how information might be spread and diffused at a chemical level. In a classic statement of the scientific method Turing wrote: 'a mathematical model of the growing embryo will be described. This model will be a simplification and an idealisation, and consequently a falsification. It is to be hoped that the features retained for discussion are those of greatest importance in the present state of knowledge'. The result was applied mathematics par excellence. Just as the simple idea of the Turing machine had sent him into fields beyond the boundaries of Cambridge mathematics, so now this simple idea in physical chemistry took him into a region of new mathematical problems" (Hodges, p. 434). "Alan Turing's paper, 'The chemical basis of morphogenesis,' has been hugely influential in a number of areas. In this paper, Turing proposed that biological pattern formation arises in response to a chemical pre-pattern which, in turn, is set up by a process now known as diffusion-driven instability. The genius of this work was that he considered a system which was stable in the absence of diffusion and then showed that the addition of diffusion, which is naturally stabilising, actually caused an instability. Thus, it was the integration of the parts that was as crucial to the understanding of embryological development as the parts themselves patterns emerged or self-organised as a result of the individual parts interacting. To see how far ahead of his time he was, one has to note that it is only now in the post-genomic era of systems biology that the majority of the scientific community has arrived at the conclusion he came to 60 years ago Applications of Turing's work to developmental biology are too numerous to list but include limb development, pigmentation patterning, hair and feather germ formation, tooth morphogenesis, phyllotaxis, hydra patterning and regeneration. Moreover, ideas of self-organization now abound in biology, chemistry and ecology. The stimulus for a lot of this work stems from Turing's original ideas. Although still very controversial, Turing's theory for morphogenesis provided a paradigm shift in our way of thinking" (Maini, in Alan Turing: his work and impact, p. 684). There are two separate issues of 'The chemical basis of morphogenesis', the genuine author's presentation offprint offered here, and a commercially produced reprint; the latter differs from the former only in the presence of a price (eight shillings) at the foot of the front wrapper. ABPC/RBH records the sale of only one copy of this offprint (Christie's, June 12, 2013, lot 136, £13,125) Provenance: Owner's name written in ink to upper right corner of front wrapper; botanist Otto L. Stein (1925-2014). The offprint is accompanied with a signed typed letter from 1956 by R.A. Brooker at the Computing Machine Laboratory Manchester in reply to Stein's request to Turing for a copy of the offprint. "Alan had thought about embryology all the time, fascinated by the fact that how such growth was determined was something 'nobody has yet made the smallest beginnings at finding out.' There had been little advance since Growth and Form [by D'Arcy Thomspon], the 1927 classic that he had read before the war. "The greatest puzzle was that of how biological matter could assemble itself into patterns which were so enormous compared to the size of the cells. How could an assemblage of cells 'know' that it must settle into a five-fold symmetry, to make a starfish? How could the Fibonacci pattern of a fir-cone be imposed in its harmonious, regular way upon a growing plant? How could matter take shape or, as biological Greek had it, what was the secret of morphogenesis? Suggestive words like 'morphogenetic field', vague as the Life Force, were employed by biologists to describe the way that embryonic tissue seemed to be endowed with an invisible pattern which subsequently dictated its harmonious development. It had been conjectured that these 'fields' could be described in chemical terms but there was no theory of how this could be. Polanyi believed that there was no explanation except by a guiding esprit de corps; the inexplicability of embryonic form was one of his many arguments against determinism. Conversely, Alan told Robin [Gandy] that his new ideas were intended to 'defeat the Argument from Design'. "There were other suggestions in the literature for the nature of the 'morphogenetic field', but at some point Alan decided to accept the idea that it was defined by some variation of chemical concentrations, and to see how far he could get on the basis of that one idea. [The problem was] to discover circumstances in which a mixture of chemical solutions, diffusing and reacting with each other, could settle into a pattern, a pulsating pattern of chemical waves; waves of concentration into which the developing tissue would harden; waves which would encompass millions of cells, organising them into a symmetrical order far greater in scale. "There was one central, fundamental problem. It was exemplified in the phenomenon of gastrulation. in which a perfect sphere of cells would suddenly develop a groove, determining the head and tail ends of the emergent animal. The problem was this: if the sphere were symmetrical, and the chemical equations were symmetrical, without knowledge of left or right, up or down, where did th.