Apparently left-handers have been in the minority for a long time, at least as far back as the Neanderthals. Researchers found the right hand was used more often than the left hand among this group when they looked at how their teeth were worn. Neanderthals softened hides by chewing and the shape of their teeth determined whether they picked the hides up with their right or left hand.
Why should we prefer one hand over the other? One theory is that handedness evolution had to do with cooperation vs. competition. Cooperation among people was important for progressing society. If the same hand was used from person to person for tools and other objects, things would work more efficiently. Preferred handedness evolved for this reason. (Why the right hand? That's not explained.) Some people remained left-handed because competition was still important for fighting and protection.
To test the competitive part of the above theory, researchers analyzed data of professional players in several competitive sports. They found there were more left-handed people playing these professional sports than in the general population, meaning greater than 10% of the athletes were left-handed with baseball and pro boxers having about 50% left-handers. This correlates with the idea that left-handers evolved to be competitive and fight to protect the tribe.
That theory was interesting, but there's got to be more to developing a preferred hand than cooperation and competition in our early ancestors, because both apes (except orangutans) and dogs prefer their right hand/paw.
To really understand handedness, we need to understand our brains and how to sort out the nature vs. nurture question. Scientists are working on it and have identified some genes associated with left-handedness. They are studying how these genes affect brain development among other things. However, that's only a small part of a very complicated question.
What I do know for now, is that my left hand works better than my right hand. And I guess that's all I really need to know.
Are you left-handed or right-handed? Do you ever think about why?
https://www.livescience.com/17009-left-handedness-ambidexterity.html
https://www.everydayhealth.com/emotional-health/0504/why-are-lefties-so-rare-blame-society.aspx
http://www.anythingleft-handed.co.uk/fighters.html
https://www.sciencefriday.com/articles/do-other-animals-show-handedness/
I just addressed left-handedness in my comment to your previous post so I won't repeat it, but I'll relay that of my 3 left-handed kids, only my Daughter would be considered a fighter as she enjoyed sports a lot and was more of a tomboy. My 2 older boys, however, never were interested in any sports and are pretty pacific (they're artistic, both are musicians and Middle Son is also a photographer). Their dad is also left-handed and also was never into sports. His mom is left-handed so I'm pretty sure there's a left-handed gene that's been passed down to our kids.
ReplyDeleteSince I'm in the majority (right-handed) and my left-handed kids are now grown, I rarely think about the left-handed aspect of things anymore. There is a whole cottage industry of items being sold that cater to left-handed people though (mugs with the graphic printed on the opposite side, but mostly a lot of gag gifts) as I'm sure you're aware. When kids approach college age, the constant reminder we hear is for them to apply to a whole bunch of scholarships, no matter how small they are, because there are "scholarships for every kind of interest, for instance there is one just for left-handed people!". Back when Oldest Son was in his Junior year of high school, I had researched that scholarship and found out that it'd been discontinued. But I still heard that advice being given to the kids with that specific example for several years afterwards :)
Congrats, by the way, on your blogging every day this month. Each post has been very interesting! You should consider continuing this in May, lol.
There are all kinds of articles out there about tendencies for left handed people. In one list, I identified with the first four, but not the next 8. It just means that we are individuals and even when the percentages are a little higher, it doesn't mean that it applies to evrryone. I guess you saw that among your kids.
DeleteI am right handed, 2 of my 3 sons are right handed and both TheHub and Son3 are left handed for all fine motor skills but are right handed for large motor skills. I grew up playing tennis and the first time TheHub and I played (his first time ever to play the stupid game) I found out quickly I could never hit it to his backhand for my advantage. He merely swapped hands holding the racquet. So ended our first and only tennis match!
ReplyDeleteI personally think sports are better not played between married people, for me any way. I'm not very good at most sports and would lose any match with my husband. It wouldn't be his fault, but I would get mad at him for winning when I'd really be mad at myself for losing. Ut-oh. Maybe that's my competitive left-handed side coming out.
DeleteHow very interesting. I am right handed, but apparently I'm left footed. When I played soccer as a kid I could never kick anything with my right foot, only my left. I do find it interesting that when playing a stringed instrument (violin, guitar, etc.) the hand that fingers the strings - so the one that works the hardest, is the left hand. So even though I'm right handed, my left hand is much more flexible, and there are things I can do with my left hand (like the Star Trek Vulcan salute) that my right hand just can't handle.
ReplyDeleteI just tried the Vulcan solute with my right hand and I had no problems. However, with my left hand, I struggled. I wonder what that's about? I'm going to start some informal data collecting to see if we're the only two who have this switch.
ReplyDeleteMixed dominance is sometimes correlated with learning problems. Didn't you say that you have some dyslexia? I don't think one causes the other, just a different way that the brain is wired. My son is mixed dominance and had some learning problems, now that I think of it.
Hmmm... very interesting. I do have a bit of dyslexia... and problems with reading. I'm not sure what you call it, but I have trouble following the text, like at the end of the line my eyes get lost and often don't wrap around to the next line successfully. I comprehend much better if someone says it out loud than by reading. So apparently my brain just gets its wires crossed! :-)
DeleteMy son doesn't have a problem with reading now, but following text was a problem when he was learning. He was very early with letters, phonics, and decoding words. However, it took a while before his eyes were coordinated enough to follow the text left to right. Until then, I hadn't thought about that skill being important for reading. Obviously, it is.
DeleteDo any of the things like a ruler or covering the page with different color translucent pages help? I know there are all kinds of things they do to help with some of these problems.
I agree with Nathalee, I enjoy your daily posts ... but I know they require a lot of work for you! Great job!
ReplyDeleteThe year my son was born, there were studies done about hair whorls and predicting handedness. I found one online but it's not very readable for the non-scientist. :) There is a 2011 study disputing the results. With my son, it was sort of a comical concept, as he has 2 hair whorls (which, I think, is what his "cowlicks" are). Each whorl went a different direction. He is left-handed, but I'm not sure I buy into the original research study.
As Cat says, we also have a dominant foot. I think handedness is more popularly talked about. We also have a dominant eye. If you put your hands in an L-shape, place them together to form a circle, hold them up and gaze through them at a distant object, then close one eye versus the other, you should be able to discover your eye dominance--your dominant eye will still see the distant object and your non-dominant one won't. Fun Friday Factoid.
When doing therapy with people, typically the dominant hand performs the highly coordinated task and the other hand is the stabilizing hand (in regards to one of Cat's comments).
It's fun to theorize about handedness.
I love to do the trick to see which is the dominant eye. I just play with it sometimes. My son who has mixed dominance is right handed and footed but is left eyed. It has caused him some problems in sports, etc.
DeleteMy first son used both hands equally until he settled down with his right one around 2 or 3. My second son used his right hand almost exclusively from the beginning. I remember commenting that there was no doubt which hand he would be using. Then one day we turned around and he was using his left hand and ended up being left handed. However, when he was being evaluated by an OT around 4 or 5 she asked me if anyone if the family was left handed. I said that I was and asked why. She said my son looks as if he should be right handed by the way he was handling the toys. She said some kids pick their handedness by copying someone. Well, I knew there could be problems with brain development, learning problems, etc.by forcing someone to use their other hand. There had been studies on this since they used to make left-handers switch to their right hand. I kind of went into panic mode and asked what we should do about it. She said nothing, leave him alone. And we did and he seems to have survived it all.
Hmmm... left eye dominant...
DeleteMe too! :) I would have thought I was right eye dominant as that's always been my stronger eye, so it was a surprise to me when I learned that.
DeleteL&L, so interesting about your son. I find brain function to be endlessly fascinating, probably because there is so much to know and so much we don't know.
So much we don't know and so much that I don't understand that we do know.
DeleteThis was a fascinating post! My maternal grandmother was left handed and crocheted with her left hand. She could't teach any of her 4 daughters to crochet because they were all right handed! I don't know how Granny learned to crochet, though.
ReplyDeleteToo bad I didn't know your maternal grandmother. She could have taught me how to crochet.
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