Welcome to brain Stuff production of I Heart Radio, Hey brain Stuff Lauren Bogelbaum. Here, the world is made up of about right handed people and ten percent left handed people. Folks who are truly ambidexterous those who use their right and left hand equally well make up a negligible sliver of the population. But is ambidexterity inherited or learned? And if learned, can it be learned as an adult? We spoke by email with Dr Sebastian Aucklenberg, a professor of
psychology at Rural University in Bochum, Germany. He said a little bit of both. Handedness is determined by about twenty percent genetic factors and non genetic factors like environmental influences. It clearly runs in families, so it is somewhat inherited, but learning might also affect it. I think ambidexterity for a specific task like hitting a tennis ball with a racket,
is possible, but full ambodexterity for all tasks is unlikely. Handedness, being the skill and comfort of person feels using one hand or the other, is considered a complex genetic trait, and since genes are involved, hand preference develops before a person is even born, But like other complex traits, handedness,
including ambedoxterity, doesn't have a simple pattern of inheritance. Yes, there is a greater chance that children of left handed parents will also be left handed than children of rights, but remember the chance of being a lefty is just ten percent overall, so most children of lefties are still right handed, and identical twins are more likely than non identical twins to both be either right or left handed, but many of both types do have opposite hand preferences.
And that's before we even talk about whether a child's handedness is allowed to develop naturally or whether parents and teachers interfere. Hand dominance typically develops around age three and is fully developed by age four to five, but it can be influenced by insisting a child uses their other hand or by happenstance. For example, when he was four years old, former Major League baseball pitcher Billy Wagner broke his right elbow and spent the summer in a cast.
In his memoir, Wagner vividly recalls being a natural righty at the time and already mad for baseball, but for the next six weeks he threw only left handed. When the cast came off, he was in for a surprise when he tried throwing with his right The ball went nowhere. Had lost not just strength but coordination for throwing with his right arm and gained it in his left. Wagner wrote, I was a natural righty then and still am. I do everything right handed, eat hold tools, right to start
the lawnmower, everything except pitch. Wagner wouldn't be considered ambidextrous, though he certainly managed to have an incredibly successful career working with his non dominant hand. Base all is full of players who switch hit, meaning they hit equally well from either the left or right side and are comfortable
facing left or right handed pitchers. Some like Hall of famers Eddie Murray, Mickey Mantle, and Chipper Jones, were very successful, but they, like Wagner, weren't truly ambidexterous, which is something that's very difficult to do. But why. Aucklenburg said, handedness is something that is generated in the brain, not the hands. As such, the half of the brain contralateral to the hand is better in controlling fine motor movements. For example,
the left brain hemisphere in right handers. The strength of this preference varies between individuals. Some people have a very strong preference for one hand and resulting from that greater issue in using the other for specific tasks. So it's the brain that sets the barrier. But if the brain sets the barrier, the brain can also remove it. Take the case of Billy McLaughlin. McLoughlin is an award winning guitarist known for a unique style of play, placing both
hands on the fretboard. He was originally predominantly a right handed guitar player, but in the late nineteen nineties, but despite having a record at number seven on the Billboard Charts, he was struggling with control problems. He was missing notes when he played, and experienced muscle spasms to the point that he was unable to perform. Finally, in two thousand one, McLoughlin was diagnosed with vocal dystonia, a movement disorder causing
muscles to contract involuntarily. Though advised to find another career, McLoughlin opted to teach himself to play left handed, and he succeeded. So this begs the question, can we teach ourselves to become ambidextrous as adults. A two thousand seven study found that as we age, we actually become more ambidextrous without even trying, in part because the hand that we use more loses its dominance. The study was small. It included sixty participants, all wrongly right handed according to
the Edinburgh Handedness Inventory. The participants completed various computerized dexterity tests, which included line tracing and aiming task and tapping. The youngest group, average age twenty five years, performed all the skills proficiently using their right hand. The middle aged participants, average age fifty years, performed well using either hand on the aiming task, while the two oldest groups, average ages seventy and eighty years, performed just as well using either
hand on all tasks except one. However, overall performance appeared to decline with increasing age, especially for the participants dominant right hand, leading researchers to believe that quote we become more ambidexterous as we get older because our dominant hand loses its superior dexterity and becomes more like our weaker hand. Some people have wondered whether attempting to become ambidexterous could strengthen the brain and potentially slow or fight the effect
of aging or dementia. Aucklandberg said that's a myth. While it is true in general that brain training is a good idea when aging, research has shown that what gets strengthened is what is trained. So if I trained to write with my non dominant hand, this would affect the motor brain areas of the contralateral half of the brain, but not the areas involved in memory. Thus a specific memory training would make more sense in aging and dementia.
Today's episode was written by Patty Resmusin and produced by Tyler Clang. For more on this and lots of other topics, visit how stuff works dot com. Brain Stuff is production of I Heart Radio. For more podcasts my heart Radio, visit the i heart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.