Why are so many left handed people nearly ambidextrous?

From experience, it seems that very few left handed people are completely left handed, compared to their right handed counterparts, who mostly show a strong bias for using their right hands. For instance, I write with my left hand, cut with scissors with either hand, use both hands for playing tennis (when I played, I never developed a backhand, as I could just swap hands quickly), bowl a cricket ball left handed, throw overarm right handed, fence left handed, kick with my right foot etc.

So, is my premise true? And, if so, what is the cause?

I’m left handed and pretty much the only thing I do right handed is use scissors or use anything that’s impossible to use left-handed (e.g., can openers). I always thought it was just learned as a matter of convenience. I never could use scissors with my left hand, though, even the ones designed to be used that way.

Because we have to be.

I’m a lefty, and I play guitar right-handed. This was out of necessity, since I learned on my brother’s guitar, so I pretty much didn’t have a choice.

S^G

It’s all about the adaptation. If 90% of what you do everyday is easier to do with your right hand, then you learn to do it with your right hand.

The bigger question is, if it’s equally easy to do with either hand, and you learned to do it left-handed by yourself (instead of being taught or imitating someone else) would you still do it with your right hand?

I think this is the closest to the truth. We are, after all, living in a predominantly right-hand world. Most of us lefties have to adapt however we can.

Sometimes we adapt by changing hands. Often we are taught mechanical techniques by right-handed people who have no idea how to change methods for a left-handed person, so they teach it the only way they know how. Sometimes we can figure out a way to do it better using a mirror-image of the way we are taught, and sometimes we just end up doing it the right-handed way.

I am a left-handed technician who was married to a left-handed artist for 23 years. Sometimes I would help her modify tools for her art, like reversing the direction of rotation on her potter’s wheel. Some things were available, like pen nibs that were cut for left-handed use. And sometimes she just used right-handed tools in her left hand – I still can’t figure out the weird way that she held right-handed scissors in her left hand and made them work. She had done it that way since she was a little girl, and couldn’t use left-handed scissors when she was exposed to them at a later age because that technique had become second nature to her.

I found it an advantage to be ambidextrous for some things – with normal, right-hand threaded bolts, it’s easier to tighten with the wrench in your right hand and loosen with the wrench in your left hand.

I find that I use my right hand for things that require strength, like throwing, and the left hand for things that require accuracy and dexterity, using the fingers and wrist more, like writing, eating and tennis.

Yeah but…

My son writes left handed but does everything else right handed.

I don’t think this is quite the case. Many of the examples I gave in the OP are hand-neutral. I still remember us being taught how to throw overarm in primary school and nobody ever forced me to use my right hand, nor my left hand for cricket. Similarly, left handed scissors were always available in school, yet I used the right handed versions.

Similarly for quite a few other left handers, in my experience.

But this is besides the point, as anecdotal data won’t resolve anything. Has there actually been any studies on whether left-handedness typically manifests itself as strongly as right-handedness?

It’s further complicated by the argument that a lot of what is traditionally thought of as “the right-handed way” perhaps isn’t, after all. I don’t have a cite, but I remember hearing that “right-handed” stance for golf or for batting in cricket or baseball is actually better suited to a dominant left hand. I’m a lefty and I bat this way. Then again, I wasn’t a “sporty” kid so I never had formal training - no coach telling me what to do.

I consider my left hand to be very dominant, but I can use my right with excellent facility for things I was forced to do that way as a child (I haven’t dialled a rotary phone in years, but I’m very confident my muscle memory is still strong for that). On the other hand (sorry), the motor skills for shifting gears are not as fine, but I know that if I went to the US and tried to drive “on the other side”, I’d really, really have to concentrate and I’d miss a lot of gears. Right-handed skills I’ve learned as an adult, I’m not so hot with. The example that springs to mind is the computer mouse - I use mine on the left (but RH-configured), but if I’m using a shared computer for less than a few moments, I’ll just leave the mouse where it is on the right. A person watching me work might not notice how awkward I feel with it. I can do it, but only just.
I could - and have in other threads - bitch about the stupid, low level discrimination we lefties face daily, but I won’t. What is more interesting is the things that seem designed for us. Computer games are one - ever since Space Invaders, I have been thankful that the joystick was on the left and the fire button on the right. I couldn’t imagine trying it the other way. RHD cars are another - I loves me my left hand gear shifts. Taps (faucets) are a good example - if somebody has turned one off too tightly, I’m often the only person who can loosen it, because - apart from being a big mofo, which is part of it - I can hit it with some serious anti-clockwise force. I’ve heard of people being unable to loosen a tap that they themselves had tightened - wouldn’t happen to me, as I have greater torque opening it. Same for jars, etc.

Quoted again for truth.

In addition, most people aren’t fully right or left dominant. As a lefty you get forced to use your right hand a lot more than any right-hander does, and you develop whatever facility you might have. Right handed people almost never have to use their left hand and so never develop their potential on the weakly dominant side.

Naturally right-handed people who have had an immobilizing or temporarily disabling injury to their right hand often develop some degree of ambidexterity or even left-handedness that continues beyond the resolution of the injury. Obviously, the longer they’re forced to adapt, the higher the chance of permanent “switching.”

I am another anecdote but since that’s not what you want, I will just comment that such a study might be problematic–how do you separate ambidextrous people from left-handed people who can do stuff with their right side? Are 15% of people left-handed, and 80% of them also have facility with the right hand, or are 12% of people ambidextrous and 3% left-handed? (Numbers totall made up to illustrate the point)