How to tell a dog is friendly: It wags its tail to the left

Now, scientists using a robot have found that the way dogs use their tails is more subtle than we thought and that dogs that wag them to the left may be more friendly.

The animal psychologists discovered that when real dogs approached a life-sized black Labrador with a mechanical tail, they were less wary of it when it was wagging its tail on the left side of its body.

When the robot’s tale wagged to the right side, far fewer dogs approached it in a confident manner.