Left-handed people make up 10 percent of the human population on average, but chances are you know a leftie.

1. They’re over-represented in athletics.  Researchers found that left-handed people are a result of the balance between cooperation and competition in human evolution. Cooperation favors same-handedness, such as for sharing tools, whereas competition favors surprise, and a left-handed person might win in a fight.

 Left-Handed

2. They’re more likely to have a slender face. According to a (somewhat odd) study, people with slender lower faces are 25 percent more likely to be left-handed. Those slender-jawed folks also are more susceptible to tuberculosis, for what it’s worth.

3. They’re good at math. Have you ever noticed the lefties in your life are particularly quick with arithmetic? While a link between mathematical ability and left-handedness has long been rumored, a 2016 study found a “moderate, yet significant correlation” between the two. Math scores were five to 10 percent higher among lefties in a study of 2,300 students in Italy between the ages of 6 and 17 who were asked to complete simple mathematical tasks and problem-solve.

Also, a 2006 study published in the journal Neuropsychology found that left-handed people were more likely to have faster connections between the right and left hemispheres of the brain, meaning they processed information faster. Researchers said this could be a beneficial skill in areas like video games or sports.

Brain

4. They’re less likely to be ‘ left-hemisphere dominant.’ For 95 percent of right-handed humans, the left side of the brain is their dominant side and where language function is localized, reports Psychology Today. However, for lefties, only 70 percent are left-hemisphere dominant, with the remaining 30 percent distributing language ability across both sides evenly or moving it to the right side of the brain.

5. They’re slightly more susceptible to allergies, migraines and some diseases. Left-handedness is a result of biological diversity, and while lefties may have the advantage in a fight, they may have disadvantages in other areas. For example, this study found that left-handed people may be predisposed to allergies earlier in life.

Remedies

6. They’re more likely to have a sleep disorder. In a 2011 study, 100 people with periodic limb movement disorder (PLMD) were divided into left-handed and right-handed groups. Researchers found 69 percent of right-handed patients had bilateral limb movements compared with 94 percent of left-handed ones, regardless of age, sex and race.

7. They feel and express emotion differently. Going back to the brain hemispheres, a 2012 study published in the journal PLoS ONE found that lefties processed motivation on the right side of the brain, whereas right-handed people had motivation activity on the left side. This finding may affect how mood disorders are treated, where the left side of the brain is stimulated.

8. Gay men are more likely to be left-handed. A 2003 study evaluated large numbers of heterosexual and homosexual men and women on handedness and gender-related personality traits.

9. They tend to drink more often. If you’ve heard that southpaws are more likely to be alcoholics, that’s a myth. A 2011 study on the rumor published in the British Journal of Health Psychology found that left-handed people do tend to drink more often, but they aren’t more prone to risky drinking.

10. The answer could lie in the spinal cord. There have been several theories as to what determines our preference for handedness. Over the past several decades, researchers have agreed that it is determined in the womb. Scientists previously thought that it was genetic differences between the hemispheres of the brain that decided if a person was born right-handed or left-handed, reports Business Insider. But a 2017 study found that the answer could lie in the spinal cord.