One fall day in 1848, a railroad foreman named Phineas Gage was tamping blasting powder into a hole in the rock with an iron rod. The powder suddenly ignited, launching the tamping rod, more than three feet long and more than an inch thick, straight through his cheek and out the top of his head. A local physician named John Harlow arrived to find Gage drenched in blood but “perfectly conscious.” The tamping iron had rocketed through his skull—his crew found it 100 feet away, smeared with brain tissue—but it missed, by fractions of an inch, several areas critical for sustaining life.
More extraordinary than Gage’s survival was the transformation of his personality. Previously a conscientious man, he became obnoxious, profane, and unreliable. “Friends and acquaintances said he was ‘no longer Gage,’ ” wrote Harlow, who hypothesized that the damage to the frontal regions of his brain was to blame. At the time, there was little evidence that personality traits were tied to specific brain regions. Modern science has confirmed this idea, but researchers are still working to understand how, exactly, different regions of the thinking organ conspire to make us who we are.
