I know, it's awfully handwavy, but it's at least one possibility that would 'make sense', and I haven't really found any others, though I've thought about it quite a bit.

Interesting side note though: If you accept the possibility of the simulation hypothesis, this 'maybe' almost seems like an inevitability, since us being possibly just computer simulations would imply that simple information processing indeed turns into consciousness just by virtue of it 'being self conscious'.