I've been struggling with this question for some time now. A member of my family and I recently got into a debate about what is natural and what is unnatural. They are Christian so their opinion was "naturally" a warped one, but it got me thinking nonetheless.
I think that what separates us from other animals is fairly straightforward from a cognitive and technological perspective, but no one, not even the omniscient Google, has been able to give me an answer as to WHY this is the case.
Why are humans more technologically and cognitively advanced than other animals? Why are we the dominant species on this planet? Are we more evolved than other animals? If so, why have we seemed to evolve further (and faster?) than others?
On a less scientific note, do you envision a world where humans de-evolve or stagnate in their evolution allowing a new dominant species to take over?