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Its not so much the invention of the wheel but rather the invention of the axle (feddit.org)
submitted 2 months ago by to c/showerthoughts@lemmy.world
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Nature creates round objects all the time (stones in a river, a hedgehog in a ball,...), but the principle of an axle is not found as far as I know.

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[–] 7 points 2 months ago* (9 children)

yep, i don't think there's basically any living organism that is made of two parts that are not solidly attached to another, sothat they can rotate against one another.

knee joint might come to mind, but that's also connected by collagene i think, so it can't rotate by more than 360°.

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  • [–] [S] 10 points 2 months ago*

    If your knee can turn 360°, you should talk to some scientists, so that they can study you.

    Rotating is in nature, but as you said: always with a maximum rotation, never free without limits.

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  • [–] 10 points 2 months ago (2 children)

    Wikipedia has a whole article on this subject:

    https://en.wikipedia.org/wiki/Rotating_locomotion_in_living_systems

    The exceptions it mentions are bacterial flagella and part of the digestive system of some bivalves.

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  • [–] 3 points 2 months ago* (last edited 2 months ago) (1 child)

    yeah thanks for the article! rotating bacterial flagella is what came to my mind as well, but it's microscopically small (i think the flagella is a single macro-molecule?) so i'm not sure whether to include it in the list of (macroscopic) "mechanical rotation"... it's more like biochemical mechanical rotation.

    if we go for biochemical mechanical rotation, there's more: ATP-Synthase is a molecule that sits in cell membranes and that rotates as well each time that a proton passes through it.

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  • [–] 7 points 2 months ago (4 children)

    How about this insect with a pair toothed gears? Not an axle, but still amazing!

    "The juvenile Issus - a plant-hopping insect found in gardens across Europe - has hind-leg joints with curved cog-like strips of opposing ‘teeth’ that intermesh, rotating like mechanical gears to synchronise the animal’s legs when it launches into a jump."

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  • [–] 7 points 2 months ago (3 children)

    it's gears, alright, but i don't think that it can rotate by more than 360°?

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  • [–] 3 points 2 months ago (2 children)

    No, that's what I meant by not an axle.

    But, come to think of it, we can swing our arms round and round, more than 360°.

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  • [–] 1 point 2 months ago (1 child)

    I would argue that's more due to the up-down and front-back limited rotations combining to form a circular mode, kinda like a Cartesian to Polar coordinate mapping

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