NEW research seems to indicate that just having a dog around can boost human cooperation levels—potentially altering well known game theory results:

In the other experiment, which used 13 groups, the researchers explored how the presence of an animal altered players' behaviour in a game known as the prisoner's dilemma. In the version of this game played by the volunteers, all four members of each group had been “charged” with a crime. Individually, they could choose (without being able to talk to the others) either to snitch on their team-mates or to stand by them. Each individual's decision affected the outcomes for the other three as well as for himself in a way that was explained in advance. The lightest putative sentence would be given to someone who chose to snitch while the other three did not; the heaviest penalty would be borne by a lone non-snitch. The second-best outcome came when all four decided not to snitch. And so on.

Having a dog around made volunteers 30% less likely to snitch than those who played without one.