I don't have the answer, but I have had an idea that isn't entirely worked out. The basic concept is that consciousness is a physical property of matter, much like magnetism. It isn't a property like mass or hardness or anything like that, but it a measure of the effect of a field on the material. So, consciousness is a universal field that permeates space, just like gravity and electromagnetism. The reason that we are "conscious" is based on our ability to react to this field, so our sense of having consciousness is simply a measure of our ability to react more strongly to the field. Just like gravity has differing impacts or effects on us based on where we are, on Earth or in the middle of space as an example, so too does consciousness have differing effects or impacts on matter. And just like iron shavings are more magnetic than sawdust, we are more conscious than a sunflower. Of course, this could get weird since gravity is, at least based on current theory, not so much a field as it is the transmission of particles known as gravitons. So, the fields I mention are really called forces which are applied at varying strengths based on the effects of subatomic particles. I guess consciousness could operate in this fashion, but this is really the point at which my idea begins to break down.
I also have some ideas about what it is that makes us more conscious as opposed to other objects or things. I think that it could partly be related to our chemical composition. There are many different elements resident in the human body - in fact, there is no human body without them. We are largely carbon, but we also have copper and iron and oxygen and selenium and sodium and potassium...the list is endless...all running through us and essential for what we know as life. I think it is possible that the concentration of one of these elements or maybe the concentration of some compounds based on these elements may be the substance that resides within us that is largely sensitive to the conscious field of the universe. If I had to place a bet, I'd say the most important element for consciousness is carbon, but that seems like a pretty obvious choice. They don't say "carbon-based lifeform" for nothing, you know.
But there is some very interesting research that has been done that suggests that consciousness is the result of the brain's function as a quantum computer. This computing happens within the microtubules, which are protein structures within our cells. These structures are not made up of lots of carbon, so maybe I am totally wrong about the element idea above. The theory that focuses on microtubules, the Orch OR theory, makes some very interesting assertions that go beyond simply suggesting that consciousness arises at the level of synaptic activity. By claiming that consciousness is built on quantum computation, it opens the door to the brain being able to assess all probabilities of any possible outcome. At the quantum level, this has nothing to do with things like seeing the future or weird ESP-like behavior. However, there have been some odd results from experimentation that suggests that the brain does somehow pick up information about the future, even when it doesn't use that information to make a "better" decision.
Whew. I almost got all New Agey for a minute there.
I think about this a lot, partly because I am fascinated by physics and how much it relates to everyday existence. But also because of two things that I firmly believe: that there is no God of any kind, but that we are something more than simply matter moving through spacetime. So, if we are more than directionless matter or perceive ourselves to be more than that and there is no divine presence, what is it that makes us all feel like we are connected to something greater? What is it that gives us a mind in the first place?
As an aside, I also often think about the idea of order in the universe and why it would exist. Order is often referenced to suggest intelligent design and a creator and all that stuff. But, I don't think any of that is needed for order to arise in a complex system. And, I think that is a different post.