
Individual behavior in clonal fish despite near-identical rearing conditions - r721
https://www.nature.com/articles/ncomms15361
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ajkjk
It seems possible to me that it would be advantageous for there to be
randomness baked into personality, to avoid things like 'decision making
deadlock'.

For instance, suppose a tribe of headstrong individuals who would never back
down in an argument, and would resort to violence before losing face. It might
be beneficial for random personality variation to exist to allow them to
settle such a debate nonviolently. Maybe one individual randomly becomes able
to laugh off conflict, or becomes more meek, or is more easy going.

It's kinda like how four cars that pull up to a four way stop at the same
instant decide who goes: some randomness in the timing of their reactions
leads to one pulling out a little before the others, and they're allowed to
go, gracefully resolving the deadlock. Four naively designed AIs might get
stuck in that situation (of course, simultaneity is implausible, but there are
similar cases that might be more realistic).

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FullMtlAlcoholc
I apologize in advance if I'm being overly pedantic, this weekend I took the
time to do a cursory study of chaotic complex, systems emergence and fractals
and i'm still trying on this new knowledge, but is it really considered
random? (I dont know the precise definition)

Even if raised in identical conditions, a small perturbation in a social
interaction (say one od the fish is looking directly at an event whilr another
only catches a glance at it from the side) can bubble up to produce large
changes in behavior?

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ajkjk
It's not (probably) random in the sense of true, quantum mechanical
randomness, but random can be thought of existing 'with respect to the certain
knowledge'. So if you flip a coin and have as input the precise physics of the
launched coin and the air, the result isn't random; if you only know 'a coin
was flipped' then it's essentially random.

So I imagine chaotic systems' outcomes seem random if you have only
approximate the initial conditions (since small perturbations will greatly
modify the outcome) (that's probably a good, equivalent definition of a
chaotic system, also).

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nolemurs
This study's result should really not be surprising to anyone. The idea that
somehow genetics + big picture environmental conditions are determinative of
outcome seems so superficially unlikely to be true to me that I'm kind of
baffled that anyone thought otherwise.

I'm sure many aspects of an individuals development _are_ largely determined
by genetics and big picture environment (anything else would be non-adaptive).
But it kind of seems obvious that within the range of reasonably adaptive
differences, the outcome is likely often chaotic. That should be the default
presumption, and absent some clear reason to expect otherwise, is what they
should have expected.

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gwern
I think you're engaged in hindsight and rather glibly biting that bullet.
Large swathes of sociology, medicine, nutrition, health research, governments
(even where genetic influences are accepted) are premised on the assumption
that one's environment and shared environment especially causally affect
outcomes in ways that can be measured and quantified and used in research and
provide paths towards understanding, control, and amelioration. Parenting, or
air pollution, things of that ilk. It certainly is not obvious to most people
that those are all minor effects of small importance compared to random
developmental noise or other things.

Of course no one would be surprised to find non shared-environment variance
components which were non-zero, but it's very surprising to find that they are
_so_ large: often larger than shared-environment effects, and sometimes as
large or larger than heritability. This is one of the most interesting and
counterintuitive findings of behavioral genetics, and experiments like OP put
this in extremely stark relief. If clones in as exactly identical environments
as researchers can create and perceive still wind up with such dramatic
individual differences, how is science even possible on what causes the
differences?

See:

\- "Three Laws of Behavior Genetics and What They Mean"
[http://people.virginia.edu/~ent3c/papers2/three_laws.pdf](http://people.virginia.edu/~ent3c/papers2/three_laws.pdf)
, Turkheimer 2000

\- "Why Are Children in the Same Family So Different? Nonshared Environment a
Decade Later"
[https://pdfs.semanticscholar.org/4091/dbfb736a4e793281e6b1aa...](https://pdfs.semanticscholar.org/4091/dbfb736a4e793281e6b1aa4a0a0974874832.pdf)
, Plomin et al 2001

\- "Epidemiology, genetics and the 'Gloomy Prospect': embracing randomness in
population health research and practice"
[http://ije.oxfordjournals.org/content/40/3/537.full](http://ije.oxfordjournals.org/content/40/3/537.full)
, Smith 2011

\- "Top 10 Replicated Findings From Behavioral Genetics"
[https://www.gwern.net/docs/genetics/2016-plomin.pdf](https://www.gwern.net/docs/genetics/2016-plomin.pdf)
, Plomin et al 2016

~~~
choxi
I have a shaky understanding of "non-shared environment", I get the sense that
it is based on the context of the study. e.g. If I do a study on genetically
identical mice and control their sugar intake, "sugar intake" would be shared
environment and something like "exposure to lead" would be non-shared. If I
did the same study and controlled their exposure to lead, it would be "shared"
in that case.

Is that an accurate understanding? Is "non-shared environment" basically the
"everything else" category after genetics and shared environment have been
controlled for?

Also,

> If clones in as exactly identical environments as researchers can create and
> perceive still wind up with such dramatic individual differences, how is
> science even possible on what causes the differences?

Another point in favor of simulation theory? :)

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jessriedel
> Is "non-shared environment" basically the "everything else" category after
> genetics and shared environment have been controlled for?

Yes. For instance, in a study of childhood development, "shared environment"
is the things that can plausibly be controlled since they are inflicted on all
children in a family (e.g., household income, or frequency of family dinners),
and "non-shared environment" is the "other" category that captures the
infinite number of uncontrolled influences that different children within the
family experience differently (e.g., having a scary fall down the stairs).

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stevesearer
Worth pointing out the movie The Boys From Brazil which explores the same
concept in humans:
[https://en.m.wikipedia.org/wiki/The_Boys_from_Brazil_(film)](https://en.m.wikipedia.org/wiki/The_Boys_from_Brazil_\(film\))

~~~
whatnotests
A bit corny but worth watching.

Also, (spoiler alert) -- Man in the High Castle.

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eveningcoffee
I am not biologist (that is the following is pure speculation based on
ignorance) but it feels to me that the method of their cloning leaves in
opportunity of minute changes in the offspring DNA.

This then still leaves open possibility that different behaviour is cause by
genetic mutations but this variation it much more amplified that presumed
previously.

I would be happy if somebody with more knowledge finds time to comment on
this.

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jacquesm
Would a DNA sequence comparison on the clones not be sufficient to rule out
such a basic mistake?

~~~
gwern
No, because DNA sequencing has lots of errors in it. This is why you might've
seen numbers like '30x' or '50x coverage': to get a decent sequence, it gets
done again and again and hopefully the random errors wash out. Identical twins
or clones are not _perfectly_ genetically identical, but the differences are
so rare that any difference in your sequence is almost certainly a sequencing
error unless you do an expensive number of passes like 70x costing several
times as much. Interestingly, this comes up a lot in criminal contexts now,
since you can, if you want to spend the money, figure out which of two
identical twins left DNA at a crime scene.

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foxyv
Biological systems are non-linear. In other news Jurassic park will be opening
today!

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robbrown451
Free will has been proven!

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pmarreck
Would this be called "personality"?

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BJanecke
We need Pshycohsitorians a la Harry Seldon

