Art can take many forms: visual; aural; text; or any combination of these. In fact anythings we are capable of experiencing can be turned into art. In essence, art is communication. We express ideas and emotions which we cannot verbalize in various ways and this becomes art. As such art is vital to human evolution, especially the evolution of the mind.
Art is subjective. Everyone reacts differently to a piece of art, regardless of the form or content. These reactions cause chain reactions causing us to think or feel things which we might not expect. Anything which can make this happen is forcing us to grow by challenging our individual ideas and beliefs. Through the ages art has been such a power for change that entire periods of history are dictated by the paintings, writings and music of the time. Some art can be so powerful that controlling organizations try to suppress it. However, if we want our brains to evolve we should be exposing ourselves to as much art as possible, regardless of the reaction it provokes within us. We learn just as much from negative experiences as we do from positive ones.
Art is constantly evolving. Technology is giving artists new forms to explore, with interactive art being the main focus of this. We can now not only experience a piece of art but involve ourselves in it as well. This magnifies the experience, and heightens our reactions to it on a logarithmic scale. With these new concepts, artists can now communicate with us in a much more complete fashion and this can only lead to us developing a better understanding of a piece of art.
In short, all art aims to take an experience, idea or emotion from one person's head to another. Any communication is going to help someone develop as a person, and in turn help humanity evolve. Art is the purest form of communication and therefore is fundamental to human evolution.