Why children brag?

All small, and sometimes and not such small, children suffer this shortcoming: they are boastful. And are ready to brag of everything, beginning from existence in a pocket of candy and finishing lack of couple of teeth ("I zubika have no Aga! "). Adults perceive children's boasting easily, considering as its integral trait of character of any kid, without thinking of the simplest thought: and why the child needs to brag? Korney Ivanovich Chukovsky in the book "From Two to Five" described the boy who, having met in the tram other boy of the same age eating lollipop, bragged of that...