Scientists have long debated how humans turned wild wolves into domesticated dogs. Several have hypothesized that people selected wolves that were especially cooperative, and continued to develop that trait when breeding the first dogs, thus creating animals that are eager to work with us. But at last week's Animal Behavior Society meeting, researchers challenged this idea with new studies showing that wolves are far more cooperative than their canine relatives are. Wolf packs are egalitarian, these scientists say, whereas those of dogs are hierarchical. Our pooches regard people as top dogs and expect to be given orders. That is also why they often fail at problem-solving tasks, while wolves succeed. Most dogs won't even try to open a sealed container of food, unless a human has given them a command to do so.