Those little critters? It's practically their life! They start training them as kids. Partially for the fun of it, partially as part of some life-changing field trip, partially to steal each other's lunch money? [He shrugs his hands; he's exaggerating perhaps a little, but he does know they don't fight in the traditional sense of throwing punches and so forth.]

Hey, don't blame the messenger on this one. My universe makes a lot more sense than theirs does.