Talk:Asymmetry
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Planning a rewrite
[edit]I would like to take a crack at doing a major rewrite of this article. If anyone would like to comment/discuss before hand, please drop me a note or comment here. Thanks! HEL 21:54, 3 November 2006 (UTC)
I moved the images from the old article here for safe-keeping. Most of these don't seem useful for illustrating asymmetry. HEL 16:55, 11 November 2006 (UTC)
Images
[edit]
Okay, I've basically rewritten the whole article. Comments, criticisms, improvements most definitely wanted! Several sections still need work: the introduction, the biology section, and the chemistry section in particular. My original motivation for doing this was to create the subsection on asymmetries in particle physics collider experiments. HEL 18:49, 11 November 2006 (UTC)
Images wanted!
[edit]It would be nice to include the following images in this article:
- A picture of a halibut (or other flatfish) showing clearly the way its two eyes are on one side of its body. The pictures in the main halibut article aren't clear enough. HEL 16:51, 11 November 2006 (UTC)
Introduction needs work
[edit]The introduction to this article needs to be rewritten. Any volunteers, please be bold! HEL 18:10, 11 November 2006 (UTC)
Asymmetry in Art?
[edit]The new edit made no sense to me and doesn't seem to actually have anything to do with asymmetry, so I've reverted it. Preserved here for posterity. HEL 17:28, 25 December 2006 (UTC)
- Postmodernism moves toward asmmetry as the sheer volume and type of work becomes insurmountable due to the digital age. Art Historians struggle to develope a unified movement and give into the inevitablity of the loss of a small group of "superstar" artists. The true loss of control by institutions began in the 1960's conceptual art movement and finally begins to materialize.
Removed sections
[edit]Evolution of asymmetry
[edit]Features of the symmetry are determined by the environment. Maximal extent of organism symmetry corresponds to a completely isotropic ecological niche.
Biological evolution, as physical evolution, represents an increase in asymmetry. The appearance of life itself represents an inside/outside asymmetry. In 1964 V. N. Beklemishev distinguished three types of symmetry (spherical, radial, and bilateral) and arranged them into evolutionary array. Simple, early life forms floating in the depths of water (unicellular and lower multicellular organisms) are quasi-spherical, with radial symmetry appearing later as result of gravity. These organisms appeared approximately 3.5 billon years ago. Asymmetrization along the “top – bottom” axis occurred under the influence of gravity. This led to the appearance of the attached, low-mobility forms (plants and coelenterates) that had radial symmetry. Asymmetrization along the “front – back” axis occurred as facilitating rapid motion to escape from the predator, or to chase a prey). As a result, the main receptors and the brain were moved to the front of the body. Organisms with bilateral symmetry were dominating last 650-800 million years. These are crustaceans, fish as well as the most progressive forms, i.e., mammals, birds, and insects. In the same vein, Sabelli proposed in 1989 that an increase in asymmetry accompanies evolution, and highlighted the tridimensional asymmetry of the human body as reflecting the three basic asymmetries found in physical processes. Back-front asymmetry reflects the asymmetry of action, the quasi-symmetry of left and right reflects the quasi-symmetry of opposites, and the vertical asymmetry represents the hierarchy of complexity.
A general evolutionary theory of symmetry/asymmetry in biological organisms was proposed by V. Geodakyan in 1993 [1]. He proposed that the evolution of the organisms consistently goes from symmetry to asymmetry. Each transition changes one axis from symmetry to asymmetry with triaxial asymmetry placed at the end of the array (spherical → radial → bilateral → triaxial). According to V. Geodakyan the organisms of triaxial and not bilateral asymmetry should be considered the most evolutionary advanced type. The same trend can be found in embryogenesis—spherical zygote, radial gastrula, bilateral embryo and triaxial asymmetric child.
The trend towards asymmetrization can be followed in phylogeny of plant organs (flower, leaf, fruits, and seeds). It is known, that zygomorphic (bilateral symmetry) flowers [Gladiolus sp., Orchids, Eyebrights and Violets] are evolutionary more progressive, than actinomorphic (radial symmetry) flowers [Primula, Narcissus, Pyrola], but are less progressive, than triaxial asymmetric ones [Cannaceae and Valerianaceae]. The morphology of a leaf during evolution follows the same picture: spherical symmetry of chlorella, radial symmetry of pine needles, bilateral symmetry of Magnolia leafs, and triaxial asymmetry of Begonia or Elms leafs.
It was unknown what creates triaxial asymmetry. According to a new theory asymmetrization along the “left – right” axis is a consequence of asynchronous evolution and occurs in time.
Theories of Asymmetry
[edit]General theory of asymmetry in organisms was proposed by V. Geodakyan in 1993. According to the theory lateral asymmetry is a consequence of asynchronous evolution.[2] Part of the theory related to brain asymmetry was published earlier in 1992,[3] and concept of handedness—in 1997.[4] The theory is based on The Principle of Conjugated Subsystems and reveals relationships between three fundamental phenomena: evolution, sexual dimorphism, and lateral dimorphism.[5]
References
- ^ Geodakyan V.A. (1993) Asynchronous asymmetry.Zh. Vyssh. Nervn. Deyat. 43 N. 3. p. 543-561
- ^ Geodakyan V.A. (1993) Asynchronous asymmetry. “Zh. Vyssh. Nervn. Deyat. 43 N. 3. p. 543-561.
- ^ Geodakyan V. A. (1992) Evolutionary Logic of the Functional Asymmetry of the Brain. “Doklady Biological Sciences, 324 N 1-6, p. 283–287. Translated from Doklady Akademii Nauk, 1992, 324 No. 6, p. 1327-1331.
- ^ Geodakyan V. A., Geodakyan K. V. (1997) A New Concept on Lefthandedness. “Doklady Biological Sciences” 356 p. 450-454. Translated from Doklady Academii Nauk 1997, 356 No. 6, p. 838-842.
- ^ Evolutionary Theories of Asymmetrization of Organisms, Brain and Body
Problems with these sections
[edit]- Not clearly written.
- What can be understood appears fantastic.
- Many factual errors, eg, constant reference to "progressive" organisms, a term with no meaning in evolutionary biology. The "three basic asymmetries found in physical processes" - which are? According to who? "a consequence of asynchronous evolution and occurs in time." what does not occur in time? What is asynchronous evolution?
This needs to be completely re-written and referenced if it is to go in an article. Tim Vickers 22:15, 2 August 2007 (UTC)
Related AfD Discussions
[edit]Ditto Tim, plus this: re such guidelines as
I point out that User:Hector Sabelli, (REMOVED) added a reference to a fringe science book by Sabelli on so-called bios theory (which I would characterize as neo-Lamarckian/Chardinian pseudoscience). A collaborator of his, (REMOVED), who has edited an IP anon and as User:Lakinekaki, has written some related articles which have come up for AfD:
where you can find more information about the anti-natural selection agenda of Sabelli and Kovacevic. ---CH (talk) 21:35, 28 July 2008 (UTC) (former Wikipedian)
- Here is a reply to above. —Preceding unsigned comment added by 216.80.119.92 (talk • contribs) 19:02, August 3, 2008
Causes of asymmetry
[edit]Under the 'in organsims' heading it could be good to add some causes of aymmetries in humans including how environmental events during development can cause asymmetry, through things like infectious disease, low food quantity and quality, toxins and poisons. Can also include how genetic events during development can cause asymmetry, through things like inbreeding and spontaneous mutations. --AH2960 (talk) 23:01, 31 January 2016 (UTC)
Types of asymmetry
[edit]Under the "evolution of asymmetry in organisms" subheading it may be important to mention the different types of asymmetries amongst organisms – that being fluctuating asymmetry (FA) and directional asymmetry (DA) (and possibly a few more). For FA a brief mention of what it is could be stated linking that text to the FA Wikipedia page. For DA one could describe what DA is and give examples: Van Valen in 1962 defined directional asymmetry (DA) as occurring when ‘there is normally a greater development of a character on one side of the plane or planes of symmetry than on the other’. Researchers have argued that the level of asymmetry variance has a genetic basis, therefore is not a measure of developmental instability.[1] [2] DA is common in animals and humans for example, the mammalian heart depicts a greater structure on the left side, variance in size of antlers in a reindeer and testes size in many vertebrates. — Preceding unsigned comment added by Janepatel (talk • contribs) 17:00, 2 February 2016 (UTC)