I think there's some kind of rhetorical confusion in taking the fact that we have trouble explaining consciousness to ourselves on a philosophical/metaphysical level, as a sign that it also requires a very special explanation on the biological side. As far as evolution is concerned we can just take things at face value: I am conscious of seeing a tree because I'm looking at it and the image gets processed by my brain, and then I think about it etc... Obviously being <i>aware</i> of things is useful for an organism, and any philosophical problems beyond that are irrelevant to evolution.<p>Sure, this may result in the conclusion that consciousness is just an evolutionary by-product of other, useful things, but when a by-product is posed as a biological problem it's usually from the angle of wasting resources. If consciousness is just a logical result of plain awareness of sensory stimul and thought there are no further resources wasted on it beyond those needed for awareness and thought. The philosophical problem of how to understand consciousness is orthogonal.