Brains.

We are our brains. Still, ''the brain is a riddle, wrapped in a mystery, inside an enigma''.
Jump to Mind (or similar) for more, or start with the riddle below (November 2012, NewScientist).

Self-Awareness with a Simple Brain.

According to an interesting article in the November 2012 issue of Scientific American Mind, numerous studies have shown that human self-awareness involves the cerebral cortex.

- but new evidence seems to suggest it might not be the complete story...

Patient R.

The new evidence comes from ''Patient R'' - After a severe bout of herpes simplex encephalitis, an inflammation of the brain caused by the herpes visus, patient ''R'', also known as Roger, suffered severe extensive brain damage.

The disease destroyed most of Roger's insular cortex, anterior singular cingulate cortex and medial prefrontal cortex, regions near or at the front surface of the brain that are thought to be essential for self-awareness.

So, only about 10 percent of his insula remains and only 1 percent of his anterior cingulate cortex remains.
He cannot remember much from 1970 - 1980 (he was born in 1955) and he has great difficulty forming new memories. But he still knows who he is. He can recognize himself in a mirror, and behaves relatively normal.

Even though his brain is simpler than most other peoples brains (!?) The article goes on to conclude, that:

Given the evidence of Roger's largely intact self-awareness scientists Philippi and Rudrauf have suggested that the insular cortex, anterior cingulate cortex and medial prefrontal cortex cannot by themselves account for conscious recognition of oneself as a thinking being. Instead Philippi and Rudrauf propose that self-awareness is a far more diffuse cognitive process, relying on many parts of the brain, including regions not located in the cerebral cortex.

So, self-awareness - this unique cognitive process layered on consciousness - might be a more universal mechanism than what was once thought. Not just a cerebral cortex mechanism.
Indeed, the fact that we humans have a large cerebral cortex might not be the only answer to why we seem more self-aware than other animals.

Surely, as Churchill might have said, how it all works is still a riddle wrapped up in an enigma.

I cannot forecast to you the action of Russia. It is a riddle, wrapped in a mystery, inside an enigma but perhaps there is a key. That key is Russian national interest...

Winston Churchill, radio broadcast in October 1939.