It doesn't. Humans aren't conscious. Nor are any other organisms. They don't have souls either, but that goes without saying since it's just an archaic synonym. Mostly this occurs because humans have painted themselves into corners morally-speaking, and they need justification to eat bacon or grow their population. And apparently "because we can and we want to" isn't the correct solution.
We'll never be able to "answer the question" because it is an absurd question on its face. "Where do we find the magical brain ghosts making us special" presupposes there is something to be found, and a negative answer proves only that we haven't looked hard enough.
>after all plants exhibit communication and response mechanisms that are similar to those in animals - without brain.
Were that line of inquiry followed to its inevitable conclusion, there would be a mass vegan suicide to look forward to.
