
A Lizard with Scales That Behave Like a Cellular Automaton - jasonhansel
https://www.nytimes.com/2017/04/12/science/ocellated-lizards-scales-cellular-automata.html?_r=0
======
tombert
It's things like this that help validate my hypothesis: If you define
something in mathematical theory, _eventually_ we'll find some way to use it
for modelling something.

I've been fascinated by Cellular Automata since I read Wolfram "A New Kind of
Science", but I was not overly sold that you could model the universe in the
way he described.

While I still think he was incredibly over-optimistic about the uses of
cellular automata, I do wonder if after a number of years we'll find some more
validation in nature.

~~~
db48x
Wolfram's "A New Kind of Science" is extremely overstated.

On the other hand, I think Turing first suggested that animal coloration might
turn out to be related to cellular automata. Sadly that's the kind of over-
broad suggestion that turns out to be largely untrue, with possibly only a few
exceptions. Mosty it's probably X-inactivation.

~~~
db48x
Well, now that it's morning I can't say that it's "mostly" X inactivation;
male zebras and tigers are striped so that's not going to be X inactivation.

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r3dk1ng
Another cellular automata seen in animals:

[https://en.wikipedia.org/wiki/Rule_30](https://en.wikipedia.org/wiki/Rule_30)

~~~
samlittlewood
Conus Textile is _very_ cool - good examples look just like computer
simulations!

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kburman
This is what I got when I clicked on the link
[https://postimg.org/image/6n8pnqidj/](https://postimg.org/image/6n8pnqidj/)

I thought it was some kind of joke or spam post until I scroll down to see
this.
[https://postimg.org/image/onyt7vbdj/](https://postimg.org/image/onyt7vbdj/)

Not the end when I tried to upload these screenshots to Imgur i received this
[https://postimg.org/image/z9g43te8n/](https://postimg.org/image/z9g43te8n/)

~~~
kburman
This is getting insane now postimg.org is down, don't believe check yourself
[https://ibb.co/mR1CO5](https://ibb.co/mR1CO5)

Since I can't update my comment now, here are updated links for the image

[https://ibb.co/n79owQ](https://ibb.co/n79owQ)
[https://ibb.co/d6F6i5](https://ibb.co/d6F6i5)
[https://ibb.co/fo6CO5](https://ibb.co/fo6CO5)

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jfarlow
Turing's paper [1] is pretty impressive. Well before the mechanics of
molecular biology were understood, Turing was able to reason out how you could
use a 'few lines of (reusable) (biological) code' to produce patterns as
sophisticated (and seemingly unrelated) as zebra stripes, leopard spots, and
even the shapes of tissues, the number of digits on a hand, and the morphology
of even a whole organism. And he was mostly correct once we came to be able to
actually describe the physical systems biology uses for patterning.

One example of a generalizable code for patterning by 'reaction diffusion':

\- Set up a 'node' that has an inverted feedback loop for producing a
'morphogen' (produce less when lots, lots when less).

\- Let the morphogen diffuse through a field.

\- Digitize the morphogen concentration by some thresholded sensor.

\- Use an orthogonal 'clock' mechanism to freeze the field in different states
digitized above.

Generally though the simulation of biology runs into just way way way too many
variables to be 'nicely' modeled. Part of the cool part is that when you have
a routine that generates a spatial pattern established, tweaking parameters
here and there create massive variation while still maintaining a coherent
'pattern'. A bit of chaos gives each run a fingerprint - literally.

One of the other biological patterning mechanisms I like is the Notch pathway,
relying on similar principles. [2]

There are fewer variables in a chemical system, but similar reaction-diffusion
related principles can be found in chemistry - which can often be 'pretty'.
See the Belousov-Zhabotinsky reaction [3].

As an aside, I like that they reference the paper that describes now
chameleons change color; "chameleons shift colour through active tuning of a
lattice of guanine nanocrystals within a superficial thick layer of dermal
iridophores." [4]

[0] (actual research referenced)
[http://www.nature.com/nature/journal/v544/n7649/full/nature2...](http://www.nature.com/nature/journal/v544/n7649/full/nature22031.html)

[1] (PDF! Turing's 1952, The Chemical Basis of Morphogenesis)
[http://dna.caltech.edu/courses/cs191/paperscs191/turing.pdf](http://dna.caltech.edu/courses/cs191/paperscs191/turing.pdf)

[2] (Notch Patterning) [http://www.cell.com/trends/cell-
biology/fulltext/S0962-8924(...](http://www.cell.com/trends/cell-
biology/fulltext/S0962-8924\(12\)00105-5)

[3] (B-Z Reaction)
[https://www.youtube.com/watch?v=3JAqrRnKFHo](https://www.youtube.com/watch?v=3JAqrRnKFHo)

[4] (chameleon's color via guanine nanocrystals)
[https://www.nature.com/articles/ncomms7368](https://www.nature.com/articles/ncomms7368)

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mizzao
Most cellular automata simulators are on a square grid, but that lizard's
scales are on a hexagonal one. I wonder if that arrangement makes it easier to
produce recurrent local patterns.

Does anyone know if there is a cellular automata simulator on a hexagonal
grid?

~~~
allenz
You can simulate a hexagonal lattice on a square grid:
[https://geometricolor.wordpress.com/2013/01/11/hexagonal-
cel...](https://geometricolor.wordpress.com/2013/01/11/hexagonal-cellular-
automata/)

Example in Golly, the most popular CA simulator:
[https://github.com/gollygang/ruletablerepository/wiki/TheRul...](https://github.com/gollygang/ruletablerepository/wiki/TheRules#hexagonal-
neighborhood)

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modzu
what can we feed it to play the game of life

~~~
ouid
anything

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ooqr
I like the HN title more than the NYT title. Something behaving like a
simulation is a funny way to describe it.

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vbwiwvbiudbiuw
Err well Cellular Automata were originally designed to simulate such
_cellular_ biological systems

~~~
pvg
Not really.
[https://en.wikipedia.org/wiki/Cellular_automaton#History](https://en.wikipedia.org/wiki/Cellular_automaton#History)

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tim_hutton
It seems odd to say "Mr. Turing" (referring to a period in the 1950s), given
that he got his Phd in 1938. The article uses "Dr." for other people.

~~~
sangnoir
A couple of days/weeks ago I saw on HN (I think) contributers saying (and
agreeing) that people with PhDs in the UK don't usually use/demand the title
of 'Dr.' unless they are medical doctors. It might _not_ be a mistake by the
times.

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palad1n
Wolfram should be all over this.

~~~
leblancfg
I expect a self-aggrandizing blog post on it any day now.

~~~
sillysaurus3
Complete with comments from people who won't stop talking about how
overbearing Wolfram is.

~~~
mmjaa
True. But consider this - there's been enough precedent on this particular
issue, that we could just be talking to a bot/AI, already, albeit one running
on wet-ware ..

~~~
pvg
Consider that bringing it up even when Wolfram isn't even mentioned is really,
really boring.

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logicallee
Oh, boy, little lizard, hope you're ready for a cease and desist from the
owner of "this kind of science". :)

(said in good fun)

