The pre-requisites for evolution are reproduction, mutation, and competition for limited resources. Most mutations will be deadly, and will therefore not be passed on to offspring. However, occasionally a mutation will occur that will confers some advantage upon the organism in question. This advantage will make the organism better able to compete for resources (food, mates etc.), and therefore give it a better chance of producing offspring.
In evolutionary terms, advantage is often conferred by a greater awareness of one's environment through sensory apparatus, and an increased ability to reason about and act upon this sensory data. Even a slight improvement in these areas will likely give some survival advantage to an organism, and increase the chance that this will be passed on. After millions of years of trial and error, and incremental increases in the brain's ability to interpret and reason about sensory inputs, evolutionary pressures finally led to a complex brain with a feedback loop - i.e. it became self-aware. This seems to have gone hand-in-hand with the development of language, and the two developments may have fed off each other. In fact, the development of language may be an essential component in the development of consciousness.
What is certain is that this development of consciousness and language gave us a huge evolutionary advantage - which is how it evolved in the first place. We now have far greater flexibility to move beyond our genetic programming, to reason and reflect, and to communicate our thoughts and ideas to others. We can therefore work together on problems, and build upon the thoughts and ideas of our ancestors and contemporaries. This has led to an exponential increase in our knowledge and understanding of the world.
But, how is all of this relevant to our appreciation of art? Well, I would suggest that the appreciation of beauty did in fact evolve in animals as it conferred them with an advantage. Furthermore, it seems to me that the precursors of this are still likely to be found in lower animals today. For example, I would speculate that there is a sense in which a bee finds a flower to be 'beautiful'; female birds find the songs, displays, or nests of the best males to be beautiful; and giraffes find a verdant landscape with lots of edible foliage to be beautiful. These responses exist as they attract animals to the best environments and food for survival, and to the most promising mates. The same types of responses exist in us too.
Of course, our greater intelligence, language, and social nature led us to develop cultural artefacts and diversity that go way beyond anything found in other animals. As part of this, we have developed many different ways in which to stimulate and extend our innate appreciation for beauty. I believe that art and music are two of the offshoots of this mixture our evolutionary and cultural heritage. As with many aspects of our current behaviour, I think that the roots are most likely to be evolutionary, but that our cultural development has built upon these roots in ways that sometimes make the original evolutionary drivers far from obvious.
Of course, art (including theatre, film, music, painting etc.) includes far more than just beauty. Nevertheless, I think that most works of art aim to stimulate or provoke some emotion or other in those viewing it, and those emotions arose in the first place as they gave an evolutionary advantage.
For example, I think it’s fairly obvious that anger would give animals an advantage when fighting over a mate or territory; fear would give them an advantage when confronted with danger; passion draws them to a mate, and love helps to keep the pair together for the benefit of the offspring; inquisitiveness and adventurousness would help them look for new and better places to live, and ways of doing things; feelings of friendship, empathy, altruism, camaraderie etc. are good survival traits for group animals such as ourselves, and so on.
We clearly get enjoyment and stimulation from suspending disbelief and invoking these emotions through artificial means, as evolution has honed us to respond strongly to emotional triggers. Furthermore, in more recent times I think that there would likely have been other survival advantages accrued from passing on important information through stories, songs, paintings etc.
I don't think that a bit of art appreciation that gives an adaptive advantage. Rather, I think that art appreciation is a side-effect of our emotions in general, and our attraction to 'beauty' in particular (and the full gamut of art in general is a cultural outgrowth of this). It is the possession of these emotions that give an incremental evolutionary advantage, and is the reason that we possess them today.
Here is an interesting article on this subject: