Why Some People Are Left-Handed

Surely you know someone who uses their left hand, not their right, and you may have wondered why that is. To curb your curiosity, 5-Minute Crafts decided to investigate this topic and discover why some people are left-handed.

How many people in the world are left-handed

Left-handedness is rare, and percentages vary from culture to culture. In the western world, only 10% to 15% of people use their left hand, while 85% to 90% of the human population is right-handed. Using both hands for different tasks and ambidextrousness — the ability to do things equally well with either hand — are very rare.

Causes of left-handedness

Archaeological findings show that left-handedness dates back as far as 500,000 years. Ancient tools and artifacts have been found that show that they were used with the left hand. However, which hand will be used as the primary one is not a choice, and it can be predicted while the baby is still in the womb. The exact cause of left-handedness has not yet been determined with certainty, and there are several hypotheses as to why it occurs.

• Genetic — evidence of gene influence exists but without an established direct connection. Today, many different genes are thought to be involved in creating left-handedness. The chance that a child with a left-handed father and a right-handed mother will be left-handed is about 17%, while the chance that both right-handed parents will have a left-handed child is about 10%.
• Gender — there are more left-handed boys than girls, which is why some researchers believe that the male hormone, testosterone, affects right-handedness and left-handedness.

• Fetal development — some scientists think that environmental factors in the uterus can affect whether we will use the right or left hand later in life.
• Competitive and cooperative evolution — there is a mathematical model that suggests these 2 points in human evolution influenced the development of the primary hand. The advantages of left-handed people are obvious in martial arts and competitive sports, such as baseball. When right-handed and left-handed people meet, those who are left-handed will be better prepared than their right-handed opponents. However, human evolution is not only driven by competition but also by cooperation, and this has influenced the balance to shift to the right. Most tools were made for right-handed people, while left-handed people had difficulty using such tools, so they became rarer over time. For example, in golf, where performance doesn’t depend on the opponent, only 4% of top players are left-handed.

Left-handedness and higher intelligence

Apart from how left-handedness develops, scientists are also interested in whether it shows higher intelligence. For now, the results are inconclusive, and more research is needed in this field to obtain more accurate data. A study in Italy concluded that left-handed students had a significant advantage in more difficult mathematical problems, such as associating a mathematical function to a set of data. Some famous left-handed people are Michelangelo, Leonardo da Vinci, Paul McCartney, David Bowie, Jimi Hendrix, James Baldwin, Nikola Tesla, Oprah Winfrey, Bill Gates, and Steve Jobs.