
Alan Turing's 'Morphogenesis' Theory Confirmed 60 Years After His Death - wrongc0ntinent
http://www.huffingtonpost.com/2014/03/20/alan-turing-morphogenesis-confirmed_n_4986583.html
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apsec112
An important discovery, but equally important to keep it in proper context:

"If you want to get a rough grasp of how the leopard might get its spots, then
building a CA model (or something similar) can be very illuminating. It will
not tell you whether that's actually how it works. This is an important
example, because there is a classic theory of biological pattern formation, or
morphogenesis, first formulated by Turing in the 1950s, which lends itself
very easily to modeling in CAs, and with a little fine-tuning produces things
which look like animal coats, butterfly wings, etc., etc. The problem is that
there is absolutely no reason to think that's how those patterns actually
form; no one has identified even a single pair of Turing morphogens, despite
decades of searching.

For a good account of the actual mechanisms of biological pattern formation,
as they are being revealed by molecular developmental biology, see John
Gerhart and Marc Kirschner, Cells, Embryos and Evolution: Toward a Cellular
and Developmental Understanding of Phenotypic Variation and Evolutionary
Adaptability (Oxford: Blackwell Scientific, 1997). This book provides an
excellent discussion of the interactions between genetic control, self-
organization, evolutionary forces and functional adpatations in development.
(There is a nice review by Danny Yee.) — The failure of experiment to turn up
any biological system working according to Turing's principles was remarked by
the late, great John Maynard Smith in his review of Depew and Weber's
Darwinism Evolving (in the New York Review of Books, vol. 42, no. 4, 2 March
1995); my search of the subsequent literature doesn't indicate that the
situation has changed.

Update, 4 March 2012: There is now a fairly convincing example of a pair of
Turing morphogens in actual biology:

Andrew D. Economou, Atsushi Ohazama, Thantrira Porntaveetus, Paul T Sharpe,
Shigeru Kondo, M. Albert Basson, Amel Gritli-Linde, Martyn T. Cobourne and
Jeremy B. A. Green, "Periodic stripe formation by a Turing mechanism operating
at growth zones in the mammalian palate", Nature Genetics 44 (2012): 348--351

Thanks to a reader for letting me know about this."

[http://vserver1.cscs.lsa.umich.edu/~crshalizi/reviews/wolfra...](http://vserver1.cscs.lsa.umich.edu/~crshalizi/reviews/wolfram/)

~~~
mjn
Yeah, the reporting is a bit strange, though the Turing paper covers a wide
range of subjects, so that's not too surprising. Turing's theory is so broad
it would be difficult to "confirm" it with any single study, because he
proposed a mechanism that he hypothesized could account for an extremely wide
range of phenomena. It's not really a theory of one particular mechanism, so
much as a meta-theory that many patterns in nature are produced by various
physical instantiations of a more general mathematical mechanism. It would be
difficult to confirm that in the strong sense with anything short of a wide-
ranging survey covering thousands of experiments, showing that an enormous
range of physical mechanisms and patterns in nature really are the result of
this abstract meta-mechanism. This paper has not done that, so it hasn't
really confirmed Turing's hypothesis in the strong sense.

On the other hand, one might be looking for a weaker sort of confirmation: not
that Turing-style morphogenesis accounts for everything, but that it accounts
for _at least something_ , i.e. there is at least one demonstrable instance
where a Turing-style explanation can be shown to account for a process as it
actually works physically & historically in nature, vs. just being a clever
way of mathematically approximating a pattern. In that case, the paper you
link above is at least one prior example, and this article adds another
domain-specific investigation.

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marktangotango
It's interesting to note that Turing, Von Nueman, and Konrad Zuse all moved
into studying cellular automata in their later years. Conway is famous for his
game of life, but but Turings work consisted of this morphogensis thing, and
Von Nueman created a self replicating automata. I don't recall what Zuse's
work consisted of. Also interesting, Wolfram mentions none of their work in
his book, "A New Kind of Science".

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baddox
> Also interesting, Wolfram mentions none of their work in his book, "A New
> Kind of Science".

There's one of the most blatant and ridiculous lies I've seen today, with such
an obvious agenda. It's disgusting.

Turing and biological pigmentation patterns:
[https://www.wolframscience.com/nksonline/page-1003g-text](https://www.wolframscience.com/nksonline/page-1003g-text)

Detailed summary of von Neumann's work in self-replication:
[https://www.wolframscience.com/nksonline/page-876b-text](https://www.wolframscience.com/nksonline/page-876b-text)

An index entry on Zuse and modelling the Universe as a cellular automaton,
although the text itself is not freely available:
[https://www.wolframscience.com/nksonline/index/z.html?Search...](https://www.wolframscience.com/nksonline/index/z.html?SearchIndex=zuse#searchword1)

Please don't use bald-faced lies to propagate hatred of anyone.

~~~
nswanberg
His wasn't an informed comment but it's best responded to with just the links
you posted.

Turing seems to be sort of a personal hero to Wolfram, so I'm sure that he'd
have some interest in the results in the post.

And for anyone interested in modeling nature with computers more generally, _A
New Kind of Science_ is wonderful reading and gives a great conceptual
framework on how to go about it. It's sad that the Shalizi review is the first
thing people refer to (it's sort of the Huffington Post of reviews).

~~~
mjn
_It 's sad that the Shalizi review is the first thing people refer to (it's
sort of the Huffington Post of reviews)._

Do you base this on just this one review, or more generally? I've mostly found
his reviews informative and much better researched than most online reviews.
They have opinions, but the opinions are more informative to me than "I like
this" or "I don't like this". I usually feel that I learn something from the
reviews, including finding new books and articles to read because they're
cited in the review. That's not exactly something that happens at HuffPo.

~~~
nswanberg
I meant to refer to that particular review, not his reviews in general. It's
been a long time since I've poked through those, and they seem reasonable,
which makes the review of Wolfram's work that much stranger.

Anyway, the history of cellular automata is sort of interesting, and the
notion of using computation to explain biological markings is also
interesting. Thought after skimming Turing's paper it looks like while Turing
makes many simplifying assumptions, did some basic computer modeling, and is
literally about biological cells, his model is not as abstract as the cellular
automata von Neumann, Conway, or Wolfram studied--unlike the others Turing's
model uses linear equations to transmit "state" from cell to cell instead of
rules. In fact Wolfram's contribution was to remove as many details as
possible from cellular automata, enumerate all the possibilities, and observe
what happens.

The bummer about referring to that review in other threads or in this case
mischaracterizing Wolfram's work is that it distracts from creating more
interesting discussions about this stuff. There are currently about 16
comments effectively discussing attribution, and precious few about what sort
of model Turing proposed.

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Splendor
Turing's paper [PDF]:
[http://www.dna.caltech.edu/courses/cs191/paperscs191/turing....](http://www.dna.caltech.edu/courses/cs191/paperscs191/turing.pdf)

~~~
nswanberg
And here is the paper covered in the original post:
[http://fraden.brandeis.edu/publications/papers/PNAS(2014).pd...](http://fraden.brandeis.edu/publications/papers/PNAS\(2014\).pdf)
with notes at
[http://www.pnas.org/content/suppl/2014/03/06/1322005111.DCSu...](http://www.pnas.org/content/suppl/2014/03/06/1322005111.DCSupplemental/pnas.201322005SI.pdf#nameddest=STXT)
It's dense but not impossibly so.

One modification they made to Turing's idea was that each cell has the same
composition. They found that, to produce the results they expected, they
needed to alternate the composition of neighboring cells.

(It would be nice if your post was at the top of the thread, since it's the
most relevant and useful so far, but it is not very controversial. Next time
consider adding something like "Biology professors hate him! Read this man's 1
weird trick for explaining morphogenesis!")

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bobjordan
Here is an interesting semi-technical read relating to how Turing's work helps
to explain drug-induced hallucinations:
[http://plus.maths.org/content/uncoiling-spiral-maths-and-
hal...](http://plus.maths.org/content/uncoiling-spiral-maths-and-
hallucinations)

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jboynyc
A great book on the general context of what counts as an explanation in
biology -- and, by extension, why the mathematical biological approach
advanced by Turing never really caught on -- is presented in Evelyn Fox
Keller's _Making Sense of Life: Explaining Biological Development with Models,
Metaphors, and Machines_ (Harvard U.P., 2003). A short version of the argument
is presented in this article from _Project Syndicate_ : [http://www.project-
syndicate.org/commentary/biology-s-clash-...](http://www.project-
syndicate.org/commentary/biology-s-clash-of-civilizations)

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moron4hire
"60 years after his suicide..."

appreciated they didn't say "death". Would have preferred "apparent suicide",
but it's a step in the right direction.

~~~
JoeAltmaier
I'm surprised by the '60 years' part - if not killed, he could be living
today! What a stupid loss.

~~~
moron4hire
Indeed. Maybe he could have made more discoveries. Maybe he could have trained
an entire, new generation of mathematicians. Maybe he could have just gotten
to live a happy life, as should be the right of all human beings.

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joshontheweb
I'm curious as to how this explains geometric drug induced hallucinations.
That has always puzzled me.

~~~
jes5199
There's a good paper about how some geometric hallucinations are formed:
[http://people.mbi.ohio-
state.edu/golubitsky.4/reprintweb-0.5...](http://people.mbi.ohio-
state.edu/golubitsky.4/reprintweb-0.5/output/papers/6120261.pdf)

~~~
codezero
Interesting, I see geometric patterns when I rub my eyes real hard, always
wondered what caused it.

~~~
3rd3
I think there is a wiki article explaining this by pressure and heat both
activating cells on the retina.

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Nursie
I went to a talk on this paper up at Bletchley Park a few years back. Very
cool, not quite what I expected (ie, not compsci theory) but really
interesting nonetheless.

As I understand it this was his last paper too, before the authorities
basically hounded him to death.

