
Alan Turing's 1950s tiger stripe theory proved - acangiano
http://www.physorg.com/news/2012-02-alan-turing-1950s-tiger-stripe.html
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impendia
The first time I ever took a graduate math course, I did my term project on
precisely this theory. Analyzed the PDE's, did some numerical experiments on
it, gave a lecture on it. I had to tell my audience "Well, we think this
produces tiger stripes and giraffe spots, but honestly we're just blindly
guessing."

What a treat to read this! Shows that us mathematicians are often fifty years
ahead of the times ;)

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mvanveen
Here is the wikipedia article on Turing's paper:
[http://en.wikipedia.org/wiki/The_Chemical_Basis_of_Morphogen...](http://en.wikipedia.org/wiki/The_Chemical_Basis_of_Morphogenesis)

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tokenadult
I read about this in 2011 in Ian Stewart's book The Mathematics of Life. I see
the relevant passage can be viewed in Google Books.

[http://books.google.com/books?id=u4X4cRaZlJUC&pg=PA199&#...</a><p>Any book by
Ian Stewart on mathematics is a good read.

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bootload
Interesting find & I wondered in this post, _"Why Startup Hubs Work"_ ~
<http://news.ycombinator.com/item?id=3077165> could the randomness of Startup
described by _"pg"_ really be Morphogenesis? ~
<http://www.flickr.com/photos/bootload/6215220131/>

The original paper, Turings last can be read here ~
[http://www.dna.caltech.edu/courses/cs191/paperscs191/turing....](http://www.dna.caltech.edu/courses/cs191/paperscs191/turing.pdf)

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gradstudent
Wouldn't "Turing's Tiger Stripe Conjecture" be a better name for this?
Considering there was no prior evidence for it until now?

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pvarangot
Hmm, I beleive conjecture is used when you are speaking about a potential
theorem (i.e. something than can be mathematically proven to be right given
certain axioms). This is a biological/chemical/natural theory, and is believed
to be true given certain findings in some observed phenomena (i.e. statistics
are involved in a certain way).

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gradstudent
A conjecture is an assertion made on the basis of incomplete evidence. I'm not
familiar with Turing's work in this area but if (as others have commented) he
studied PDEs and that appear to mimic biological processes, yet did not find a
definitive link, then the conclusion that a connection between the two may
exist can only be described as conjecture.

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SimHacker
The late Andy Witkin's classic SIGGRAPH paper on reaction diffusion textures:
<http://www.cs.cmu.edu/~aw/pdf/texture.pdf>

We present a method for texture synthesis based on the simulation of a process
of local nonlinear interaction, called reaction-diffusion, which has been
proposed as a model of biological pattern formation. We extend traditional
reaction-diffusion systems by allowing anisotropic and spatially non-uniform
diffusion, as well as multiple competing directions of diffusion. We adapt
reaction-diffusion systems to the needs of computer graphics by presenting a
method to synthesize patterns which compensate for the effects of non-uniform
surface parameterization. Finally, we develop efﬁcient algorithms for
simulating reactiondiffusion systems and display a collection of resulting
textures using standard texture- and displacement-mapping techniques.

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tim_hutton
The physorg article summary is wrong, I think. The first morphogens were found
in 2006, for hair-follicle placement in mice:
[http://phylogenous.wordpress.com/2010/12/01/alan-turings-
rea...](http://phylogenous.wordpress.com/2010/12/01/alan-turings-reaction-
diffusion-model-simplification-of-the-complex/)

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yread
I am quite surprised that such a simple question of why does a tiger have
stripes (which kids are asking all the time) went so long unanswered. I wonder
how many questions like this are there?

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pja
This doesn't explain why a tiger has stripes. It explains _how_ a tiger has
stripes.

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Shorel
True.

The why seems simpler: camouflage.

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yread
why

1.

for what? for what reason, cause, or purpose? [1]

I am talking about _cause_ and you're talking about _purpose_. I think we can
both ask why

[1] <http://dictionary.reference.com/browse/why>

