There are problems with evolutionary accounts for beauty or aesthetics, mainly it is an attempt to define in reverse, a backwards reading of the situation. The sense of beauty is reduced to a peahen's choosing a mate as being one and the same. There is no need to attribute a peahen with a human aesthetic choice.
Does the peahen find the peacock's feathers beautiful? Why would she think this? Is the beautiful then a thought rather than simply an aesthetic experience (whatever that might mean). Isn't the thought the experience?
Are we not really hungry unless we think 'I am hungry?' - no.
I am hungry, the sensation, the thought holds no further meaning, the experience does not stand for the thought. The experience is enough.
Does art do this, or is it something else? That is to say, something unique.
(This should induce cold shivers)
There is nothing 'special' in this unique sense, art cannot be a different case of family resemblances (Wittgenstein) anymore than truth or any other philosophically dense concept can, but art is not a philosophical case, although asthetics makes it one.
What then is it fundamentally? - Why ask for fundamentals here, this only takes us backwards.
What is fundamental about aesthetics is that it is not grounds for anything, i.e. it isn't truly fundamental at all. It is a simple activity rooted in our natural seeing or elsewise in our natural use of resemblance.