There are just too many lefties for brain damage to be the major culprit, 'so we look to genetics.' 'But if that's true, that's probably the minority of cases,' Corballis says. Researchers used to think that minor brain damage early in development caused left-handedness, he notes. That frees up the other hemisphere to do something else, such as sort out the speech's emotional content. It would be inefficient for both sides to, for example, process a person's speech when one hemisphere can do that just fine on its own. Early in human history, and possibly even in our pre-human ancestors, evolution delegated different cognitive responsibilities to the brain's two hemispheres, he posits. That's probably no accident, Corballis says. That means the vast majority of people on this planet have strongly lateralized brains. The remaining 10 percent are either left-handed or some degree of ambidextrous, though people with 'true' ambidexterity-i.e., no dominant hand at all-only make up about 1 percent of the population. Researchers are exploring these unusually balanced brains and finding out why that's the case.Ībout 90 percent of people are right-handed, says Corballis. 'Otherwise, information has to cross back and forth across the corpus callosum, and that can sometimes cause problems.'Ī strongly symmetrical brain, like Einstein's, leaves people open to mental dysfunction, but it also paves the way for creative thinking.

'There's an advantage to cerebral dominance because it localizes function to one hemisphere,' he says. His brain's hemispheres were more symmetrical-a trait typical of left-handers and the ambidextrous.īy comparison, 95 percent of righties have brains that strictly divvy up tasks: The left hemisphere almost exclusively handles language and speech, the right handles emotion and image processing-but only about 20 percent of lefties have brains that divide up these duties so rigidly.īrain hemisphere specialist Michael Corballis, PhD, a psychologist at the University of Auckland in New Zealand, points out that having the hemispheres manage different tasks might increase the brain's efficiency. While he was certainly right-handed, autopsies suggest his brain didn't reflect the typical left-side dominance in language and speech areas.

Myriad photos show him writing on a chalkboard with his right hand, for example.īut handedness has its roots in the brain-right-handed people have left-hemisphere-dominant brains and vice versa-and the lefties who claim Einstein weren't all that far off. The problem is, Einstein's left-handedness is a myth. You may even see people tying Einstein's genius to his left-handedness. Browse through a list of history's most famous left-handers and you are likely to see Albert Einstein's name.

Left and right hemisphere test