 The researchers theorized that pet dogs are trained not to engage in conflicts over resources, promoting a level of tolerance, which may facilitate cooperation.The pack dogs were used to competition over resources and thus were likely to have conflict avoidance strategies, which constrain cooperation.Marshall-Pescini, Schwarz, Kostelnik, Virányi, and Range set out to test two competing hypotheses regarding cooperation in wolves ("Canis lupus") and dogs.