|A snuggly California mouse pair. |
Photo from the Marler lab.
|A lone wire-walking white-footed mouse. |
Photo by the National Park Service.
Cathy Marler and her colleagues at the University of Wisconsin at Madison recently explored this question. They compared four groups of male mice: (1) California mice that won three challenges and had a saline injection after each win, (2) white-footed mice that won three challenges and had a testosterone injection after each win, (3) white-footed mice that won three challenges and had a saline (without hormone) injection after each win, and (4) white-footed mice that were handled by researchers three times (and had no dominance challenges) and had a testosterone injection after each time they were handled. Then they placed each mouse with a new challenger and measured what percentage of males in each group were dominant versus subordinate.
However, testosterone injections alone were not enough to increase the chances of winning: the white-footed mice that had testosterone injections without winning challenges were just as likely to lose their next challenge as those that had saline injections and won previous challenges. It’s the combination of winning experience paired with a surge of testosterone that is the winning formula. You can think of it this way: When (fictional) scientists gave frail Steve Rogers "Super Soldier Serum" to turn him into Captain America, it only worked because Steve Rogers was already a winner at heart. Had they given the serum to someone less remarkable, Michael Cera, for example, they just would have ended up with this:
|Michael Cera's attempt to be Captain America. Photo by Gage Skidmore.|
In the end, the experience of winning is critical to the Winner Effect: Testosterone alone won’t help you win your next challenge. So don’t think steroids are gonna help you if you suck at your sport of choice. You have to already be a winner for extra testosterone to help you win… and at that point, who needs it?
Want to know more? Check these out:
1. Fuxjager MJ, Montgomery JL, & Marler CA (2011). Species differences in the winner effect disappear in response to post-victory testosterone manipulations. Proceedings. Biological sciences / The Royal Society, 278 (1724), 3497-503 PMID: 21490015
2. Oyegbile TO, & Marler CA (2005). Winning fights elevates testosterone levels in California mice and enhances future ability to win fights. Hormones and behavior, 48 (3), 259-67 PMID: 15979073