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Comment by hcrisp | Hacker News Reader

I was just thinking about this. Does folding your hands count as a gear? The interlocked fingers make for a tighter grasp. When viewed from the palm side they even look like a gear. It is not the natural state of the hands but many gears also spend time in an unmeshed state. What is the definition of a gear anyway?

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Not an expert, but I feel like interlocking your hands does not count because the definition of a gear includes rotation, and transmission of motion. Interlocked hands don't rotate and they don't transmit motion.

Interlocking hands seems to me to be about grip strength. Sometimes it's easier to grip your other hand by interlocking than it is to grip the object you're lifting.

Then the "gear" from this insect would also not count as it does not transfer motion. Its more like a joint that has teeth for extra grip.

> an intricate gearing system that locks their back legs together, allowing both appendages to rotate at the exact same instant

That sounds like transmission of motion to me?

If I lock my hands together, rotating one of my wrists also rotates the other wrist. I'm not saying it's a _useful_ transfer of motion though!

Only if one leg is pushing the other leg

> To confirm that the gears performed this function, the researchers performed a neat (albeit morbid) trick with some dead Issus. They manually cocked their legs back in a jumping position, then electrically stimulated the main jumping muscle in one leg so that the leg extended. Because it was rotationally locked by the gears, the other non-stimulated leg moved as well, and the dead insect jumped forward.

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