It's important to point out that Copeland and other researchers don't define bullying broadly, in a way that encompasses a lot of mutual conflict among kids, or one-time fighting. Bullying is physical or verbal harassment that takes place repeatedly and involves a power imbalance — one kid, or group of kids, making another kid miserable by lording power over him. As Dan Olweus, the Scandinavian psychologist who launched the field of bullying studies in the 1960s, has been arguing for many years, this is a particular form of harmful aggression. And so the effort to prevent bullying isn't about pretending that kids will always be nice to each other, or that they don't have to learn to weather some adversity.
If the results of this study are dismaying because they indicate that bullying is permanently scarring, the findings also strengthen the argument for prevention. Copeland underscores this idea. "Consider me a reluctant convert, but I'm starting to view bullying the same way I do abuse in the home," he said. "I honestly think the affects we're observing here are just as potent. And that's definitely not the way American researchers look at things. They want to know all about what parents are doing at home. Peers aren't considered a priority. But these days, with all the time they spend on the Internet, kids are spending even more time with their peers, and that's a factor we need to pay more attention to."
Bazelon is a Slate senior editor and writes about law, family, and kids. Her new book is "Sticks and Stones: Defeating the Culture of Bullying and Rediscovering the Power of Empathy and Character." Find her at email@example.com or on Facebook or Twitter.