is one that strengthens the relationship between the two and it can create an ever stronger bond. It can help dogs establish stronger relationships by being able to communicate better with humans, as well as other dogs. Dogs will start to act and react much like their owners do, as they begin to sync their behaviors to those of their owners. Dogs will pick up on how their owners respond towards strangers and nonfriendly dogs. The pointing gesture is a human-specific signal, is referential in its nature, and is a foundational building block of human communication. Human infants acquire it weeks before the first spoken word. In 2009, a study compared the responses to a range of pointing gestures by dogs and human infants. The study showed little difference in the performance of 2-year-old children and dogs, while 3-year-old children's performances were higher. The results also showed that all subjects were able to generalize from their previous experience to respond to relatively novel pointing gestures. This can be explained as a joint outcome of their evolutionary history as well as their socialization in a human environment. One study has indicated that dogs are able to tell how big another dog is just by listening to its growl. The research also shows that dogs do not, or can not, misrepresent their size, and this is the first time research has shown animals can determine another's size by the sound it makes. The test, using images of many kinds of dogs, showed a small and big dog and played a growl. Twenty of the 24 test dogs looked at the image of the appropriately sized dog first and looked at it longest. Depending on the context, a dog's bark can vary in timing, pitch, and amplitude. It is possible that these have different meanings. Additionally, most people can tell from a bark whether a dog was alone or being approached by a stranger, playing or being aggressive, and able to tell from a growl how big the dog is. This is thought to be evidence of human-dog coevolution. Visual Dogs communicating emotions through body positioning were illustrated in Charles Darwin's The Expression of the Emotions in Man and Animals published in 1872. In her book On Talking Terms with Dogs, Turid Rugaas identifies around 30 signals that she calls calming signals. The notion of dominance and submission is much debated. In her