This makes a lot of sense given what I've read about prehistoric warfare. Far less people died or were injured in prehistoric, formal battle, but the smaller percentage of casualties was more tribally significant, because every able-bodied man you had was essential. It was also logistically impossible to sustain protracted conflicts, so there was a pageantry and a "code" to formal battle that more rarely escalated to "total war." Your guys face off, have a show of force, a few people are injured, and it's done. You all have crops to tend to at home, and you can't afford to risk more casualties.