Chimps from one troop invariably attack individuals from a rival troop when the attackers have an overwhelming number advantage and hence a minimal risk of death or injury.

• 当某群黑猩猩拥有压倒性的优势、死亡或受伤的风险也最小时，这群黑猩猩的个体便会攻击敌对群体的黑猩猩。