Introduction: Welcome to a world where hominids developed to have two different sized hands (similar to the male fiddler crab). We have developed societies, art, and naturally war.

But, how exactly does our world look like?

Facts about the creatures: They have developed pretty much along the lines of humans and even look similar, besides the obvious thing, their hands. The following list describes describes what their hands look and work like:

  • main-hand:
    • 6 (or even more) fingers
    • long fingers
    • quite dexterous
  • off-hand:
    • 3 or 4 fingers
    • short, stubby fingerlets
    • comparably stronger, sturdier
  • the gene for a left-main-hand is recessive

What design related thoughts have to be made for the development of tools & appliances in such a world?

I can imagine things like swords and basic writing utils to look quite similar to earth. But I cannot fathom how things such as computers or cars would have to be changed based on these facts.

  • 1
    $\begingroup$ Why do you assume they would have a different development process? There are people who have polydactyly and oligodactyly who do just fine. $\endgroup$
    – Frostfyre
    May 19, 2016 at 15:30
  • 1
    $\begingroup$ "Tools" is very broad, and then you go on to discuss both cars and computers as well. Could you narrow this down a bit; say, "how would such beings interact with electronic devices requiring alphanumeric input?" instead? (I'm not sure even that would be all that good, but it would at least be a lot more specific.) $\endgroup$
    – user
    May 19, 2016 at 15:39
  • $\begingroup$ @Frostfyre because in this case it's not a minority of people but the majority, and it's fully usable digits :) $\endgroup$
    – dot_Sp0T
    May 19, 2016 at 15:39
  • $\begingroup$ @MichaelKjörling now that's a tricky thing in my opinion. I strongly feel that questions about specific classes of tools would rather be follow-up questions to this. But I might find a way to get more into the general design-issues of two different size/capability hands $\endgroup$
    – dot_Sp0T
    May 19, 2016 at 17:03
  • $\begingroup$ One less/or more digit on each hand isn't likely going to significantly changes things. Now if you start altering the hand, or perhaps one hand is thumb-less that would impact the usability of tools. As it stands though I don't think the change is as impactful as you would think. $\endgroup$
    – James
    May 19, 2016 at 18:27

2 Answers 2


We have dissimilar hands.

Most people use the right hand for everything, and use his left hands only if the actual activity needs both hands. There is a minority doing the same, but with the left hands.

There are two-handed people, but it is very rare and it is nearly always a learned skill.

The result: our devices are also optimized for the right hand, which causes minor problems for the left-handed people. It is very visible in the case of scissors and most of keyboard / mouse designs.

Although, sometimes it can be also an advantage. The best is your example to show that: in case of fights, most left handed people has already a big experience to fight with right-handed enemies, but the right-handed have only a little experience in fights with left-handed enemies.

If there would be also a large physical difference between our left and right hands, it had similar, but more strong effects.


Tools would probably end up being designed for a specific hand and the populace at large would be much more consistent in which hands they use (no more left vs right handedness as we know it).

A tool that requires precision or a less firm grip would probably find a role in the smaller hand. Compare, for instance, a pencil versus a hammer. A larger hand and more fingers provide a better grip on the hammer while the pencil requires more deliberate and precise movements. A knife benefits from a firm full-hand grip while a fork does not. The large hand would pick up a large mug of beer but the smaller one might grasp the stem of a wine glass.

While the design of some tools might need to change, modern weapons and tools would still be quite usable. A sword would be held in the large hand while a shield would be strapped to the small hand and arm. The large hand grips the bow while the small one draws back the arrow. The small hand pulls the trigger and the large hand grips the frame of the gun. Computers might initially seem tricky, but consider that we would simply redesign the keyboard to serve the new structural norm. Here, the precision of the smaller hand lends itself to the mouse while the extra fingers make the larger hand more suited to hitting keys.

Muscle development is also an area of consideration. If the larger gripping hand becomes more suited to lifting, it’s possible that a significant disparity might develop between the muscle mass in the left arm vs the right.

Left handedness vs right handedness would not be as much of an issue. Everyone would use the proper hand for each activity, but society might find that some professions such as writing or soldiering cause people to become much more skilled at using one hand (and therefore performing certain sets of tasks) than the other over the course of their lives.

  • $\begingroup$ Well, one thing I might point out is that the one with longer fingers is described as more "dexterous", indicating it is more suited for things that require less strength and more finesse. $\endgroup$ May 23, 2016 at 14:29

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