It's long been known that besting a foe – be it in tennis or Tetris – gives a boost to a dude's testosterone levels. But according to a new study published in the journal Human Nature, men throughout the ages have just been, well, wasting their time. After all – why spend all that effort on actually winning, when it turns out you can get the same result from simply thinking you did?
Researchers from the University of Cambridge carried out an experiment to see how the outcome of a rowing competition would affect various attributes of a group of young, heterosexual men. Rowing, the study notes in a manner pleasantly reminiscent of some fascinated extraterrestrial observer, was chosen "because of its physically demanding nature... victory strongly implies the possession of greater physical strength than the opponent, a trait said to be valued by women in choosing a mate."
After the competition, the scientists measured changes in the participants' testosterone levels, self-esteem, and "sociosexuality" – how open they were to sexual activity outside a committed relationship.
But there was a catch: the winners and losers of these head-to-head battles had been randomly selected, regardless of who actually proved themselves the stronger rower. The question the scientists hoped to answer: is testosterone higher in winners because physically powerful people tend to win, or is it the social experience of winning itself that provides the boost?
The results were pretty conclusive: not only did "winners" experience a surge in their testosterone and self-esteem levels, but they also saw their "level of endorsement of, or willingness to engage in, unrestricted sexual relations without closeness and commitment" rise – that is to say, they became more open to casual hookups. They became more likely to approach women they found attractive – and, slightly amusingly, more likely to avoid people who might make them spend time with children. Meanwhile, "losers" experienced the opposite effect: their testosterone levels decreased – although most other attributes didn't change much.

As lead study author Daniel Longman explained, it's all to do with status.
"Much of evolution consists of trade-offs in energy investment... One reproductive approach is short-term, investing time and energy in attracting and pursuing many mates, and fighting off competition. Another approach is long-term, investing energy in raising offspring with a single mate," he said. "We found that a perceived shift in social status can cause male physiology to adapt by preparing to shift mating strategies to optimise reproductive success."
In other words, when men think their status has increased – when they've just rowed a challenger into submission, for example – their testosterone surges, and they seek out short-term, no-strings, um, "reproductive success".
But for any guys thinking this gives them an excuse for bad behavior, Longman has a word of warning.
"Male physiology may shift to take advantage of certain situations," he cautioned, "but ultimately a man's decisions are up to him."