The idea of genius is socially constructed and not, in any meaningful sense, scientific. People speak about a "genius-level IQ," but the IQ test measures disability and "giftedness"—not genius status—and it does so in a very imperfect and general way. What's more, we never speak of geniuses in terms of their IQ scores—you might assume Leonardo da Vinci had a high IQ because of his work, but you wouldn't assume that any random person with an equal or higher IQ could produce work of comparable quality.
In today's Daily Beast, Edward Platt reviews the literature surrounding the unusual habits of people we think of as geniuses, centering on Daniel Fink's theory that both genius and neurosis often center on an inability to suppress the action of the precuneus, a part of the brain that is associated with self-consciousness, memory, and introspection. But we don't actually know very much about what the precuneus does, and the sample size in Fink's study is small enough that it may not accurately reflect the neurophysiology of genius. It's a step in the right direction—and much more promising than IQ, at any rate—but at this point, it doesn't give us much to work with.
There are other theories of how genius works as a capacity, but they are neither as old and well-established as the IQ theory nor as interesting (to me) as the precuneus-activity theory.
And what these theories have in common is that they look at genius as something that can be defined in passive terms, whether it's expressed or not, which means that they tend to be theories that we apply after the fact to people that we already think of as geniuses. This tends to calcify our assumptions rather than challenging them.
I agree with Stephen Jay Gould: "I am somehow less interested," he told New Scientist, "in the weight and convolutions of Einstein's brain than in the near certainty that people of equal talent have lived and died in cotton fields and sweatshops." Since we don't know where genius comes from, we should probably assume that it can come from anywhere—and do what we can to make sure everybody can make the most of their potential.
Art professor and entrepreneur Raphael DiLuzio talks about his recovery from a severe brain injury, and what he has subsequently learned about the creative process, here:
What I find interesting about DiLuzio's speech is that the man is obviously and conspicuously intelligent, but he is also struggling with a few higher-level cognitive functions that most of us take for granted. He is gifted and disabled—and not because he is in any sense a savant. Could it be that the rest of us are in the same boat—that we call people geniuses when their intellectual strengths, properly nourished and cultivated, happen to correlate with what we want or need at the time? Is that really all genius is, or does it mean more than that?
That's not a rhetorical question. I'm very interested in your thoughts on the matter; you can share them in the comments below.