With individual training intended to show the animals that if both ropes were held in the mouth, they could get the treat, three of four wolf pairs succeeded multiple times. Two of six dog pairs succeeded — once.
Dr. Marshall-Pescini said both wolves and dogs were raised in exactly the same conditions at the center, where they live in groups with a lot of human contact but are not kept as pets. The reason for wolves performing much better, she said, might be that in the wild they must cooperate in bringing down big game and sharing it if they are to survive.
Dogs, whether they are free-ranging, foraging at garbage dumps or looking for discarded food, don’t need teamwork.
But defining tolerance, which is supposed to aid cooperation, is tricky.
“Wolves argue a lot around food,” she said. “But in the end they eat together.” As for dogs, she said, “They don’t even argue about it.” An earlier study of free-ranging dogs, she said, showed that the dominant dog ate first and other dogs waited.
Of course, pet dogs often eat together with two bowls. And dogs can be trained to do just about anything; even the act of training may change their ability to cooperate.
In a previous study, dogs that had been highly trained — not at the rope pull test, but for other tasks — were much better able to succeed at the rope pull.