Most dominance contests among non-human animals are also non-lethal. It's very common for there to be a sort of "rules of engagement". For instance, cobras don'

Most dominance contests among non-human animals are also non-lethal. It's very common for there to be a sort of "rules of engagement". For instance, cobras don't strike each other when they fight --- they do this weird body-slamming thing.[1] Rams never sneak-attack each other side-on, they only square up. There's a good explanation of this in The Selfish Gene. These behaviours come from the pay-off matrix. The stakes of these contests are often low, in comparison to the possible losses if your competitor fights dirty, too. So it's not worth the risk of breaking the rules of engagement first. So: yes, kicks to the balls might be a winning strategy. But if you shoot first and miss, you might get kicked. Even if you win 90% of fights with your groin shot, you'll take enough groin shots back that this is not worthwhile. [1] https://www.youtube.com/watch?v=fdNuFgsobDY https://www.youtube.com/watch?v=fdNuFgsobDY