Right-Handed or Left-Handed: Recent Study Explains The Reason For Hand Preference; See Details Here!

A recent study suggests that a preference for the left or the right hand can be traced back to that asymmetry. The researchers stated that these findings have fundamentally changed their understanding of the cause of hemispheric asymmetries.

Preference in the womb

Before the current study, it has been thought that the differences in gene activity of the right and left hemisphere could be responsible for a person being either right-handed or left-handed. The researchers noted that according to ultrasound scans conducted in the 80s, a preference for either moving the left or right hand develops in the womb from the eighth week of gestation.

They added that the fetus may prefer to suck either their right or their left thumb starting from when the pregnancy is 13 weeks old. The movement of the arm is initiated through the motor cortex in the brain, which then sends a corresponding signal to the spinal cord. The spinal cord, in turn, translates the command from the motor cortex into a motion, according to Science Daily.

However, the motor cortex is said not to be connected to the spinal cord from the beginning of the process as precursors of handedness become clear even before the formation of the connection. This is the major reason why the researchers have concluded that the cause of right respective left preference must be rooted in the spinal cord instead of being rooted in the brain.

The influence of environmental factors

The researchers then went ahead to analyze the gene expression in the spinal cord between eight and twelve weeks of gestation. They were able to detect marked right-left differences in the eighth week, precisely, in the segments of the spinal cord that controls the movements of arms and legs. These findings are said to be solid as a previous study also found that fetus carry out asymmetric hand movements just as early as that.

In addition, the study authors traced the cause of asymmetric gene activity and found that epigenetic factors appear to be the major cause of it, thereby reflecting environmental influences. For instance, these environmental influences could lead to enzymes bonding methyl groups to the DNA, which will, in turn, affect and minimize the reading of genes, according to CTS.

The researchers added that since it occurs to a different extent in the left and the right spinal cord, there is a significant difference with the activity of genes on both sides. They published the findings of the study in the journal eLife.

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