Anyone interested in the scientific study of consciousness should read Nick Humphrey’s most recent lectures, Seeing Red, and perhaps the piece he had in a fairly recent JCS Solving the Mind Body Problem.
I’m not sure that he’s right in his explanation of where consciousness came from and what it does — in fact I feel sure that he is wrong — but what’s interesting in this context is that his belief that the fitness-enhancing role of human consciousness is essentially that it makes life more interesting entirely expresses his (admirably) optimistic and can-do temperament. My own doubts no doubt express a similarly temperamental rancidity. But it is surely true that any historical explanation of human consciousness must satisfy all sorts of unconscious criteria as well as all the obvious rational ones.
There is another essay to be written on the selectionist attitudes that flicker in and out of his papers. But I doubt I will write it this summer. I have to read an enormous amount of Swedish detective stories in the next six weeks.
Harvard University Press offers a pdf of the first two chapters: http://www.hup.harvard.edu/catalog/HUMSEE.html