Quizatzhaderac wrote:Chopsticks use three fingers and six points of contact:
Hello. I meant, not how do people use them, but how do they themselves work "as fingers". In otherwords, Edward
Chopstickhands. Maybe you're also willing to explain how they work efficiently enough to survive along with the fork, the spoon, and even just going commando (using fingers directly)?
The grip used to hold chopsticks typically constrains them to a single plane of pincher-like movement. The lower chopstick is held immobile, while the upper chopstick is free to move up and down but cannot move left or right.
Think about a lobster's foreclaw. The larger "finger" of the claw is fixed, while the smaller "finger" may open or close but does not move perpendicularly.
From a mechanistic standpoint, this limitation on degrees of freedom is highly advantageous for the lobster and other clawed crustaceans, because it allows for greater force to be applied consistently and stably by only a few muscles. In contrast, our fingers are all triple-jointed (including the thumb, though its first joint is buried in the wrist), which gives them a nearly unlimited range of motion and fine control along their surfaces (e.g., if you hold a ball bearing between your thumb and any finger, you can roll it forward and backward, left and right, and any planar direction in between) but reduces the stability of the "open-shut" motion. More degrees of freedom means less stability in tension/compression motions.
With polyjointed digits, then, we need to use two or three or all four fingers working together to increase the stability of our grip. A lobster has a self-stabilizing grip with only one moving digit, but obviously lacks the fine manipulation control of our fingers.
Because chopsticks are used in a self-stabilizing way, they allow you to exert greater force with less effort, using very small gripping surfaces that can fit into a smaller space than your fingertips can. For a task like picking up sushi or other discrete food items, this is fantastic; you can choose exactly how much force to use more easily than with your fingers, which are comparatively less stable.
Forks are somewhat easier to use, but they are necessarily a "destructive" way of picking something up. "You can't pick this up without piercing holes in it" might not seem like a problem for something you're going to chew up anyway...but then again, have you ever tried to stab a single piece of lettuce with a fork? Or a tiny piece of carrot that keeps sliding around on the plate? When you stab something, the underlying surface needs to act as your opposable control tool, and that makes things tricky. What if all you have is a shitty plastic fork and the tines keep bending, or what if your plate is made of styrofoam? Maybe the pieces of food are just resting on a napkin in your hand and you'd rather not stab yourself, or maybe the piece of food is part of a delicate table arrangement that doesn't give you any surface to poke against. Perhaps you want to pick up a cherry tomato but don't want the juice to squirt everywhere like it does when you stab it. In all of these cases, it would be preferable to have a non-destructive means of picking up and moving the object.
There's a very good reason why tractors/trucks used in numerous industries (recycling, salvage, shipping, logging, construction, landscaping, utility work, and more) are often equipped with a powered grapple/claw arm rather than just having a fixed arm with long stabby tines on the end.
However, it's true that chopsticks suck for trying to "scoop" independent objects simultaneously. A fork is better for this, but only accidentally because it can mimic the action of a spoon.