what is the benefit of having a dominant hand/leg as compared to having equally skilled limbs?

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what is the benefit of having a dominant hand/leg as compared to having equally skilled limbs?

In: Biology

27 Answers

Anonymous 0 Comments

It takes hours and hours of practice to develop that skill. It takes twice as long to learn it twice, and maintain it on both sides. Animals have preferred sides as well.

Anonymous 0 Comments

It takes less time training and requires less muscle. The benefit of being ambidextrous is relatively small so it’s almost always better to concentrate on making one limb stronger and more skillful.

Compare two people: one with two equally good arms and one person with a dominant arm. Usually the dominant arm will be better than the equally good arms and the advantage that gives is greater than the disadvantage of having a weaker arm.

So, presumably for this reason, people’s brains have evolved to have dominant limbs.

Anonymous 0 Comments

Most animals don’t have the kind of dexterity we do. I think the more likely case is that as we developed enhanced dexterity and control, one hand was good enough and the mutation that allowed it happened to work out that way. If ambidexterity was a rare/complex mutation to that and/or it didn’t provide a significant advantage to breeding prospects, it wouldn’t develop species wide.

Evolution, despite the “survival of the fittest” line, is more of a race to the good enough.

Anonymous 0 Comments

There doesn’t have to be an advantage in order for a feature of anatomy to have arisen through evolution. It just has to be small enough of a disadvantage that it does not hamper survival/reproduction chances.

Humans have many flaws, our breathing holes and food holes are combined, and it results in around 5000 deaths per year in the US due to choking on food. It’s significant, but not enough for it to be an evolutionary disadvantage to the species.

Having a dominant an non-dominant hand is the same kind of deal. It’s just not a significant disadvantage.

Anonymous 0 Comments

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Anonymous 0 Comments

It takes a ton of processing power, more actual muscle, and thousands of hours of practice for your dominant side to be as skilled, dextrous, and powerful as it is.

Making both sides that good would double all of those costs, and NOT double the benefits since most things you can just choose to do with the good hand/arm/leg.

With the time and energy available, if you committed to making both sides equally good, they would end up both being less good than your current good side. Which is worse overall since now you have no hands dextrous enough for fine skills you could previously do.

Anonymous 0 Comments

Instead of thinking of it as if being good at both hands is the default, and asking why one hand is worse, it helps to think of it as if being BAD at both hands is the default, and then asking why it’s good enough to be good at just one hand.

The quality of human hand dexterity is *amazing* and takes *work* and processing power. The difference between having zero good hands and one is enormous. The difference between having one good hand and having two good hands is less so. You get less “bang for your buck” putting the same effort into having a second good hand than you got for having at least one good hand. One good hand plus one merely okay hand seems to be a “good enough” solution.

I think the more interesting ELI5 question is, if our arms have mirrored symmetry, then why is picking the right hand to be the one all that effort goes into so much more common than picking the left?

The existence of left-handed people proves it’s not really any detriment to be left-handed (except culturally because right-handedness is such a common assumption when making things).

Is it nature, or nurture, that makes most of humanity right-handed? I’d have assumed nurture, except that doesn’t explain why so many different cultures became right-hand dominant independently before they contacted each other.

Anonymous 0 Comments

A lot of what I see in the comments of this post excludes tbe people who are dextrous in different things with different hands. I am an excellent example. I am a right-handed person in general, but I am left-handed when I play golf, baseball, do cardistry, or try to aim a throw. But everything else, I am right-handed.

***It’s litetally a matter of what hand/leg developped the muscle memory for what action, and the people who notice an increased dexterity with one side, will tend to keep working with that side for dexterity.***

Anonymous 0 Comments

Also you other hand is really getting good at holding and supporting. Often they work in tandem. Both takes practice.

Anonymous 0 Comments

Something nobody else seems to have pointed out is that the more dextrous side, in almost all cases, is the same side that your brain’s language processing happens on. (That means left handed people more frequently have their brain’s language centers flipped around, too)

It’s theorized that this is needed for the extremely fine motor control required to produce speech, and your hand also being more accurate on that side is basically an “unintended” side effect.

It’s *not* just training/habituation as some people have tried arguing, because we know that left-handed people forced to conform to right-handed training perform more poorly than when allowed to use their dominant hand. If it were entirely habituated, left handedness basically wouldn’t exist, because every child is taught to use its right hand to write first. (Or, if you want to argue that the difference is settled at a younger age, then the right/left distinction would be basically random)

~~Also, since ambidextrous people exist, we *know* the mutation for ambidextrosity is out there in the gene pool. So the fact that most people are still right-handed means that being ambidextrous simply isn’t enough of an advantage. (Or possibly a disadvantage)~~

Edit: Unsure about the last paragraph, probably best ignored.