Have you ever come across people using their left hand to perform all the tasks that you could never perform without your right hand? They are the left-handed people of our society who are less in numbers, globally. But what caused left-handedness in people when the majority of the people are right-handed?
There are different theories regarding the cause of left-handedness in people.
According to the researches back in the 1980s, our left or right-handedness was decided in the womb, way before we were born. It could be shown in the eighth week of pregnancy through ultrasound.
The right and left hemispheres of the brain were considered responsible for the left and right-handedness in a child.
New research, published recently by a group of scientists from the Netherlands and South Africa said, that the cause of left-handedness lies in the spinal cord and not the brain. They reported, due to the asymmetrical gene performance in the spinal cord during pregnancy, the baby became either left or right-handed.
The motor cortex is the brain area where the movement of arm and hand takes place. Motor cortex sends motion signals to the spinal cord, which results in the movement of the arm and hand. But the researchers stated in the recent study that the motor cortex and the spinal cord are not connected to each other until 15 weeks. But right or left-handedness is decided way before that, as in the thirteenth week of pregnancy, ultrasound shows the baby sucking left or right hand.
So the new study states, before even the brain can control our body functions, babies tend to choose their left or right-handedness and start moving.
Organisms are affected by environmental factors, causing changes in the gene expression and affecting the growth of the baby. Due to these gene-expression differences affecting the left-right parts of the spinal cord, babies become left or right-handed.
It is believed if both the parents are left-handed, their child will have a 26% chance of inheriting that pattern.
Even though the cause of right and left-handedness is based on genetics, but society plays a great role in it as the majority of the preference is given to right-handedness. Due to this, children who were genetically born left-handed, are made to use their right hands because the majority of the people in society are right-handed.
Another theory suggests that the ultrasound performed to see the development of the baby during pregnancy has a high effect on the brain of the unborn baby. The rays of the ultrasound result in left-handedness in the child.
Even though left-handedness in people is not much common, with only 10% of the global population being left-handed, but they are considered to be more creative and skilful.
How many of our viewers are left-handed? How does it feel to be different from others? And which theory do you find more accurate? Let us know in the comments below.
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Until next time,
Team Doctor ASKY!