Aggression Is Its Own Reward
Mice will engage in behavior that brings an intruder into a cage to be attacked--the mice appear to find increased dopamine levels associated with the aggression to be rewarding. Steve Mirsky explains, with reporting by Harvey Black.

SUBSCRIBE TO Science Quickly
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Gonna watch the NFL conference championship games on Sunday? You’ll see evidence for a new finding: aggression is rewarding. In what scientists from Vanderbilt University say is the first study of its kind, they report that aggressive behavior triggers dopamine, a neurotransmitter in the brain that is known to be part of a reward system. Dopamine levels increase when people and animals get food, sex, and drugs like cocaine.
The researchers report in the online edition of the journal Psychopharmacology that when a caged male mouse was faced with an intrusive male mouse that replaced a female previously in the cage, the first male got aggressive. He bit and boxed the interloper. But when the intruder was removed, the mouse would engage in behavior the he learned would bring his target back. The researchers think that aggression was its own reward.
More evidence: when the mouse that was deprived of his female companion got a drug that inactivated dopamine receptors, he brought the intruder back less frequently. So remember that when Michael Strahan is smashing into Brett Favre, he really, really likes it.
—Steve Mirsky, with reporting by Harvey Black
Subscribe to Support Independent Journalism
Great science journalism requires human expertise, time, effort and creativity. And it costs money. That’s why I and the journalists here at Scientific American hope you’ll join our community.
When you subscribe, you are supporting staff and freelance journalists who are passionate about telling science stories that are true, important and compelling. Our editors and reporters are often experts in their fields, which means they understand the nuances of big discoveries and can untangle the breakthroughs from the hype. With a subscription, you are also supporting rigorous fact-checking to ensure the words we publish are precise and accurate. And you’re supporting original illustrations, graphics and photos that bring you closer to an advanced laboratory, an ice sheet in Antarctica or a space mission in orbit. You’re helping us craft other types of high-quality journalism as well: Our newsletters are carefully written, edited and curated by staffers you have or will come to know and love. Our Science Quickly podcast is based on original reporting, collaboration with editors and scientists and exacting production.
Subscriptions keep this engine running so we can continue to deliver thoughtful, rigorous and independent science journalism to you. In an era of viral misinformation, this work is crucial. If you value what we do, I hope you’ll consider joining us as a subscriber