[HN Gopher] Life's preference for symmetry is like 'a new law of...
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Life's preference for symmetry is like 'a new law of nature'
Author : mhb
Score : 26 points
Date : 2022-04-02 20:40 UTC (2 hours ago)
(HTM) web link (www.nytimes.com)
(TXT) w3m dump (www.nytimes.com)
| forgotmypw17 wrote:
| In sexual selection, a type of evolutionary selection driven by
| mate choice rather than raw survival fitness, yes, that piece of
| Darwin's writing which was suppressed by Victorian ideology for
| about 100 years until being rediscovered in the 1960s, symmetry
| is an easy show of control over the physical enviroment.
|
| By making more than one of identical somethings, you're showing
| that it was not through chance or accident that you developed
| this piece, but through deliberate growth and control, and you
| can prove it, because you've made two or more of them, and the
| viewer can easily check them against each other.
| systemvoltage wrote:
| A deeper way to think about this is that any phenomenon that
| pumps out entropy from the system by injecting work + heat
| tends to stand up like a sore thumb in the rather dull
| sponteneaty of nature. I don't mean entropy in the naive sense
| (order vs disorder), but as dispersal of energy (third law).
| Not sure what the cause of such locality is - perhaps we can
| call that intelligence?
| antattack wrote:
| "Why does symmetry reign supreme? Biologists aren't sure --
| there's no reason based in natural selection for symmetry's
| prevalence in such varied forms of life and their building
| blocks."
|
| Of course there is a natural selection reason - symmetrical
| structures are stronger.
| jlawson wrote:
| They're also info-compressed. You can re-use the same DNA for
| both sides. This means you have less meaningful information to
| maintain against random mutation pressure over time.
|
| Symmetry is also challenging to maintain and very visible; any
| malformation is obvious. This is useful in showing health and
| genetic fitness to mates.
|
| Many tasks are also inherently symmetrical, like locomotion.
| Evolving the two legs totally separately would be very error-
| prone and you'd never quite get it right. Having them both just
| be copies of the same structure is much cleaner and always
| efficiently completes the task.
|
| Same for things like binocular vision, having ears that hear
| equally and so can easily echolocate, etc.
| jameshart wrote:
| "symmetrical structures are stronger" - citation needed.
|
| Stronger under what condition? For the same amount of material?
| For the same amount of information needed to describe how to
| build the structure?
|
| Do we see evidence of structures which don't require strength
| being more likely to evolve to be asymmetric?
|
| Or do you just mean 'stronger' in a survival-of-the-fittest
| sense - symmetrical structures are fitter?
|
| It's not at all obvious to me that this should be the case.
| Indeed, some very strong natural structures like shells are not
| symmetric at all.
| TheOtherHobbes wrote:
| Mobile Cambrian seabed dwellers with asymmetrical legs
| probably didn't last very long.
| jameshart wrote:
| Among the most successful seabed-dwelling form factors are
| crabs and lobsters, which frequently have distinctively
| asymmetrical legs, and gaits.
|
| Crabs are such a successful shape, crustaceans have evolved
| into it five separate times.
| Barrin92 wrote:
| I'm surprised that this is characterized as such a novel idea in
| the article because I'm almost certain I've had this discussion
| ages ago on HN here. I think it was someone asking "why the hell
| are there spirals everywhere" and multiple people pretty quickly
| pointed out that self-repeating, symmetric, and fractal patterns
| are simply a very easy, 'low-information' ways to build larger
| structures.
| zitterbewegung wrote:
| A preprint of the information that was derived to make the
| above article has been available for a year.
|
| https://www.biorxiv.org/content/10.1101/2021.07.28.454038v2
| jazzyjackson wrote:
| a mind-rewiring video by numberphile concerning the golden
| ratio [0] made sense of all the spiral overlay art:
|
| yes, plants use it because it is an optimal solution for
| minimizing overlap when sprouting leaves during growth,
| maximizing spatial coverage
|
| but also, as a number that is least able to be approximated by
| rational, erm, ratios - it is a pattern that most closely
| approximates random patterns. So more than any other spiral, a
| fibonacci spiral has the highest likelihood of overlapping
| random points in 2D space... (and fibonacci series converges on
| the golden ratio because they are equivelent expressions of the
| continued fraction 1+(1/(1+(1/(1+(1/(1+(1/...
|
| [0] https://youtu.be/sj8Sg8qnjOg
| Aerroon wrote:
| > _' low-information' ways to build larger structures._
|
| And I assume that these low-information ways are more likely to
| emerge by random chance, because you have to get fewer bits
| right?
| amelius wrote:
| The problem with spirals, though, is that they are not
| symmetric. They are either left-turning or right-turning, not
| both.
| TuringTest wrote:
| They are not symmetric, but they are self-repeating. You can
| grow a spiral from a very simple set of rules on its lower
| level substrate.
| TheOtherHobbes wrote:
| They're not geometrically symmetric, but they are symmetric
| in the more general sense of applying an invariant
| transformation.
| stardenburden wrote:
| https://archive.is/CVYlp
| jw1224 wrote:
| The universe appears to be fractal-like in nature, so I would
| speculate these biological symmetries are a reflection of the
| symmetries we find in the laws of physics, too.
|
| ScienceClic is an extremely underrated YouTube channel producing
| incredible visualisations for scientific theories. They manage to
| cover some very advanced concepts, in an easily accessible way.
|
| Their video on "The Symmetries of the Universe" was eye-opening,
| and somewhat mindblowing in the context of the bigger picture:
|
| https://www.youtube.com/watch?v=hF_uHfSoOGA&
| wrnr wrote:
| Nature uses symmetrie when it is useful, but if it isn't it
| doesn't. Many such examples, L-sucrose vs R-sucrose, male-
| female differences. The same in physics and mathematics, Higgs
| mechanism is dependent on symmetry breaking of the weak force,
| and in mathematics the very nature of symmetry (group theory)
| has all sort of random exceptions of the pariah group of the
| sporadic simple groups.
| jazzyjackson wrote:
| Personally I consider any "random" abberations to be symptoms
| of the hairy dog theorom: you cant comb all the hair to lie
| flat, somewhere on the spherical dog, you're going to get a
| cowlick, it is unavoidable
|
| in the meantime, chirality is simply mirror symmetry :
| curious part to me, is how mirror symmetry works out as one
| half being the "inside out" version of the other, turn a left
| handed glove inside out and it will fit the right hand. Maybe
| points to 4th dimensional stuffs, I never could grok how to
| turn a sphere inside out without pinching
| DennisP wrote:
| The article kinda says the opposite: that even when symmetry
| gives the organism no particular advantage, it still tends to
| get used because it's easier to code in the DNA.
|
| That doesn't mean there will be no counterexamples ever.
| Sometimes asymmetry gives an advantage so it's worth the
| extra coding.
| hcrisp wrote:
| The article mentions the human heart is asymmetrical, which was
| an exception I thought of immediately. And actually there are
| many more internal organs that are too (maybe more than are
| not?), such as: - lungs (the right has 3 lobes,
| the left only 2) - stomach - pancreas -
| instestines - gall bladder - liver
|
| I once heard of someone that went to the ER for appendicitis and
| when they imaged him, some of his internal organs were left-right
| reversed!
| beefman wrote:
| Paper: https://www.pnas.org/doi/full/10.1073/pnas.2113883119
|
| Preprint:
| https://www.biorxiv.org/content/10.1101/2021.07.28.454038v2
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