We wrote last week about the question of the nature of 'awareness' or 'self' in Nature (here and here). We know our own consciousness, but really not much about that of other organisms--indeed, not really and truly about other individuals than ourselves.
Studying the 'neural correlates' or behavioral indications of consciousness can get us only so far, mainly descriptive phenomenology. But either religions are right, and there really is something we call the 'soul' that is separate from our biology, or our consciousness is somehow the result of our genomes. That is naturally one of the biggest prizes for research to try to understand.
But consciousness or other kinds of awareness--self-awareness or otherwise--would seem to be so far removed from the direct level of the genome, so dependent on inordinately complex interactions of components, that it is difficult to see how genomes will ever explain it. The term for this is that consciousness is an 'emergent' trait, relative to genomes.
There's little if any doubt that we'll learn many genes that, when mutated, damage consciousness or alter states of 'awareness' (we're not talking about recreational drugs here---or are they relevant?). How can interacting proteins--what genes code for--produce the kind of self-aware monitoring of the inside and outside world? We may have to develop some very different ways of knowing, in order to know even what we mean in this kind of research.
If our basic understanding of evolution is close to the truth, if and when we eventually develop such scientific approaches, one thing that can be predicted safely is that we'll find the genes, and hence the roots, of consciousness much more widely distributed in Nature than our usual, human-centered view has led us to think. Indeed, many of the same phenomena may be found in plants--and many precedents suggest we'll find rudiments even in bacteria.
Whether we'll ever be able to ask the carrot how it 'feels' is another question.