今日のボヤキ 5/20
「なぜ左利きではなく、右利きが多いのだろう」と感じたことはありませんか？
生活している中で右だと不自由ないけど、左だと....ということありませんか？
例えば、字を書くとき特に漢字。あるいは、駅の改札。
世界で右利きの割合はおよそ90％。残りの10％が左利きのようです。
このようにしてみると、確かに右利きの為の作りが多いのもわかる気がします。
人が右利きになる理由
人間の脳には「右脳」と「左脳」がある。そして、主に身体の右半身を左脳が動かし、左半身を右脳が動かすという特徴があり、脳からの命令を伝える神経は左右交差している。左脳には言葉を話す時に使う「言語野（げんごや）」という領域があり、これが右利きの人が多い理由だと考えられている。
人間は言葉をよく話すと左脳がどんどん発達していく。そして、左脳が発達すると右手・右足を使う動作が上手になる。つまり、人類は言葉を話すようになったことで左脳が発達し、右利きの人が増えたというわけである。
逆に左利きが生まれるメカニズム
胎内での姿勢 プレヴィックは、胎内での胎児の姿勢が、聴覚系の発達に影響を及ぼし、それが小脳を通じて利き手に影響するという説を提出している。 この理論では多数の人間が右利きとなるが、妊娠後期の胎児の前庭器官に何らかの損傷が発じると、聴覚系のシステムが変容され、左利きが生まれる。
左利きがスポーツで良く活躍しているのを目にすると、左ってかっこええな～と思ってしまします。それは単に左だからといううことではなく、幼少期の何かしらの出来事によって頑張った結果左利きの人は強い！！というイメージを世間的に持っているのかもしれませんね。
English edition
Blurbs of the Day
Have you ever wondered why so many people are right-handed instead of left-handed?
In your daily life, you are not inconvenienced when you are right-handed, but when you are left-handed, you are .... Have you ever had such a feeling?
For example, when you write letters, especially Kanji. Or, when you use the ticket gate at the station.
The percentage of right-handed people in the world is about 90%. The remaining 10% are left-handed.
When you look at it this way, you can certainly understand why there are so many things made for right-handed people.
Why people are right-handed
The human brain has a "right brain" and a "left brain. And it is mainly characterized by the fact that the left brain moves the right half of the body and the right brain moves the left half of the body, and the nerves that carry commands from the brain cross over from left to right. The left brain contains an area called the "language area," which is used for speech, and this is thought to be the reason why many people are right-handed.
When humans speak well, the left brain develops more and more. And as the left brain develops, we become better at using our right hand and right foot. In other words, as humans became more verbal, their left brains developed and the number of right-handed people increased.
Conversely, the mechanism that produces left-handedness
Posture in utero Previc submits the theory that the posture of the fetus in utero affects the development of the auditory system, which in turn affects the dominant hand through the cerebellum. According to this theory, the majority of humans will be right-handed, but if some damage occurs to the vestibular organs of the fetus in late pregnancy, the auditory system is altered and a left-handed person is born.
https://ja.wikipedia.org/wiki/%E5%B7%A6%E5%88%A9%E3%81%8D
When I see left-handed people playing well in sports, I think left is cool. It is not just because they are left-handed, but as a result of some event in their childhood, left-handed people are strong! I think people have an image that left-handed people are strong as a result of their hard work due to some events in their childhood.
