SWEET TOOTH

THE STORY OF WHY WE CRAVE CHOCOLATE AND OTHER SUGARY TREATS

- Mark Schatzker

Dana Small was 11 years old when she knew she wanted to study the brain. Six years earlier, her mother had developed epilepsy. Small watched as a woman she'd known to be quick witted and brilliant struggled to get out of bed in the morning. “That's what sparked my interest in the fragility of consciousness,” Small says, “which is what led to the brain.”

In 2001, she received her PhD from McGill University, after conducting one of her first and most famous experiments. In it, she gave subjects Lindt chocolates to suck on as their brains were being scanned. The scans revealed that with each successive chocolate, pleasure-or “reward value, as the study called it—diminished. The parts of the brain that were brought to glowing life by the first chocolate became more and more dim. The study, published in Brain: A Journal of Neurology, was a breakout success. To this day, Small remembers Wolfram Schultz, one of the world's most prominent neuroscientists, telling her that it was the most comprehensive study yet of motivation in humans. Since publication in 2001, it has been cited more than 1,300 times by other scientists exploring the nature of pleasure, not to mention by an untold number of journalists who use it as proof of humanity's hardwired and dangerous love of sweetness.