
Was Alan Turing right about the mechanism behind tiger stripes? - nature24
https://simonsfoundation.org/features/science-news/biologists-home-in-on-turing-patterns/
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blauwbilgorgel
You can generate your own Turing patterns with OpenCV.

Watching them slowly change and with different parameters can be very
mesmerizing:

Video: <http://www.youtube.com/watch?v=KKwbDKRKG7k> multiscale turing pattern
(python+opencv)

Code (Python):
[https://code.ros.org/trac/opencv/browser/trunk/opencv/sample...](https://code.ros.org/trac/opencv/browser/trunk/opencv/samples/python2/turing.py?rev=6080)

Paper: [http://www.jonathanmccabe.com/Cyclic_Symmetric_Multi-
Scale_T...](http://www.jonathanmccabe.com/Cyclic_Symmetric_Multi-
Scale_Turing_Patterns.pdf)

~~~
goostavos
Wow, that is awesome!

I spent the past weekend tying to wrap my head around OpenCV. After 3 days of
bagging my head against the wall trying to get template matching to work, I
determined that I am not yet smart enough for computer vision. The domain
knowledge required seems to be very deep.

So, seeing the cool things people do with the library is inspirational, (but
also makes me incredibly jealous).

~~~
femto
Have you looked at the book "Learning OpenCV", by Bradski and Kaehler,
published by O'Reilly? I haven't done much work with OpenCV, but I have read
the entire book and it seemed to be a good introduction. A companion
collection of examples is available online, consisting of a set of programs
that can be compiled and used as a starting point for further hacking. A
Google search on the title, happens to yield a link to the full text.

~~~
elteto
The O'Reilly book is very good to get a grasp of OpenCV but it is a bit
outdated as it doesn't include the C++ API. You can still run through the
examples but you might have to use Google a lot since a lot of function
signatures have changed since the book was written. However the book is worth
reading since it also introduces and explains a lot of computer vision
concepts, as well as providing practical examples on how to use them.

~~~
femto
Of note, there is a second edition due out in June, its subtitle is "Computer
Vision in C++ with the OpenCV Library".

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kingkawn
No mention of recent developments in biology related to pattern expression or
the older idea of heterozygous genetic expression:

The Notch signaling pathway:
<http://en.wikipedia.org/wiki/Notch_signaling_pathway>

Heterozygous genetic expresson: <http://en.wikipedia.org/wiki/Calico_cat>
<http://en.wikipedia.org/wiki/Barr_body>

~~~
robbiep
Perhaps because those systems aren't chemical gradient systems such as
elucidated by Turing?

It's meant to be an interest story/article, not a comprehensive analysis of
cell signalling and phenotype display

~~~
toufka
However, the question is about tiger stripes. And modern cell-signaling
analysis has given us the answer. So why no discussion about the answer?

~~~
robbiep
Well, it has and it hasn't. For example tiger stripes don't have anything to
do with the NOTCH signalling pathway, and the awesomeness of the
x-inactivation in tortoise shell cats also has nothing to do with tiger
stripes.

Rather, the Hox genes seem quite tied up with this. The Hox genes are nothing
new, they were well characterised when I was doing undergrad genetics in 2006.

This article doesn't directly answer th question of tiger stripes but is
trying to tie turing's old paper, which focused on tiger stripes as an
example, with new research.

Interestingly it seems like this is all just reaearch which has been pooled
together with the particular aim of celebrating turing's 100th last year (see
[1]) and little of the research is intrinsically ground breaking or unknown to
science, but almost done with the express purpose of celebrating Turing.

[1] [http://www.eurekalert.org/pub_releases/2012-02/kcl-
spt021712...](http://www.eurekalert.org/pub_releases/2012-02/kcl-
spt021712.php)

By the by, did anyone think that the textile seashell pictured in the article
looked like some of the shapes created in iterations of the game of life?

~~~
kingkawn
Tiger stripes are an example of biological patterning, as is the Notch pathway
impact on neural tissue development and also the fur characteristics in other
animals. Barr Bodies, Notch, trisomy, all have major impacts on pattern
production.

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tolmasky
BBC's "The Secret Life of Chaos" covers some of this from kind of a historical
perspective. It's a nice pretty superficial documentary, I enjoyed it:
<http://topdocumentaryfilms.com/secret-life-chaos/>

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gosub
How Mathematicians Think About Patterns - Professor Ian Stewart FRS

<http://www.youtube.com/watch?v=xLkQFC-Z-Vk>

there is a section about tiger stripes, leopard spots etc etc

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kbenson
> A protein called fibroblast growth factor (FGF) serves as the activator, and
> a gene variant dubbed Sonic hedgehog (Shh) acts as an inhibitor.

That brightened my day just a little bit...

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j2labs
I wonder if these patterns are related to male pattern baldness too?

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omegaworks
>convicted of engaging in homosexual acts and sentenced to chemical
castration. Amid that personal drama, he still found the time to publish a
visionary paper

Even in the face of his entire society condemning him to a crippled existence,
it's a testament to his fortitude that he continued producing brilliant works,
unfettered. We're left to wonder what other insights Turing might have
contributed to human progress had he not been stifled and squandered by the
people in power in his day.

History is filled with examples of intellect being trampled on by the
establishment: Galileo, Socrates, and even now Aaron Swartz. We still haven't
grown out of it. We still need to fight it.

~~~
Guthur
Wiki has a slightly different account of the conviction.

He was not sentenced to chemical castration, though that was the result, the
treatment was to reduce the libido.

Interestingly Arnold Murray was released on probation.

Source is wiki of course so possibilities of inaccuracies.

[http://en.wikipedia.org/wiki/Alan_Turing#Conviction_for_inde...](http://en.wikipedia.org/wiki/Alan_Turing#Conviction_for_indecency)

Also apparently jail sentences for 'gross indecency' were rarer at the time,
"(only 174 of the 746 men convicted of 'gross indecency' in 1951 received
prison sentences-typically less than six months)"

According to this: [http://drvitelli.typepad.com/providentia/2011/04/the-
turing-...](http://drvitelli.typepad.com/providentia/2011/04/the-turing-
problem.html)

~~~
spot
what source has no possibility of inaccuracy?

