Dogs wag their tails to express joy - but is this popular belief actually true, or is there something to this cute action that we haven't really thought about? Three researchers recently published an article in the journal Biology Letters in which they examined about 100 major scientific studies that investigated and dealt with the understanding of dog tail wagging. The researchers uncovered a very special phenomenon related to the kashkush - when a dog meets someone or something that it wants to investigate and approach, the angle of the wagging will lean to the right, but in the event that it want to move away from the cause, it will wagging to the left.