Left-handedness has long been a fascinating topic to many people. Approximately 10% of the global population is left-handed, meaning they prefer using their left hand for tasks like writing, throwing, and eating. But why are some people left-handed while most are right-handed? Is it something you’re born with or does it develop over time? Here we’ll explore some quick answers about the origins and genetics behind left-handedness.
Are you born left-handed or do you develop it?
Research indicates left-handedness is linked to genetics and inherited from your parents. While experiences growing up can strengthen hand preference, studies of twins show that genetics plays a very strong role in determining left or right handedness. The chances of being left handed are much higher if your parents or close relatives are lefties.
Why are left-handed people in the minority?
Throughout history, left-handedness was often discouraged socially and lefties were forced to use their right hand instead. The negative stigma decreased the prevalence of left-handedness over centuries. Today left-handedness is more accepted, but the genetic trait still occurs in a minority of the population.
Are more men or women left-handed?
Studies show more men are left-handed than women. About 12% of men are lefties compared to 10% of women. Scientists aren’t entirely sure why, but this difference suggests testosterone levels in the womb could play a role in which hand preference develops.
Genetic Factors Behind Left-Handedness
Left-handedness definitely runs in families and has a genetic component. But which genes are involved and how do they increase chances of being left-handed? Let’s review what scientists have learned about the genetics so far:
LRRTM1 gene
This gene is related to brain development and the connection between left and right hemispheres. A variant of LRRTM1 was identified in a study of dyslexic left-handers. Researchers found it occurred more frequently in lefties and may disrupt hemispheric brain asymmetry. More research is needed to confirm the link.
PCSK6 gene
Discovered in a genome-wide association study of hand preference in tens of thousands of participants. People with a variant of PCSK6 were about 25% more likely to be left-handed. The gene is involved in the development of organs like the heart, but scientists think it impacts brain asymmetry early in development.
AR gene
The androgen receptor gene plays a role in sex hormone signaling. A study found that a variant of this gene was more prevalent among left-handed men, but not women. This suggests testosterone exposure in the womb could be connected to development of left-handedness in males.
Other Genetic Factors
While no “left-handed gene” has been identified, these genes demonstrate that hand preference is linked to biology. Other genetic factors associated with left-handedness include:
– Variants in genes related to brain asymmetry and development like PRODH, CCKAR, SETDB2.
– Differences in certain DNA regions that regulate gene activity.
– Excess or reduced production of hormones like testosterone and estrogen prenatally.
More research is needed on the genetics, but it’s clear left-handedness runs in families. If you’re a lefty, you can thank the DNA you inherited from your parents.
Environmental Factors Influencing Left-Handedness
So genes load the gun when it comes to handedness, but does environment also play a role? Here we’ll go over how external factors before and after birth might impact someone’s chances of being left-handed:
Prenatal testosterone exposure
Testosterone levels in utero are thought to affect asymmetry in the brain. Higher levels could lead more neural connections on the left side and increase odds of left-handedness. This might explain why more males are lefties.
Birth stress
Difficult or stressful births may increase likelihood of being left-handed. The trauma can impact brain development and hemispheric dominance. However, the link is still being debated.
Early childhood factors
Forcing children to switch handedness used to be common and may have shaped natural preference. But today most experts don’t believe handedness can be changed significantly after infancy when lateralization sets in.
The Verdict on Environmental Impact
While certain prenatal and early life factors show some correlation to left-handedness, most researchers agree that genetics are the primary driver. The environment can nudge handedness in one direction or another, but cannot change the underlying genetics.
Is Left-Handedness Linked to Other Traits?
Non-right-handedness doesn’t just affect what hand you write with. Many studies have explored how left-handedness is connected to other physical attributes, health conditions, and psychological traits:
Physical Traits
- Better bodily coordination and athleticism – Perhaps linked to lefties using both hemispheres more for motor skills.
- Taller stature on average – Likely related to prenatal testosterone exposure influencing growth.
- More symmetrical and attractive faces – Caused by balanced hormone levels and growth rates in the womb.
Health Conditions
- Increased anxiety and mood disorders – Possibly tied to struggles adapting to a right-handed world.
- Elevated risk of schizophrenia – Related to atypical lateralization of brain function.
- Enhanced creativity and divergent thinking – Lateralization allows more cross-talk between hemispheres.
Cognitive Abilities
- Better verbal skills but worse spatial skills on average – Linked to brain hemisphere dominance.
- Higher risk of learning disabilities like dyslexia – Likely caused by atypical language processing in the brain.
- Reduced ability to process sensations like sounds – Also attributed to differences in brain laterality.
Of course these are just general observations and won’t apply to all left-handed people. But it shows how handedness preference is tied to multiple aspects of physiology and psychology.
Does Left-Handedness Affect Life Expectancy?
Studies investigating whether left-handers have shorter lifespans have produced mixed results:
| Study | Findings |
|---|---|
| 1991 study of baseball players | Left-handed players lived an average of 9 years less than righties. |
| Large 2006 Danish study | No significant difference in lifespan between right-handed and non-right-handed people. |
| 2017 study in Scotland | Left-handed women had lower life expectancy compared to right-handed women. |
Based on the inconsistent evidence, most experts believe hand preference does not directly impact longevity. Apparent differences in smaller studies are likely coincidental.
However, some theories on why left-handers might have shorter average lifespans include:
- Heightened risk of fatal accidents due to living in a right-handed world.
- Increased chance of underlying health conditions that can reduce lifespan.
- Greater levels of psychological stress when adapting to societal norms.
But more research is needed to prove any connections between left-handedness and lifespan. Hand preference alone is unlikely to affect how long someone lives.
What Are the Pros and Cons of Being Left-Handed?
Are there advantages and disadvantages to being a southpaw? Here are some key pros and cons research has uncovered about being left-handed in a predominantly right-handed world:
Pros of Left-Handedness
- Better adaptation skills and problem-solving abilities.
- Superior multi-tasking and ambidexterity.
- Enhanced creativity and imagination.
- More diverse thinking patterns and cognitive flexibility.
- Element of surprise in sports and activities.
- Possible improvements inverbal and artistic skills.
Cons of Left-Handedness
- Difficulty using tools and objects designed for righties.
- Increased risk of physical injury while using right-handed devices.
- Challenges finding adequate left-handed school supplies.
- Higher odds of language and learning disabilities.
- Possible rise in anxiety, mood disorders and risk of schizophrenia.
- Shorter average lifespans according to some studies.
But while there may be challenges, most lefties succeed just as well as righties. The advantages and disadvantages likely balance out over a lifetime.
Famous and Successful Left-Handed People
Looking at famous and influential left-handed people throughout history helps shatter the stigma. Here are just a few of the many high-achieving southpaws:
| Names | Occupations |
|---|---|
| Barack Obama | Politician, Former U.S. President |
| Bill Gates | Business Magnate, Microsoft Founder |
| Oprah Winfrey | Media Executive and Talk Show Host |
| Paul McCartney | Musician, Beatles Member |
| Tom Cruise | Actor |
| Leonardo da Vinci | Inventor and Polymath |
| Marie Curie | Physicist and Chemist |
| Albert Einstein | Theoretical Physicist, Developer of Theory of Relativity |
This list shows being left-handed is certainly no barrier to success. Lefties can thrive in any profession including politics, science, arts, business, and athletics.
Famous Left-Handed Athletes
In sports like baseball, boxing, tennis and fencing, being left-handed can provide a competitive edge. Here are some all-time great left-handed athletes across major sports:
Baseball
- Babe Ruth
- Ted Williams
- Sandy Koufax
- Barry Bonds
Tennis
- Rafael Nadal
- John McEnroe
- Martina Navratilova
- Jimmy Connors
Boxing
- Manny Pacquiao
- Marvin Hagler
- Oscar de la Hoya
- Terry Norris
Fencing
- Benjamin Krebs
- Lee Keifer
- Becca Ward
- Jason Rogers
Southpaws have a strategic edge in sports where players compete head-to-head. The natural tendencies of lefties are unexpected and can bewilder right-handed opponents.
Takeaway on Left-Handedness
Left-handedness clearly has a strong genetic component inherited from your parents. Certain genes linked to brain structure and prenatal hormone exposure increase the likelihood of left-handedness.
While some possible disadvantages exist, left-handers succeed in all walks of life throughout history. Handedness alone doesn’t determine your future prospects or health.
With decreasing stigma, lefties can leverage their unique wiring and abilities to excel. All the evidence indicates left-handedness is a natural variation that arises based on your DNA and biology. Rather than a weakness, it simply represents the diversity of the human population.
