Researchers are beginning to crack the code that gives humans our way with words.

Research like Geschwind's sits at the intersection of two fields: behavioral genetics and evolutionary bi­ology. Each field depends on the other to make sense of the flood of studies on the genetics of language now pouring out of labs around the world. To peer into the human brain and see how it typically stores, uses, and comprehends words, Geschwind investigates not only normal human brains but also those where the process goes awry, studying the genes of families afflicted by autism, dyslexia, schizophrenia, and other conditions that can involve speech and language disorders. This research may help make diagnosis and treatment of language-related disorders more precise, but it also has a more basic purpose. "Studying disease is really a fundamental way to understand normal function," says Geschwind. "Disease has given us extraordinary insight to understand how the brain works or might not work."