What Is Left-handedness?
Left-handedness is an individual’s preference to use the left-hand as the dominant hand to perform various tasks. In the world, about 10 percent of individuals are left-handed. Men are more likely to be left-handed than women and express the left-hand more dominantly. According to studies, between 70-95 percent of the world’s population is right-handed. Among them are ambidextrous individuals who can use either hand equally well, though it is very rare to find ambidexterity.
When it comes to handedness, there are different types.
- Right-handedness is the most common type and the most dominant. Right-handed people are more skilled in performing tasks with the right hand. An overwhelming majority of people on the planet are right handed. As a result, most gadgets and devices are designed with the right-hand use in mind. Studies suggest that 70-95 percent of individuals have the right hand as the more dominant one.
- Left-handedness is less common and can be found in about 10-12 percent of individuals on earth. The more skilled left-hand can present a challenge since most devices, gadgets and tools are designed for right-hand use. Men are 23 percent more likely to be left-handed than women. Over the years, the percentage of people who are left-handed has continued to rise. It is approximated that 2 percent of the world population was left-handed in 1860, 4 percent in 1920 and currently stands at 10-12 percent.
- Mixed-handedness is the phenomenon of using both hands interchangeably when the task demands. Only about 1 percent of people can do this.
- Ambidexterity is when a person is able to use both the right hand and the left hand equally well. Ambidexterity can be learned even though people tend to prefer using their more dominant hand to perform tasks.
Factors That Cause Left-handedness
Several theories explain the development of left-handedness in humans. Prenatal development is a major factor when determining the more dominant hand after birth. Researchers have established that handedness can be predicted in the womb, where fetuses tend to prefer either left or right hand. After birth, they stick to their more dominant hand.
Genetic factors play a major role in determining the preferred hand. Handedness is influenced by the dominant hands of the parents. If both parents are left-handed, there’s a 26 percent chance that the child will be left-handed. A right-handed father and a left-handed mother have a 22 percent chance of having a left-handed child. A left-handed father and a right-handed mother have a 17 percent chance of having a child who is left-handed.
Division of labor is a common theory explaining the emergence of left-handedness. The brain hemisphere associated with speaking and handiwork operates in one sphere instead of it being divided. This theory asserts that left-handed people have a reversed brain division which makes the left-hand more dominant.
It is suggested that ultrasounds may affect the brain of unborn babies which may lead to higher rates of left-handedness if the mother did receive ultrasounds during pregnancy.
In conclusion, left-handed people are associated with higher intelligence in language and are generally a group of above-average high achievers. When it comes to health matters, left-handed people are more likely to have been born with a lower birth weight. They have an increased risk for mood disorders, dyslexia, and ADHD according to a study conducted in 2010 by Pediatrics.