Are you ever confused when you see a hot girl (in real life, or in a movie) pass over the nerdy sensitive best friend for the better looking jerk? Maybe you are like me and were rooting for the nerd the whole time. Maybe you let loose a tear or two when this happens in a movie, and you continue to wonder for the rest of your life if the nerd found a new love that was actually worthy of him (see: Duckie in Pretty in Pink).
Anyway, those of us with a scientific brain may also look at the situation and think that this phenomenon is easily explained by survival of the fittest. Jerk looks better than nerd. Jerk can beat up the nerd. Jerk gets the girl. Problem solved. This may be common in nature, but it is not universal. We see the opposite in humans often enough. I'm going to go out on a limb here and suggest that most females actually prefer a male that is sensitive to her needs. Amazingly, humans are not the only species that show this preference. While many female organisms tend to show preference towards the more fit and aggressive males, female water striders prefer the more laid back and sensitive males.
Water striders are insects; you have probably seen one resting on top of water in a stream or pond. A recent study found that female water striders tend to reject the more aggressive and persistent males. Females will leave areas where they are hounded by extremely aggressive males and move to areas with males that are less aggressive.
The result of this preference? Both the aggressive males and non-aggressive males are able to reproduce. The hyper-aggressive males still reproduce due to the monopolizing of females. However, it is the less aggressive males that are reproducing more overall.
This study shows that more cooperative males have a better chance of reproducing than selfish males- at least when it comes to water striders. It's good to see an example in nature that you do not have to be the biggest, best-looking, or meanest male to get the ladies (or vice versa for you females). Pardon my stereotype- but that's good news for us scientists.