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The human hand can be flexed at the wrist, extended and even abducted or adducted while the forearm can also be twisted in supination or pronation giving the illusion of the wrist twisting.

All of these movements are necessary for all basic human functions.

But what if the there was not such thing as a wrist? what if the hand would be directly attached to the forearm.

Would things like writing as we know it be possible, if not then what other method of writing would humans have invented? And would there be any advantages to not having wrist or there would be only downsides to not having wrists?

why would such a thing come to pass? how did that limb accomplish its original function of perambulation without a hinge for flexion, assuming that ceature was a quadriped, as all amphibian-derived land animals on earth

Said humans or creatures have an exoskeleton that doesn't allow movements at the wrist, there's no actual wrist.

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    $\begingroup$ why would such a thing come to pass? how did that limb accomplish its original function of perambulation without a hinge for flexion, assuming that ceature was a quadriped, as all amphibian-derived land animals on earth. $\endgroup$
    – theRiley
    Nov 4, 2018 at 14:50
  • $\begingroup$ Seriously, don't just copy-paste comments into your question. And adding information like having an exoskeleton instead of an endoskeleton changes the whole question. Try using the sandbox to figure out what you want to ask. $\endgroup$
    – nzaman
    Nov 5, 2018 at 13:26
  • $\begingroup$ You should do research on people that get permanent metal plates installed after wrist injuries; their wrist dexterity is severely impaired. $\endgroup$
    – MonkeyZeus
    Nov 5, 2018 at 13:32
  • $\begingroup$ I knew someone born with no arms at all but hands attached at her shoulders. She was definitely able to write with those hands (albeit with some difficulty), so I'd say mere the lack of wrist would pale in comparison to that. $\endgroup$ Nov 5, 2018 at 19:41

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I’m not sure about potential advantages/disadvantages to not having wrists, but as it’s definitely possible to write, draw, and paint without the use of one’s hands, having fixed wrists wouldn’t negate the possibility of writing. I know it’s just a Wikipedia page, but there’s an association set up for artists who use only their feet or mouths to paint, so it’s absolutely possible to create incredible works of art without hands, wrists, or arms. (Also, from personal experience with a broken arm, one can write with an arm and wrist in a cast - it’s tiring, because it requires much grosser motor skills than normal, but it does work).

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One thing to consider: without a wrist allowing the radius and ulna to segue into carpals, all your finger muscles would have to connect to the radius and ulna in straight lines, rather than be spread out over your hand. So, you'd either have to have fewer fingers or less mobility. Of course, you could have wider forearm bones to compensate, but that would lead to a clumsier upper arm, as the muscles from the wide forearm plates would have to connect to the much narrower humerus. Then you could make the humerus wider.... you get the picture.

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  • $\begingroup$ Finger muscles do connect to the forearm bones. en.wikipedia.org/wiki/Flexor_digitorum_profundus_muscle $\endgroup$
    – David K
    Nov 5, 2018 at 13:57
  • $\begingroup$ @DavidK: So noted and corrected $\endgroup$
    – nzaman
    Nov 5, 2018 at 14:10
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    $\begingroup$ The real problem seems to be where to put the joints at the base of the finger bones. To accommodate four fingers and a thumb of the same relative size as a human's, you would need to widen the forearm bones, but only at one end (far from the humerus). IIRC there are examples of this in other known species. Fewer fingers might be a reasonable choice. $\endgroup$
    – David K
    Nov 5, 2018 at 14:17
  • $\begingroup$ @DavidK: The question's changed since I posted my answer. We're now apparently talking about exoskeletons which is a different game altogether $\endgroup$
    – nzaman
    Nov 5, 2018 at 14:34
  • $\begingroup$ Yes, this was an interesting exercise in anatomy but it seems the OP wanted to go in a different direction. $\endgroup$
    – David K
    Nov 5, 2018 at 14:35
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I agree with other answers on reduced dexterity. Writing will likely consist of straight lines, like Nordic runs, or cuneiform.

Advantages will be few, but could include better tolerance of hard manual labor, like digging or mining. Those activities are very hard on weak joints like wrist.

This will not give them advantage in combat, since dexterity is more important. They might be better at shield wall and spear trust, but they will get slaughtered if they break ranks

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    $\begingroup$ As far as combat goes, single handed weapons probably wouldn't exist, or exist in the form of blades attached to the forearm: why hold it in your hand if you can hold it only at a fixed angle? Spear-like weapons with longer handles would still allow them to control the stabbing direction, using both of their hands. $\endgroup$
    – Headcrab
    Nov 5, 2018 at 3:55
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It is definitely possible to write and draw with a fixed wrist. All you need is to put your wrist in a cast or stabilizing bandage to try it out. Of course that presupposes that your fingers are still as flexible and dexterous as usual.

Advantages

The wrist is a rather vulnerable part of the arm because it's composed of a lot of tiny bones and sinews. Twisting and pulling can easily damage the wrist and put the bones out of alignment. The bones break under less force than bigger, hollowed bones and sinews that were cut do not reattach naturally. Not having a wrist eliminates these vulnerabilities to a limited extend (there are still the fingers that can be damaged just as well)

Disadvantages

Obviously not having the flexibility of a wrist limits the dexterity of our hand. We can use most tools like pens, tweezers and pliers without utilizing our wrist, but they aren't of much use if we cannot maneuver them into the right position.

People who have their wrist stabilized rotate their elbows and shoulders to compensate for the wrist, but this is often strenuous and inferior to the mobility of a wrist. But a species that evolved without a wrist in the first place would have probably adapted that way. Take industrial robot arms for example: They move in a (for humans) unnatural way to compensate for the shortcomings of their joints.

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Humans are obligatory tool users.

Our dexterity using our tools largely comes from the dexterity available in our wrists and fingers. Consider first your average toolbox, how many of these tools are entirely dependent on wrist movement to use? Most of them. How many could be modified to be used by someone without wrist movement? Few if any without making a simple tool much more complex.

It's highly unlikely this species would have made it out of the stone age. It's possible they'd have trouble getting into the stone age.

Hunting would be hard. The ability to aim a spear or equivalent thrown weapon is tied to the movement of the wrist. Knapping flint requires you to get precise angles between the stones to get the right effect, it's all in the wrist. Even the simplest of actions like eating with your hands, or picking a small item off the ground become significantly more difficult tasks.

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