20 Little-Known Facts About Being Left-Handed
4 hours ago Theories suggest that left-handedness is most likely due to a combination and two single gene model theories have been proposed to date. For example, if both parents of a child are left-handed, there is a 26% To date, two theoretical single gene models have been. Alcoholism runs in families not only because there is a genetic component to Gay women and gay men are more likely to be left-handed or.
For other one-sided brain functions, such as attention, emotion, music, and face perception, she says, there are less data.
Participants were shown two columns of abstract illustrations and asked which seemed more intelligent, happy, honest, and attractive.
20 Little-Known Facts About Being Left-Handed
Righties were more likely to choose the illustrations in the right column, while lefties were more likely to choose the drawings in the left column. He believes this may even influence the way we vote on ballots, or which candidates we prefer when watching presidential debates.
It can affect school performance In a study of children 11 and younger, Australian researchers found that left-handed kids performed worse than right-handers several measures, including vocabulary, reading, writing, social development, and gross and fine motor skills. Mixed-handed kids performed even worse than lefties. Mixed-handed and left-handed children are more likely to use the two halves of their brains in unusual ways, which may put them at risk for mild learning disabilities, says Yeo.
Studies have also found links between non-right-handedness and dyslexia, attention deficit hyperactivity disorder, and some mood disorders. In his book The Puzzle of Left-Handedness, linguist Rik Smits explains that athletes, left- and right-handed usually train against right-handed opponents. When finally facing a southpaw, lefties can easily adjust—but righties are at a double disadvantage.
It goes back to the idea that lefties have a physical advantage over righties. In violent societies, researchers theorize, left-handers benefit from their unexpected left hook. Types[ edit ] Right-handedness is the most common type. Right-handed people are more skillful with their right hands when performing tasks. Left-handed people are more skillful with their left hands when performing tasks.
Breastfeeding could impact your child's handedness
Those who learn it still tend to favor their originally dominant hand. Occurrences during prenatal development may be important; researchers studied fetuses in utero and determined that handedness in the womb was a very accurate predictor of handedness after birth. Since speaking and handiwork require fine motor skills, its presumption is that it would be more efficient to have one brain hemisphere do both, rather than having it divided up.
Since in most people, the left side of the brain controls speaking, right-handedness predominates. This theory also predicts that left-handed people have a reversed brain division of labor.
Left-handed individuals have a heterogeneous brain organization in which their brain hemispheres are either organized in the same way as right-handers but with the hemispheres reversed or even such that both hemispheres are used for verbal processing.
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When the average is taken across all types of left-handedness, it shows that left-handers are less lateralized. However, the growing weight of evidence from linkage and genome-wide association studies suggests that genetic variance in handedness cannot be explained by a single genetic locus.
Nodal signaling and ciliogenesis also play a role in the development of brain asymmetry handedness is an outward reflection of brain asymmetry for motor function. Diethylstilbestrol animal studies "suggest that estrogen affects the developing brain, including the part that governs sexual behavior and right and left dominance".
About two-thirds of fetuses present with their left occiput back of the head at birth.
This partly explains why prematurity results in a decrease in right-handedness. Previc argues that asymmetric prenatal positioning creates asymmetric stimulation of the vestibular system, which is involved in the development of handedness.
In fact, every major disorder in which patients show reduced right-handedness is associated with either vestibular abnormalities or delay,  and asymmetry of the vestibular cortex is strongly correlated with the direction of handedness. Research on this topic suggests there may exist a weak association between ultrasound screening sonography used to check on the healthy development of the fetus and mother during pregnancy and left-handedness.
This is especially shown when observing hand dominance in one versus two-handed grasping tasks. Between 36 and 48 months, variability between handedness in one handed grasping begins to decline significantly. This difference can be seen earlier in bi-manual manipulation tasks. Children aged 18 to 36 months showed more hand preference when performing bi-manipulation tasks than simple grasping. The increase in required single hand grasping activities such as writing or coloring can force children to develop a hand preference.
Handedness and mathematical ability and List of musicians who play left-handed In his book Right-Hand, Left-Hand, Chris McManus of University College London argues that the proportion of left-handers is increasing and left-handed people as a group have historically produced an above-average quota of high achievers.
He says that left-handers' brains are structured differently in a way that increases their range of abilities and the genes that determine left-handedness also govern development of the language centers of the brain. Left-handers' brains are structured differently from right-handers' in ways that can allow them to process language, spatial relations and emotions in more diverse and potentially creative ways.
Also, a slightly larger number of left-handers than right-handers are especially gifted in music and math.
They found significant differences between left and right-handedness in the segments of the spinal cord that control arm and leg movement. They concluded that the asymmetrical nature of the spinal cord could be down to something called epigenetics — which is how organisms are affected by changes in their genes' expressions, rather than in the genes themselves.
These changes are often brought about by environmental influences, and can affect how the baby grows. These gene expression differences could affect the right and left spinal cord differently, resulting in lefties and righties. So why are lefties so rare? Some scientists have tried to answer this question, such as inwhen researchers at Northwestern University developed a mathematical model to show how the percentage of left-handed people is a result of human evolution.
They hypothesised that a balance of cooperation and competition in our evolution has led to this divide.
In other words, although the basis may be genetic, there could be a social factor to it too, hence why the ratio is so high. Abrams, the author of the model and an assistant professor of engineering sciences and applied mathematics at the McCormick School of Engineering and Applied Science, told LiveScience.
In humans, this has resulted in a right-handed majority.