Saturday, December 29, 2007
Symmetricity in Evolution
Anyone knows any reference or answer to why living things had to evolve so symmetrically? For example, what was the need that we should have exactly two similar hands with the symmetricity of all fingers to the highest extend possible? Is there any living animal which has asymmetric features in his body? I am convinced from the mathematical point of veiw, being symmetric is the most optimum way for keeping the balance. In physics it also results in the most smooth movement which is ultimately beneficial for saving energy. But why is it that nature has already found this optimum feature? Or is that that our organs are not yet “perfectly” symmetric in submicron scale? For instance, maybe the number, size and orientation of the cells in left/right side of the body are very slightly different? It sounds absurd to me but maybe I don’t know much in biology. A quick googling didn’t bring up much relevant pages, so I thought I need maybe some better key words or direction.
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http://www.talkorigins.org/indexcc/CB/CB751.html
ReplyDeletehttp://pharyngula.org/index/weblog/comments/why_are_flounder_funny_looking/
I told you - almost all topics re: evolution is covered somehow in talkorigins...
pharyngula link since the comments ran out of room, heh
ReplyDeleteI know damping Matrices are antisymmetric,(at least not symmetric) and you know damping is the source of stability in motion,...
ReplyDeleteI do not know much about the art,but I read somewhere (?) that, "against classic point of view which measure beauty with symmetry in modern view,(?) antisymmetry is also a measure of beauty.
a correction: structural damping are artificial models so they may be modeled in symmetric form
ReplyDeleteIt seems you are online:D
ReplyDeletehttp://www.pantheaa.com/
why do n't you go to my private blog? do you want me to delet you?
Midooni "Gardan kaj" to farsi kenaye az chie? haminjoori yadam omad:)
ReplyDeleteWhat I have to ask you is... is there a point for our organs to be symmetric?
ReplyDeleteYes Linda! as I said in my blog, and also nature apparently has already discovered it, symmetricity is a key element in optimazation which is often linked to energy saving.
ReplyDeleteBut I don't think that is a requirement. On the exterior, having symmetric growth may improve one's aerodynamics. There are instances where this does not. There is a type of fish that we often eat in Chinese cuisine, called "Ping Yu" (ping for flat, and yu for fish). It has an asymmetric body: imagine a fish with two eyes on one side of the head, and a distorted mouth. On one side, the fish has bright silver shiny scales, and on the other, it has white soft skin. The fish dorments against rocks as a defense mechanism, and thus does not require eyes on one side. This is an exception in your assumption.
ReplyDeleteInternal organs do not focus on symmetry for aerodynamics. The purpose of organs is for converting solids into energy for an organism's survival. The lung is used for capturing oxygen therefore it has tissues specializing in capturing the most amount of oxygen and transporting it into blood. In humans, we have 2 symmetrically placed lung. However, one is smaller than the other, due to placement of the heart. It may be the case that internal organs are involving to be symmetric, but the only purpose to have symmetric bodily parts is only for improved aerodynamics... Since organs do not need to improve aerodynamics, then what is the purpose of having symmetric parts?
Each part of the organ is compartmentalized. Its focus is in the capability of chemical reactions and sustaining the organism for survival. This is why I question your assumption.
Linda and Mohsen,
ReplyDeleteEven for improving aerodynamic effects, you do not need symmertry always. At least there are really high performance artificial airfoils that are not symmetric and works better...
Really? Can you give me a link to one of these aerodynamics? interesting!
ReplyDeletefor example, all NACA nonsymetric airfoils. NACA 0012 is symetric these 00 shows symetry, look for something like NACA 2412.
ReplyDeleteBTW, you have a productive blog, I love it;)
ReplyDeleteOne more thing, I was thinking about your idea, now I see when the prons and cons of symmetry and unsymmetry are almost equal in a design problem, we usually look at the symmetry case because it is more easier to model it and explore it, so you may see symmetric design more often:)
ReplyDeleteThanks zizi, airfoil designs is really interesting, I know. I looked up the NACA but I didnt quite get your saying that high performance artificial airfoils that are not symmetric and works better. Ofcourse airfoil by itself is not a symmetric feature and this is imposed by the its complusary design requirements. It is like one of our hands. Our 5 fingers do not show any symmetricity an this is simply because an assymetric hand gives a better manipulation flexibility. Bu we have exactly two symmetric hands at sides! Like we must have two exactly similar wing and airfoils at each side of all planes. For the case of the plane, we human have designed them and it has been quite intutive for our engineers to think that symmetricity saves much is design efforts and also energy conservation. But in nature, it sounded surprising to me that how evolution has already caught this rule to this great extend!
ReplyDeleteI already replied you in my previous comment, I guess (not quit sure) one of the reasons to design aircrafts in symmetry is our traditional way of looking the problem in a symmetric way. It has at least less manipulation in analysis.
ReplyDeleteI do not know any non symmetric aircraft however I do not see your point about energy, let's talk about in messenger this sat if you are free and then you can publish it:)
This comment has been removed by the author.
ReplyDeleteBTW, I understand your point about airfoils, I just pointed it out after Linda's discussion about aerodynamics of fish. What I wanna mention is we can design non symmetric aerodynamic shape with better aerodynamic performance than symmetric case.
ReplyDeleteMost fishes are non symmetric in one plane however they have symmetry the other plane...
Oops, I need a paper and pen to draw :(( a long discussion;)