Seed has a short article by V.S. Ramachandran on the evolution of consciousness:
I suggest that a new set of brain structures evolved during hominid evolution, turning the output from more primitive sensory areas of the brain into what I call a “meta- representation.” I think they edited, enhanced and packaged sensory information into more manageable chunks, used for juggling symbols and language.
Ramachandran is director of the Center for Brain and Cognition at the University of California, San Diego.
In the film below, Ramachandran discusses phantom limb sydrome, synaesthesia and mirror neurons. The lecture he gives in the film is one of 12 given at IBM’s Almaden Institute Conference on Cognitive Computing. (‘Rama’ starts his talk about four-and-a-half minutes into the film.)
Mo Costandi 
This is an invitation to view my theory on consciousness at my web site: http://www.freewebs.com/consciousnessdecoded
Tim, by strange coincidence, you wrote your comment as I was adding the finishing touches to the post on neuroanthropology.
Your definition of consciousness as “the mind’s on-going interpretation of its immediate environment” is very similar to the definitions that I mention in that post.
Get more of Ramachandran’s lectures at http://www.bbc.co.uk/radio4/reith2003/lecturer.shtml
He was the 2003 lecturer for the annual Reith Lectures. He covers, Phantoms in the Brain, Synapses and the Self, the Artful Brain, and Neuroscience – the New Philosophy. You can listen to the lectures in Real Audio format or read the transcripts. Each of the lectures has question/answer sessions and one includes questions by Oxford professors Richard Dawkins and David Deutsch.