More than 90% of the adult population is right handed and, therefore, is left-hemisphere dominant. About 96% of the adult population is left-hemisphere dominant for speech... Other researchers have shown that the speech area of the adult cortex is larger on the left than on the right, whereas the two hemispheres of the newborn are believed to have equipotential capabilities. During childhood, one hemisphere slowly comes to dominate the other and only after the first decade does the dominance become fixed. This would explain why a 5-year-old child with damage to dominant hemisphere can easily learn to become left-handed and speak well, whereas this is almost impossible in the adult.