• Question: why are some people left handed and some people right?

    Asked by 10cargeoa to Hannah, Ian, Jono, Mark on 26 Jun 2013.
    • Photo: Hannah Brotherton

      Hannah Brotherton answered on 26 Jun 2013:


      Hi 10cargeoa,
      I am brain scientist so I actually had to study this at uni 😀

      Our brain is split into two halves, the left and right side

      The left side controls the ride side of the body, and the right side of the brain controls the left side of the body. 85% of people in the world at right handed

      People think our genes just determine if we are right or left, some people think we follow our parents. But there is no right or wrong. You can be whatever.

      Di you know dogs can be right or left handed.
      So a guide dog is chosen if it is right handed (it starts walking on its right paw) – this is because they think right handed dogs are sweeter and more calm.

      That must mean I am calm and sweet ? Are you left or right handed?

    • Photo: Ian Wilson

      Ian Wilson answered on 26 Jun 2013:


      Hi 10cargeoa,

      This is mostly down to genetics. There are 2 copies of the gene that decides which hand you write with – ‘C’ and ‘D’. ‘D’ is more common and means you are better at writing with your right hand. ‘C’ isn’t seen very often but makes people left-handed. Given that 85% of people in the world are right-handed it clearly as some advantages. I think it makes the brain work more efficiently, but I’m not sure.

      But, if being right-handed is clearly preferable, why are left-handed people, like myself, still around? Should evolution not have killed this ability off? Well, there’s an interesting theory that says that left-handed people are more likely to win in a fight than right-handed people!

      If the majority of people in a population are right-handed then you’d expect an opponent in a fight to throw a punch with their right arm. So when a left arm comes at you instead you’d be taken by surprise and the left-handed person would get an advantage in the fight! This means that this genetic mutation lives on as left-handed people are more likely to survive conflicts.

      Not sure how much I believe that but I like the theory!

      Ian

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