The ripple effects of this research are enough to make one's mind spin. Will brain scans someday declare that sex offenders can't be cured? If a killer knows the difference between right and wrong but neurologically can't control his behavior, where does this leave us? How will fMRIs reframe the insanity defense? What about the right to be judged by our actions and not our thoughts? Questions like these have prompted the emergence of a whole new field of inquiry. In May 2006, the Neuroethics Society was formed to promote the responsible application of neuroscience through better understanding of its capabilities and its consequences.

With the addition of behavioral genetics, the questions may become even more controversial, says Judy Illes, PhD, professor of neurology and the Canada research chair in neuroethics at the University of British Columbia. She predicts that the hybrid science of fMRI techniques and genetics—"imaging genomics"—will become one of the most powerful tools of the decade. "We're looking at a technology that is poised to be a true revolution in both psychiatry and neurology," she says.

Illes believes that scientists may be able, for example, to decode a 7-year-old's genes and scan the brain to determine his or her risk for future criminal behavior. "The question is," she says, "What is acceptable accuracy? How do we respond to such children? What if we get it wrong? It might even turn into a self-fulfilling prophecy."

How would society handle a boy who has the potential to become a terrorist? Lock him up? What if the impulses never materialize into crimes? And then, would we require all 7-year-olds to get scanned, just in case—even though judging someone by what he might do, rather than what he has done, flies in the face of the very essence of our judicial system?

As technology hurtles forward along with such questions, a few words of wisdom from a scientist who shaped our lives for more than a century may be comforting. "It is not the strongest of the species that survive, nor the most intelligent," Charles Darwin reportedly said, "but the one that is most adaptive to change."

From the November 2008 issue of O, The Oprah Magazine

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