I think every cell (and every bacteria) has this capacity, but higher intelligence can be disabled by some molecular switch (other senses cannot be disabled, they are the property of life) . The one that carries the illusion of human "I" is not particularly "advanced", but again, it's just a matter of some extra axon or something :). I'm pretty sure humans were designed by bacteria (or their descendants), but our species plays very modest role in the overall scheme of things. We are certainly not the ones calling the shots :)
You can start here: https://www.youtube.com/watch?v=gBGt5OeAQFk