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Individual behavior in clonal fish despite near-identical rearing conditions

• stevesearer 9y ago
  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 9y ago
    A bit corny but worth watching. Also, (spoiler alert) -- Man in the High Castle.
    • deleted 9y ago
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• ajkjk 9y ago
  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).
  • Gravityloss 9y ago
    Two thoughts here. If you look at fingerprints or the spongy interior of bones, clearly there's a lot of detail there. But the position of every skin whorl or bone void is not specified directly by a gene. Identical twins don't have identical fingerprints. This doesn't matter for finger or bone functionality, as long as the material works on a statistical, higher level. If you think of it as a blueprint for a bone, like for a building, the specification just says "x percentage of void with average cell size y and variance z", just like a building specification doesn't specify the location of every grain of sand. And of course then it also grows in response to how it's stressed. Anyway, this is because it wouldn't make sense to store all the exact information, you just store some metadata and generate the actual stuff when building. Also you do testing and build more after that. With the brain, it's the same, the amount of neurons and synapses is large compared to the amount of genes or "blueprints". But in a brain, as opposed to a bone or a finger, because the whole thing is designed to amplify weak signals, detail differences can have more effect on the function of the whole. There is this whole internal testing pattern going on while the brain is being built, but it seems it's not so perfect that clear differences creep in easily.
    • irickt 9y ago
      Yes, I was surprised that the article didn't mention neurogenesis. It's worth pointing out a result from game theory: Given related individuals (using the example of two shepard brothers who may signal each other for help) there are many signaling equilibria. The particular path is sensitive to random initial conditions. Interestingly, even for a simple game where a non-signaling altruistic solution dominates, a signaling solution reliably emerges and converges. Game Theory Evolving, Herbert Gintis, 2000 (first edition), pp 321-323.
  • FullMtlAlcoholc 9y ago
    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?
    • Retric 9y ago
      QM effects are considered random and influence just about every real world system. PS: At the 'other end' relativity actually influences a lot of chemistry because electrons are just that fast in orbit around atoms. But, that's generally ignored by just about everyone. https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry https://en.wikipedia.org/wiki/Relativistic_quantum_chemistry
    • ajkjk 9y ago
      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).
  • 65827 9y ago
    That's basically the thesis of the paper, there is some randomness completely independent of both genes and environment. I think it's super cool but I can see how some (white) people would find this upsetting.
    • dang 9y ago
      You've repeatedly been violating the HN guidelines by posting inflammatory, unsubstantive comments and dropping gratuitous flamebait. If you continue to do this, we're going to have to ban your account, so please (re)-read the following and fix this: https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newswelcome.html https://news.ycombinator.com/newswelcome.html
    • deleted 9y ago
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  • gwern 9y ago
    > 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'. There is no need for randomness there. This scenario is handled by frequency-dependent selection like the 'hawk and dove' model or the male/female sex ratio. If aggressiveness becomes too common, then it gets selected against until it's driven back down to a frequency where it's neutral. This sort of frequency-dependent selection is one of the behavioral genetics interpretation of why we have personality factors, actually: see "The Evolutionary Genetics of Personality" http://www.unm.edu/~gfmiller/newpapers_sept6/penke%202007%20targetarticle.pdf http://www.unm.edu/~gfmiller/newpapers_sept6/penke%202007%20... , Penke et al 2007; & "The Evolutionary Genetics of Personality Revisited" http://www.larspenke.eu/pdfs/Penke_&_Jokela_in_press_-_Evolutionary_Genetics_of_Personality_Revisited.pdf http://www.larspenke.eu/pdfs/Penke_&_Jokela_in_press_-_Evolu... , Penke & Jokela 2016 (I ran into a nifty mouse study on personality the other day demonstrating this sort of thing: https://academic.oup.com/beheco/article/26/5/1285/242100/Temporally-fluctuating-selection-on-a-personality https://academic.oup.com/beheco/article/26/5/1285/242100/Tem... )
  • ouid 9y ago
    It's not just decision making deadlock that receives a benefit. The survival of my offspring is often dependent on them expressing strategic diversity from one another. The only feature that you share in common with your ancestors who survived snowball earth is the uncertainty of inheritance through mutation. If uncertainty is adaptive, it makes sense that it would also be encoded into the genome.
  • qb45 9y ago
    > It seems possible to me that it would be advantageous for there to be randomness baked into personality There is also a question of possibility. Do we really understand how few hundred megabytes of information driving a soup of self-replicating peptides could encode the details of large, complex organisms, completely with all their behaviors, regardless of environment and random flukes? It's a miracle that this stuff works even as far as we can observe it working. And on a somewhat tangential note: People discovered genes and sorta jumped to conclusion that there must be genes for every adjective they have ever come up with to describe organisms. They used genetics to justify various eugenics movements. 100 years later, we still have trouble finding genes responsible for complex features. I somewhat trollishly call it "intelligent design" or, more specifically, "anthropomorphically-intelligent design" because it really is an assumption that life is a sort of machinery designed in the same way the current generation of humans would go about engineering that kind of stuff, i.e. describe the "features" we think organisms have and figure out ways to "implement" them using biological processes we assume to be possible. I'm not saying that I know a better way. I'm just not really surprised when science delivers less than people hope and hype.
• robbrown451 9y ago
  Free will has been proven!
• eveningcoffee 9y ago
  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.
  • jacquesm 9y ago
    Would a DNA sequence comparison on the clones not be sufficient to rule out such a basic mistake?
    • eveningcoffee 9y ago
      Yes, it should, but how precise is this method and does it take the full DNA into account? Edit: the fish reproduces gynogenetically, that is the offspring contains only maternal DNA. But this does not mean that mutations in DNA do not occur. They also say to use genetic sampling which translates into my understanding as an approximate method.
    • gwern 9y ago
      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.
• nolemurs 9y ago
  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.
  • rectangletangle 9y ago
    Phenotypic plasticity is a well documented phenomena in biology, this study seems to help confirm it exists in fish. In plants it gets pushed to interesting extremes due to their sessile nature. For instance etiolation occurs when plants are grown in the absence of light. They adapt by growing long thin brittle stems, to optimize the individual's morphology for longer reach, and minimal metabolic impact. "Personality" in animals is just an extremely variable/adaptable manifestation of this.
  • d4mi3n 9y ago
    That's science—even a failed experiment can have significance. So long as it was methodically done and well recorded, work like this is still valuable in that it improves our understanding of the world.
    • nolemurs 9y ago
      Ohh, absolutely. I'm glad they did the study. I'm just responding to the expectation stated in the paper. I really don't understand what sort of mindset would lead someone who has actually given it serious thought to expect what they did.
  • mowenz 9y ago
    >not surprisingly [...] the outcome is likely often chaotic. Ok so if we have assumption that to make Identical[DNA + environment] equal to a chaotic outcome, then we need to add variable, random. Random would be determimed by environmental noise or possibly even (even more random) random quantum noise. Why should we expect the effect of Random to be large enough to create easily identifiable personalities, or more accurately, behavior patterns? So to be fair about this: I'm not aware of a specific reason it was so obvious to you (you don't provide any). Your intuition in hindsight will always seem like common sense to you. That's why it's good we do these types of experiments which question our intuition.
• BJanecke 9y ago
  We need Pshycohsitorians a la Harry Seldon
• pmarreck 9y ago
  Would this be called "personality"?
• foxyv 9y ago
  Biological systems are non-linear. In other news Jurassic park will be opening today!