Daniel Geschwind reaches up to his office bookshelf, takes down a three-dimensional puzzle of the human brain, and begins trying to snap the plastic pieces together. A neurogeneticist at the University of California, Los Angeles, Geschwind hopes the puzzle will help him describe the parts of the brain that control speech and language. But for the life of him, he can’t figure out how the left and right hemispheres attach. “I’m really bad spatially, so don’t make fun of me,” he pleads. “It’s like I’m having a little stroke or something. I’ll get it together, and then I’ll figure it out.”
The plastic model may have momentarily flummoxed Geschwind, but when it comes to the genes that govern the brain’s development and functions, he excels at putting the pieces together. Over the past few years, he has emerged as one of the leading geneticists in a nascent field that aims to spell out which genes are related to speech and language development–and how our intelligence and communication skills evolved beyond those of our ape relatives, giving us the unique ability to speak.
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.”