5 Mar 2021

Why Are Some People Left Handed - Why Are Some People Born Left Handed

Why are some people left-handed? Which hand would be the dominant hand is decided in the womb or after our birth? Does it has anything to do with our brain or the environment?
Do you know that around 10% of the people all over the world are left-handed and August 13 is celebrated as International Left Handers Day.

Why Are Some People Born Left Handed Video

Left-handed people are unique in themselves and there are some advantages and disadvantages of being left-handed. So let's now come to our main question, why some people are born left-handed.

Why Are Some People Left Handed 

It was previously believed that the left or right hemisphere of our brain is responsible for determining the dominant hand even before we are born. But later in a study done in 2017 it was found that it has nothing to do with the brain. Actually answer to this lies in our spinal cord. According to the research, before the brain starts controlling the body movement, it is determined in the womb whether the child would be left-handed or right-handed. Let's now understand how it happens. There is an area called motor cortex in the brain which controls arm and hand movements. This motor cortex sends Signal to the spinal cord and the signal is translated into a motion. Here it is to be noted that the motor cortex of brain and the spinal cord are not connected up until about 15 weeks of pregnancy. But the baby starts to show signals of dominant hand in the womb before 15 weeks of pregnancy. It has been observed that babies tend to suck either their right or left thumb from week 13 in the womb. It clearly indicates that the brain is not responsible for deciding left handedness or right handedness as it is not connected to the spinal cord up until 15 weeks of pregnancy. It means, the spinal cord decides the hand preference. During a study a team analyzed the gene expression in the spinal cord. The study was conducted during the 8th 12th week of pregnancy. It was found that there was significant difference between left and right handedness in the segments of the spinal cord which is responsible for controlling arm and leg movement. So it is the difference in gene expressions in the spinal cord not the brain that makes a person lefty or righty. Friends now you know why some people are left-handed. Credits and Source: https://www.businessinsider.in/science/biology/scientists-think-they-have-found-the-reason-some-people-are-left-handed-and-it-has-nothing-to-do-with-the-brain/articleshow/62368041.cms

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