Consciousness is the quality or state of being aware of an external object or something within oneself. Profoundly different states of awareness of both the external and internal world are apparent between each individual. While with the external world people can cross reference what they are aware of and come to an agreement that both are aware of the same thing, the internal world remains a subjective experience unique to certain extents to each individual person, which none the less can be studied scientifically by various changes in the physical body and brain in the external world.
Someones state of consciousness is inextricably linked to cognition and the molecules in their brain and blood. One such molecule found in the blood and brain of humans is DMT, a psychedelic that has profound effect on consciousness. One the things about DMT besides what it does is the fact that is such a simple molecule. If you look at it's structure you only really have four places that you can attach something to, so you can make diethyl or diproply analogues of it, or a few others, which do give you new compounds but their effects are very different from natural nn-DMT.
Bio-synthetically it's two steps from tryptophan, which is just two trivial enzymatic steps from DMT, and tryptophan is an amino acid which is everywhere in nature. Pretty much all organisms have tryptophan, and the enzymes needed to do this are all over the place and pretty much everywhere in nature, so theoretically anything could synthesize DMT.
No one really knows why it is there or what it's function is. Why is it in all sorts of plants and animals? What is the role it plays in humans? The conventional view of a few decades ago was that these molecules had no real function that they were just physiological noise, but that is a very naive understanding. What we now understand is that these secondary compounds are in a sense the language of plants. These are messenger molecules, this are what plants use to mediate their relationship between other organisms and the environment. There is important information to be learned from such molecules, and we are wired to experience this. I don't think it is universally present in nature by accident. It really fits that DMT may be the common molecular language, a resonant language if you will, between all living organisms. In fact this may be a good way to classify if something is conscious or not. Whether something is alive or not is a trickier question ...
I can't think of a more powerful tool to explore the question of what is consciousness. And DMT enables a totally unique, natural way to not only study the external aspects of consciousness (the molecule and binding profile) but to also study the internal world of consciousness and how it effects both. Any model of consciousness not based on similar molecular structures and conscious experience is an incomplete model. Other similar compounds with similar effects need to also be included in such considerations, and the subjective effects as well as the external effects explained and addressed by science.