Lefties think differently. The left side of the brain—which controls the right hand—is in charge of speech, language, writing, logic, math and science. The right side—which controls the left hand—is responsible for music, art, perception and emotion. The right side handles abstract, big picture ideas; the left side thinks in straight lines.
Right-handers' brain organization is usually quite rigid. The right side only handles language and logic; the left side only handles emotion and perception.
Meanwhile, left-handers' brains tend to be more flexible—understanding of music could be on the left side or math could be on the right. As a result, the corpus callosum, the part of the brain that allows the two hemispheres of the brain to communicate with each other, can be 11 percent larger in left-handed brains than right-handed ones.
Some think left-handers' brain structures may be the product of living in a right-handed world. "Growing up surrounded by right-handed equipment, instruments, appliances and tools, lefties give their nondominant side more exercise than the average righty," Melissa Roth wrote in The Left Stuff. "Biomechanic research has revealed that training the nondominant side of the body actually enhances the dominant side—something known as the cross-training effect—since the body's neural network is integrated on both sides."