Although cerebral dominance, the specialization of each side of the brain for different functions, was discovered in the 1860s, almost nothing was known for many years about its biological foundations, the study of which has undergone what can only be described as a revolution in the past decade and a half.

Norman Geschwind and Albert Galaburda, two of the leaders of this new field, have assembled a distinguished group of investigators, each a pioneer in some aspect of the biology of dominance. The authors document human brain asymmetry at gross and microscopic levels in both adults and fetuses, its visualization in life by radiological methods, and its manifestation in brain waves. The evolutionary history of brain asymmetry over more than 300,000 years is shown in fossil skulls of humans and apes. In a dramatic reversal of older beliefs, asymmetry of anatomy, function, and chemistry has been demonstrated in many nonhuman species, and experiments have shown the role of hormones and other prenatal influences in the production of asymmetry. The surprising associations of non-right-handedness with twinning and immune disorders are discussed, as well as the asymmetrical malformation of the cortex in childhood dyslexia.

This volume, combining scholarly authority and the excitement of the birth of a new discipline, will be welcomed by those to whom the implications of dominance are becoming evident—neuroscientists, neurologists, linguists, psychologists, experts in learning disorders, speech pathologists—and by specialists in nearly every branch of biology, medicine, and psychology.