even little tiny fruit flies do it

(In case you didn't notice, the title I chose for this entry is a modification part of a famous song.)
http://www.sciencedaily.com/releases/2008/04/080415210626.htm

Fittest Males Don't Always Get The Girl

ScienceDaily (Apr. 16, 2008)
The fittest males don't always get the girl, USC biologists report. Study tackles a paradox in species from fruit flies to humans: If warriors win the spoils, why don't males evolve towards super-aggressiveness?

There is more to mating than beating up the competition, according to a new study. Female fruit flies sometimes choose males who win fights, sometimes choose males who do not fight, and sometimes choose males for no obvious reason, say biologists from the University of Southern California; Cal State University, Sacramento; and the University of California, Davis.

The findings help explain the large variation in aggressiveness in most species, including humans.
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One reason for the variation, according to the study and to previous research on lizards by other groups, may be that no fighting strategy works all the time, just as in the game rock-scissors-paper.
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"There's no single way to win a fight, or win mates," he added. "Females didn't necessarily prefer aggressive males -- some males mated less when they lost fights, but some males mated more if they didn't fight. Moreover, different females preferred different males."

"Unexpected interactions between individuals can define winners and losers (so-called 'chemistry')," Foley concluded. "In order to understand why flies, and humans, and other animals, are so genetically different from each other, we need to stop imagining there's a 'best' kind of strategy."